1h-pyridazino[4,3-e][1,3,4]thiadiazine and spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine] derivatives as GPR65 agonists for the treatment of inflammatory diseases

Abstract

The disclosures herein relate to novel compounds of the formula (1) such as e.g. 1H-pyridazino[4,3-e][1,3,4]thiadiazine and spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine] derivatives, as GPR65 agonists for the treatment of inflammatory diseases including inflammatory bowel disease (IBD), atopic dermatitis (AD) and asthma; treatment of bone resorption diseases, including osteoporosis; neuroinflammatory disorders, including multiple sclerosis (MS).

Description

[0001] 1 GPR65 AGONISTS The present invention relates to novel compounds and their use as GPR65 agonists. Compounds described herein may be useful in the treatment, amelioration or prevention of 5 diseases in which GPR65 is involved. The present invention also relates to pharmaceutical compositions comprising these compounds and to the manufacture and use of these compounds and compositions in the treatment, amelioration or prevention of diseases in which GPR65 is involved. 10 BACKGROUND OF THE INVENTION G protein-coupled receptor 65 (GPR65, aka TDAG8) is a proton-sensing G protein-coupled receptor predominantly expressed in immune cells (Biochim. Biophys. Acta. Mol. Basis Dis. 2022, 1868 (1), 166288). GPR65 signals through Gαs- and Gα12 / 13-mediated pathways and its downstream effects have been associated with a wide range of chronic inflammatory 15 diseases including inflammatory bowel disease (IBD), atopic dermatitis (AD) and asthma (Allergy 2023, 00, 1-3). However, the contribution of each of the aforementioned pathways to the disease phenotype has not been elucidated. Inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis, is a 20 complex disease involving chronic inflammation of the gastrointestinal tract, often resulting in diarrhea, rectal bleeding, abdominal pain and weight loss. Although the causal genetic factors for the disease have not been fully elucidated, accumulating evidence delineates GPR65 and more specifically the loss-of-function variant GPR65*Ile231Leu (I231L) as a prevalent risk factor for IBD development (Immunity 2016, 441392-13405). These studies associate 25 decreased GPR65 activity with increased susceptibility to colitis, due to compromised lysosomal function, bacterial phagocytosis and increased inflammatory signalling (Cell. Signal. 2022, 93, 110294). In mice, GPR65 has been shown to protect from intestinal inflammation in colitis models of dextran sulfate sodium (DSS). Disease severity parameters such as fecal score, colon shortening, histopathology, and mesenteric lymph node enlargement were 30 aggravated in GPR65 KO mice compared to WT mice treated with DSS. Elevated leukocyte infiltration and fibrosis were observed in the inflamed colon of GPR65 KO mice when compared to WT mice. (Biochim. Biophys. Acta. Mol. Basis Dis.2022, 1868 (1), 166288). Introduction of the GPR65*Ile231Leu allele into mice has shown how this less active protein 35 might be linked to inflammation. GPR65*Ile231Leu knock-in mice were shown to be highly susceptible to both bacterial infection-induced and T cell-driven colitis. Mechanistically, GPR65 231Leu elicits a cytokine imbalance through impaired helper type 17 T cell (Th17 cell) 2 and Th22 cell differentiation and interleukin (IL)-22 production in association with altered cellular metabolism controlled through the cAMP–CREB–DGAT1 axis. In dendritic cells, GPR65*231Leu elevates IL-12 and IL-23 release at acidic pH and alters endo-lysosomal fusion and degradation capacity, resulting in enhanced antigen presentation (Nat. 5 Immunol.2022, 23(7), 1063-1075). GPR65 has been shown to maintain mucosal homeostasis via regulating antimicrobial defence and restraining gut inflammation. Forced AMP induction assays conducted in vivo or in ex vivo colonoids revealed that intestinal epithelial cell (IEC)-intrinsic GPR65 signalling 10 drove antimicrobial defence. Mechanistically, GPR65 signalling promoted STAT3 phosphorylation, thereby optimising mucosal defence responses. Epithelial cell line and colonoid assays further confirmed that epithelial GPR65 sensing pH synergised with IL-22 to facilitate antimicrobial responses. Moreover, the expression of GPR65 is markedly decreased in the inflamed epithelia of IBD patients and DSS colitis mice. Taken together, these data 15 suggest that potentiation of GPR65 with an agonist may constitute a valuable therapeutic approach towards the treatment of IBD (Biochim. Biophys. Acta. Mol. Basis Dis.2022, 1868 (1), 166288; Gut Microbes 2023, 15 (2), 2257269). THE INVENTION 20 The present invention provides compounds having activity as GPR65 agonists. Provided is a compound of Formula (1): or a salt thereof, wherein: X is NR3or CR3R3a; 25 Y is S or O; Z is S, CHR6or O; R1is a group -(CR1aR1b)mQ, -O(CR1aR1b)mQ or -NR1a(CR1aR1b)mQ where m is 0-3 and Q is H, halo, CN, NR1aR1b, OR1a, SR1a, C≡CR1a, CO2R1a, CONR1aR1b, a C1-6alkyl group which is optionally substituted with 1 to 3 fluorine atoms, or a 3 to 10-membered carbocyclic or 30 heterocyclic ring system which is optionally substituted with 1 to 3 R4groups; R2is a 4 to 6-membered carbocyclic or heterocyclic ring which is optionally substituted with 1 to 3 R5groups; R3and R3aare independently H, a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms or a 3 to 5-membered carbocyclic ring which is optionally substituted with 1 to 3 3 fluorine atoms; or R3and R3amay be joined to form a 3 to 6-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms; each R4is independently H, halo, CN, OR4a, NHR4a, CH2OR4a, a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms, or a 3 to 6-membered carbocyclic or 5 heterocyclic ring which is optionally substituted with 1 to 3 fluorine atoms; each R5is independently H, halo, CN, NO2, OR5a, a 3 to 6-membered carbocyclic or heterocyclic ring system or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms; each R1a, R1b, R4aand R5ais independently H or a C1-3alkyl group which is optionally 10 substituted with 1 to 3 fluorine atoms; R6is H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms; and R10is H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms. Compounds of the present invention may be used as GPR65 modulators. Compounds of the 15 present invention may be used as GPR65 agonists. Compounds of the present invention may be used in the treatment of a disease or disorder associated with GPR65. Compounds of the present invention may be used in the treatment of a disease or disorder that would benefit from the modulation of GPR65 activity. Compounds of the present invention may be used in the manufacture of medicaments. The compounds or medicaments may be for use in treating, 20 preventing, ameliorating, controlling or reducing the risk of diseases or disorders in which GPR65 is involved. Compounds of the present invention may be for use as a single agent or in combination with one or more additional pharmaceutical agents. Compounds of the present invention may be useful in the treatment of inflammatory bowel 25 disease (IBD), including Crohn’s disease and ulcerative colitis, atopic dermatitis (AD), asthma, bone resorption diseases, including osteoporosis, neuroinflammatory disorders, including multiple sclerosis (MS) or disorders or symptoms related thereto. DETAILED DESCRIPTION OF THE INVENTION 30 The invention relates to novel compounds. The invention also relates to the use of novel compounds as modulators of GPR65, in particular as GPR65 agonists. The invention further relates to the use of novel compounds in the manufacture of medicaments for use as GPR65 agonists. The invention further relates to compounds, compositions and medicaments that may be useful in the treatment of a disease or disorder involving GPR65. 35 Provided is a compound of Formula (1): 4 or a salt thereof, wherein: X is NR3or CR3R3a; Y is S or O; 5 Z is S, CHR6or O; R1is a group -(CR1aR1b)mQ, -O(CR1aR1b)mQ or -NR1a(CR1aR1b)mQ where m is 0-3 and Q is H, halo, CN, NR1aR1b, OR1a, SR1a, C≡CR1a, CO2R1a, CONR1aR1b, a C1-6alkyl group which is optionally substituted with 1 to 3 fluorine atoms, or a 3 to 10-membered carbocyclic or heterocyclic ring system which is optionally substituted with 1 to 3 R4groups; 10 R2is a 4 to 6-membered carbocyclic or heterocyclic ring which is optionally substituted with 1 to 3 R5groups; R3and R3aare independently H, a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms or a 3 to 5-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms; or R3and R3amay be joined to form a 3 to 6-membered carbocyclic ring 15 which is optionally substituted with 1 to 3 fluorine atoms; each R4is independently H, halo, CN, OR4a, NHR4a, CH2OR4a, a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms, or a 3 to 6-membered carbocyclic or heterocyclic ring which is optionally substituted with 1 to 3 fluorine atoms; each R5is independently H, halo, CN, NO2, OR5a, a 3 to 6-membered carbocyclic or 20 heterocyclic ring system or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms; each R1a, R1b, R4aand R5ais independently H or a C1-3 alkyl group which is optionally substituted with 1 to 3 fluorine atoms; R6is H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms; and 25 R10is H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms. Also provided is a compound of Formula (1): or a salt thereof, wherein: 30 X is NR3or CR3R3a; 5 Y is S or O; Z is S, CHR6or O; R1is a group -(CR1aR1b)mQ, -O(CR1aR1b)mQ or -NR1a(CR1aR1b)mQ where m is 0-3 and Q is H, halo, CN, NR1aR1b, OR1a, SR1a, C≡CR1a, CO2R1a, CONR1aR1b, a C1-6alkyl group which is 5 optionally substituted with 1 to 3 fluorine atoms, or a 3 to 10-membered carbocyclic or heterocyclic ring system which is optionally substituted with 1 to 3 R4groups; R2is a 4 to 6-membered carbocyclic or heterocyclic ring which is optionally substituted with 1 to 3 R5groups; R3and R3aare independently H, a C1-3alkyl group which is optionally substituted with 1 to 3 10 fluorine atoms or a 3 to 5-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms; or R3and R3amay be joined to form a 3 to 6-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms; each R4is independently H, halo, CN, OR4a, CH2OR4a, a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms, or a 3 to 6-membered carbocyclic or heterocyclic ring 15 which is optionally substituted with 1 to 3 fluorine atoms; each R5is independently H, halo, CN, NO2, OR5aor a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms; each R1a, R1b, R4aand R5ais independently H or a C1-3 alkyl group which is optionally substituted with 1 to 3 fluorine atoms; 20 R6is H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms; and R10is H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms. Also provided is a compound of Formula (1): 25 or a salt thereof, wherein: X is NR3or CR3R3a; Y is S or O; Z is S, CHR6or O; R1is a group -(CR1aR1b)mQ, -O(CR1aR1b)mQ or -NR1a(CR1aR1b)mQ where m is 0-3 and Q is H, 30 halo, CN, NR1aR1b, OR1a, SR1a, C≡CR1a, CO2R1a, CONR1aR1b, a C1-6alkyl group which is optionally substituted with 1 to 3 fluorine atoms, or a 3 to 10-membered carbocyclic or heterocyclic ring system which is optionally substituted with one or more R4groups; R2is a 4 to 6-membered carbocyclic or heterocyclic ring which is optionally substituted with one or more R5groups; 6 R3and R3aare independently H, a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms or a 3 to 5-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms; or R3and R3amay be joined to form a 3 to 6-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms; 5 each R4is independently H, halo, CN, OR4a, a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms, or a 3 to 6-membered carbocyclic or heterocyclic ring which is optionally substituted with 1 to 3 fluorine atoms; each R5is independently H, halo, CN, NO2, OR5aor a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms; 10 each R1a, R1b, R4aand R5ais independently H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms; R6is H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms; and R10is H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms. 15 Also provided is a compound of Formula (1): or a salt thereof, wherein: X is NR3or CR3R3a; Y is S or O; 20 Z is S, CHR6or O; R1is a group -(CR1aR1b)mQ, -O(CR1aR1b)mQ or -NR1a(CR1aR1b)mQ where m is 0-3 and Q is H, halo, CN, NR1aR1b, OR1a, SR1a, C≡CR1a, CO2R1a, CONR1aR1b, a C1-6 alkyl group which is optionally substituted with 1 to 3 fluorine atoms, or a 3 to 10-membered carbocyclic or heterocyclic ring system which is optionally substituted with one or more R4groups; 25 R2is a 4 to 6-membered carbocyclic or heterocyclic ring which is optionally substituted with one or more R5groups; R3and R3aare independently H, a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms or a 3 to 6-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms; or R3and R3amay be joined to form a 3 to 6-membered carbocyclic ring 30 which is optionally substituted with 1 to 3 fluorine atoms; each R4is independently H, halo, CN, OR4a, a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms, or a 3 to 6-membered carbocyclic or heterocyclic ring which is optionally substituted with 1 to 3 fluorine atoms; 7 each R5is independently H, halo, CN, NO2, OR5aor a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms; each R1a, R1b, R4aand R5ais independently H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms; 5 R6is H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms; and R10is H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms. In the compounds herein, X is NR3or CR3R3a. X can be NR3. X can be CR3R3a. X can be NCH3, NCH2CH3, NCD3, N-cyclopropyl, can be NCH3, N-10 cyclopropyl . X can be NCH3. X can be N-cyclopropyl. X can be .In the compounds herein, Y is S or O. Y can be S. Y can be O. In the compounds herein, Z is S, CHR6or O. Z can be S or O. Z can be S. Z can be O. Z can 15 be CHR6. Z can be CH2. In the compounds herein, Y and Z can both be S. In the compounds herein, R6is H or a C1-3alkyl group which is optionally substituted with 1 to 20 3 fluorine atoms. R6can be H. R6can be a C1-3 alkyl group which is optionally substituted with 1 to 3 fluorine atoms. R6can be CH3. In the compounds herein, R3and R3aare independently H, a C1-3 alkyl group which is optionally substituted with 1 to 3 fluorine atoms or a 3 to 5-membered carbocyclic ring which is optionally 25 substituted with 1 to 3 fluorine atoms; or R3and R3amay be joined to form a 3 to 6-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms. R3can be H, a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms or a 3 to 6-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms; or 30 R3may be joined with R3ato form a 3 to 5-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms. R3can be H, a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms or a 3 to 6-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms; or R3may be joined with R3ato form a 3 to 6-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms. R3can be H, a C1-3 8 alkyl group which is optionally substituted with 1 to 3 fluorine atoms or a 3 to 6-membered non-aromatic carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms. R3may be joined with R3ato form a 3 to 6-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms. R3can be H, CH3, CH2CH3, CD3, cyclopropyl or CH2CFH2. R3can 5 be CH3, CH2CH3, CD3, cyclopropyl or CH2CFH2. R3can be H, CH3, CH2CH3, cyclopropyl or CH2CFH2. R3can be CH3, CH2CH3, cyclopropyl or CH2CFH2. R3can be CH3or cyclopropyl. R3can be CH3. R3can be joined to R3ato form a cyclopropyl ring. R3acan be H, a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms or a 10 3 to 6-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms; or R3amay be joined with R3to form a 3 to 5-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms. R3acan be H, a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms or a 3 to 6-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms; or R3amay be joined with R3to form a 3 to 6-membered 15 carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms. R3acan be H, a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms or a 3 to 6-membered non-aromatic carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms. R3amay be joined with R3to form a 3 to 6-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms. R3acan be H, CH3, CH2CH3, CD3, cyclopropyl or CH2- 20 CFH2. R3acan be H. R3acan be joined to R3to form a cyclopropyl ring. R3can be selected from: CH3, CH2CH3, CD3, cyclopropyl and CH2CFH2. R3can be joined with R3ato form a cyclopropyl ring. 25 In the compounds herein, R1is a group -(CR1aR1b)mQ, -O(CR1aR1b)mQ or -NR1a(CR1aR1b)mQ where m is 0-3 and Q is H, halo, CN, NR1aR1b, OR1a, SR1a, C≡CR1a, CO2R1a, CONR1aR1b, a C1-6alkyl group which is optionally substituted with 1 to 3 fluorine atoms, or a 3 to 10- membered carbocyclic or heterocyclic ring system which is optionally substituted with 1 to 3 R4groups. R1can be a group -(CR1aR1b)mQ, -O(CR1aR1b)mQ or -NR1a(CR1aR1b)mQ where m is 30 0-3 and Q is H, halo, CN, NR1aR1b, OR1a, SR1a, C≡CR1a, CO2R1a, CONR1aR1b, a C1-6alkyl group which is optionally substituted with 1 to 3 fluorine atoms, or a 3 to 10-membered monocyclic or bicyclic ring system which is optionally substituted with 1 to 3 R4groups, wherein the ring system optionally comprises 1 to 5 N, O or S heteroatoms. R1can be a group - (CR1aR1b)mQ, -O(CR1aR1b)mQ or -NR1a(CR1aR1b)mQ where m is 0-3 and Q is a 3 to 10- 35 membered monocyclic or bicyclic ring system which is optionally substituted with 1 to 3 R4groups, wherein the ring system optionally comprises 1 to 5 N, O or S heteroatoms. 9 R1can be a group -(CR1aR1b)mQ, -O(CR1aR1b)mQ or -NR1a(CR1aR1b)mQ where m is 0-3 and Q is H, halo, CN, NR1aR1b, OR1a, SR1a, C≡CR1a, CO2R1a, CONR1aR1b, a C1-6alkyl group which is optionally substituted with 1 to 3 fluorine atoms, or a 3 to 10-membered carbocyclic or heterocyclic ring system which is optionally substituted with one or more R4groups. R1can be 5 a group -(CR1aR1b)mQ, -O(CR1aR1b)mQ or -NR1a(CR1aR1b)mQ where m is 0-3 and Q is H, halo, CN, NR1aR1b, OR1a, SR1a, C≡CR1a, CO2R1a, CONR1aR1b, a C1-6alkyl group which is optionally substituted with 1 to 3 fluorine atoms, or a 3 to 10-membered monocyclic or bicyclic ring system which is optionally substituted with one or more R4groups, wherein the ring system optionally comprises one or more N, O or S heteroatoms. R1can be a group -(CR1aR1b)mQ, - 10 O(CR1aR1b)mQ or -NR1a(CR1aR1b)mQ where m is 0-3 and Q is a 3 to 10-membered monocyclic or bicyclic ring system which is optionally substituted with one or more R4groups, wherein the ring system optionally comprises one or more N, O or S heteroatoms. R1can be selected from the group consisting of: 10 In the compounds herein, each R4is independently H, halo, CN, OR4a, NHR4a, CH2OR4a, a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms, or a 3 to 6-membered carbocyclic or heterocyclic ring which is optionally substituted with 1 to 3 fluorine atoms. Each 5 R4can be independently H, halo, CN, OR4a, CH2OR4a, a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms, or a 3 to 6-membered carbocyclic or heterocyclic ring which is optionally substituted with 1 to 3 fluorine atoms. Each R4can be independently selected from H, Cl, F, CH3, OCH3, CN, OCH2CH2NH2and morpholinyl. Each R4can be independently selected from H, Cl, F, CH3, OCH3, CN, OH, NH2, OCH2CH2NH2and 10 morpholinyl. In the compounds herein, R2is a 4 to 6-membered carbocyclic or heterocyclic ring which is optionally substituted with 1 to 3 R5groups. R2can be a 6-membered carbocyclic or heterocyclic ring which is optionally substituted with 1 to 3 R5groups. R2can be a phenyl, 11 pyridyl or pyrimidinyl ring which is optionally substituted with 1 to 3 R5groups. R2can be a phenyl or pyridyl ring which is optionally substituted with 1 to 3 R5groups. R2can be a phenyl ring which is optionally substituted with 1 to 3 R5groups. R2can be a pyridyl ring which is optionally substituted with 1 to 3 R5groups. R2can be a pyrimidinyl ring which is optionally 5 substituted with 1 to 3 R5groups. R2can be a 4 to 6-membered carbocyclic or heterocyclic ring which is optionally substituted with one or more R5groups. R2can be a 6-membered carbocyclic or heterocyclic ring which is optionally substituted with one or more R5groups. R2can be a phenyl, pyridyl or pyrimidinyl 10 ring which is optionally substituted with one or more R5groups. R2can be a phenyl or pyridyl ring which is optionally substituted with one or more R5groups. R2can be a phenyl ring which is optionally substituted with one or more R5groups. R2can be a pyridyl ring which is optionally substituted with one or more R5groups. R2can be a pyrimidinyl ring which is optionally substituted with one or more R5groups. 15 R2can be selected from: . R2can be selected from: 20 . R2can be: . 25 R2can be: . R2can be selected from the group consisting of: 12 5 . In the compounds herein, each R5is independently H, halo, CN, NO2, OR5a, a 3 to 6- membered carbocyclic or heterocyclic ring system or a C1-3alkyl group which is optionally 10 substituted with 1 to 3 fluorine atoms. Each R5can be independently H, halo, CN, NO2, OR5aor a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms. Each R5can be independently selected from: H, Cl, Br, F, I, CN, NO2, CH3, CF3, OCF3, CF2H, CFH2and . Each R5can be independently selected from: H, Cl, Br, F, I, CN, NO2, CH3, CF3, OCF3, CF2H and CFH2. Each R5can be independently selected from: H, Cl, Br, F, I, CN, CH3, 15 CF3, CH2F and CFH2. In the compounds herein, R1a, R1b, R4aand R5aare independently H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms. 13 R1acan be H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms. R1acan be H. R1acan be a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms. R1acan be CH3. 5 R1bcan be H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms. R1bcan be H. R1bcan be a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms. R1bcan be CH3. R4acan be H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms. R4a10 can be H. R4acan be a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms. R4acan be CH3. R5acan be H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms. R5acan be H. R5acan be a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine 15 atoms. R5acan be CH3. In the compounds herein, R10is H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms. R10can be H. R10can be a C1-3 alkyl group which is optionally substituted with 1 to 3 fluorine atoms. R10can be CH3. 20 The compound can be a compound of Formula (2): or a salt thereof. 25 The compound can be a compound of Formula (2a) or (2b): or a salt thereof. The compound can be a compound of Formula (3a) or (3b): 30 or a salt thereof. 14 The compound can be a compound of Formula (4a) or (4b): or a salt thereof. 5 The compound can be a compound of formula (5a), (5b), (5c), (5d): or a salt thereof. 10 The compound can be a compound of Formula (6a), (6b), (6c) or (6d): or a salt thereof. 15 The compound can be a compound of Formula (7): 15 or a salt thereof. The compound can be a compound of Formula (8a) or (8b): 5 or a salt thereof. The compound can be a compound of Formula (9): 10 or a salt thereof. The compound can be a compound of Formula (10): or a salt thereof. 15 The compound can be a compound of Formula (11a), (11b), (11c), (11d) or (11e): 16 or a salt thereof. 5 The compound can be a compound of Formula (12): or a salt thereof. The compound can be a compound of Formula (13): 10 or a salt thereof. The compound can be a compound of Formula (14): 15 or a salt thereof. The compound can be a compound of Formula (15): 17 or a salt thereof. The compound can be selected from any one of Examples 1 to 100 as shown in Table 1 or a 5 salt thereof. The compound can be selected from any one of Examples 1 to 87 as shown in Table 1 or a salt thereof. The compound can be selected from any one of Examples 1 to 40 as shown in Table 1 or a salt thereof. The compound can be selected from the group consisting of:12-[(7-chloro-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;22-[(7-chloro-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-iodobenzonitrile;32-[(1-cyclopropyl-7-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;42-[(1-methyl-7-morpholin-4-ylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;52-[[7-(dimethylamino)-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;62-[(1-methyl-7-phenylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;72-[(7-chloro-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(fluoromethyl)benzonitrile;82-[(7-fluoro-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;92-[(7-bromo-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;102-[[7-(furan-2-yl)-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;11 7-chloro-3-[(2,4-dichlorophenyl)methylsulfanyl]-1-methylpyridazino[4,3-e][1,3,4]thiadiazine;122-[(1-methyl-7-methylsulfanylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;132-[(1-methyl-7-pyridin-3-ylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;147-chloro-3-[(2-chloro-4-iodophenyl)methylsulfanyl]-1-methylpyridazino[4,3-e][1,3,4]thiadiazine;152-[(1-methyl-7-prop-1-ynylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;165-chloro-2-[(7-chloro-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]benzonitrile; 18177-chloro-1-methyl-3-[[2-methyl-4-(trifluoromethyl)phenyl]methylsulfanyl]pyridazino[4,3-e][1,3,4]thiadiazine;182-[(7-ethynyl-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;192-[(1-methyl-7-pyrrolidin-1-ylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;20 2-[(1,7-dimethylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-iodobenzonitrile;212-[(1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;222-[[1-methyl-7-(8-oxa-3-azabicyclo[3.2.1]octan-3-yl)pyridazino[4,3-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;232-[(1-methyl-7-pyrazol-1-ylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;242-[(3'-chlorospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;252-[(7-ethyl-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;262-[(7-cyclopropyl-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;272-[(1-methyl-7-pyridin-2-ylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;282-[[7-(difluoromethoxy)-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;293-[(4-bromo-2-chlorophenyl)methylsulfanyl]-1,7-dimethylpyridazino[4,3-e][1,3,4]thiadiazine;302-[[1-methyl-7-(1H-pyrazol-5-yl)pyridazino[4,3-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;312-[[7-(1-bicyclo[1.1.1]pentanylamino)-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;322-[[1-methyl-7-(2,2,2-trifluoroethoxy)pyridazino[4,3-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;332-[[1-methyl-7-(trifluoromethyl)pyridazino[4,3-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;343-[[3-[[2-cyano-4-(trifluoromethyl)phenyl]methylsulfanyl]-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-7-yl]-methylamino]propanoic acid;353-[[2-cyano-4-(trifluoromethyl)phenyl]methylsulfanyl]-1-methylpyridazino[4,3-e][1,3,4]thiadiazine-7-carbonitrile;362-[[1-methyl-7-(3-oxa-8-azabicyclo[3.2.1]octan-8-yl)pyridazino[4,3-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;372-[[1-methyl-7-(oxetan-3-yloxy)pyridazino[4,3-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;382-[[3'-(dimethylamino)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;393-[[2-cyano-4-(trifluoromethyl)phenyl]methylsulfanyl]-N,1-dimethylpyridazino[4,3-e][1,3,4]thiadiazine-7-carboxamide;403-[[2-cyano-4-(trifluoromethyl)phenyl]methylsulfanyl]-1-methylpyridazino[4,3-e][1,3,4]thiadiazine-7-carboxamide; 19417'-[[2-cyano-4-(trifluoromethyl)phenyl]methylsulfanyl]spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-3'-carbonitrile;422-[[1-methyl-7-(1,3,4-oxadiazol-2-yl)pyridazino[4,3-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;432-[[3'-(3-oxa-8-azabicyclo[3.2.1]octan-8-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;442-[[3'-(oxetan-3-ylmethoxy)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;453-[[7'-[[2-cyano-4-(trifluoromethyl)phenyl]methylsulfanyl]spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-3'-yl]-methylamino]propanoic acid;462-[[3'-(3-hydroxypropoxy)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;472-[[3'-(2-hydroxyethoxy)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;482-[[3'-[2-hydroxyethyl(methyl)amino]spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;492-[[3'-(1H-triazol-4-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;502-[[3'-(1,3,4-oxadiazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;512-[[3'-(1H-pyrazol-4-yloxy)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;522-[[3'-(1,3-oxazol-4-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;532-[(3'-ethoxyspiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;542-[[3'-(1,3,4-thiadiazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;552-[[3'-(1,2,4-oxadiazol-5-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;562-[[3'-(1,2,4-oxadiazol-3-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;572-[[3'-(oxolan-3-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;582-[[3'-(4H-1,2,4-triazol-3-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;592-[[3'-[methyl(2H-tetrazol-5-ylmethyl)amino]spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;602-[[3'-(1,3-oxazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;612-[[3'-(1,3-thiazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;622-[(3'-pyridin-2-ylspiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;632-[[3'-(1,3-benzoxazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;642-[[3'-(triazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile; 20652-[[3'-(triazol-1-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;662-[(3'-pyrimidin-2-ylspiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;672-[[3'-(2,2-difluoroethoxy)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;682-[[3'-(5-methyl-1,3,4-thiadiazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;695-[[3'-(triazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-2-(trifluoromethyl)pyridine-4-carbonitrile;702-[[3'-(4-methyltriazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;712-[[3'-(4-methyltriazol-1-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;722-[[3'-(1,3,5-triazin-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;732-[[3'-(triazolo[4,5-c]pyridin-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;745-(difluoromethyl)-2-[[3'-(triazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]benzonitrile;752-[[3'-(tetrazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;762-[[3'-(tetrazol-1-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;772-[[3'-[4-(methoxymethyl)triazol-2-yl]spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;782-[[3'-(triazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)pyridine-3-carbonitrile;792-[[3'-(1,3-oxazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)pyridine-3-carbonitrile;805-[[3'-(1,3-oxazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-2-(trifluoromethyl)pyridine-4-carbonitrile;815-(fluoromethyl)-2-[[3'-(triazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]benzonitrile;822-[[3'-(4-methoxy-1,3-oxazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;832-[[3'-(1,2,4-triazol-1-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;843-[[3'-(triazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-6-(trifluoromethyl)pyridine-2-carbonitrile;853-[[3'-(1,3-oxazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-6-(trifluoromethyl)pyridine-2-carbonitrile;865-[[3'-(4H-1,2,4-triazol-3-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-2-(trifluoromethyl)pyridine-4-carbonitrile;872-[[3'-[2-(trideuteriomethoxy)ethoxy]spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;885-[(3'-pyrimidin-2-ylspiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl)sulfanylmethyl]-2-(trifluoromethyl)pyridine-4-carbonitrile; 2189 2-[[3'-[(3-hydroxy-1,2-oxazol-5-yl)methyl-methylamino]spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;902-[[3'-(4-aminotriazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;912-[[3'-(2,2-difluoroethoxy)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)pyridine-3-carbonitrile;925-[[3'-(triazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-2-(trifluoromethyl)pyrimidine-4-carbonitrile;932-[[3'-(3-oxo-1H-pyrazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;942-[[3'-(1,2,4-triazol-1-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)pyridine-3-carbonitrile;955-chloro-2-[[3'-(triazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]benzonitrile;965-chloro-2-[[3'-(1,3-oxazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]benzonitrile;975-chloro-2-[[3'-(triazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]pyridine-3-carbonitrile;985-chloro-2-[[3'-(1,3-oxazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]pyridine-3-carbonitrile;995-(1,3,4-oxadiazol-2-yl)-2-[[3'-(triazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]benzonitrile;1005-[[3'-(2,2-difluoroethoxy)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-2-(trifluoromethyl)pyridine-4-carbonitrile;or a salt thereof. Further embodiments of the invention include the use of a compound of Formula (1) or a salt thereof or a pharmaceutical composition comprising a compound of Formula (1) in medicine. Also included is the use of a compound of Formula (1) or a pharmaceutically acceptable salt 5 thereof or a pharmaceutical composition comprising a compound of Formula (1) or a pharmaceutically acceptable salt thereof as a GPR65 modulator. Compounds of the present invention may be used as GPR65 modulators. Compounds of the present invention may be used as GPR65 agonists. Compounds of the present invention may be used in the treatment of a disease or disorder associated with GPR65 or in the treatment of a disease or disorder 10 that would benefit from the modulation of GPR65. Compounds of the present invention may be used in the treatment of inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis, atopic dermatitis (AD), asthma, bone resorption diseases, including osteoporosis, neuroinflammatory disorders, including 15 multiple sclerosis (MS) and disorders or symptoms related thereto. 22 In some embodiments, compounds and compositions detailed herein are used as GPR65 agonists. Provided herein is a method of treating a disease in an individual comprising administering an effective amount of a compound of Formula (1) or any embodiment, variation or aspect thereof. 5 Also provided is a method of treating a disorder associated with GPR65 or that would benefit from the modulation of GPR65 activity in a patient, comprising administering a compound of Formula (1) or any embodiment, variation or aspect thereof. 10 Also provided is a method of treating inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis, atopic dermatitis (AD), asthma, bone resorption diseases, including osteoporosis, neuroinflammatory disorders, including multiple sclerosis (MS) or disorders or symptoms related thereto in a patient, comprising administering a compound of Formula (1) or any embodiment, variation or aspect thereof. 15 Compounds as GPR65 agonists as disclosed herein can be useful as a prophylactic or therapeutic agent for GPR65 associated diseases. In some embodiments, a compound or salt thereof described herein or a composition described herein may be used in a method of treating inflammatory bowel disease (IBD) disease in an individual. 20 Also provided herein are uses of a compound described herein or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition described herein, in the manufacture of a medicament. In some embodiments, the manufacture of a medicament is for the treatment of a disorder or disease described herein. In some embodiments, the manufacture of a 25 medicament is for the prevention and / or treatment of a disorder or disease mediated by GPR65. In some embodiments, a compound or salt thereof described herein, or a composition described herein may be used in a method as either a stand-alone therapy, or as a conjunctive 30 therapy with other agents that are either palliative (e.g., agents that relieve the symptoms of the disorder to be treated), and / or agents that target the aetiology of the disorder. Compounds or compositions of the present invention may be used or administered in combination with a second therapeutic agent. 35 Also provided are combinations comprising a compound of the present invention and a therapeutic agent which upregulates cyclic adenosine monophosphate (cAMP). Also provided are combinations comprising a compound of the present invention and a phosphodiesterase 23 (PDE) inhibitor. The PDE inhibitor may be a PDE1, PDE2, PDE3, PDE4, PDE7, PDE8 or PDE11 inhibitor. The PDE inhibitor may be selected from the group consisting of Rolipram, Roflumilast, Crisaborole, Apremilast and Ibudilast. 5 The combinations may be used in the treatment of inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis, atopic dermatitis (AD), asthma, bone resorption diseases, including osteoporosis, neuroinflammatory disorders, including multiple sclerosis (MS) and disorders or symptoms related thereto. 10 In some embodiments, (a) a compound described herein, or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition described herein and (b) an agent are sequentially administered, concurrently administered or simultaneously administered. In certain embodiments, (a) a compound described herein, or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition described herein and (b) an agent are administered 15 with a time separation of about 15 minutes or less, such as about any of 10, 5, or 1 minutes or less. In certain embodiments, (a) a compound described herein, or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition described herein and (b) an agent are administered with a time separation of about 15 minutes or more, such as about any of 20, 30, 40, 50, 60, or more minutes. Either (a) a compound described herein, or a 20 pharmaceutically acceptable salt thereof, or a pharmaceutical composition described herein and (b) an agent may be administered first. In certain embodiments, (a) a compound described herein, or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition described herein and (b) an agent are administered simultaneously. 25 DEFINITIONS In this application, the following definitions apply, unless indicated otherwise. The term “GPR65 modulator” as used herein refers to any compound which binds to and modulates the function of GPR65. The term “modulator” should be interpreted to include 30 modulation by modalities including, but not limited to agonists. The term “treatment”, in relation to the uses of any of the compounds described herein, including those of Formula (1), is used to describe any form of intervention where a compound is administered to a subject suffering from, or at risk of suffering from, or potentially at risk of 35 suffering from the disease or disorder in question. Thus, the term “treatment” covers both preventative (prophylactic) treatment and treatment where measurable or detectable symptoms of the disease or disorder are being displayed. 24 The term “effective therapeutic amount” (for example in relation to methods of treatment of a disease or condition) refers to an amount of the compound which is effective to produce a desired therapeutic effect. For example, if the condition is pain, then the effective therapeutic 5 amount is an amount sufficient to provide a desired level of pain relief. The desired level of pain relief may be, for example, complete removal of the pain or a reduction in the severity of the pain. Chemical terms are all used in their conventional sense (e.g. as defined in the IUPAC Gold 10 Book), unless indicated otherwise. The term "alkyl" as used herein, means straight or branched chain, saturated alkyl groups. The term “carbocyclic ring” as used herein, means a saturated or unsaturated carbocyclic 15 group containing the indicated number of carbon atoms and includes, for example, phenyl, cyclohexane, cyclopentane, cyclopropane and bicyclo[1.1.1]pentane ring systems. The term “heterocyclic ring” as used herein, refers to a saturated or unsaturated ring containing the indicated number of total ring member atoms in which one or more of the ring 20 members is a heteroatom selected from O, S and N, and oxidised forms thereof and the remaining atoms are C. The term “heterocyclic ring” as used herein, includes, for example, pyridine, morpholine, furan, pyrrolidine, 8-oxa-3-azabicyclo[3.2.1]octane, pyrazole, 3-oxa-8- azabicyclo[3.2.1]octane, oxetane, 1,3,4-oxadiazole, 1,2,3-triazole, oxazole, 1,3,4-thiadiazole, 1,2,4-oxadiazole, 1,2,4-triazole, tetrazole, thiazole, benzoxazole, pyrimidine, 1,3,5-triazine, 25 2H-[1,2,3]triazolo[4,5-c]pyridine, isoxazole and 1,2-dihydro-3H-pyrazol-3-one ring systems. The number of carbon atoms that are possible in the referenced groups herein may be indicated by subscript "Cn1-n2”. Thus, for example, the term "C1-3alkyl” represents an alkyl group having 1, 2 or 3 carbon atoms and includes methyl, ethyl, n-propyl and iso-propyl. 30 The term “optionally substituted” as applied to any group means that the said group may if desired be substituted with one or more substituents, which may be the same or different. Thus, for example, the term “optionally substituted with 1-6 fluorine atoms” as applied to a group means that the said group may if desired be substituted with 1, 2, 3, 4, 5 or 6 fluorine 35 atoms. 25 To the extent that any of the compounds described have chiral centres, the present invention extends to all optical isomers of such compounds, whether in the form of racemates or resolved enantiomers. The invention described herein relates to all crystal forms, solvates and hydrates of any of the disclosed compounds however so prepared. To the extent that any of 5 the compounds disclosed herein have acid or basic centres such as carboxylates or amino groups, then all salt forms of said compounds are included herein. In the case of pharmaceutical uses, the salt should be seen as being a pharmaceutically acceptable salt. Salts or pharmaceutically acceptable salts that may be mentioned include acid addition salts 10 and base addition salts. Such salts may be formed by conventional means, for example by reaction of a free acid or a free base form of a compound with one or more equivalents of an appropriate acid or base, optionally in a solvent, or in a medium in which the salt is insoluble, followed by removal of said solvent, or said medium, using standard techniques (e.g. in vacuo, by freeze-drying or by filtration). Salts may also be prepared by exchanging a counter-ion of a 15 compound in the form of a salt with another counter-ion, for example using a suitable ion exchange resin. Examples of pharmaceutically acceptable salts include acid addition salts derived from mineral acids and organic acids, and salts derived from metals such as sodium, magnesium, 20 potassium and calcium. Examples of acid addition salts include acid addition salts formed with acetic, 2,2- dichloroacetic, adipic, alginic, aryl sulfonic acids (e.g. benzenesulfonic, naphthalene-2- sulfonic, naphthalene-1,5-disulfonic and p-toluenesulfonic), ascorbic (e.g. L-ascorbic), L-25 aspartic, benzoic, 4-acetamidobenzoic, butanoic, (+) camphoric, camphor-sulfonic, (+)-(1S)- camphor-10-sulfonic, capric, caproic, caprylic, cinnamic, citric, cyclamic, dodecylsulfuric, ethane-1,2-disulfonic, ethanesulfonic, 2-hydroxyethanesulfonic, formic, fumaric, galactaric, gentisic, glucoheptonic, gluconic (e.g. D-gluconic), glucuronic (e.g. D-glucuronic), glutamic (e.g. L-glutamic), α-oxoglutaric, glycolic, hippuric, hydrobromic, hydrochloric, hydriodic, 30 isethionic, lactic (e.g. (+)-L-lactic and (±)-DL-lactic), lactobionic, maleic, malic (e.g. (-)-L-malic), malonic, (±)-DL-mandelic, metaphosphoric, methanesulfonic, 1-hydroxy-2-naphthoic, nicotinic, nitric, oleic, orotic, oxalic, palmitic, pamoic, phosphoric, propionic, L-pyroglutamic, salicylic, 4-amino-salicylic, sebacic, stearic, succinic, sulfuric, tannic, tartaric (e.g.(+)-L- tartaric), thiocyanic, undecylenic and valeric acids. 35 Also encompassed are any solvates of the compounds and their salts. Preferred solvates are solvates formed by the incorporation into the solid state structure (e.g. crystal structure) of the 26 compounds of the invention of molecules of a non-toxic pharmaceutically acceptable solvent (referred to below as the solvating solvent). Examples of such solvents include water, alcohols (such as ethanol, isopropanol and butanol) and DMSO. Solvates can be prepared by recrystallising the compounds of the invention with a solvent or mixture of solvents containing 5 the solvating solvent. Whether or not a solvate has been formed in any given instance can be determined by subjecting crystals of the compound to analysis using well known and standard techniques such as thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray crystallography. 10 The solvates can be stoichiometric or non-stoichiometric solvates. Particular solvates may be hydrates, and examples of hydrates include hemihydrates, monohydrates and dihydrates. For a more detailed discussion of solvates and the methods used to make and characterise them, see Bryn et al, Solid-State Chemistry of Drugs, Second Edition, published by SSCI, Inc of West Lafayette, IN, USA, 1999, ISBN 0-967-06710-3. 15 The term “pharmaceutical composition” in the context of this invention means a composition comprising an active agent and comprising additionally one or more pharmaceutically acceptable carriers. The composition may further contain ingredients selected from, for example, diluents, adjuvants, excipients, vehicles, preserving agents, fillers, disintegrating 20 agents, wetting agents, emulsifying agents, suspending agents, sweetening agents, flavouring agents, perfuming agents, antibacterial agents, antifungal agents, lubricating agents and dispersing agents, depending on the nature of the mode of administration and dosage forms. The compositions may take the form, for example, of tablets, dragees, powders, elixirs, syrups, liquid preparations including suspensions, sprays, inhalants, tablets, lozenges, emulsions, 25 solutions, cachets, granules, capsules and suppositories, as well as liquid preparations for injections, including liposome preparations. The compounds of the invention may contain one or more isotopic substitutions, and a reference to a particular element includes within its scope all isotopes of the element. For 30 example, a reference to hydrogen includes within its scope1H,2H (D), and3H (T). Similarly, references to carbon and oxygen include within their scope respectively12C,13C and14C and 16O and18O. In an analogous manner, a reference to a particular functional group also includes within its scope isotopic variations, unless the context indicates otherwise. For example, a reference to an alkyl group such as an ethyl group or an alkoxy group such as a methoxy 35 group also covers variations in which one or more of the hydrogen atoms in the group is in the form of a deuterium or tritium isotope, e.g. as in an ethyl group in which all five hydrogen atoms are in the deuterium isotopic form (a perdeuteroethyl group) or a methoxy group in which all 27 three hydrogen atoms are in the deuterium isotopic form (a trideuteromethoxy group). The isotopes may be radioactive or non-radioactive. Therapeutic dosages may be varied depending upon the requirements of the patient, the 5 severity of the condition being treated, and the compound being employed. Determination of the proper dosage for a particular situation is within the skill of the art. Generally, treatment is initiated with the smaller dosages which are less than the optimum dose of the compound. Thereafter the dosage is increased by small increments until the optimum effect under the circumstances is reached. For convenience, the total daily dosage may be divided and 10 administered in portions during the day if desired. The magnitude of an effective dose of a compound will, of course, vary with the nature of the severity of the condition to be treated and with the particular compound and its route of administration. The selection of appropriate dosages is within the ability of one of ordinary skill 15 in this art, without undue burden. In general, the daily dose range may be from about 10 μg to about 30 mg per kg body weight of a human and non-human animal, preferably from about 50 μg to about 30 mg per kg of body weight of a human and non-human animal, for example from about 50 μg to about 10 mg per kg of body weight of a human and non-human animal, for example from about 100 μg to about 30 mg per kg of body weight of a human and non-human 20 animal, for example from about 100 μg to about 10 mg per kg of body weight of a human and non-human animal and most preferably from about 100 μg to about 1 mg per kg of body weight of a human and non-human animal. PHARMACEUTICAL FORMULATIONS 25 While it is possible for the active compound to be administered alone, it is preferable to present it as a pharmaceutical composition (e.g. formulation). Accordingly, in some embodiments of the invention, there is provided a pharmaceutical composition comprising at least one compound of Formula (1) as defined above together with 30 at least one pharmaceutically acceptable excipient. The pharmaceutically acceptable excipient(s) can be selected from, for example, carriers (e.g. a solid, liquid or semi-solid carrier), adjuvants, diluents (e.g solid diluents such as fillers or bulking agents; and liquid diluents such as solvents and co-solvents), granulating agents, 35 binders, flow aids, coating agents, release-controlling agents (e.g. release retarding or delaying polymers or waxes), binding agents, disintegrants, buffering agents, lubricants, preservatives, anti-fungal and antibacterial agents, antioxidants, tonicity-adjusting agents, 28 thickening agents, flavouring agents, sweeteners, pigments, plasticizers, taste masking agents, stabilisers or any other excipients conventionally used in pharmaceutical compositions. 5 The term “pharmaceutically acceptable” as used herein means compounds, materials, compositions, and / or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of a subject (e.g. a human subject) without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit / risk ratio. Each excipient must also be “acceptable” 10 in the sense of being compatible with the other ingredients of the formulation. Pharmaceutical compositions containing compounds of the Formula (1) can be formulated in accordance with known techniques, see for example, Remington’s Pharmaceutical Sciences, Mack Publishing Company, Easton, PA, USA. The pharmaceutical compositions can be in any 15 form suitable for oral, parenteral, intravenous, intramuscular, intrathecal, subcutaneous, topical, intranasal, intrabronchial, sublingual, buccal, ophthalmic, otic, rectal, intra-vaginal, or transdermal administration. Pharmaceutical dosage forms suitable for oral administration include tablets (coated or 20 uncoated), capsules (hard or soft shell), caplets, pills, lozenges, syrups, solutions, powders, granules, elixirs and suspensions, sublingual tablets, wafers or patches such as buccal patches. The composition may be a tablet composition or a capsule composition. Tablet compositions 25 can contain a unit dosage of active compound together with an inert diluent or carrier such as a sugar or sugar alcohol, eg; lactose, sucrose, sorbitol or mannitol; and / or a non-sugar derived diluent such as sodium carbonate, calcium phosphate, calcium carbonate, or a cellulose or derivative thereof such as microcrystalline cellulose (MCC), methyl cellulose, ethyl cellulose, hydroxypropyl methyl cellulose, and starches such as corn starch. Tablets may also contain 30 such standard ingredients as binding and granulating agents such as polyvinylpyrrolidone, disintegrants (e.g. swellable crosslinked polymers such as crosslinked carboxymethylcellulose), lubricating agents (e.g. stearates), preservatives (e.g. parabens), antioxidants (e.g. BHT), buffering agents (for example phosphate or citrate buffers), and effervescent agents such as citrate / bicarbonate mixtures. Such excipients are well known and 35 do not need to be discussed in detail here. 29 Tablets may be designed to release the drug either upon contact with stomach fluids (immediate release tablets) or to release in a controlled manner (controlled release tablets) over a prolonged period of time or with a specific region of the GI tract. 5 The pharmaceutical compositions typically comprise from approximately 1% (w / w) to approximately 95%, preferably% (w / w) active ingredient and from 99% (w / w) to 5% (w / w) of a pharmaceutically acceptable excipient (for example as defined above) or combination of such excipients. Preferably, the compositions comprise from approximately 20% (w / w) to approximately 90% (w / w) active ingredient and from 80% (w / w) to 10% of a pharmaceutically 10 acceptable excipient or combination of excipients. The pharmaceutical compositions comprise from approximately 1% to approximately 95%, preferably from approximately 20% to approximately 90%, active ingredient. Pharmaceutical compositions according to the invention may be, for example, in unit dose form, such as in the form of ampoules, vials, suppositories, pre-filled syringes, dragées, powders, tablets or capsules. 15 Tablets and capsules may contain, for example, 0-20% disintegrants, 0-5% lubricants, 0-5% flow aids and / or 0-99% (w / w) fillers / or bulking agents (depending on drug dose). They may also contain 0-10% (w / w) polymer binders, 0-5% (w / w) antioxidants, 0-5% (w / w) pigments. Slow-release tablets would in addition typically contain 0-99% (w / w) release-controlling (e.g. 20 delaying) polymers (depending on dose). The film coats of the tablet or capsule typically contain 0-10% (w / w) polymers, 0-3% (w / w) pigments, and / or 0-2% (w / w) plasticizers. The composition may be a parenteral composition. Parenteral formulations typically contain 0-20% (w / w) buffers, 0-50% (w / w) cosolvents, and / or 0-99% (w / w) Water for Injection (WFI) 25 (depending on dose and if freeze dried). Formulations for intramuscular depots may also contain 0-99% (w / w) oils. The pharmaceutical formulations may be presented to a patient in “patient packs” containing an entire course of treatment in a single package, usually a blister pack. 30 The compounds of the Formula (1) will generally be presented in unit dosage form and, as such, will typically contain sufficient compound to provide a desired level of biological activity. For example, a formulation may contain from 1 nanogram to 2 grams of active ingredient, e.g. from 1 nanogram to 2 milligrams of active ingredient. Within these ranges, particular sub- 35 ranges of compound are 0.1 milligrams to 2 grams of active ingredient (more usually from 10 milligrams to 1 gram, e.g.50 milligrams to 500 milligrams), or 1 microgram to 20 milligrams 30 (for example 1 microgram to 10 milligrams, e.g. 0.1 milligrams to 2 milligrams of active ingredient). For oral compositions, a unit dosage form may contain from 1 milligram to 2 grams, more 5 typically 10 milligrams to 1 gram, for example 50 milligrams to 1 gram, e.g.100 milligrams to 1 gram, of active compound. The active compound will be administered to a patient in need thereof (for example a human or animal patient) in an amount sufficient to achieve the desired therapeutic effect (effective 10 amount). The precise amounts of compound administered may be determined by a supervising physician in accordance with standard procedures. EXAMPLES The invention will now be illustrated, but not limited, by reference to the following examples 15 shown in Table 1. Table 1 - Examples 31 32 33 34 PREPARATION OF THE COMPOUNDS OF THE INVENTION Compounds of Formula (1) and derivatives or synthetic intermediates thereof may be prepared in accordance with synthetic methods known to the skilled person. In some embodiments, a 35 process for the preparation of a compound of Formula (1) is provided. Compounds of the invention may be prepared according to the methods described below. LCMS methods 36 HPLC purification methods Abbreviations and acronyms 37 Synthesis of Intermediates Procedure for the preparation of 2-(((7-amino-1-methyl-1H-pyridazino[4,3- e][1,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (Intermediate 1) 5 To a mixture of 2-[(7-chloro-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (400 mg, 0.962 mmol, Example 1) in THF (4 mL) was added TMSN3(332.46 mg, 2.89 mmol, 379.52 μL). The mixture was heated to 60 °C and stirred for 36 h. After cooling to rt, the mixture was diluted with the water (20 mL) and was extracted with 10 EtOAc (3 x 10 mL). The combined organic layers were washed with brine (3 x 10 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-50% EtOAc in petroleum ether) to afford 2-(((7-azido-1-methyl-1H-pyridazino[4,3-e][1,3,4]thiadiazin-3-yl)thio)methyl)-5- (trifluoromethyl)benzonitrile (310 mg, 73%) as yellow solid. 38 1H NMR (400 MHz, DMSO-d6): δ 8.38 (s, 1H), 8.10 (br d, J = 8.2 Hz, 1H), 7.95 (d, J = 8.2 Hz, 1H), 7.50 (s, 1H), 4.62 (s, 2H), 3.38 (s, 3H). To a solution of 2-(((7-azido-1-methyl-1H-pyridazino[4,3-e][1,3,4]thiadiazin-3-yl)thio)methyl)- 5 5-(trifluoromethyl)benzonitrile (310 mg, 0.734 mmol) in EtOH (6 mL) was added HCl (12 M, 775.00 μL) and SnCl2.2H2O (496.80 mg, 2.20 mmol). The mixture was stirred at 80 °C for 1 h. The mixture was poured onto cold saturated Na2CO3(4 mL) to achieve ~pH 7, then sat. aq. KF (5 mL) was added. The mixture was stirred for 5 min, then the solids were removed by vacuum filtration. The filtrate was extracted with EtOAc (3 x 5 mL). The combined organic 10 layers were washed with brine (3 x 5 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by prep HPLC (Method C) to afford 2-(((7-amino-1-methyl-1H-pyridazino[4,3-e][1,3,4]thiadiazin-3-yl)thio)methyl)-5- (trifluoromethyl)benzonitrile (177.72 mg, 60%, Intermediate 1) as yellow solid. 1H NMR (400 MHz, DMSO-d6): δ 8.36 (s, 1H), 8.07 (d, J = 8.3 Hz, 1H), 7.91 (d, J = 8.3 Hz, 15 1H), 6.38 (s, 2H), 5.94 (s, 1H), 4.55 (s, 2H), 3.20 (s, 3H). LCMS: 1.82 min, 397.1 [M+H]+, Method B. Procedure for the preparation of 4-bromo-6-cyclopropylpyridazin-3(2H)-one (Intermediate 2) 20 To a solution of 6-cyclopropylpyridazin-3(2H)-one (3.6 g, 26.44 mmol) in AcOH (36 mL) was added KOAc (7.78 g, 79.32 mmol) and Br2(8.45 g, 52.88 mmol, 2.72 mL) at 10 °C. The mixture was heated to 80 °C and stirred for 2 h. The mixture was quenched by adding the sat. aq. Na2SO3with stirring until the suspension turn to off-white in colour from brown. The mixture 25 was extracted with EtOAc (3 x 50 mL). The combined organic layers were washed with brine (3 x 50 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-100% EtOAc in heptane) to afford 4-bromo-6-cyclopropylpyridazin-3(2H)-one (0.73 g, 12%, Intermediate 2) as pale yellow solid. 301H NMR (400 MHz, DMSO-d6): δ 13.07 (br s, 1H), 7.88 (s, 1H), 1.97 - 1.88 (m, 1H), 0.95 - 0.86 (m, 2H), 0.83 - 0.75 (m, 2H). 39 Procedure for the preparation of 5-bromo-6-oxo-1,6-dihydropyridazine-3-carbonitrile (Intermediate 3) 5 To a solution of methyl 6-oxo-1,6-dihydropyridazine-3-carboxylate (25 g, 162.21 mmol) in AcOH (250 mL) was added KOAc (47.76 g, 486.62 mmol) and Br2(51.84 g, 324.42 mmol, 16.71 mL) at 10 °C. The mixture was heated to 80 °C and stirred for 12 h. The mixture was quenched by addition of sat. aq. Na2SO3with stirring until the suspension turned off-white from brown. The solids were collected by vacuum filtration, washed with water and dried under 10 reduce pressure. The solid was triturated with MeOH (50 mL) at 10 °C for 0.5 h twice to afford methyl 5-bromo-6-oxo-1,6-dihydropyridazine-3-carboxylate (61 g, 81%) as a white solid. 1H NMR (400 MHz, DMSO-d6): δ = 13.93 (br s, 1H), 8.26 (s, 1H), 3.85 (s, 3H). A mixture of methyl 5-bromo-6-oxo-1,6-dihydropyridazine-3-carboxylate (5 g, 21.46 mmol) in 15 NH3•H2O (50 mL) was stirred at rt for 12 h. The reaction mixture was evaporated to dryness under reduced pressure to afford 5-bromo-6-oxo-1,6-dihydropyridazine-3-carboxamide (4.68 g, quantitative yield) as white solid. 1H NMR (400 MHz, DMSO-d6): δ 13.42 (br s, 1H), 8.23 (s, 1H), 7.86 (br s, 1H), 7.67 (br s, 1H). 20 To a solution of d 5-bromo-6-oxo-1,6-dihydropyridazine-3-carboxamide (4.68 g, 21.47 mmol) in DMF (46 mL) was added POCl3(16.46 g, 107.34 mmol, 10.00 mL) at 0 °C, then the mixture was stirred at rt for 2 h. The mixture was added slowly into ice water (100 mL), then extracted with EtOAc (3 x 30 mL). The combined organic layers were washed with brine (3 x 30 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure to afford 5- 25 bromo-6-oxo-1,6-dihydropyridazine-3-carbonitrile (2 g, 47%, Intermediate 3) as white solid. 1H NMR (400 MHz, DMSO-d6): δ 14.46 - 14.11 (m, 1H), 8.46 (s, 1H). Procedure for the preparation of 3,4-dichloro-6-(difluoromethoxy)pyridazine (Intermediate 4) 40 To a stirred solution of 5,6-dichloropyridazin-3(2H)-one (1.0 g, 5.128 mmol) in MeCN (10.0 mL) was added 2,2-difluoro-2-(fluorosulfonyl)acetic acid (1.8 g, 10.250 mmol) at rt. The reaction mixture was heated at 80 °C and stirred for 16 h. The reaction mixture was diluted 5 with water (50 mL) and extracted with EtOAc (2 x 50 mL). The combined organic layers were dried over Na2SO4, filtered, and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-30 % EtOAc in n-hexane) to afford 5,6- dichloro-2-(difluoromethyl)pyridazin-3(2H)-one (0.4 g, 1.86 mmol, 31%, Intermediate 4). ¹H NMR (400 MHz, DMSO-d6): δ 8.21 (s, 1H), 7.86 (t, J = 71.0 Hz, 1H). 10 Procedure for the preparation of 4-bromo-6-(trifluoromethyl)pyridazin-3(2H)-one (Intermediate 5) To a stirred solution of 6-(trifluoromethyl)pyridazin-3(2H)-one (1.5 g, 9.14 mmol) and LiOH.H2O 15 (0.750 g, 18.29 mmol) in MeOH (15 mL) was added Br2(0.7 mL, 13.71 mmol). The mixture was stirred at 60 °C for 16 h. The reaction mixture was diluted with water (50 mL) and extracted with EtOAc (2 x 50 mL). The combined organic layers were dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-40 % EtOAc in n-hexane) to afford 4-bromo-6-(trifluoromethyl)pyridazin- 20 3(2H)-one (0.860 g, 3.55 mmol, 39%, Intermediate 5). ¹H NMR (400 MHz, CDCl3): δ 12.18 (s, 1H), 7.95 (s, 1H). Procedure for the preparation of 3-((2-cyano-4-(trifluoromethyl)benzyl)thio)-1-methyl- 1H-pyridazino[4,3-e][1,3,4]thiadiazine-7-carboxylic acid (Intermediate 6) 41 To a solution of methyl 6-oxo-1,6-dihydropyridazine-3-carboxylate (25 g, 162.21 mmol) in AcOH (250 mL) was added KOAc (47.76 g, 486.62 mmol) and Br2(51.84 g, 324.42 mmol, 16.71 mL) at 10 °C, then the mixture was heated to 80 °C and stirred for 12 h. The reaction 5 mixture was quenched by adding the sat. aq. Na2SO3with stirring until the suspension turn off-white from brown. The mixture was filtered and the solid was collected. The solid was washed with water, dried under reduce pressure, then triturated with MeOH (50 mL) at 10 °C twice to afford methyl 5-bromo-6-oxo-1,6-dihydropyridazine-3-carboxylate (61 g, 81%) as a white solid. 101H NMR (400 MHz, DMSO-d6): δ 13.93 (br s, 1H), 8.26 (s, 1H), 3.85 (s, 3H). A solution of methyl 5-bromo-6-oxo-1,6-dihydropyridazine-3-carboxylate (10 g, 42.91 mmol) in POCl3 (31.59 g, 205.99 mmol, 19.20 mL) was stirred at 110 °C for 12 h. The mixture was concentrated under reduced pressure. The residue was poured into ice water (100 mL) and 15 extracted with EtOAc (3 x 50 mL). The combined organic layers were dried over Na2SO4, filtered and evaporated to dryness under reduced pressure to afford methyl 5,6- dichloropyridazine-3-carboxylate (6.2 g, 28.84 mmol, 67%) as an off-white solid. 1H NMR (400 MHz, CDCl3): δ 8.29 (s, 1H), 4.10 (s, 3H). 20 To the solution of methyl 5,6-dichloropyridazine-3-carboxylate (13.3 g, 64.25 mmol) in MeOH (200 mL) was added tert-butyl 2-methylhydrazine-1-carboxylate (28.18 g, 192.74 mmol). The mixture was stirred at 50 °C for 15 h. The mixture was cooled to rt and concentrated under reduced pressure. The residue was poured into water (200 mL) and extracted with EtOAc (3 x 100 mL). The combined organic layers were washed with brine (100 mL), dried over 25 anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude product was purified by prep HPLC (Method A) to afford methyl 5-(2-(tert-butoxycarbonyl)-1- methylhydrazineyl)-6-chloropyridazine-3-carboxylate (9 g, 28.41 mmol, 44%) as a white solid. 42 1H NMR (400 MHz, CDCl3): δ 7.64 (br s, 1H), 7.02 (br s, 1H), 4.06 (s, 3H), 3.36 (s, 3H), 1.45 (br s, 9H). To a solution of methyl 5-(2-(tert-butoxycarbonyl)-1-methylhydrazineyl)-6-chloropyridazine-3- 5 carboxylate (0.94 g, 2.97 mmol) in DCM (9 mL) was added 4 M HCl in dioxane (18.8 mL) and the mixture was stirred at 30 °C for 2 h. The reaction mixture was filtered and the solids collected to afford methyl 6-chloro-5-(1-methylhydrazineyl)pyridazine-3-carboxylate hydrogen chloride (0.75 g, quantitative yield) as a yellow solid. 1H NMR (400 MHz, DMSO-d6): δ 8.22 (s, 1H), 3.98 (s, 3H), 3.32 (s, 3H). 10 To a solution of methyl 6-chloro-5-(1-methylhydrazineyl)pyridazine-3-carboxylate hydrogen chloride (0.65 g, 2.57 mmol) in DMF (13 mL) was added DIPEA (1.33 g, 10.27 mmol, 1.79 mL) and CS2(2.93 g, 38.52 mmol, 2.32 mL). The mixture was stirred at 30 °C for 2 h. 2- (bromomethyl)-5-(trifluoromethyl)benzonitrile (678.14 mg, 2.57 mmol) in DMF (2 mL) was 15 added and the mixture was stirred at 30 °C for 0.5 h. The mixture was poured into water (100 mL) and extracted with DCM (4 x 20 mL). The combined organic layers were washed with brine (30 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-50% EtOAc in petroleum ether) to afford methyl 3-((2-cyano-4-(trifluoromethyl)benzyl)thio)-1-methyl-1H- 20 pyridazino[4,3-e][1,3,4]thiadiazine-7-carboxylate (1 g, 2.28 mmol, 89%) as a yellow solid. 1H NMR (400 MHz, CDCl3): δ 7.93 (s, 1H), 7.87 - 7.82 (m, 1H), 7.79 - 7.74 (m, 1H), 7.04 (s, 1H), 4.48 (s, 2H), 4.03 (s, 3H), 3.35 (s, 3H). A mixture of methyl 3-((2-cyano-4-(trifluoromethyl)benzyl)thio)-1-methyl-1H-pyridazino[4,3- 25 e][1,3,4]thiadiazine-7-carboxylate (0.94 g, 2.14 mmol) and LiOH.H2O (179.53 mg, 4.28 mmol) in THF (15 mL), water (5 mL) and MeOH (5 mL) was stirred at 30 °C for 0.5 h. The pH of the mixture was adjusted to ~4 using 1 N HCl. The mixture was extracted with EtOAc (5 x 20 mL). The combined organic layers were dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure to afford 3-((2-cyano-4-(trifluoromethyl)benzyl)thio)-1-methyl-1H- 30 pyridazino[4,3-e][1,3,4]thiadiazine-7-carboxylic acid (700 mg, 72%, Intermediate 6) a yellow solid. 1H NMR (400 MHz, CDCl3): δ 7.94 (s, 1H), 7.85 (br d, J = 8.3 Hz, 1H), 7.76 (d, J = 8.3 Hz, 1H), 7.09 (s, 1H), 4.49 (s, 2H), 3.36 (s, 3H). 43 Procedure for the preparation of 5-(1-aminocyclopropyl)-6-chloropyridazine-3- carbonitrile (Intermediate 7) A solution of 6-chloropyridazine-3-carbonitrile (6.36 g, 45.60 mmol) and 1-((tert- 5 butoxycarbonyl)amino)cyclopropane-1-carboxylic acid (15.6 g, 77.53 mmol) in water (130 mL) was degassed and purged with N23 times. AgNO3(774.69 mg, 4.56 mmol) was added at rt, then the mixture was heated to 70 °C. Ammonia;sulfooxy hydrogen sulfate (20.81 g, 91.21 mmol, 19.82 mL) in water (26 mL) was added at 70 °C and the mixture was stirred at 70 °C for 2 h under a N2atmosphere. The mixture was cooled to rt and poured onto ice. The pH was 10 adjusted to pH 9 by addition of NH3.H2O. The residue was diluted with water (200 mL) and extracted with EtOAc (3 x 100 mL). The combined organic layers were washed with brine (200 mL), dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by prep-HPLC (Method D) to afford tert-butyl (1-(3-chloro-6-cyanopyridazin-4- yl)cyclopropyl)carbamate as a white solid (1.4 g, 4.75 mmol, 10%). 151H NMR (400 MHz, DMSO-d6): δ 8.50 - 8.41 (m, 1H), 8.06 - 7.99 (m, 1H), 1.62 - 1.50 (m, 2H), 1.30 (s, 9H), 1.18 - 1.12 (m, 2H). A solution of tert-butyl (1-(3-chloro-6-cyanopyridazin-4-yl)cyclopropyl)carbamate (400 mg, 1.06 mmol) in TFA (1 mL) and DCM (3 mL) was stirred at rt for 2 h. The mixture was20 concentrated under reduced pressure to afford 5-(1-aminocyclopropyl)-6-chloropyridazine-3- carbonitrile; trifluoroacetic acid (400 mg, quantitative yield, Intermediate 7) as a yellow solid, which was used directly in the next step. LCMS: 0.123 min, 195.2 [M+H]+, Method F. 25 Procedure for the preparation of 2-(((3'-bromospiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazin]-7'-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (Intermediate 8) 44 To a suspension of 3,6-dibromopyridazine (50 g, 210.19 mmol), 1-((tert- butoxycarbonyl)amino)cyclopropane-1-carboxylic acid (84.59 g, 420.38 mmol) in water (1000 mL) was added AgNO3(3.57 g, 21.02 mmol) at rt. A solution of ammonia;sulfooxy hydrogen sulfate (95.93 g, 420.38 mmol) in water (200 mL) was then added dropwise to the above 5 suspension at 55-68 °C (inner temperature). The reaction mixture was stirred at 70 °C for 2 h. The reaction mixture was cooled to rt, and the solid formed was collected by filtration. The filter cake was dried under reduced pressure to afford tert-butyl (1-(3,6-dibromopyridazin-4- yl)cyclopropyl)carbamate (52.5 g, 133.56 mmol, 64%) as a light yellow solid. LCMS: 0.482 min, 391.9 / 393.8 [M+H]+, Method G. 10 To a solution of tert-butyl (1-(3,6-dibromopyridazin-4-yl)cyclopropyl)carbamate (40 g, 101.76 mmol) in DCM (400 mL) was added TFA (122.80 g, 1.08 mol, 80 mL), then the reaction was stirred at rt for 2 h. The reaction was concentrated under reduced pressure to afford 1-(3,6- dibromopyridazin-4-yl)cyclopropan-1-amine;trifluoroacetic acid (55 g, quantitative yield) as 15 brown solid. LCMS: 0.736 min, 293.8 / 295.8 [M+H]+, Method G. To a solution of 1-(3,6-dibromopyridazin-4-yl)cyclopropan-1-amine;trifluoroacetic acid (55 g, 105.57 mmol) and DIPEA (68.22 g, 527.83 mmol, 91.94 mL) in DMF (500 mL) was added20 CS2(80.38 g, 1.06 mol, 63.64 mL). The mixture was stirred at rt for 1 h under N2. 2- (Bromomethyl)-5-(trifluoromethyl)benzonitrile (29.39 g, 111.32 mmol) was added at 0 °C and the mixture was stirred at rt for 1 h under N2. The reaction mixture was diluted with water (3000 mL) and then extracted with EtOAc (5 x 500 mL). The combined organic layers were washed with brine (1000 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced25 pressure. The residue was triturated with MTBE (3 x 100 mL) to afford 2-(((3'- bromospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5- (trifluoromethyl)benzonitrile (25.6 g, 54.32 mmol, 49%, Intermediate 8) as a white solid. 1H NMR (400 MHz, CDCl3): δ 7.90 (s, 1H), 7.84 - 7.78 (m, 1H), 7.74 - 7.68 (m, 1H), 6.90 (s, 1H), 4.45 (s, 2H), 1.64-1.58 (m, 2H), 1.46-1.41 (m, 2H). 30 Procedure for the preparation of methyl 7'-((2-cyano-4- (trifluoromethyl)benzyl)thio)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-3'- carboxylate (Intermediate 9) 45 To a stirred solution of 2-(((3'-bromospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'- yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (4.0 g, 8.510 mmol, Intermediate 8) in MeOH (40 mL) was added TEA (4.0 mL, 25.53 mmol) and PdCl2(dppf) (0.6 g, 0.815 mmol). The mixture 5 was stirred under an atmosphere of CO (gas) at 50 psi at 50 °C for 16 h. The reaction mixture was concentrated under reduced pressure and purified by flash column chromatography (40% EtOAc in hexane) to afford methyl 7'-((2-cyano-4-(trifluoromethyl)benzyl)thio) spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-3'-carboxylate (2.0 g, 4.44 mmol, 53%, Intermediate 9). 10 LCMS: 2.42 min, 451.1 [M+H]+, Method D. Procedure for the preparation of 7'-((2-cyano-4-(trifluoromethyl)benzyl)thio)-N'- formylspiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-3'-carbohydrazide 15 (Intermediate 10) To a stirred solution of methyl 7'-((2-cyano-4-(trifluoromethyl)benzyl)thio)spiro[cyclopropane- 1,5'-pyridazino[4,3-e][1,3]thiazine]-3'-carboxylate (2.0 g, 4.44 mmol, Intermediate 9) in MeOH (20 mL) was added hydrazine hydrate (4.0 mL, 2 vol). The mixture was stirred at rt for 1 h. 20 The reaction mixture was concentrated under reduced pressure and purified by trituration using 1:1 EtOAc:ether to afford 7'-((2-cyano-4-(trifluoromethyl)benzyl)thio)spiro[cyclopropane- 1,5'-pyridazino[4,3-e][1,3]thiazine]-3'-carbohydrazide (1.2 g, 2.660 mmol, 60%). LCMS: 2.16 min, 451.17 [M+H]+, Method D. 25 A stirred solution of 7'-((2-cyano-4-(trifluoromethyl)benzyl)thio)spiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazine]-3'-carbohydrazide (1.0 g, 2.127 mmol) in formic acid (15 mL) was stirred at 80 °C for 1 h. The reaction mixture was quenched with sat. aq. NaHCO3 (50 mL) and extracted with EtOAc (2 x 50 mL). The combined organic layers were dried over Na2SO4, filtered, and concentrated under reduced pressure. The crude material was purified30 by trituration using ether to afford 7'-((2-cyano-4-(trifluoromethyl)benzyl)thio)-N'- 46 formylspiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-3'-carbohydrazide (0.9 g, 1.880 mmol, 71%, Intermediate 10). LCMS: 2.14 min, 478.9 [M+H]+, Method D. 5 Procedure for the preparation of methyl 6-bromo-5-(1-((tert- butoxycarbonyl)amino)cyclopropyl)pyridazine-3-carboxylate (Intermediate 11) To a suspension of 3,6-dibromopyridazine (50 g, 210.19 mmol), 1-((tert- butoxycarbonyl)amino)cyclopropane-1-carboxylic acid (84.59 g, 420.38 mmol) in water (1000 10 mL) was added AgNO3(3.57 g, 21.02 mmol) at rt. A solution of ammonia;sulfooxy hydrogen sulfate (95.93 g, 420.38 mmol) in water (200 mL) was then added dropwise to the above suspension at 55-68 °C (inner temperature). The reaction mixture was stirred at 70 °C for 2 h. The reaction mixture was cooled to rt, and the solid formed was collected by filtration. The filter cake was dried under reduced pressure to afford tert-butyl (1-(3,6-dibromopyridazin-4- 15 yl)cyclopropyl)carbamate (52.5 g, 133.56 mmol, 64%) as a light yellow solid. LCMS: 0.482 min, 391.9 / 393.8 [M+H]+, Method G. A solution of tert-butyl (1-(3,6-dibromopyridazin-4-yl)cyclopropyl)carbamate (5 g, 12.72 mmol), TEA (5.31 mL, 38.16 mmol) and Pd(dppf)Cl2.CH2Cl2(2.08 g, 2.54 mmol) in MeOH (70 mL) 20 was stirred at 50 °C under a CO atmosphere (50 psi) for 1 hr. The reaction mixture was filtered and the filtrate was concentrated under reduced pressure. The crude material was purified by flash column chromatography (20-25% EtOAc in petroleum ether) to afford methyl 6-bromo- 5-(1-((tert-butoxycarbonyl)amino)cyclopropyl)pyridazine-3-carboxylate (2.8 g, 59%, Intermediate 11) as a white solid. 251H NMR (400 MHz, CDCl3): δ 8.22 (br s, 1H), 5.61 (br s, 1H), 4.05 (s, 3H), 1.36 (br s, 11H), 1.24 - 1.18 (m, 2H). Procedure for the preparation of 1-(3-chloro-6-(1,2,4-oxadiazol-5-yl)pyridazin-4- yl)cyclopropan-1-amine (Intermediate 12) 47 To a solution of methyl 6-bromo-5-(1-((tert-butoxycarbonyl)amino)cyclopropyl)pyridazine-3- carboxylate (600 mg, 1.61 mmol, Intermediate 11) in MeOH (5 mL) was added ammonium hydroxide (6 mL, 46.74 mmol, 30% in water) at rt. The reaction mixture was stirred at rt for 2 5 h. The reaction was repeated on the same scale, then the reaction mixtures were combined and concentrated under reduced pressure. The resulting residue was diluted with water (30 mL) and extracted with ethyl acetate (3 × 15 mL). The combined organic phases were washed with brine (10 mL), dried over sodium sulfate, filtered, and concentrated under reduced pressure to afford tert-butyl (1-(3-bromo-6-carbamoylpyridazin-4-yl)cyclopropyl)carbamate 10 (1.17 g, 81%) as a white solid. 1H NMR: (400 MHz, DMSO-d6): δ = 8.56 (s, 1H), 8.15 - 7.96 (m, 2H), 7.88 (br s, 1H), 1.29 (s, 9H), 1.19 (br d, J = 2.0 Hz, 4H). A solution of tert-butyl (1-(3-bromo-6-carbamoylpyridazin-4-yl)cyclopropyl)carbamate (550 15 mg, 1.54 mmol, 1 eq) in DMF-DMA (6 mL) was stirred at rt under a nitrogen atmosphere. The reaction mixture was heated to 80 °C and stirred at 80 °C for 1 h. The reaction was repeated on the scale and, after cooling to rt, the reaction mixtures were combined and concentrated under reduced pressure to afford tert-butyl (Z)-(1-(3-bromo-6- (((dimethylamino)methylene)carbamoyl)pyridazin-4-yl)cyclopropyl)carbamate (1 g, 79%) as a 20 white solid. 1H NMR: (400 MHz, DMSO-d6): δ 8.71 (s, 1H), 8.18 (s, 1H), 7.90 - 7.54 (m, 1H), 3.35 (s, 3H), 3.25 (s, 3H), 1.29 (s, 9H), 1.21 - 1.13 (m, 4H). To a solution of tert-butyl (Z)-(1-(3-bromo-6-(((dimethylamino)methylene)carbamoyl)pyridazin- 25 4-yl)cyclopropyl)carbamate (100 mg, 0.243 mmol) in AcOH (1 mL) and EtOH (5 mL) was 48 added hydroxylammonium chloride (84.28 mg, 1.21 mmol) at rt. The reaction mixture was stirred at 60 °C for 2 h. Four reactions on the same scale were performed. After cooling to rt, all five reaction mixtures were combined and concentrated under reduced pressure. The residue was purified by flash column chromatography (10-20% EtOAc in petroleum ether) to 5 afford tert-butyl (1-(3-chloro-6-(1,2,4-oxadiazol-5-yl)pyridazin-4-yl)cyclopropyl)carbamate (200 mg, 49%) as a white solid. 1H NMR: (400 MHz, DMSO-d6): δ 9.37 (s, 1H), 8.44 - 8.30 (m, 1H), 8.16 - 7.99 (m, 1H), 1.34 - 1.12 (m, 13H). 10 To a solution of tert-butyl (1-(3-chloro-6-(1,2,4-oxadiazol-5-yl)pyridazin-4- yl)cyclopropyl)carbamate (200 mg, 0.592 mmol) in dichloromethane (2 mL) was added TFA (0.4 mL, 5.39 mmol) at rt. The reaction mixture was stirred at rt for 1 h. The reaction mixture concentrated under reduced pressure to afford 1-(3-chloro-6-(1,2,4-oxadiazol-5-yl)pyridazin- 4-yl)cyclopropan-1-amine;trifluoroacetic acid (140 mg, quantitative yield, Intermediate 12) as 15 a yellow solid. LCMS: 0.352 min, 238.3 [M+H]+, Method G. Procedure for the preparation of 1-(3-chloro-6-(1,2,4-oxadiazol-3-yl)pyridazin-4- yl)cyclopropan-1-amine (Intermediate 13) 20 To a solution of tert-butyl (1-(3-chloro-6-cyanopyridazin-4-yl)cyclopropyl)carbamate (1.6 g, 2.66 mmol, Intermediate 7) in EtOH (20 mL) at rt was added TEA (403.74 mg, 3.99 mmol, 555.36 μL) and HONH2-HCl (369.69 mg, 5.32 mmol). The reaction mixture was stirred at 80 °C for 2 h. After cooling to rt, the reaction mixture was diluted with water (30 mL) and extracted 25 with ethyl acetate (3 x 20 mL). The combined organic phases were washed with brine (3 x 10 mL), dried over sodium sulfate, filtered and the filtrate was concentrated under reduced pressure to afford tert-butyl (1-(3-chloro-6-(N-hydroxycarbamimidoyl)pyridazin-4- yl)cyclopropyl)carbamate (2 g, 80%) as a yellow solid. LCMS: 1.156 min, 328.1 [M+H]+, Method E. 30 49 To a solution of tert-butyl (1-(3-chloro-6-(N-hydroxycarbamimidoyl)pyridazin-4- yl)cyclopropyl)carbamate (2 g, 2.14 mmol) in triethyl orthoformate (20 mL) was added TFA (730.55 mg, 6.41 mmol, 475.93 μL) under a nitrogen atmosphere. The mixture was stirred at 80 °C for 3 h. After cooling to rt, the reaction mixture was diluted with water (30 mL) and 5 extracted with ethyl acetate (3 × 30 mL). The combined organic phases were washed with brine (3 × 20 mL), dried over sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure. The crude material was purified by flash column chromatography (25-40% EtOAc in petroleum ether) to afford tert-butyl (1-(3-chloro-6-(1,2,4-oxadiazol-3-yl)pyridazin-4- yl)cyclopropyl)carbamate (450 mg, 49%) as a yellow solid. 101H NMR (400 MHz, DMSO-d6): δ 9.93 (s, 1H), 8.26 (br s, 1H), 8.07 - 7.96 (m, 1H), 1.30 (s, 9H), 1.27 - 1.23 (m, 2H), 1.21 - 1.16 (m, 2H). To a solution of tert-butyl (1-(3-chloro-6-(1,2,4-oxadiazol-3-yl)pyridazin-4- yl)cyclopropyl)carbamate (510 mg, 1.19 mmol) in DCM (5 mL) was added TFA (1 mL). The 15 mixture was stirred at rt for 1 h. The reaction mixture was concentrated under reduced pressure to afford 1-(3-chloro-6-(1,2,4-oxadiazol-3-yl)pyridazin-4-yl)cyclopropan-1-amine (283.4 mg, 60%, Intermediate 13) as a black solid. LCMS: 0.114 min, 238.1 [M+H]+, Method G. 20 Procedure for the preparation of 1-(3-bromo-6-(4H-1,2,4-triazol-3-yl)pyridazin-4- yl)cyclopropan-1-amine (Intermediate 14) To a solution of methyl 6-bromo-5-(1-((tert-butoxycarbonyl)amino)cyclopropyl)pyridazine-3- carboxylate (1 g, 2.69 mmol, Intermediate 11) in MeOH (10 mL) was added NH4.OH (9.10 g, 25 64.92 mmol, 10 mL). The mixture was stirred at rt for 1 h. The solids formed in the reaction 50 mixture were collected by vacuum filtration to afford tert-butyl (1-(3-bromo-6- carbamoylpyridazin-4-yl)cyclopropyl)carbamate (0.77 g, 2.10 mmol, 78%) as a white solid. 1H NMR (400 MHz, DMSO-d6): δ 8.58 (s, 1H), 8.10 (br s, 1H), 8.01 (br s, 1H), 7.94 - 7.58 (m, 1H), 1.29 (s, 9H), 1.18 (s, 4H). 5 A mixture of tert-butyl (1-(3-bromo-6-carbamoylpyridazin-4-yl)cyclopropyl)carbamate (0.77 g, 2.16 mmol) in DMF-DMA (7.18 g, 60.22 mmol, 8 mL) was stirred at 80 °C for 2 h under a nitrogen atmosphere. The mixture was cooled to rt and the solids formed were collected by vacuum filtration to afford tert-butyl (Z)-(1-(3-bromo-6- 10 (((dimethylamino)methylene)carbamoyl)pyridazin-4-yl)cyclopropyl)carbamate (0.75 g, 1.81 mmol, 84%) as an off-white solid. 1H NMR (400 MHz, DMSO-d6): δ 8.72 (s, 1H), 8.18 (s, 1H), 7.90 - 7.58 (m, 1H), 3.26 (s, 3H), 3.16 (s, 3H), 1.29 (s, 9H), 1.17 (s, 4H). 15 To a solution of tert-butyl (Z)-(1-(3-bromo-6-(((dimethylamino)methylene)carbamoyl)pyridazin- 4-yl)cyclopropyl)carbamate (0.45 g, 1.09 mmol) in AcOH (4.72 g, 78.61 mmol, 4.50 mL) was added hydrazine (1 M in THF, 5.62 mL). The mixture was stirred at 90 °C for 1 h. The mixture was cooled to rt, poured onto sat. aq. NaHCO3 (100 mL) and extracted with ethyl acetate (3 x 50 mL). The combined organic phases were washed with brine (50 mL), dried with anhydrous20 Na2SO4, filtered and concentrated under reduced pressure to afford tert-butyl (1-(3-bromo-6- (4H-1,2,4-triazol-3-yl)pyridazin-4-yl)cyclopropyl)carbamate (0.4 g, 1.05 mmol, 96%) an off- white solid. LCMS: 0.349 min, 381.0 / 383.0 [M+H]+, Method G. 25 To a mixture of tert-butyl (1-(3-bromo-6-(4H-1,2,4-triazol-3-yl)pyridazin-4- yl)cyclopropyl)carbamate (0.4 g, 1.05 mmol) in DCM (6 mL) was added TFA (3.07 g, 26.92 mmol, 2 mL). The mixture was stirred at rt for 30 min. The mixture was concentrated under reduced pressure to afford 1-(3-bromo-6-(4H-1,2,4-triazol-3-yl)pyridazin-4-yl)cyclopropan-1- amine;trifluoroacetic acid (0.53 g, 1.04 mmol, 99%, Intermediate 14) as a brown oil. 30 LCMS: 0.091 min, 281.0 / 282.9 [M+H]+, Method G. 51 Procedure for the preparation of N-methyl-1-(2-trityl-2H-tetrazol-5-yl)methanamine (Intermediate 15) Intermediate 15To a stirred solution of 5-(chloromethyl)-2H-tetrazole (1.19 g, 10.03 mmol) in DCM (10 mL) 5 was added DIPEA (1.48 g, 11.54 mmol) and TrCl (2.79 g, 10.03 mmol). The reaction mixture was stirred at rt for 40 min, then diluted with water (50 mL) and extracted with EtOAc (2 x 50 mL). The combined organic layers were dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by trituration using n- pentane (15 mL) to afford 5-(chloromethyl)-2-trityl-2H-tetrazole (2.0 g, 5.55 mmol, 55%). 10 ¹H NMR (400 MHz, DMSO-d6): δ 7.42 - 7.41 (m, 9H), 7.03 - 7.00 (m, 6H), 5.08 (s, 2H). A mixture of 5-(chloromethyl)-2-trityl-2H-tetrazole (0.500 g, 1.38 mmol) in 2 M methyl amine in THF (15 mL) was stirred at 50 °C for 3 h. The reaction mixture was concentrated under reduced pressure, then azeotroped with THF (10 mL) and DCM (10 mL) to afford N-methyl-1- 15 (2-trityl-2H-tetrazol-5-yl)methanamine (0.6 g, 1.69 mmol, quantitative yield, Intermediate 15). ¹H NMR (400 MHz, DMSO-d6): δ 7.42 - 7.39 (m, 9H), 7.03 - 7.00 (m, 6H), 3.94 (s, 2H), 2.26 (s, 3H). Procedure for the synthesis of 2-(((3'-fluorospiro[cyclopropane-1,5'-pyridazino[4,3- 20 e][1,3]thiazin]-7'-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (Intermediate 16) To a stirred solution of 3,6-difluoropyridazine (3.25 g, 28.0 mmol) and 1-((tert- butoxycarbonyl)amino)cyclopropane-1-carboxylic acid (8.44 g, 42.0 mmol) in water (82.0 mL) was added AgNO3(0.476, 2.80 mmol) at rt. A solution of ammonium persulfate (12.76 g, 56.0 25 mmol) in water (65 mL) was added dropwise at 60 °C and the mixture was stirred for 10 min. 52 The reaction mixture was diluted with water (500 mL) and extracted with EtOAc (3 x 200 mL). The combined organic layers were dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure. The crude material was purified by flash column chromatography (22% EtOAc in hexane) to afford tert-butyl (1-(3,6-difluoropyridazin-4- 5 yl)cyclopropyl)carbamate (3.89 g, 14.35 mmol, 25%). LCMS: 1.98 min, 272.2 [M+H]+, Method D. To a stirred solution of tert-butyl (1-(3,6-difluoropyridazin-4-yl)cyclopropyl)carbamate (2.6 g, 9.50 mmol) in DCM (26.0 mL) was added TFA (13 mL, 5 vol) at 0 °C and the mixture was 10 stirred and allowed to warm to rt over 4 h. The reaction mixture was diluted with water (400 mL). The aqueous layer was basified using aqueous NaOH solution (pH 12-13) and extracted with EtOAc (3 x 200 mL). The combined organic layers were dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure to afford 1-(3,6-difluoropyridazin-4- yl)cyclopropan-1-amine (1.31 g, 7.6 mmol, 79%). 15 LCMS: 0.973 min, 172.0 [M+H]+, Method D. To a stirred solution of 1-(3,6-difluoropyridazin-4-yl)cyclopropan-1-amine (1.30 g, 7.60 mmol) in DMF (13 mL) was added carbon disulfide (2.6 mL, 2 vol) and the mixture was stirred at rt for 16 h. DIPEA (3.9 mL, 22.0 mmol) and 2-(bromomethyl)-5-(trifluoromethyl)benzonitrile (2.19 20 g, 8.30 mmol) was added and the mixture was stirred at rt for 15 min. The reaction mixture was diluted with water (200 mL) and EtOAc (3 x 200 mL). The organic layers were dried over Na2SO4, filtered, and concentrated under reduced pressure. The crude material was purified by flash column chromatography (22% EtOAc in n-hexane) to afford 2-(((3'- fluorospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5- 25 (trifluoromethyl)benzonitrile (1.0 g, 2.4 mmol, 32%, Intermediate 16). LCMS: 2.55 min, 411.2 [M+H]+, Method D. Procedure for the preparation of N'-acetyl-7'-((2-cyano-4- (trifluoromethyl)benzyl)thio)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-3'- 30 carbohydrazide (Intermediate 17) 53 To a stirred solution of methyl 7'-((2-cyano-4-(trifluoromethyl)benzyl)thio)spiro[cyclopropane- 1,5'-pyridazino[4,3-e][1,3]thiazine]-3'-carboxylate (2.0 g, 4.44 mmol, Intermediate 9) in MeOH (20 mL) was added hydrazine hydrate (4.0 mL, 2 vol). The mixture was stirred at rt for 1 h. 5 The reaction mixture was concentrated under reduced pressure and purified by trituration using 1:1 EtOAc:ether to afford 7'-((2-cyano-4-(trifluoromethyl)benzyl)thio)spiro[cyclopropane- 1,5'-pyridazino[4,3-e][1,3]thiazine]-3'-carbohydrazide (1.2 g, 2.660 mmol, 60%). LCMS: 2.16 min, 451.17 [M+H]+, Method D. 10 To a stirred solution of 7'-((2-cyano-4-(trifluoromethyl)benzyl)thio)spiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazine]-3'-carbohydrazide (0.5 g, 1.109 mmol) in DCM (5.0 mL) was added K2CO3(0.306 g, 2.219 mmol) at rt and the mixture was stirred for 10 min. Acetic anhydride (0.192 g, 1.886 mmol) was added at rt and the mixture was stirred for 1 h. The reaction mixture was diluted with water (50 mL) and extracted with EtOAc (3 x 30 mL). The 15 combined organic layers were dried over Na2SO4, filtered and concentrated under reduced pressure to afford N'-acetyl-7'-((2-cyano-4-(trifluoromethyl)benzyl)thio)spiro[cyclopropane- 1,5'-pyridazino[4,3-e][1,3]thiazine]-3'-carbohydrazide (0.45 g, 0.913 mmol, 82%, Intermediate 17). LCMS: 2.14 min, 493.2 [M+H]+, Method D. 20 Procedure for the preparation of 5-(bromomethyl)-2-(trifluoromethyl)isonicotinonitrile (Intermediate 18) To a solution of 5-bromo-2-(trifluoromethyl)isonicotinic acid (9 g, 33.33 mmol) in DCM (60 mL) 25 was added oxalyl chloride (4.44 g, 35.00 mmol, 3.06 mL) and DMF (0.15 mL) dropwise, and 54 then the mixture was stirred at rt for 1 h. The reaction mixture was concentrated under reduced pressure to give 5-bromo-2-(trifluoromethyl)isonicotinoyl chloride (9.6 g, 99.9%) as pale yellow oil. LCMS: 0.50 min, 284.0 / 286.0 [M-Cl+OMe+H]+, Method F. 5 To a solution of NH3.H2O (93.31 g, 25%, 665.63 mmol, 102.54 mL) was added 5-bromo-2- (trifluoromethyl)isonicotinoyl chloride (9.6 g, 33.28 mmol) in MeCN (5 mL) dropwise at 0 °C, and then the mixture was stirred at 0 °C for 20 min. The precipitate formed in the reaction mixture was collected by vacuum filtration and washed with water (100 mL). The filter cake 10 was dried under vacuum to afford 5-bromo-2-(trifluoromethyl)isonicotinamide (8.7 g, 96%) as a white solid. 1H NMR (400 MHz, DMSO-d6): δ 9.02 (s, 1H), 8.20 (br s, 1H), 8.03 (br s, 1H), 8.00 (s, 1H). A mixture of 5-bromo-2-(trifluoromethyl)isonicotinamide (8.7 g, 32.34 mmol) in POCl3(32.23 15 g, 210.21 mmol, 19.59 mL) was stirred at 70 °C for 12 h. The reaction mixture was cooled to rt and poured onto ice. The mixture was neutralized with careful addition of 50% aqueous sodium hydroxide. The resulting off-white solid was collected by filtration, washed with water (50 mL) and dried under vacuum to afford 5-bromo-2-(trifluoromethyl)isonicotinonitrile (7.64 g, 93%) as an off-white solid. 201H NMR (400 MHz, CDCl3): δ 9.05 (s, 1H), 7.91 (s, 1H). Two reactions were carried out in parallel. A solution of 5-bromo-2- (trifluoromethyl)isonicotinonitrile (3.3 g, 13.15 mmol), MeB(OH)2(2.36 g, 39.44 mmol), K2CO3(7.27 g, 52.59 mmol) and Pd(dppf)Cl2(961.99 mg, 1.31 mmol) in dioxane (33 mL) was stirred 25 at 80 °C for 1 h under a nitrogen atmosphere. The two reaction mixtures were combined and quenched with sat. NH4Cl solution (200 mL) and extracted with EtOAc (100 mL × 3). The combined organic layers were washed with brine (100 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The residue was purified by flash column chromatography (0-50% EtOAc in petroleum ether) to afford 5-methyl-2- 30 (trifluoromethyl)isonicotinonitrile (3.9 g, yield 77.93%, 97.80% purity) as a colourless solid. 1H NMR (400 MHz, CDCl3): δ 8.80 (s, 1H), 7.85 (s, 1H), 2.66 (s, 3H). 55 Solution 1: To a solution of 5-methyl-2-(trifluoromethyl)isonicotinonitrile (3.2 g, 17.19 mmol) in MeCN (64 mL) was added NBS (4.59 g, 25.79 mmol). Solution 1 was pumped by Pump 1 {S1, P1, 0.67 mL / min}to flow reactor 1 {FLR1, FEP, Coils reactor, 3.175(1 / 8’’) mm, 10.048 mL, 450 nm, 600 W, 45 °C}. The residence time of flow reactor 1 was {FLR1, 30 min}. The reaction 5 mixture was concentrated under reduced pressure. The residue was diluted with water (50 mL) and extracted with EtOAc (50 mL × 3). The combined organic layers were washed with brine (50 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The residue was purified by flash column chromatography (0-50% EtOAc in petroleum ether) to afford 5-(bromomethyl)-2-(trifluoromethyl)isonicotinonitrile (3.1 g, 63%, 10 Intermediate 18) as a white solid. 1H NMR (400 MHz, CDCl3): δ 8.98 (s, 1H), 7.92 (s, 1H), 4.67 (s, 2H). Procedure for the preparation of 2-(bromomethyl)-5-(difluoromethyl)benzonitrile (Intermediate 19) 15 To a stirred solution of 5-formyl-2-methylbenzonitrile (1.5 g, 10.33 mmol) in DCM (15 mL) was added DAST (2.49 g, 15.50 mmol) at 0 °C. The reaction mixture was stirred at rt for 6 h. The reaction mixture was diluted with sat. NaHCO3 solution (50 mL) and extracted with EtOAc (2 x 50 mL). The combined organic layers were dried over Na2SO4, filtered, and concentrated20 under reduced pressure. The crude material was purified by flash column chromatography (0- 10 % EtOAc in hexane) to afford 5-(difluoromethyl)-2-methylbenzonitrile (1.0 g, 5.982 mmol, 58%). ¹H NMR (400 MHz, DMSO-d6): δ 7.99 (s, 1H), 7.80 (d, J = 8.0 Hz, 1H), 7.61 (d, J = 8.0 Hz, 1H), 7.06 (t, J = 55.6 Hz, 1H), 2.53 (s, 3H). 25 To a stirred solution of 5-(difluoromethyl)-2-methylbenzonitrile (1.0 g, 5.988 mmol) in triflurotoluene (10 mL) were added NBS (1.59 g, 8.981 mmol) and AIBN (0.09 g, 0.591 mmol) at rt. The reaction mixture was stirred at 100 °C for 2 h. The reaction mixture was diluted with water (50 mL) and extracted with EtOAc (2 x 50 mL). The combined organic layers were dried 30 over Na2SO4, filtered, and concentrated under reduced pressure. The crude material was 56 purified by flash column chromatography (0-10% EtOAc in hexane) to afford 2-(bromomethyl)- 5-(difluoromethyl)benzonitrile (0.8 g, 3.25 mmol, 54%, Intermediate 19). ¹H NMR (400 MHz, DMSO-d6): δ 8.14 (s, 1H),8.08 - 7.87 (m, 2H), 7.10 (t, J = 55.4 Hz, 1H), 4.86 (s, 2H). 5 Procedure for the preparation of 2-(bromomethyl)-5-(trifluoromethyl)nicotinonitrile (Intermediate 20) A solution of 2-chloro-5-(trifluoromethyl)nicotinonitrile (3 g, 14.52 mmol) in dioxane (90 mL) 10 was degassed with a stream of nitrogen for 15 min. Pd(PPh3)4(839.18 mg, 726.21 μmol) was added followed by Al(CH3)3(2 M in toluene, 14.52 mL). The reaction mixture was heated to 100 °C under nitrogen and stirred for 1 h. The reaction mixture was quenched with methanol (100 mL) and concentrated under reduced pressure. The resulting material was partitioned between EtOAc (200 mL) and water (200 mL), then filtered to remove the precipitate that had 15 formed. The two layers of the filtrate were separated and the aqueous phase was extracted with additional ethyl acetate (200 mL × 3). The combined organic phases were washed with brine, dried over sodium sulfate, filtered, and concentrated under reduced pressure. The residue was purified by flash column chromatography (0-50% EtOAc in heptane) to afford 2- methyl-5-(trifluoromethyl)nicotinonitrile (1.89 g, 63%) as colorless solid. 201H NMR (400 MHz, CDCl3): δ 8.95 (s, 1H), 8.15 (d, J = 1.6 Hz, 1H), 2.89 (s, 3H). Flow chemistry: To a mixture of 2-methyl-5-(trifluoromethyl)nicotinonitrile (1.7 g, 9.13 mmol) in MeCN (51 mL) was added NBS (4.06 g, 22.83 mmol), TFA (208.28 mg, 1.83 mmol, 135.69 μL) in one portion. The solution was pumped by Pump 1 {S1, P1, 0.502 mL / min} to flow reactor 25 1 {FLR1, FEP, Coils reactor, 3.175(1 / 8’’) mm, 10.048 mL, 45 °C}. The residence time of flow reactor 1 was {FLR1, 20 min}. A 450 nm ELD light (600W) was used and collection of the reaction mixture after started after running the reaction for 20 min. The reaction mixture was concentrated and purified by prep-HPLC (Method M) to afford 2-(bromomethyl)-5- (trifluoromethyl)nicotinonitrile (750 mg, 29%, Intermediate 20) as brown oil. 301H NMR (400 MHz, CDCl3): δ 9.03 (d, J = 1.8 Hz, 1H), 8.24 (d, J = 1.8 Hz, 1H), 4.77 (s, 2H). 57 Procedure for the preparation of 2-(bromomethyl)-5-(fluoromethyl)benzonitrile (Intermediate 21) 5 To a solution of 5-formyl-2-methylbenzonitrile (5 g, 34.45 mmol) in THF (25 mL) and MeOH (25 mL) was added NaBH4(912.20 mg, 24.11 mmol) at 0 °C, then the reaction was stirred at 0 °C for 2 h. The reaction mixture was quenched by addition of sat.NH4Cl (100 mL) at 0 °C and extracted with EtOAc (30 mL×3). The combined organic layers were washed with brine (30 mL), dried over Na2SO4, filtered and concentrated under reduced pressure to afford 5- 10 (hydroxymethyl)-2-methylbenzonitrile (5.05 g, quantitative yield) as a white solid. 1H NMR (400 MHz, CDCl3): δ 7.62 (s, 1H), 7.51 - 7.46 (m, 1H), 7.32 (d, J = 8.0 Hz, 1H), 7.30 - 7.30 (m, 1H), 4.71 (s, 2H), 2.55 (s, 3H). Under a nitrogen atmosphere, DAST (10.95 g, 67.95 mmol, 8.98 mL) was added to a solution 15 of 5-(hydroxymethyl)-2-methylbenzonitrile (5 g, 33.97 mmol, 1 eq) in DCM (100 mL) at 0 °C, and the mixture was stirred at 0 °C for 1 h. Saturated aqueous NaHCO3solution (300 mL) was added and the mixture was extracted with DCM (100 mL × 2). The combined organic phases were washed with water (100 mL), dried over Na2SO4, filtered, and concentrated under reduced pressure. The residue was purified by flash column chromatography (0-20% EtOAc 20 in heptane) to afford 5-(fluoromethyl)-2-methylbenzonitrile (3 g, 59%) as pale yellow oil. 1H NMR (400 MHz, CDCl3): δ 7.62 (s, 1H), 7.50 (br d, J = 8.0 Hz, 1H), 7.37 (d, J = 8.0 Hz, 1H), 5.46 - 5.28 (d, J = 48.0 Hz, 2H), 2.58 (s, 3H). 5-(Fluoromethyl)-2-methylbenzonitrile (2.8 g, 18.77 mmol) and NBS (3.67 g, 20.65 mmol) in 25 anhydrous MeCN (56 mL) were passed through a flow reactor (hv = 450 nm / 600 W*2 at 45 °C) for 15 min. The reaction mixture was cooled to rt and concentrated under reduced pressure. The residue was purified by prep-HPLC (Method D) afford 2-(bromomethyl)-5- (fluoromethyl)benzonitrile (1.2 g, 28%, Intermediate 21) as a pale yellow oil. 58 1H NMR (400 MHz, CDCl3): δ 7.68 (s, 1H), 7.65 - 7.55 (m, 2H), 5.52 - 5.34 (d, J = 44, 2H), 4.65 (s, 2H). Procedure for the preparation of 3-(bromomethyl)-6-(trifluoromethyl)picolinonitrile 5 (Intermediate 22) 4 batches: A mixture of 2-chloro-3-methyl-6-(trifluoromethyl)pyridine (0.47 g, 2.40 mmol) and CuCN (645.73 mg, 7.21 mmol, 1.57 mL) in NMP (5 mL) was stirred at 140 °C for 60 h, then 180 °C for 4 h. Three additional reactions were performed as described. The 4 reaction 10 mixtures were combined, filtered, diluted with EtOAc (20 mL) / water (30 mL) and then filtered again. The organic layer was separated, and the aqueous layer was extracted with EtOAc (20 mL × 3). The combined organic layers were washed with brine (30 mL) and dried over Na2SO4, filtered and concentrated under reduced pressure. The crude product was purified by flash column chromatography (0-25% EtOAc in hexane) to afford 3-methyl-6- 15 (trifluoromethyl)picolinonitrile (1 g, 56%) as a colourless oil. 1H NMR (400 MHz, CDCl3): δ 7.89 (d, J = 8.0 Hz, 1H), 7.82 - 7.77 (d, J = 8.0 Hz, 1H), 2.68 (s, 3H). 3-Methyl-6-(trifluoromethyl)picolinonitrile (0.85 g, 4.57 mmol), NBS (2.44 g, 13.70 mmol) and 20 TFA (104.14 mg, 913.32 μmol, 67.84 μL) in anhydrous MeCN (25 mL), were reacted in a flow reactor (hv = 395 nm / 600 W*2, 20 min) at 45 °C. The resulting mixture 3-(bromomethyl)-6- (trifluoromethyl)picolinonitrile and 3-(dibromomethyl)-6-(trifluoromethyl)picolinonitrile in MeCN (25 mL) was used directly in the next step. 25 To the mixture of 3-(bromomethyl)-6-(trifluoromethyl)picolinonitrile and 3-(dibromomethyl)-6- (trifluoromethyl)picolinonitrile (4.56 mmol) in MeCN (25 mL) isolated from the previous step was added DIPEA (884.96 mg, 6.85 mmol, 1.19 mL), then 1-ethoxyphosphonoyloxyethane (630.43 mg, 4.56 mmol, 588.08 μL) dropwise at 0 °C. The mixture was stirred at 0 °C for 10 min. The mixture was poured into water (60 mL) and stirred for 5 min. The aqueous phase 30 was extracted with ethyl acetate (30 mL×2). The combined organic phases were dried over 59 anhydrous Na2SO4, filtered and concentrated under reduced pressure. The residue was purified by flash column chromatography (0-25% EtOAc in petroleum ether) to afford 3- (bromomethyl)-6-(trifluoromethyl)picolinonitrile (1 g, 83%, Intermediate 22) as a pale yellow oil. 51H NMR (400 MHz, CDCl3): δ 8.15 (d, J = 8.0 Hz, 1H), 7.91 (d, J = 8.0 Hz, 1H), 4.69 (s, 2H). Procedure for the synthesis of 1-(3,6-difluoropyridazin-4-yl)cyclopropan-1-amine (Intermediate 23) 10 To a stirred solution of 3,6-difluoropyridazine (3.25 g, 28.0 mmol) and 1-((tert- butoxycarbonyl)amino)cyclopropane-1-carboxylic acid (8.44 g, 42.0 mmol) in water (82.0 mL) was added AgNO3(0.476, 2.80 mmol) at rt. A solution of ammonium persulfate (12.76 g, 56.0 mmol) in water (65 mL) was added dropwise at 60 °C and the mixture was stirred for 10 min. The reaction mixture was diluted with water (500 mL) and extracted with EtOAc (3 x 200 mL). 15 The combined organic layers were dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure. The crude material was purified by flash column chromatography (22% EtOAc in hexane) to afford tert-butyl (1-(3,6-difluoropyridazin-4- yl)cyclopropyl)carbamate (3.89 g, 14.35 mmol, 25%). LCMS: 1.98 min, 272.2 [M+H]+, Method D. 20 To a stirred solution of tert-butyl (1-(3,6-difluoropyridazin-4-yl)cyclopropyl)carbamate (2.6 g, 9.50 mmol) in DCM (26.0 mL) was added TFA (13 mL, 5 vol) at 0 °C and the mixture was stirred and allowed to warm to rt over 4 h. The reaction mixture was diluted with water (400 mL). The aqueous layer was basified using aqueous NaOH solution (pH 12-13) and extracted 25 with EtOAc (3 x 200 mL). The combined organic layers were dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure to afford 1-(3,6-difluoropyridazin-4- yl)cyclopropan-1-amine (1.31 g, 7.6 mmol, 79%). LCMS: 0.973 min, 172.0 [M+H]+, Method D. 60 Procedure for the preparation of 5-(((3'-fluorospiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazin]-7'-yl)thio)methyl)-2-(trifluoromethyl)isonicotinonitrile (Intermediate 24) To a solution of 1-(3,6-difluoropyridazin-4-yl)cyclopropan-1-amine (0.3 g, 873.75 μmol) and 5 DIPEA (451.70 mg, 3.49 mmol, 608.76 μL) in DMF (3 mL) was added CS2(665.28 mg, 8.74 mmol, 526.74 μL) and the mixture was stirred at rt for 2.5 h under nitrogen. The resulting solution of 3'-fluorospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-thiol in DMF (3 mL) was used directly in the next step without workup. LCMS: 0.41 min, 228.1 [M+H]+, Method G. 10 To the solution of 3'-fluorospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-thiol (0.198 g, 871.17 μmol) in DMF (3 mL) isolated from the previous step was added 5- (bromomethyl)-2-(trifluoromethyl)isonicotinonitrile (230.89 mg, 871.17 μmol) and the mixture was stirred at rt for 0.5 h under nitrogen. The mixture was poured into water (15 mL) and 15 extracted with ethyl acetate (10 mL × 3). The combined organic phases were washed with brine (20 mL), dried with anhydrous Na2SO4, filtered and concentrated under reduced pressure. The residue was purified by flash column chromatography (0-25% EtOAc in hexane) to afford 5-(((3'-fluorospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)- 2-(trifluoromethyl)isonicotinonitrile (0.26 g, 73%, Intermediate 24) as a yellow solid. 201H NMR (400 MHz, CDCl3): δ 8.94 (s, 1H), 7.88 (s, 1H), 6.52 (s, 1H), 4.44 (s, 2H), 1.71 - 1.63 (m, 2H), 1.53 - 1.45 (m, 2H). Procedure for the preparation of 1-(3,6-dibromopyridazin-4-yl)cyclopropan-1- amine;trifluoroacetic acid (Intermediate 25) 61 To a suspension of 3,6-dibromopyridazine (50 g, 210.19 mmol), 1-((tert- butoxycarbonyl)amino)cyclopropane-1-carboxylic acid (84.59 g, 420.38 mmol) in water (1000 mL) was added AgNO3(3.57 g, 21.02 mmol) at rt. A solution of ammonia;sulfooxy hydrogen 5 sulfate (95.93 g, 420.38 mmol) in water (200 mL) was then added dropwise to the above suspension at 55-68 °C (inner temperature). The reaction mixture was stirred at 70 °C for 2 h. The reaction mixture was cooled to rt, and the solid formed was collected by filtration. The filter cake was dried under reduced pressure to afford tert-butyl (1-(3,6-dibromopyridazin-4- yl)cyclopropyl)carbamate (52.5 g, 133.56 mmol, 64%) as a light yellow solid. 10 LCMS: 0.482 min, 391.9 / 393.8 [M+H]+, Method G. To a solution of tert-butyl (1-(3,6-dibromopyridazin-4-yl)cyclopropyl)carbamate (40 g, 101.76 mmol) in DCM (400 mL) was added TFA (122.80 g, 1.08 mol, 80 mL), then the reaction was stirred at rt for 2 h. The reaction was concentrated under reduced pressure to afford 1-(3,6- 15 dibromopyridazin-4-yl)cyclopropan-1-amine;trifluoroacetic acid (55 g, quantitative yield, Intermediate 25) as brown solid. LCMS: 0.736 min, 293.8 / 295.8 [M+H]+, Method G. Procedure for the preparation of 2-(((3'-bromospiro[cyclopropane-1,5'-pyridazino[4,3- 20 e][1,3]thiazin]-7'-yl)thio)methyl)-5-(difluoromethyl)benzonitrile (Intermediate 26) To a stirred solution of 1-(3,6-dibromopyridazin-4-yl)cyclopropan-1-amine (0.5 g, 1.70 mmol, Intermediate 25) in DMF (5 mL) was added CS2(2.0 vol) at rt and the mixture was stirred for 16 h. DIPEA (0.66 g, 5.118 mmol) and 2-(bromomethyl)-5-(difluoromethyl)benzonitrile (0.46 g, 25 1.87 mmol, Intermediate 19) was added and the mixture was stirred at rt for 1 h. The reaction mixture was diluted with water (50 mL) and extracted with ethyl acetate (2 x 50 mL). The 62 organic layers were dried over Na2SO4, filtered, and concentrated under reduced pressure. The crude material was purified by flash column chromatography (28% EtOAc in hexane) to afford 2-(((3'-bromospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5- (difluoromethyl)benzonitrile (0.4 g, 0.88 mmol, 47%, Intermediate 26). 5 ¹H NMR (400 MHz, DMSO-d6): δ 8.09 – 8.06 (m, 1H), 7.89 (d, J = 8.0 Hz, 1H), 7.78 (d, J = 8.0 Hz, 1H), 7.59 (s, 1H), 7.08 (t, J = 55.2 Hz, 1H), 4.51 (s, 2H), 1.72 - 1.68 (m, 2H), 1.45 - 1.42 (m, 2H). Procedure for the preparation of 4-(methoxymethyl)-2H-1,2,3-triazole (Intermediate 27) 10 To a solution of 3-methoxyprop-1-yne (200 mg, 2.85 mmol) in DCM (1.5 mL) and water (0.5 mL) was added 1-(azidomethyl)-4-methoxy-benzene (512.18 mg, 3.14 mmol), CuSO4.5H2O (28.50 mg, 114.14 μmol) and sodium ascorbate (22.61 mg, 114.14 μmol) under a nitrogen atmosphere. The mixture was stirred under nitrogen at rt for 12 h. The reaction mixture was 15 then diluted with water (10 mL) and extracted with ethyl acetate (5 mL × 3). The combined organic layers were washed with brine (5 mL), dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (50% EtOAc in hexane) to afford 1-(4-methoxybenzyl)-4-(methoxymethyl)-1H-1,2,3-triazole (540 mg, 80%) as a yellow solid. 201H NMR (400 MHz, CDCl3): δ 7.41 (s, 1H), 7.24 (d, J = 8.6 Hz, 2H), 6.90 (d, J = 8.6 Hz, 2H), 5.46 (s, 2H), 4.56 (s, 2H), 3.81 (s, 3H), 3.40 (s, 3H). 1-(4-Methoxybenzyl)-4-(methoxymethyl)-1H-1,2,3-triazole (260 mg, 1.11 mmol) was added to TFA (3 mL). The reaction mixture was stirred at 100 °C for 12 h. The reaction mixture was 25 concentrated under reduced pressure to afford 4-(methoxymethyl)-2H-1,2,3-triazole (126 mg, quantitative yield, Intermediate 27) as green solid. 1H NMR (400 MHz, CDCl3): δ 13.71 (br s, 3H), 8.00 (s, 1H), 4.71 (s, 2H), 3.47 (s, 3H). 63 Procedure for the preparation of 2-(((3'-fluorospiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazin]-7'-yl)thio)methyl)-5-(trifluoromethyl)nicotinonitrile (Intermediate 28) To a solution of 3'-fluorospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-thiol (330 5 mg, 1.45 mmol, Intermediate 23) in DMF (5 mL) was added the solution of 2-(bromomethyl)- 5-(trifluoromethyl)nicotinonitrile (384.81 mg, 1.45 mmol, Intermediate 19) in DMF (4 mL), then the mixture was stirred at rt for 0.5 h. The reaction mixture was quenched with water (50 mL) and extracted with EtOAc (50 mL × 3). The combined organic layers were washed with brine (50 mL × 3), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. 10 The residue was purified by flash column chromatography (0-50% EtOAc in petroleum ether) to afford 2-(((3'-fluorospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)- 5-(trifluoromethyl)nicotinonitrile (390 mg, 57%, Intermediate 28) as a yellow solid. 1H NMR (400 MHz, CDCl3): δ 9.02 (d, J = 1.8 Hz, 1H), 8.18 (d, J = 1.8 Hz, 1H), 6.50 (s, 1H), 4.62 (s, 2H), 1.74 - 1.67 (m, 2H), 1.49 - 1.41 (m, 2H). 15 Procedure for the preparation of 2-(((3'-bromospiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazin]-7'-yl)thio)methyl)-5-(trifluoromethyl)nicotinonitrile (Intermediate 29) To a solution of 1-(3,6-dibromopyridazin-4-yl)cyclopropan-1-amine (220 mg, 750.96 μmol) in 20 DMF (3 mL) at rt was added CS2(571.79 mg, 7.51 mmol, 452.72 μL) and DIPEA (388.22 mg, 3.00 mmol, 523.21 μL) under a nitrogen atmosphere. The mixture was stirred at rt for 2 h. The resulting solution of 3'-bromospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-thiol in DMF (3 mL) was used directly in the next step. 64 To a solution of 3'-bromospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-thiol (216 mg, 749.51 μmol) in DMF (3 mL) was added a solution of 2-(bromomethyl)-5- (trifluoromethyl)nicotinonitrile (198.64 mg, 749.51 μmol) in DMF (1 mL) at rt and the mixture 5 was stirred for 0.5 h. The reaction mixture was quenched with water (10 mL) and extracted with EtOAc (10 mL × 3). The combined organic layers were washed with brine (50 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The residue was purified by flash column chromatography (0-50% EtOAc in petroleum ether) to afford 2-(((3'- bromospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5- 10 (trifluoromethyl)nicotinonitrile (290 mg, 75%) as a yellow solid. 1H NMR (400 MHz, CDCl3): δ 9.02 (d, J = 1.8 Hz, 1H), 8.18 (d, J = 1.8 Hz, 1H), 6.90 (s, 1H), 4.61 (s, 2H), 1.72 - 1.63 (m, 2H), 1.46 - 1.38 (m, 2H). Procedure for the preparation of 5-(((3'-bromospiro[cyclopropane-1,5'-pyridazino[4,3- 15 e][1,3]thiazin]-7'-yl)thio)methyl)-2-(trifluoromethyl)isonicotinonitrile (Intermediate 30) To a solution of 1-(3,6-dibromopyridazin-4-yl)cyclopropan-1-amine (220 mg, 750.96 μmol, Intermediate 25) in DMF (3 mL) was added DIPEA (388.22 mg, 3.00 mmol, 523.21 μL) and CS2 (571.79 mg, 7.51 mmol, 452.72 μL) under a nitrogen atmosphere. The reaction mixture20 was stirred at rt for 1 h. The resulting solution of 3'-bromospiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazine]-7'-thiol in DMF (3 mL) was used directly in the next step. To a solution of 3'-bromospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-thiol (216 mg, 749.51 μmol) in DMF (3 mL) was added 5-(bromomethyl)-2- 25 (trifluoromethyl)isonicotinonitrile (198.64 mg, 749.51 μmol, Intermediate 18) at rt, and then the mixture was stirred at rt for 1 h. The reaction mixture was diluted with water (10 mL) and extracted with EtOAc (5 mL × 3). The combined organic layers were washed with brine (5 mL), 65 dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (30-100% EtOAc in petroleum ether) to afford 5-(((3'-bromospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)- 2-(trifluoromethyl)isonicotinonitrile (300 mg, yield 74%, Intermediate 30) as a yellow solid. 51H NMR (400 MHz, DMSO-d6): δ 9.05 (s, 1H), 8.52 (s, 1H), 7.59 (s, 1H), 4.57 (s, 2H), 1.74 - 1.67 (m, 2H), 1.48 - 1.42 (m, 2H). Procedure for the preparation of 5-(fluoromethyl)-2-(((3'-fluorospiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)benzonitrile (Intermediate 31) 10 To a solution of 1-(3,6-difluoropyridazin-4-yl)cyclopropan-1-amine (0.3 g, 873.75 μmol, Intermediate 21) and DIPEA (451.70 mg, 3.49 mmol, 608.76 μL) in DMF (3 mL) was added CS2(665.28 mg, 8.74 mmol, 526.74 μL) and the mixture was stirred at 30 °C for 1.5 h under a nitrogen atmosphere. A solution of 3'-fluorospiro[cyclopropane-1,5'-pyridazino[4,3- 15 e][1,3]thiazine]-7'-thiol (873.75 μmol, 99.7%) in DMF (3 mL) was used directly in the next step as a yellow liquid. LCMS: 0.41 min, 228.1 [M+H]+, Method G. To the solution of 3'-fluorospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-thiol20 (198.00 mg, 871.17 μmol) in DMF (3 mL) isolated from the previous step was added 2- (bromomethyl)-5-(fluoromethyl)benzonitrile (198.68 mg, 871.17 μmol) at rt and the mixture was stirred at rt for 0.5 h under a nitrogen atmosphere. The mixture was poured into sat. aq. NH4Cl (20 mL). The aqueous phase was extracted with ethyl acetate (10 mL × 3). The combined organic phases were washed with brine (20 mL), dried over anhydrous Na2SO4, 25 filtered and concentrated under reduced pressure. The residue was purified by flash column chromatography (25-100% EtOAc in hexane) to afford 5-(fluoromethyl)-2-(((3'- 66 fluorospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)benzonitrile (0.25 g, 77%, Intermediate 31) as a yellow solid. 1H NMR (400 MHz, CDCl3): δ 7.66 (s, 1H), 7.63 - 7.52 (m, 2H), 6.52 (s, 1H), 5.51 - 5.33 (m, 2H), 4.44 (s, 2H), 1.71 - 1.65 (m, 2H), 1.49 - 1.43 (m, 2H). 5 Procedure for the preparation of 2-(((3'-iodospiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazin]-7'-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (Intermediate 32) To a solution of 2-(((3'-bromospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'- 10 yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (32 g, 67.89 mmol, Intermediate 8) in dioxane (600 mL) was added TMEDA (3.16 g, 27.16 mmol, 4.10 mL), NaI (20.35 g, 135.79 mmol) and CuI (646.53 mg, 3.39 mmol) under a nitrogen atmosphere. The mixture was stirred at 80 °C for 12 h. The reaction mixture was cooled to rt, filtered and the filtrate was concentrated. The residue was purified by flash column chromatography (0-25% EtOAc in hexane) to afford 2-15 (((3'-iodospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5- (trifluoromethyl)benzonitrile (32.5 g, 57.69 mmol, 85%, Intermediate 32) obtained as a grey solid. 1H NMR (400 MHz, DMSO-d6): δ 8.34 (s, 1H), 7.99 - 8.14 (m, 1H), 7.86 – 7.82 (m, 1H), 7.64 (s, 1H), 4.53 (s, 2H), 1.61 - 1.74 (m, 2H), 1.28 - 1.46 (m, 2H). 20 Procedure for the preparation of 4-methoxyoxazole (Intermediate 33) To a solution of ethyl 4-bromooxazole-5-carboxylate (2 g, 9.09 mmol) in MeOH (20 mL) was added NaOMe (1.47 g, 27.27 mmol) at rt. The reaction mixture was stirred at 80 °C for 12 h. 25 The reaction mixture was diluted with water (80 mL) and 1 N HCl (30 mL), then extracted with 67 ethyl acetate (3 × 20 mL). The combined organic layers were washed with brine (20 mL), dried over sodium sulfate, filtered and concentrated under reduced pressure to afford 4- methoxyoxazole-5-carboxylic acid (296 mg, 21%) as a yellow solid. 1H NMR (400 MHz, DMSO-d6): δ 12.98 (br s, 1H), 8.40 (s, 1H), 3.97 – 3.94 (m, 3H). 5 CuO (32.91 mg, 413.70 μmol) was added to 4-methoxyoxazole-5-carboxylic acid (296 mg, 2.07 mmol) at rt. The reaction mixture was heated to 180 °C and 4-methoxyoxazole (50 mg, 24%, Intermediate 33) was collected via Vigreux distillation apparatus under normal pressure. 1H NMR (400 MHz, CDCl3): δ 7.62 (s, 1H), 7.15 – 7.12 (m, 1H), 3.81 (s, 3H). 10 Procedure for the preparation of 3-(((3'-fluorospiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazin]-7'-yl)thio)methyl)-6-(trifluoromethyl)picolinonitrile (Intermediate 34) To a solution of 1-(3,6-difluoropyridazin-4-yl)cyclopropan-1-amine (0.3 g, 873.75 μmol, 15 Intermediate 23) and DIPEA (564.63 mg, 4.37 mmol, 760.95 μL) in DMF (3 mL) was added CS2(665.28 mg, 8.74 mmol, 526.74 μL) and the mixture was stirred at 30 °C for 2 h under a nitrogen atmosphere. The resulting solution of 3'-fluorospiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazine]-7'-thiol in DMF (3 mL) was used directly in the next step directly. LCMS: 0.41 min, 228.1 [M+H]+, Method G. 20 To the solution of 3'-fluorospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-thiol (0.198 g, 871.17 μmol) in DMF (5 mL) telescoped through from the previous step was added 3-(bromomethyl)-6-(trifluoromethyl)picolinonitrile (355.21 mg, 871.17 μmol, Intermediate 22) in DMF (0.5 mL) and the mixture was stirred at 30 °C for 20 min under a nitrogen atmosphere. 25 The mixture was poured into water (10 mL) and extracted with ethyl acetate (5 mL × 3). The combined organic phases were washed with brine (5 mL), dried over anhydrous Na2SO4, 68 filtered and concentrated under reduced pressure. The residue was purified by flash column chromatography (0-50% EtOAc in petroleum ether) to afford 3-(((3'-fluorospiro[cyclopropane- 1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-6-(trifluoromethyl)picolinonitrile (0.2 g, 54%, Intermediate 34) as off-white solid. 51H NMR (400 MHz, CDCl3): δ 8.15 (d, J = 8.4 Hz, 1H), 7.87 (d, J = 8.4 Hz, 1H), 6.49 (s, 1H), 4.45 (s, 2H), 1.70 - 1.62 (m, 2H), 1.50 - 1.42 (m, 2H). Procedure for the preparation of 3-(((3'-bromospiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazin]-7'-yl)thio)methyl)-6-(trifluoromethyl)picolinonitrile (Intermediate 35) 10 To a solution of 1-(3,6-dibromopyridazin-4-yl)cyclopropan-1-amine (0.5 g, 1.07 mmol, Intermediate 25) and DIPEA (694.60 mg, 5.37 mmol, 936.12 μL) in DMF (5 mL) was added CS2(818.43 mg, 10.75 mmol, 648.00 μL) and the mixture was stirred at 30 °C for 2 h under a nitrogen atmosphere. The resulting solution of 3'-bromospiro[cyclopropane-1,5'- 15 pyridazino[4,3-e][1,3]thiazine]-7'-thiol (0.309 g, 99%) in DMF (5 mL) was used directly in the next step. LCMS: 0.44 min, 288.0 / 290.0 [M+H]+, Method G. To the solution of 3'-bromospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-thiol20 (0.309 g, 1.07 mmol) in DMF (5 mL) telescoped through from the previous step was added 3- (bromomethyl)-6-(trifluoromethyl)picolinonitrile (437.19 mg, 1.07 mmol) in DMF (1 mL) and the mixture was stirred at 30 °C for 20 min under a nitrogen atmosphere. The mixture was poured into water (10 mL) and extracted with ethyl acetate (5 mL × 3). The combined organic phases were washed with brine (5 mL), dried over anhydrous Na2SO4, filtered and concentrated under 25 reduced pressure. The residue was purified by flash column chromatography (0-50% EtOAc in petroleum ether) to afford 3-(((3'-bromospiro[cyclopropane-1,5'-pyridazino[4,3- 69 e][1,3]thiazin]-7'-yl)thio)methyl)-6-(trifluoromethyl)picolinonitrile (0.38 g, 75%, Intermediate 35) as off-white solid. 1H NMR (400 MHz, CDCl3): δ 8.14 (d, J = 8.4 Hz, 1H), 7.87 (d, J = 8.4 Hz, 1H), 6.88 (s, 1H), 4.44 (s, 2H), 1.65 - 1.60 (m, 2H), 1.47 - 1.40 (m, 2H). 5 Procedure for the preparation of 7'-(((2- (trimethylsilyl)ethoxy)methyl)thio)spiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazine]-3'-carbonitrile (Intermediate 36) 10 A solution of tert-butyl (1-(3-chloro-6-cyanopyridazin-4-yl)cyclopropyl)carbamate (5 g, 16.96 mmol, Intermediate 7) in TFA (10 mL) and DCM (50 mL) was stirred at rt for 1 h. The reaction mixture was concentrated under reduced pressure to afford 5-(1-aminocyclopropyl)-6- chloropyridazine-3-carbonitrile (3.3 g, 99%) as a brown solid. LCMS: 0.37 min, 195.0 [M+H]+, Method G. 15 To a solution of 5-(1-aminocyclopropyl)-6-chloropyridazine-3-carbonitrile (3.3 g, 16.96 mmol) in DMF (15 mL) was added CS2(19.37 g, 254.34 mmol, 15.33 mL) and DIPEA (21.91 g, 169.56 mmol, 29.53 mL) at rt. The mixture was heated to 30 °C and stirred at 30 °C for 1 h. The reaction mixture was concentrated under reduced pressure to afford 7'- 20 mercaptospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-3'-carbonitrile (3.97 g, 99%) as a black liquid. LCMS: 0.41 min, 232.9 [M-H]-, Method G. To a solution of 7'-mercaptospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-3'- 25 carbonitrile (3.9 g, 14.65 mmol) in DMF (20 mL) was added SEM-Cl (2.44 g, 14.65 mmol, 2.59 mL) at 0 °C. The mixture was warmed to rt and stirred for 0.5 h. The reaction mixture was diluted with water (30 mL) and extracted with ethyl acetate (3 × 30 mL). The combined organic phases were washed with brine (3 × 20 mL), dried over sodium sulfate, filtered and concentrated under reduced pressure. The crude material was purified by flash column30 chromatography (10-85% EtOAc in hexane) to afford 7'-(((2- 70 (trimethylsilyl)ethoxy)methyl)thio)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-3'- carbonitrile (1.5 g, 21%) as a yellow oil. 1H NMR (400 MHz, DMSO-d6): δ 7.91 (s, 1H), 5.26 (s, 2H), 3.59 – 3.55 (m, 2H), 1.77 - 1.70 (m, 2H), 1.56 - 1.49 (m, 2H), 0.92 - 0.81 (m, 2H), -0.02 (s, 9H). 5 Procedure for the preparation of 5-((methylamino)methyl)isoxazol-3-ol (Intermediate 37) To a solution of methyl 3-hydroxyisoxazole-5-carboxylate (3.37 g, 23.55 mmol) in DMF (20 10 mL) was added K2CO3(3.65 g, 26.38 mmol) at 0 °C and after 10 min PMB-Cl (4.43 g, 28.26 mmol, 3.84 mL) was added. The yellow suspension was stirred for 15 min at 0 °C, 15 min at 20 °C and 4 h at 60 °C. The reaction mixture was poured into aqueous 1 N HCl (30 mL), extracted with EtOAc (3 x 10 mL), then washed with 1 N HCl (15 mL) and brine (20 mL). The organic layer was dried over Na2SO4, filtered and concentrated under reduced pressure to 15 afford a residue. The residue was purified by flash column chromatography (10-30% ethyl acetate in hexane) to afford methyl 3-((4-methoxybenzyl)oxy)isoxazole-5-carboxylate (5.0 g, 81%) as a colourless oil which solidified after stood overnight. 1H NMR (400 MHz, CDCl3): δ 7.38 (d, J = 8.6 Hz, 2H), 6.92 (d, J = 8.6 Hz, 2H), 6.54 (s, 1H), 5.24 (s, 2H), 3.94 (s, 3H), 3.82 (s, 3H). 20 To a solution of methyl 3-((4-methoxybenzyl)oxy)isoxazole-5-carboxylate (2 g, 7.60 mmol) in EtOH (20 mL) at 0 ° C was added NaBH4(574.86 mg, 15.19 mmol) in portions under nitrogen. Then the mixture was warmed to rt and stirred for 2 h. The reaction mixture was quenched slowly with aqueous NH4Cl (30 mL) and extracted with EtOAc (3 x 20 mL). The organic layer 25 was washed with brine (20 mL), dried over Na2SO4, filtered and concentrated under reduced pressure to afford the crude product. The crude product was purified flash column chromatography (0-30% ethyl acetate in hexane) to afford (3-((4-methoxybenzyl)oxy)isoxazol- 5-yl)methanol (1.5 g, 84%) as colourless oil which solidified after stood overnight. 71 1H NMR (400 MHz, CDCl3): δ 7.38 (d, J = 8.8 Hz, 2H), 6.92 (d, J = 8.8 Hz, 2H), 5.89 (s, 1H), 5.19 (s, 2H), 4.66 (s, 2H), 3.82 (s, 3H). To a solution of (3-((4-methoxybenzyl)oxy)isoxazol-5-yl)methanol (1 g, 4.25 mmol) in DCM (20 5 mL) at 0 °C was added Dess-Martin periodinane (3.61 g, 8.50 mmol) in portions under nitrogen. The mixture was warmed to rt and stirred under nitrogen for 4 h. The reaction mixture was quenched slowly with saturated aqueous NaHCO3(20 mL) and then extracted with DCM (3 x 10 mL). The combined organic phases were washed with brine, dried over sodium sulfate, filtered and concentrated under reduced pressure, and purified flash column chromatography10 (10-20% ethyl acetate in hexane) to afford 3-((4-methoxybenzyl)oxy)isoxazole-5- carbaldehyde (0.5 g, 50%) as white solid. 1H NMR (400 MHz, CDCl3): δ 9.84 (s, 1H), 7.39 (d, J = 8.6 Hz, 2H), 6.93 (d, J = 8.6 Hz, 2H), 6.56 (s, 1H), 5.27 (s, 2H), 3.82 (s, 3H). 15 To a solution of 3-((4-methoxybenzyl)oxy)isoxazole-5-carbaldehyde (500 mg, 2.14 mmol) in DCM (10 mL) was added methanamine (2 M in THF, 1.18 mL) and AcOH (128.75 mg, 2.14 mmol, 122.73 μL). The mixture was stirred for 10 min and then NaBH(OAc)3 (908.76 mg, 4.29 mmol) was added and the mixture was stirred at rt under nitrogen for 12 h. The reaction mixture was quenched with water (10 mL) and extracted with DCM (3 x 10 mL). The combined 20 organic layer was washed with brine (20 mL), dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified flash column chromatography (0- 50% methanol in ethyl acetate) to afford 1-(3-((4-methoxybenzyl)oxy)isoxazol-5-yl)-N- methylmethanamine (200 mg, 38%) as white solid. 1H NMR (400 MHz, DMSO-d6): δ 7.40 (d, J = 8.6 Hz, 2H), 6.95 (d, J = 8.6 Hz, 2H), 6.20 (s, 25 1H), 5.14 (s, 2H), 3.85 (s, 2H), 3.76 (s, 3H), 2.36 (s, 3H). 1-(3-((4-methoxybenzyl)oxy)isoxazol-5-yl)-N-methylmethanamine (100 mg, 402.78 μmol) was added into a solution of HBr (2.98 g, 14.73 mmol, 2 mL, 40% wt in AcOH) and then the mixture was stirred at 100 °C for 2 h. The reaction mixture was concentrated under reduced pressure 30 to afford the crude product. The crude product was purified by prep-HPLC (Method J) to afford 5-(methylaminomethyl)isoxazol-3-ol (30 mg, 58%, Intermediate 37) as white solid. 1H NMR (400 MHz, DMSO-d6): δ 5.83 (s, 1H), 3.60 (s, 2H), 2.26 (s, 3H). 72 Procedure for the preparation of 5-(bromomethyl)-2-(trifluoromethyl)pyrimidine-4- carbonitrile (Intermediate 38) 5 A solution of 5-bromo-2-(trifluoromethyl) pyrimidine (10 g, 44.06 mmol) in dioxane (100 mL) was degassed with a stream of nitrogen for 15 min. Pd(PPh3)4(2.55 g, 2.20 mmol) was added followed by AlMe3(2 M, 44.06 mL). The reaction mixture was heated to 100 °C under nitrogen and stirred for 1 h. After cooling to rt, the reaction mixture was quenched with methanol (15 mL) and then concentrated under reduced pressure. The resulting material was partitioned 10 between ethyl acetate (30 mL) and water (30 mL) and then filtered to remove the precipitate that formed. The two layers of the filtrate were separated and the aqueous phase was extracted with additional ethyl acetate (3 × 30 mL). The combined organic extracts were washed with brine, dried over sodium sulfate, filtered, concentrated and purified by flash column chromatography (0-10% EtOAc in hexane) to afford 5-methyl-2-(trifluoromethyl) 15 pyrimidine (3 g, 42%) as white solid. 1H NMR (400 MHz, CDCl3): δ 8.73 (s, 2H), 2.44 (s, 3H). To a solution of 5-methyl-2-(trifluoromethyl)pyrimidine (2 g, 12.34 mmol) and UHP (2.61 g, 27.76 mmol) in DCM (20 mL) was added TFAA (7.77 g, 37.01 mmol, 5.14 mL) at 0 °C under 20 nitrogen. The mixture was stirred at rt for 12 h under a nitrogen atmosphere. The mixture was diluted with DCM (50 mL), washed with sat. aq. Na2SO3(50 mL), sat. aq. NaHCO3(50 mL) and brine (30 mL), then dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-50% EtOAc in hexane) to afford 5-methyl-1-oxido-2-(trifluoromethyl) pyrimidin-1-ium (1.2 g, 55%) as off-white solid. 251H NMR (400 MHz, CDCl3: δ 8.34 (s, 1H), 8.15 (s, 1H), 2.41 (s, 3H). 73 To a solution of TEA (1.14 g, 11.23 mmol, 1.56 mL) in CHCl3(20 mL) at 0 °C was added POCl3(1.72 g, 11.23 mmol, 1.05 mL) dropwise under a nitrogen atmosphere. Then 5-methyl-1-oxido- 2-(trifluoromethyl)pyrimidin-1-ium (1 g, 5.61 mmol) in CHCl3(6 mL) was added at 0 °C under a nitrogen atmosphere. The mixture was stirred at 70 °C for 18 h. After cooling to room 5 temperature, the mixture was diluted with DCM (15 mL), washed with sat. aq. NaHCO3(25 mL) and brine (30 mL), dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-10% EtOAc in hexane) to afford 4-chloro-5-methyl-2-(trifluoromethyl) pyrimidine (450 mg, 41%) as light black oil. 1H NMR (400 MHz, CDCl3): δ = 8.68 (s, 1H), 2.48 (s, 3H). 10 To a solution of 4-chloro-5-methyl-2-(trifluoromethyl)pyrimidine (450 mg, 2.29 mmol) in DMF (5 mL) was added dicyanozinc (403.25 mg, 3.43 mmol, 217.97 μL) and Pd(PPh3)4(264.55 mg, 228.94 μmol) under a nitrogen atmosphere. The mixture was stirred at 130 °C for 3 h. The reaction mixture was diluted with water (10 mL) and extracted with ethyl acetate (3 × 10 15 mL). The combined organic phases were washed with brine (10 mL), dried over sodium sulfate, filtered and the filtrate was concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-10% EtOAc in hexane) to afford 5-methyl-2- (trifluoromethyl) pyrimidine-4-carbonitrile (286 mg, 67%) as light yellow oil. 1H NMR (400 MHz, CDCl3): δ 9.01 (s, 1H), 2.67 (s, 3H). 20 To a solution of 5-methyl-2-(trifluoromethyl)pyrimidine-4-carbonitrile (270 mg, 1.44 mmol) in MeCN (8.1 mL) was added TFA (32.90 mg, 288.6 μmol, 21.44 μL) and NBS (770.44 mg, 4.33 mmol). The mixture was stirred at 45 °C for 20 min under hv (450 nm) irradiation. The reaction mixture was concentrated under reduced pressure to give a residue, which was purified by25 flash column chromatography (0-30% EtOAc in hexane) to afford 5-(bromomethyl)-2- (trifluoromethyl) pyrimidine-4-carbonitrile (130 mg, 34%, Intermediate 38) as colourless oil. 1H NMR (400 MHz, CDCl3) δ = 9.21 (s, 1H), 4.66 (s, 2H). Procedure for the preparation of 1-(3-bromo-6-(2H-1,2,3-triazol-2-yl)pyridazin-4- 30 yl)cyclopropan-1-amine (Intermediate 39) 74 To a solution of tert-butyl N-[1-(3,6-dibromopyridazin-4-yl)cyclopropyl]carbamate (25 g, 63.60 mmol) in dioxane (450 mL) was added 2H-1,2,3-triazole (4.39 g, 63.60 mmol, 3.69 mL), caesium carbonate (62.17 g, 190.80 mmol) and dicyclohexyl-[2-(2,4,6-triisopropylphenyl) 5 phenyl]phosphane;methanesulfonate;[2-[2-(methylamino)phenyl]phenyl]palladium(1+) (5.47 g, 6.36 mmol) under nitrogen. The mixture was stirred at 100 °C for 12 h under nitrogen. The reaction mixture was filtered and the filtrate was concentrated under reduced pressure to give a residue, which was purified by flash column chromatography (0-33% ethyl acetate in hexane) to afford tert-butyl (1-(3-bromo-6-(2H-1,2,3-triazol-2-yl)pyridazin-4-10 yl)cyclopropyl)carbamate (2.2 g, 9%) as pale yellow solid and tert-butyl (1-(3-bromo-6-(1H- 1,2,3-triazol-1-yl)pyridazin-4-yl)cyclopropyl)carbamate (5 g, 21%) as pale yellow solid. 1H NMR (400 MHz, CDCl3): δ 8.36 (br s, 1H), 8.00 (s, 2H), 5.64 (br s, 1H), 1.38 (br s, 11H), 1.32 - 1.24 (m, 2H). 15 To a solution of tert-butyl N-[1-[3-bromo-6-(triazol-2-yl) pyridazin-4-yl]cyclopropyl]carbamate (4.4 g, 11.54 mmol) in MeCN (50 mL) was added TsOH (3.97 g, 23.08 mmol). The mixture was stirred at 50 °C for 1 h. The solids formed in the reaction mixture were collected by filtration. The crude material was purified by trituration with acetonitrile (50 mL) to afford 1-[3-bromo-6- (triazol-2-yl) pyridazin-4-yl]cyclopropanamine (4.5 g, 77%, TsOH salt, Intermediate 1) as white 20 solid. 1H NMR (400 MHz, D2O): δ 8.53 (s, 1H), 8.15 (s, 2H), 7.58 (d, J = 8.0 Hz, 2H), 7.27 (br d, J = 8.0 Hz, 2H), 2.32 (s, 3H), 1.72 - 1.64 (m, 2H), 1.53 - 1.44 (m, 2H). Procedure for the preparation of 1-(3-chloro-6-(oxazol-2-yl)pyridazin-4-yl)cyclopropan- 25 1-amine (Intermediate 40) 75 To a solution of tert-butyl (1-(3,6-dibromopyridazin-4-yl)cyclopropyl)carbamate (8 g, 20.35 mmol) in dioxane (100 mL) was added tributyl(oxazol-2-yl)stannane (10.93 g, 30.53 mmol) and Pd(PPh3)2Cl2(4.29 g, 6.11 mmol) under a nitrogen atmosphere. The mixture was stirred 5 at 100 °C for 8 h under a nitrogen atmosphere. After cooling to room temperature, the reaction mixture was diluted with water (150 mL) and extracted with EtOAc (3 × 80 mL). The combined organic layers were washed with brine (200 mL), dried over Na2SO4, filtered and concentrated under reduced pressure. The residue was purified by flash column chromatography (0-33% ethyl acetate in hexane) to afford tert-butyl N-[1-(3-bromo-6-oxazol-2-yl-pyridazin-4-yl) 10 cyclopropyl] carbamate (2.1 g, 27%) as yellow solid. 1H NMR (400 MHz, DMSO-d6): δ 8.47 (s, 1H), 8.21 (br s, 1H), 7.95 (br s, 1H), 7.61 (s, 1H), 1.29 (s, 9H), 1.24 – 1.18 (m, 4H). To a solution of tert-butyl (1-(3-bromo-6-(oxazol-2-yl)pyridazin-4-yl)cyclopropyl)carbamate 15 (100 mg, 262.31 μmol) in DCM (1 mL) was added HCl / EtOAc (4 M, 3 mL). The mixture was stirred at rt for 1 h. The mixture was concentrated to afford 1-(3-chloro-6-(oxazol-2- yl)pyridazin-4-yl)cyclopropan-1-amine (70 mg, 256.30 μmol, HCl, Intermediate 40) as a pale yellow solid, which was used in the next step directly. LCMS: 0.26 min, 237.2 [M+H]+, Method G. 20 Procedure for the preparation of 2-(bromomethyl)-5-chloronicotinonitrile (Intermediate 41) 76 A mixture of methyl 5-chloro-2-methyl-pyridine-3-carboxylate (1 g, 5.39 mmol) in NH3 / MeOH (7 M, 12.31 mL) was stirred at 60 °C for 12 h. The reaction mixture was concentrated under reduced pressure to afford 5-chloro-2-methylnicotinamide (900 mg, crude) as a white solid. 1H NMR (400 MHz, DMSO-d6): δ 8.54 (s, 1H), 8.00 (br s, 1H), 7.87 (s, 1H), 7.68 (br s, 1H), 5 2.53 (s, 3H). To a solution of 5-chloro-2-methyl-pyridine-3-carboxamide (1 g, 5.86 mmol) in DCM (15 mL) was added Burgess reagent (2.79 g, 11.72 mmol). The mixture was stirred at rt for 2 h. The reaction mixture was diluted with water (30 mL) and extracted with DCM (3 × 15 mL). The 10 combined organic layers were washed with brine (50 mL), dried over Na2SO4, filtered and concentrated under reduced pressure to give a residue, which was purified by flash column chromatography (0-5% ethyl acetate in hexane) to afford 5-chloro-2-methylnicotinonitrile (770 mg, 86%) as a white solid. 1H NMR (400 MHz, DMSO-d6): δ 8.79 (d, J = 2.0 Hz, 1H), 8.52 (d, J = 2.0 Hz, 1H), 2.66 (s, 15 3H). Solution 1: 5-chloro-2-methyl-pyridine-3-carbonitrile (600 mg, 3.93 mmol) was dissolved in MeCN (20 mL). NBS (839.85 mg, 4.72 mmol) and TFA (89.68 mg, 786.47 μmol) were added. The solution 1 was pumped by Pump 1 {S1, P1, 0.67 mL / min} to flow reactor 1 {FLR1, FEP, 20 Coils reactor, 3.175(1 / 8’’) mm, 10.048 mL, 450 nm, 600 W, 45 °C}. The residence time of flow reactor 1 was {FLR1, 15 min}. The reaction mixture was diluted with water (30 mL) and extracted with ethyl acetate (3 × 15 mL). The combined organic layers were washed with brine (50 mL), dried over Na2SO4, filtered and concentrated under reduced pressure to give a residue, which was purified by flash25 column chromatography (0-5% ethyl acetate in hexane) to afford 2-(bromomethyl)-5- chloronicotinonitrile (460 mg, 50%, Intermediate 41) as a yellow oil. 1H NMR (400 MHz, DMSO-d6) δ 8.91 (d, J = 2.4 Hz, 1H), 8.67 (d, J = 2.4 Hz, 1H), 4.79 (s, 2H). 30 Procedure for the preparation of 2-(bromomethyl)-5-(1,3,4-oxadiazol-2-yl)benzonitrile (Intermediate 42) 77 To a solution of 3-cyano-4-methylbenzoic acid (2 g, 12.41 mmol) in DCM (20 mL) was added (COCl)2 (1.89 g, 14.89 mmol, 1.30 mL) and DMF (90.71 mg, 1.24 mmol, 95.49 μL) at rt. The mixture was stirred for 1 h. The reaction mixture was concentrated under reduced pressure to 5 afford 3-cyano-4-methylbenzoyl chloride (2.3 g, crude) as a yellow solid. LCMS: 0.49 min, 176.2 [M+H]+(methyl ester, sample quenched using MeOH), Method G. To a solution of 3-cyano-4-methylbenzoyl chloride (2.3 g, 12.81 mmol) in EtOH (25 mL) was added N2H4-H2O (8.01 g, 128.06 mmol, 7.76 mL, 80% purity) at 0 °C under nitrogen. The 10 resulting mixture was stirred at rt for 3 h. The solids formed in the reaction mixture were collected by filtration and were washed with water (30 mL). The filtrate was extracted with EtOAc (3 × 10 mL). The combined organic layers were washed with brine (20 mL), dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was triturated with 25% EtOAc in hexane (30 mL) at rt for 0.5 h. The solids were collected by filtration and 15 the filter cake was dried under reduced pressure to afford 3-cyano-4-methylbenzohydrazide (0.5 g, 20%) as a white solid. LCMS: 0.30 min, 176.2 [M+H]+, Method G. To a mixture of 3-cyano-4-methylbenzohydrazide (0.25 g, 1.43 mmol) in CH(OMe)3(2.42 g, 20 22.80 mmol, 2.50 mL) was added TsOH (24.57 mg, 142.70 μmol) at rt. The mixture was heated to 100 °C and stirred at 100 °C for 1 h. After cooling to room temperature, the reaction mixture was concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-33% ethyl acetate in hexane) to afford 2-methyl-5-(1,3,4-oxadiazol-2- yl)benzonitrile (0.2 g, 68%) as a white solid. 25 LCMS: 0.41 min, 186.1 [M+H]+, Method G. 78 Solution 1: 2-methyl-5-(1,3,4-oxadiazol-2-yl)benzonitrile (0.15 g, 810.01 μmol) was dissolved in MeCN (3 mL), and NBS (173.00 mg, 972.02 μmol) and TFA (18.47 mg, 162.00 μmol, 12.03 μL) were added at rt. The solution 1 was pumped by Pump 1 { S1, P1, 0.67 mL / min } to flow reactor 1 { FLR1, FEP, Coils reactor, 3.175(1 / 8’’) mm, 10.048 mL, 450 nm, 600 W, 45 °C}. The 5 residence time of flow reactor 1 was {FLR1, 15 min}. The reaction mixture was poured into water (30 mL) and extracted with EtOAc (3 × 10 mL). The combined organic layers were washed with brine (10 mL), dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-50% ethyl acetate in hexanes) to afford 2-(bromomethyl)-5-(1,3,4-oxadiazol-2-yl)benzonitrile (0.2 g, 10 84%, Intermediate 42) as a white solid. LCMS: 0.43 min, 264.0 / 266.0 [M+H]+, Method G. Synthesis of Examples Route A 15 Typical procedure for the preparation of 7-chloro-1-methyl-1H-pyridazino[4,3- e][1,3,4]thiadiazines as exemplified by 2-[(7-chloro-1-methylpyridazino[4,3- e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 1) To a solution of 4-bromo-3,6-dichloropyridazine (2 g, 8.78 mmol) in MeOH (20 mL) was added 20 methylhydrazine (3.18 g, 27.61 mmol, 3.63 mL) at rt under nitrogen, then the mixture was stirred at rt for 4 h. The mixture was concentrated under reduced pressure and triturated with MTBE (3 mL) to afford 3,6-dichloro-4-(1-methylhydrazineyl)pyridazine (1 g, 5.13 mmol, 58%) as white solid. 1H NMR (400 MHz, DMSO-d6): δ 7.40 (s, 1H), 5.00 (s, 2H), 3.32 (s, 3H). 25 To a solution of 3,6-dichloro-4-(1-methylhydrazineyl)pyridazine (200 mg, 1.04 mmol) in NMP (4 mL) was added KOH (5 M, 621.65 μL) and the mixture was stirred at rt for 10 min. Carbon 79 disulfide (788.88 mg, 10.36 mmol, 624.61 μL) and 18-crown-6 (273.86 mg, 1.04 mmol) were added and the mixture was stirred at rt for 2 h. 2-(bromomethyl)-5-(trifluoromethyl)benzonitrile (273.57 mg, 1.04 mmol) was added and the mixture was stirred at rt for 4 h. The mixture was poured into water (30 mL) and extracted with EtOAc (3 x 10 mL). The combined organic layers 5 were washed with brine (3 x 10 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by prep HPLC (Method A) to afford 2-[(7-chloro-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (126.9 mg, 29% yield) as a yellow solid. Analytical data for Example 1 can be found in Table 2. 10 Route B Typical procedure for the preparation of 7-methyl-1H-pyridazino[4,3- e][1,3,4]thiadiazines as exemplified by 2-(((1-cyclopropyl-7-methyl-1H-pyridazino[4,3- e][1,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (Example 3) 15 4-bromo-6-methylpyridazin-3(2H)-one (2 g, 10.58 mmol) in POCl3(20 mL) was stirred at 80 °C for 5 h. The reaction mixture was concentrated under reduced pressure, diluted with water (30 mL) and extracted with EtOAc (3 x 20 mL). The combined organic layers were washed with brine (20 mL), dried over Na2SO4, filtered and concentrated under reduced pressure to 20 afford 3,4-dichloro-6-methylpyridazine (1.6 g, 9.52 mmol, 90%) as light yellow solid. 1H NMR (400 MHz, DMSO-d6): δ 8.10 (s, 1H), 2.66 - 2.57 (m, 3H). To a solution of 3,4-dichloro-6-methylpyridazine (600 mg, 3.68 mmol) and cyclopropylhydrazine hydrochloride (999.08 mg, 9.20 mmol) in MeOH (6 mL) was added 25 DIPEA (2.38 g, 18.40 mmol, 3.21 mL). The reaction was stirred at rt for 12 h. The reaction was concentrated under reduced pressure and purified by flash column chromatography (10-100% EtOAc in petroleum ether) to give 3-chloro-4-(1-cyclopropylhydrazineyl)-6-methylpyridazine (340 mg, 1.56 mmol, 42%) as light brown solid. 80 1H NMR (400 MHz, CDCl3): δ 7.09 (s, 1H), 2.85 - 2.82 (m, 1H), 2.63 (s, 3H), 1.03 - 0.88 (m, 2H), 0.75 - 0.62 (m, 2H). To a solution of 3-chloro-4-(1-cyclopropylhydrazineyl)-6-methylpyridazine (200 mg, 1.01 5 mmol) in NMP (2 mL) was added 5 M KOH (604.07 μL) and the mixture was stirred at rt for 10 min. Carbon disulfide (766.57 mg, 10.07 mmol, 606.94 μL) and 18-crown-6 (266.11 mg, 1.01 mmol) were added and the mixture was stirred at rt for 2 h under nitrogen. 2- (bromomethyl)-5-(trifluoromethyl)benzonitrile (265.83 mg, 1.01 mmol) was added and the mixture was stirred at rt for 1 h under nitrogen. The reaction mixture was diluted with water 10 (30 mL) and extracted with EtOAc (3 x 10 mL). The combined organic layers were washed with brine (10 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The residue was purified by prep HPLC (Method A) to afford 2-(((1-cyclopropyl-7- methyl-1H-pyridazino[4,3-e][1,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (88.49 mg, 0.207 mmol, 21%) as light yellow solid. 15 Analytical data for Example 3 can be found in Table 3. Route C Typical procedure for the preparation of 1-methyl-1H-pyridazino[4,3-e][1,3,4]thiadiazin- 7-amines as exemplified by 2-[(1-methyl-7-morpholin-4-ylpyridazino[4,3- 20 e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 4) A solution of 2-[(7-bromo-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (Example 1, 200 mg, 0.481 mmol) in morpholine (2.10 g, 24.05 mmol, 2.12 mL) was stirred at 50 °C for 12 h. The reaction mixture was concentrated under25 reduced pressure and purified by prep HPLC (Method A) to afford 2-[(1-methyl-7-morpholin- 4-ylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (103.39 mg, 0.222 mmol, 46% yield) as a light yellow solid. Analytical data for Example 4 can be found in Table 4. 81 Route D Typical procedure for the preparation of 1-methyl-1H-pyridazino[4,3- e][1,3,4]thiadiazines via halogenation of 3-chloropyridazine intermediates as 5 exemplified by 2-[(1-methyl-7-phenylpyridazino[4,3-e][1,3,4]thiadiazin-3- yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 6) A solution of n-BuLi (2.5 M, 2.52 mL) was added to a stirred mixture of 2, 2, 6, 6- tetramethylpiperidine (963.29 mg, 6.82 mmol, 1.16 mL) in THF (anhydrous, 40 mL) at -30°C 10 under nitrogen. The mixture was warmed to 0 °C and stirred for 30 min. The mixture was cooled to -70 °C and a cooled (-70 °C) solution of 3-chloro-6-phenylpyridazine (1 g, 5.25 mmol) in THF (5 mL) was added. The mixture was stirred at -70 °C for 1.5 h. I2(1.46 g, 5.77 mmol, 1.16 mL) was added and the mixture was stirred at -70 °C for 1.5 h. The reaction mixture was quenched at -70 °C using a solution of THF:EtOH:HCl (4:1:1, 10 mL). The mixture was warmed 15 to rt and sat. aq. NaHCO3was added. The solution was decolorised with Na₂S₂O₃ and concentrated under reduced pressure. The residue was extracted with DCM (3 x 20 mL), then the combined organic layers were dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0- 50% EtOAc in petroleum ether) to afford 3-chloro-4-iodo-6-phenylpyridazine (0.260 g, 0.808 20 mmol, 15% yield) as an off-white solid. 1H NMR (400 MHz, CDCl3): δ 8.36 (s, 1H), 8.09 - 7.97 (m, 2H), 7.60 - 7.48 (m, 3H). To a solution of 3-chloro-4-iodo-6-phenylpyridazine (260 mg, 0.808 mmol) in MeOH (3 mL) was added methylhydrazine (283.83 mg, 2.46 mmol, 324.38 μL) dropwise. The reaction 25 mixture was stirred at 35 °C for 12 h. Additional methylhydrazine (283.83 mg, 2.46 mmol, 324.38 μL) was added and the mixture was stirred at 35 °C for a further 2 h. The reaction mixture was quenched by water (10 mL), then extracted with EtOAc (3 x 10 mL). The organic layers were combined, washed with brine (20 mL), dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column 82 chromatography (0-50% EtOAc in petroleum ether) to afford 3-chloro-4-(1-methylhydrazineyl)- 6-phenylpyridazine (75 mg, 0.305 mmol, 37% yield) as a light yellow solid. 1H NMR (400 MHz, CDCl3): δ 8.08 - 7.96 (m, 2H), 7.72 (s, 1H), 7.57 - 7.44 (m, 3H), 3.40 (s, 3H). 5 To a stirred solution of 3-chloro-4-(1-methylhydrazineyl)-6-phenylpyridazine (75 mg, 0.305 mmol) in NMP (1.5 mL) was added KOH (5 M, 191.75 μL) at rt and the mixture was stirred for 10 min. Carbon disulfide (243.33 mg, 3.20 mmol, 192.66 μL) and 18-crown-6 (84.47 mg, 0.320 mmol) were added at rt and the mixture was stirred for 2 h. 2-(bromomethyl)-5- 10 (trifluoromethyl)benzonitrile (84.38 mg, 0.320 mmol) was added at rt and the mixture was stirred for 12 h. The reaction mixture was concentrated under reduced pressure and purified by prep HPLC (Method A) to afford 2-[(1-methyl-7-morpholin-4-ylpyridazino[4,3- e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (66.58 mg, 0.145 mmol, 45%) as a yellow solid. 15 Analytical data for Example 6 can be found in Table 5. Route E Procedure for the preparation of 2-[(7-fluoro-1-methylpyridazino[4,3-e][1,3,4]thiadiazin- 3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 8) 20 To a solution of 2-(((7-amino-1-methyl-1H-pyridazino[4,3-e][1,3,4]thiadiazin-3-yl)thio)methyl)- 5-(trifluoromethyl)benzonitrile (Intermediate 1, 50 mg, 0.126 mmol) in HF•Py. (1.25 g, 12.61 mmol, 1.14 mL) was added NaNO2(87.02 mg, 1.26 mmol) at 0 °C, then the mixture was stirred at 0 °C for 20 min. Additional NaNO2(43.51 mg, 0.631 mmol) was added to the mixture at 0 25 °C and the mixture was stirred at 0 °C for 10 min. The mixture was poured into sat. a.q. NaHCO3(20 mL) and extracted with EtOAc (3 x 15 mL). The combined organic layers were washed with brine (3 x 10 mL), filtered and concentrated under reduced pressure. The crude material was purified by prep HPLC (Method B) to afford 2-[(7-fluoro-1-methylpyridazino[4,3- 83 e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (12.01 mg, 0.029 mmol, 23%) as a yellow solid. Analytical data for Example 8 can be found in Table 6. 5 Route F Typical procedure for the preparation of 1-methyl-1H-pyridazino[4,3- e][1,3,4]thiadiazines via synthesis of 3-chloropyridazine intermediates using a Suzuki- Miyaura coupling, followed by halogenation as exemplified by 2-[[7-(furan-2-yl)-1- methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5- 10 (trifluoromethyl)benzonitrile (Example 10) To a solution of furan-2-ylboronic acid (5 g, 44.69 mmol), 3,6-dichloropyridazine (7.99 g, 53.62 mmol) and K2CO3(18.53 g, 134.06 mmol) in 1,4-dioxane (50 mL) and water (20 mL) was added Pd(dppf)Cl2(1.63 g, 2.23 mmol). The mixture was stirred at 90 °C for 12 h. The reaction 15 was quenched with water (50 mL) and extracted with EtOAc (3 x 50 mL). The organic layers were combined, washed with brine (50 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-50% EtOAc in petroleum ether). The product-containing fractions were combined and evaporated to dryness under reduced pressure. The product was triturated 20 using MTBE(10 mL) to afford 3-chloro-6-(furan-2-yl)pyridazine (2 g, 10.50 mmol, 24%) as a white solid. 1H NMR (400 MHz, MeOD): δ 8.05 - 8.03 (m, 1H), 7.85 - 7.76 (m, 2H), 7.35 - 7.34 (m, 1H), 6.69 - 6.68 (m, 1H). 84 A solution of n-BuLi (2.5 M, 3.99 mL) was added to a stirred mixture of 2, 2, 6, 6- tetramethylpiperidine (1.53 g, 10.80 mmol, 1.83 mL) in THF (anhydrous, 60 mL) at -30 °C under nitrogen. The mixture was warmed to 0 °C and stirred for 30 min. The mixture was cooled to -70 °C and a cold (-70 °C) solution of afford 3-chloro-6-(furan-2-yl)pyridazine (1.5 g, 5 8.31 mmol) in THF (7.5 mL) was added. The mixture was stirred at -70 °C for 1.5 h. I2(2.32 g, 9.14 mmol, 1.84 mL) was added and the mixture was stirred at -70 °C for 1.5 h. The reaction mixture was quenched at -70 °C using a solution of THF:EtOH:HCl (4:1:1, 15mL). The mixture was warmed to rt and basified using sat. aq. NaHCO3solution. The solution was decolorised using Na₂S₂O₃ and concentrated under reduced pressure. The residue was extracted with 10 DCM (3 x 20 mL). The combined organic layers were dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-50% EtOAc in petroleum ether) to afford 3-chloro-6-(2-furyl)-4-iodo- pyridazine (330 mg, crude) as an off-white solid. LCMS: 1.48 min, 306.9 / 308.8 [M+H]+, Method E. 15 To a solution of 3-chloro-6-(2-furyl)-4-iodo-pyridazine (300 mg, 0.979 mmol) in MeOH (3 mL) was added methylhydrazine (338.22 mg, 2.94 mmol, 386.54 μL) dropwise. The reaction mixture was stirred at 35 °C for 2 h. The reaction was quenched by water (10 mL) and extracted with EtOAc (3 x 10 mL). The organic layers were combined, washed with brine (20 20 mL), dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-50% EtOAc in petroleum ether) to afford 3-chloro-6-(furan-2-yl)-4-(1-methylhydrazineyl)pyridazine (170 mg, 0.757 mol, 77%) as a light yellow solid. 1H NMR (400 MHz, MeOD): δ = 7.81 (s, 1H), 7.74 (m, 1H), 7.26 - 7.20 (m, 1H), 6.65 - 6.64 (m, 25 1H), 3.40 (s, 3H). To a stirred solution of 3-chloro-6-(furan-2-yl)-4-(1-methylhydrazineyl)pyridazine (170 mg, 0.757 mmol) in NMP (4 mL), KOH (5 M, 454.05 μL) was added at rt and the mixture was stirred for 10 min. Carbon disulfide (576.19 mg, 7.57 mmol, 456.21 μL) and 18-crown-6 (200.02 mg,30 0.757 mmol) were added at rt and the mixture was stirred for 2 h. 2-(bromomethyl)-5- (trifluoromethyl)benzonitrile (199.81 mg, 0.757 mmol) was added at rt and the mixture was stirred at rt for 1h. The reaction mixture was concentrated under reduced pressure and purified by prep HPLC (Method A) to afford 2-[[7-(furan-2-yl)-1-methylpyridazino[4,3- e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (50.44 mg, 0.112 mmol, 35 15%) as a yellow solid. 85 Analytical data for Example 10 can be found in Table 7. Route G Procedure for the preparation of 2-[(1-methyl-7-methylsulfanylpyridazino[4,3- 5 e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 12) To a solution of 2-[(7-bromo-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (Example 1, 40 mg, 0.096 mmol) in EtOH (1 mL) was added thiourea (36.61 mg, 0.481 mmol) at rt, then the mixture was stirred at 80 °C for 3 h. The solids 10 formed in the reaction mixture were collected by vacuum filtration and dried under reduced pressure to afford 2-(((7-mercapto-1-methyl-1H-pyridazino[4,3-e][1,3,4]thiadiazin-3- yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (39 mg, 0.077 mmol, 81%) as a yellow solid. 1H NMR (400 MHz, DMSO-d6): δ 13.86 (s, 1H), 8.37 (s, 1H), 8.11 - 8.08 (m, 1H), 7.93 - 7.91 (m, 1H), 6.48 (s, 1H), 4.58 (s, 2H), 3.26 (s, 3H). 15 To a solution of 2-(((7-mercapto-1-methyl-1H-pyridazino[4,3-e][1,3,4]thiadiazin-3- yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (34 mg, 0.082 mmol) in DMF (1 mL) was added K2CO3(56.83 mg, 0.412 mmol) and MeI (11.67 mg, 0.082 mmol, 5.12 μL) at rt. The mixture was stirred at rt for 15 min. The reaction mixture was poured into water (20 mL) and extracted 20 with EtOAc (3 x 15 mL). The combined organic layers were washed with brine (3 x 10 mL), dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was triturated with MeCN (12 mL) to afford 2-[(1-methyl-7-methylsulfanylpyridazino[4,3- e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (14.80 mg, 0.034 mmol, 41% yield) as a yellow solid. 25 Analytical data for Example 12 can be found in Table 8. Route H Typical procedure for the preparation of 7-ethynyl-1-methyl-1H-pyridazino[4,3- e][1,3,4]thiadiazines as exemplified by 2-[(7-ethynyl-1-methylpyridazino[4,3- 30 e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 18) 86 To a solution of 2-[(7-bromo-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (Example 9, 125 mg, 0.272 mmol) and ethynyltrimethylsilane (533.45 mg, 5.43 mmol, 752.40 μL) in MeCN (1.8 mL) was added CuI (5.17 mg, 0.027 mmol), 5 Pd(PPh3)2Cl2 (19.06 mg, 0.027 mmol), TEA (82.44 mg, 0.815 mmol, 113.40 μL) under nitrogen. The reaction mixture was stirred at 60 °C for 8 h. The solids were removed from the reaction mixture using vacuum filtration and the filtrate concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-25% EtOAc in petroleum ether) to afford 2-(((1-methyl-7-((trimethylsilyl)ethynyl)-1H-pyridazino[4,3-e][1,3,4]thiadiazin- 10 3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (60 mg, 0.118 mmol, 22%) as yellow solid. 1H NMR (400 MHz, CDCl3): δ 7.92 (s, 1H), 7.87 - 7.81 (m, 1H), 7.78 - 7.74 (m, 1H), 6.44 (s, 1H), 4.47 (s, 2H), 3.29 (s, 3H), 0.29 (s, 9H). To a solution of 2-(((1-methyl-7-((trimethylsilyl)ethynyl)-1H-pyridazino[4,3-e][1,3,4]thiadiazin- 15 3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (70 mg, 0.147 mmol) in MeOH (2.8 mL) was added K2CO3(20.26 mg, 0.147 mmol). The reaction mixture was stirred at rt for 0.5 h. The solids were removed from the reaction mixture using vacuum filtration and the filtrate concentrated under reduced pressure. The crude material was purified by prep HPLC (Method A) to afford 2-[(1-methyl-7-prop-1-ynylpyridazino[4,3-e][1,3,4]thiadiazin-3- 20 yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (10.09 mg, 0.024 mmol, 17%) as yellow solid. Analytical data for Example 18 can be found in Table 9. Route I Typical procedure for the preparation of 7-substituted 1-methyl-1H-pyridazino[4,3-25 e][1,3,4]thiadiazines via a benzophenone-protected intermediate as exemplified by 2- [(1-methyl-7-pyrazol-1-ylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (Example 23) 87 To a solution of compound 3,4,6-trichloropyridazine (30 g, 163.56 mmol) in MeOH (300 mL) was added methylhydrazine (40.65 g, 352.93 mmol, 46.46 mL, 40%). The reaction was stirred at rt for 3 h under nitrogen. The solids formed in the reaction mixture were collected by vacuum 5 filtration. The filtrate was cooled with to -78 °C and the solids formed were collected by vacuum filtration and washed with MeOH (2 x 20 mL). The collected solids were combined and dried under reduce pressure to afford 3,6-dichloro-4-(1-methylhydrazineyl)pyridazine (29.5 g, 152.82 mmol, 93%) as white solid. LCMS: 0.269 min, 193.0 / 195.0 [M+H]+, Method F. 10 A mixture of 3,6-dichloro-4-(1-methylhydrazineyl)pyridazine (6.5 g, 33.67 mmol) and benzophenone (6.14 g, 33.67 mmol) in EtOH (65 mL) was stirred at 80 °C for 14 h. The reaction mixture was concentrated under reduced pressure and purified by flash column chromatography (0-50% EtOAc in petroleum ether) to afford 3,6-dichloro-4-(2- 15 (diphenylmethylene)-1-methylhydrazineyl)pyridazine (3 g, 8.40 mmol, 25%) as yellow solid. 1H NMR (400 MHz, CDCl3): δ 7.67 - 7.61 (m, 3H), 7.54 - 7.46 (m, 4H), 7.45 - 7.39 (m, 2H), 7.38 - 7.32 (m, 2H), 3.01 (s, 3H). A mixture of compound 3,6-dichloro-4-(2-(diphenylmethylene)-1-methylhydrazineyl)pyridazine 20 (2 g, 5.60 mmol), 1H-pyrazole (457.36 mg, 6.72 mmol) and NaH (224 mg, 5.60 mmol, 60% purity) in toluene (40 mL) was stirred at 110 °C for 12 h. The reaction mixture was cooled to rt, water (30 mL) was added water and the mixture was stirred for 10 min. The mixture was extracted with EtOAc (3 x 30 mL). The combined organic phases were washed with brine (30 mL), dried with anhydrous Na2SO4, filtered and concentrated under reduced pressure. The25 crude material was purified by prep HPLC (Method B) to afford 3-chloro-4-(2- 88 (diphenylmethylene)-1-methylhydrazineyl)-6-(1H-pyrazol-1-yl)pyridazine (0.35 g, 0.900 mmol, 16%) as yellow solid. 1H NMR (400 MHz, CDCl3): δ 8.72 - 8.67 (m, 1H), 8.18 (s, 1H), 7.81 - 7.75 (m, 1H), 7.71 - 7.62 (m, 2H), 7.54 - 7.33 (m, 8H), 6.56 - 6.48 (m, 1H), 3.06 (s, 3H). 5 To a mixture of 3-chloro-4-(2-(diphenylmethylene)-1-methylhydrazineyl)-6-(1H-pyrazol-1- yl)pyridazine (0.35 g, 0.900 mmol) in 1,4-dioxane (7 mL) was added HCl (9.65 g, 97.91 mmol, 9.46 mL, 37% purity) and the mixture was stirred at rt for 2 h. The reaction mixture was diluted with water (10 mL), and basified to ~pH 9 using sat. aq. Na2CO3. The mixture was extracted 10 with EtOAc (8 x 10 mL). The combined organic phases were dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-50% EtOAc in petroleum ether) to afford 3-chloro-4-(1- methylhydrazineyl)-6-(1H-pyrazol-1-yl)pyridazine (0.07 g, 0.312 mmol, 35%) as white solid. LCMS: 0.353 min, 225.2 / 227.1 [M+H]+, Method F. 15 To a stirred solution of 3-chloro-4-(1-methylhydrazineyl)-6-(1H-pyrazol-1-yl)pyridazine (0.07 g, 0.312 mmol) in NMP (1.4 mL) was added KOH (5 M, 186.96 μL) and the mixture was stirred at rt for 10 min. Carbon disulfide (284.70 mg, 3.74 mmol, 225.42 μL) and 18-crown-6 (82.36 mg, 0.312 mmol) were added and the mixture was stirred at rt for 2 h. 2-(bromomethyl)-5- 20 (trifluoromethyl)benzonitrile (82.27 mg, 0.312 mmol) was added and the mixture was stirred at rt for 1 h. The reaction mixture was filtered and the filtrate was purified by prep HPLC (Method A) to afford 2-[(1-methyl-7-pyrazol-1-ylpyridazino[4,3-e][1,3,4]thiadiazin-3- yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (56.88 mg, 0.123 mmol, 40%) as a yellow solid. 25 Analytical data for Example 23 can be found in Table 10. Route J Typical procedure for the preparation of spiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazine] as exemplified by 2-[(3'-chlorospiro[cyclopropane-1,5'-pyridazino[4,3- 30 e][1,3]thiazine]-7'-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 24) 89 Flow chemistry. Solution 1: A solution of 3,6-dichloropyridazine (30 g, 201.37 mmol) and 1- ((tert-butoxycarbonyl)amino)cyclopropane-1-carboxylic acid (81.04 g, 402.74 mmol), 4CzIPN (3.18 g, 4.03 mmol) and DBU (45.98 g, 302.06 mmol, 45.53 mL) in DMF (1500 mL). Volume 5 of flow reactor 1 {1 / 8” FEP coil}: 55 mL. Residence time of flow reactor 1: 60 min. Bath temperature of flow reactor 1: 60 °C. Flow rate of pump 1: 0.9 mL / min for solution 1. The reaction mixture was collected after running the reaction for 1 h, diluted with water (5000 mL) and extracted with EtOAc (3 x 1500 mL). The combined organic layers were washed with water (2 x 800 mL) and brine (800 mL), then dried over Na2SO4, filtered and concentrated10 under reduced pressure. The crude material was purified by flash column chromatography (0- 25% EtOAc in petroleum ether) to afford tert-butyl (1-(3,6-dichloropyridazin-4- yl)cyclopropyl)carbamate (7.3 g, 16.08 mmol, 8%) as yellow solid. 1H NMR (400 MHz, CDCl3): δ 7.75 - 7.61 (m, 1H), 5.51 (br s, 1H), 1.39 (s, 9H), 1.35 - 1.30 (m, 2H), 1.22 - 1.15 (m, 2H). 15 To a solution of tert-butyl (1-(3,6-dichloropyridazin-4-yl)cyclopropyl)carbamate (0.5 g, 1.64 mmol) in DCM (5 mL) was added TFA (3.75 g, 32.88 mmol, 2.44 mL). The reaction was stirred at rt for 2 h. The reaction mixture was concentrated under reduced pressure and purified by prep HPLC (Method A) to afford 1-(3,6-dichloropyridazin-4-yl)cyclopropan-1-amine (0.22 g, 20 1.08 mmol, 66%) as white solid. 1H NMR (400 MHz, CDCl3): δ 7.44 (s, 1H), 1.29 - 1.18 (m, 2H), 1.03 - 0.94 (m, 2H). To a solution of 1-(3,6-dichloropyridazin-4-yl)cyclopropan-1-amine (0.1 g, 0.490 mmol) in DMF (1 mL) was added carbon disulfide (373.13 mg, 4.90 mmol, 295.43 μL) and the mixture was25 stirred at rt for 4 h under nitrogen. DIPEA (190.01 mg, 1.47 mmol, 256.07 μL) and 2- (bromomethyl)-5-(trifluoromethyl)benzonitrile (129.40 mg, 0.490 mmol) were added and the reaction mixture was stirred at rt for 2 h under nitrogen. The reaction mixture was purified by prep HPLC (Method A) to afford 2-[(3'-chlorospiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazine]-7'-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (58.73 mg, 0.138 mmol, 30 28%) as yellow solid. Analytical data for Example 24 can be found in Table 11. 90 Route K Typical procedure for the preparation of 7-substituted 1-methyl-1H-pyridazino[4,3- e][1,3,4]thiadiazines using 3,4-bis(benzyloxy)-6-chloropyridazine as an intermediate as exemplified by 2-[(7-ethyl-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3- 5 yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 25) To a solution of 3,4,6-trichloropyridazine (15 g, 81.78 mmol) and benzyl alcohol (17.69 g, 163.56 mmol, 16.94 mL) in THF (240 mL) was added KOtBu (20.19 g, 179.91 mmol) at 0 °C. The reaction mixture was warmed to rt and stirred for 12 h. The reaction mixture was quenched 10 by addition of sat. aq. NH4Cl (500 mL) at 0 °C and was then extracted with EtOAc (3 x 300 mL). The combined organic layers were washed with brine (100 mL), dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by prep HPLC (Method C). The product-containing fractions were combined and concentrated under pressure to the organic solvent. The resulting aqueous mixture was extracted with EtOAc (3 x 15 800 mL). The combined organic layers were washed with brine (200 mL), dried over Na2SO4, filtered and concentrated under reduced pressure to afford 3,4-bis(benzyloxy)-6- chloropyridazine (14 g, 42.72 mmol, 52%) as light yellow solid. 1H NMR (400 MHz, CDCl3): δ 7.51 (s, 1H), 7.48 - 7.30 (m, 10H), 5.50 (s, 2H), 5.28 (s, 2H). 20 A mixture of 3,4-bis(benzyloxy)-6-chloropyridazine (5.2 g, 15.91 mmol), potassium hydride;trifluoro(vinyl)boron (3.20 g, 23.87 mmol), K2CO3(5.50 g, 39.78 mmol) and Pd(PPh3)4(1.84 g, 1.59 mmol) in 1,4-dioxane (52 mL) and water (5.2 mL) was stirred at 80 °C for 12 h under nitrogen. The reaction mixture was filtered through a pad of Celite, washing with EtOAc (3 x 50 mL). The combined filtrates were evaporated to dryness under pressure. The crude 25 material was purified by flash column chromatography (0-50% EtOAc in petroleum ether) to afford 3,4-bis(benzyloxy)-6-vinylpyridazine (2.1 g, 6.46 mmol, 41%) as light yellow solid. 91 1H NMR (400 MHz, CDCl3): δ 7.58 - 7.52 (m, 2H), 7.45 - 7.30 (m, 8H), 6.96 - 6.86 (m, 2H), 5.99 - 5.90 (m, 1H), 5.66 (s, 2H), 5.58 - 5.49 (m, 1H), 5.23 (s, 2H). To a solution of Pd / C (367.69 mg, 0.346 mmol, 10% purity) in THF (10 mL) and MeOH (10 5 mL) was added 3,4-bis(benzyloxy)-6-vinylpyridazine (1.1 g, 3.46 mmol) under argon. The mixture was degassed under vacuum and purged with hydrogen several times. The mixture was stirred under a hydrogen atmosphere (15 psi) at rt for 12 h. The suspension was filtered through a pad of Celite, washing with EtOAc (5 x 30 mL). The combined filtrates were evaporated to dryness under reduced pressure to afford 6-ethylpyridazine-3,4-diol (451 mg, 10 3.22 mmol, 93%). 1H NMR (400 MHz, DMSO-d6): δ 12.64 (br s, 1H), 10.72 - 10.66 (m, 1H), 6.54 (s, 1H), 2.48 - 2.41 (m, 2H), 1.14 - 1.08 (m, 3H). A solution of 6-ethylpyridazine-3,4-diol (0.7 g, 5.00 mmol, 1 eq) in POCl3(14 mL) was stirred 15 at 110 °C for 12 h. The reaction mixture was concentrated under reduced pressure. The residue was quenched by addition water (30 mL) and extracted with EtOAc (3 x 20 mL). The combined organic layers were washed with brine (20 mL), dried over Na2SO4, filtered and concentrated under reduced pressure to afford 3,4-dichloro-6-ethylpyridazine (275 mg, 1.09 mmol, 22%) as brown solid. 20 LCMS: 0.41 min, 177.0 / 179.0 [M+H]+, Method F. To a solution of 3,4-dichloro-6-ethylpyridazine (275 mg, 1.55 mmol) in MeOH (2.8 mL) was added methyl hydrazine (536.76 mg, 4.66 mmol, 613.44 μL, 40%). The reaction mixture was stirred at rt for 12 h. The reaction mixture was concentrated under reduced pressure and 25 purified by prep HPLC (Method A) to afford 3-chloro-6-ethyl-4-(1-methylhydrazineyl)pyridazine (100 mg, 0.536 mmol, 34%) as white solid. 1H NMR (400 MHz, DMSO-d6): δ = 7.28 (s, 1H), 4.75 (s, 2H), 3.19 (s, 3H), 2.78 (q, J = 7.6 Hz, 2H), 1.24 (t, J = 7.6 Hz, 3H). 30 To a solution of 3-chloro-6-ethyl-4-(1-methylhydrazineyl)pyridazine (30 mg, 0.161 mmol), carbon disulfide (122.38 mg, 1.61 mmol, 96.90 μL) and TEA (48.79 mg, 0.482 mmol, 67.12 μL) in EtOH (0.6 mL) was added 2-(bromomethyl)-5-(trifluoromethyl)benzonitrile (42.44 mg, 0.161 mmol). The mixture was stirred at rt for 3.5 h under nitrogen. The reaction mixture was concentrated under reduced pressure and purified by prep HPLC (Method A) to afford 2-[(7- 92 ethyl-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (41.22 mg, 0.098 mmol, 31%) as yellow solid. Analytical data for Example 25 can be found in Table 12. 5 Route L Procedure for the preparation of 3-[[3-[[2-cyano-4- (trifluoromethyl)phenyl]methylsulfanyl]-1-methylpyridazino[4,3-e][1,3,4]thiadiazin-7- yl]-methylamino]propanoic acid (Example 34) 10 A stirred solution of 2-(((7-chloro-1-methyl-1H-pyridazino[4,3-e][1,3,4]thiadiazin-3- yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.5 g, 1.20 mmol) and DIPEA (0.2 mL, 1.20 mmol) in (ethyl 3-(methylamino)propanoate (5 mL) was stirred at 120 °C for 1 h under microwave irradiation. The reaction mixture was diluted with water (40 mL) and extracted with EtOAc (3 x 40 mL). The combined organic layers were dried over Na2SO4, filtered and 15 concentrated under reduced pressure. The crude material was purified by flash column chromatography (37% EtOAc in n-hexane) to afford ethyl 3-((3-((2-cyano-4- (trifluoromethyl)benzyl)thio)-1-methyl-1H-pyridazino[4,3-e][1,3,4]thiadiazin-7- yl)(methyl)amino)propanoate (0.16 g, 0.313 mmol, 26%). LCMS: 2.18 min, 511.2 [M+H]+, Method D. 20 To a stirred solution of 3-((3-((2-cyano-4-(trifluoromethyl)benzyl)thio)-1-methyl-1H- pyridazino[4,3-e][1,3,4]thiadiazin-7-yl)(methyl)amino)propanoate 0.2 g, 0.444 mmol) in THF:water (1:1, 1.4 mL) was added LiOH.H2O (0.115 g, 2.74 mmol) and the mixture was stirred at rt for 1 h. The reaction mixture was diluted with water (20 mL) and extracted with 25 EtOAc (10 x 50 mL). The combined organic layers were dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by reverse-phase chromatography (40% MeCN in [0.05% FA in water]) to afford 3-((3-((2-cyano-4- (trifluoromethyl)benzyl)thio)-1-methyl-1H-pyridazino[4,3-e][1,3,4]thiadiazin-7- yl)(methyl)amino)propanoic acid (0.018 g, 0.037 mmol, 12%). 30 Analytical data for Example 34 can be found in Table 13. 93 Route M Typical procedure for the preparation of 7-substituted 1-methyl-1H-pyridazino[4,3- e][1,3,4]thiadiazines via synthesis of 3-chloropyridazine intermediates using a SNAr, followed by iodination as exemplified by 2-[[1-methyl-7-(3-oxa-8- 5 azabicyclo[3.2.1]octan-8-yl)pyridazino[4,3-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (Example 36) To a stirred solution of 3,6-dichloropyridazine (1.0 g, 6.71 mmol) and 3-oxa-8- azabicyclo[3.2.1]octane (1.13 g, 10.06 mmol) in DMSO (10 mL) was added TEA ( 1.35 g, 10 10.06 mmol) and the mixture was stirred at 110 °C for 3 h. The reaction mixture was diluted with water (30 mL) and extracted with EtOAc (3 x 30 mL). The combined organic layers were dried over Na2SO4and concentrated under reduced pressure. The crude material was purified by flash column chromatography (35% EtOAc in n-hexane) to afford 8-(6-chloropyridazin-3- yl)-3-oxa-8-azabicyclo[3.2.1]octane (1.25 g, 4.68 mmol, 83%). 15 LCMS: 1.64 min, 226.2 [M+H]+, Method D. To a stirred solution of n-BuLi (16.66 mL, 26.66 mmol) in THF (12 mL) were added TMP (3.76 g, 26.66 mmol) and ZnCl2.TMEDA (1.34 g, 5.33 mmol) at 0 °C and the mixture was stirred for 10 min. 8-(6-chloropyridazin-3-yl)-3-oxa-8-azabicyclo[3.2.1]octane (1.2 g, 5.33 mmol) was 20 added and the mixture was stirred at 0 °C for 3 h. I2(1.0 g, 4.235 mmol) was added at 0 °C and the mixture was stirred and allowed to warm to rt over 16 h. The reaction mixture was diluted with water (50 mL) and extracted with EtOAc (3 x 50 mL). The combined organic layers were dried over Na2SO4and concentrated under reduced pressure. The crude material was 94 purified by flash column chromatography (9% EtOAc in n-hexane) to afford 8-(6-chloro-5- iodopyridazin-3-yl)-3-oxa-8-azabicyclo[3.2.1]octane (1.1 g, 3.13 mmol, 59%). LCMS: 2.02 min, 352.1 [M+H]+, Method D. 5 To a stirred solution of 8-(6-chloro-5-iodopyridazin-3-yl)-3-oxa-8-azabicyclo[3.2.1]octane (0.5 g, 1.42 mmol) in MeOH (10 mL) was added methyl hydrazine (1.5 mL) and the mixture was stirred at 80 °C for 5 h. The reaction mixture was concentrated under reduced pressure to afford 8-(6-chloro-5-(1-methylhydrazinyl)pyridazin-3-yl)-3-oxa-8-azabicyclo[3.2.1]octane (1.5 g, quantitative yield). 10 LCMS: 1.31 min, 270.2 [M+H]+, Method D. To a stirred solution of 8-(6-chloro-5-(1-methylhydrazinyl)pyridazin-3-yl)-3-oxa-8- azabicyclo[3.2.1]octane (1.5 g, 5.57 mmol) in DMF (37.5 mL) was added NaOH (0.44 g, 11.15 mmol) followed by water (3 mL) at rt and the mixture was stirred for 10 min. Carbon disulfide15 (0.4 mL) was added at rt and the mixture was stirred for 3 h. 2-(bromomethyl)-5- (trifluoromethyl)benzonitrile (1.46 g, 5.57 mmol) was added and the mixture was stirred at rt for 16 h. The reaction mixture was poured into cold brine (200 mL) and extracted with EtOAc (3 x 100 mL). The combined organic layers were dried over Na2SO4, filtered, and concentrated under reduced pressure. The crude material was purified by reverse-phase column20 chromatography (30% MeCN in [0.05% FA in water]) to afford 2-(((7-(3-oxa-8- azabicyclo[3.2.1]octan-8-yl)-1-methyl-1H-pyridazino[4,3-e][1,3,4]thiadiazin-3-yl)thio)methyl)- 5-(trifluoromethyl)benzonitrile (0.05 g, 0.10 mmol, 2%). Analytical data for Example 36 can be found in Table 14. 25 Route N Typical procedure for the preparation of 7-substituted 1-methyl-1H-pyridazino[4,3- e][1,3,4]thiadiazines via synthesis of 3-chloropyridazine intermediates using a SNAr, followed by bromination as exemplified by 2-[[1-methyl-7-(oxetan-3- yloxy)pyridazino[4,3-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5- 30 (trifluoromethyl)benzonitrile (Example 37) 95 To a solution of oxetan-3-ol (7.5 g, 101.24 mmol) in DMF (100 mL) was added NaH (5.26 g, 131.62 mmol, 60% purity) at 0 °C. The mixture was warmed to 10 °C and stirred for 0.5 h. Then a solution of 3,6-dichloropyridazine (30.17 g, 202.49 mmol) in DMF (100 mL) was added 5 at 0 °C. The mixture was warmed to rt and stirred for 2 h. The mixture was poured into ice water (800 mL) and extracted with EtOAc (3 x 200 mL). The combined organic layers were washed with brine (3 x 100 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-25% EtOAc in petroleum ether) to afford 3-chloro-6-(oxetan-3-yloxy)pyridazine (14 g, 73%) as a 10 white solid. 1H NMR (400 MHz, DMSO-d6): δ 7.86 (d, J = 9.3 Hz, 1H), 7.46 (d, J = 9.3 Hz, 1H), 5.74 - 5.65 (m, 1H), 4.95 - 4.89 (m, 2H), 4.64 - 4.57 (m, 2H). To a solution of 3-chloro-6-(oxetan-3-yloxy)pyridazine (1 g, 5.39 mmol) in THF (10.7 mL) was 15 added TMPMgCl•LiCl (1 M, 6.43 mL) at -70 °C. The mixture was stirred at this temperature for 1 h, then a solution of (CCl2Br)2(2.62 g, 8.04 mmol, 964.89 μL) in THF (10.7 mL) was added. The mixture was stirred at -70 °C for 2 h. The mixture was quenched using sat. aq. NH4Cl solution (30 mL) and extracted with EtOAc (3 x 10 mL). The combined organic layers were washed with brine (3 x 10 mL), dried over anhydrous Na2SO4, filtered and concentrated20 under reduced pressure. The crude material was purified by flash column chromatography (0- 25% EtOAc in petroleum ether) to afford 4-bromo-3-chloro-6-(oxetan-3-yloxy)pyridazine (160 mg, 9%) as a yellow solid. 1H NMR (400 MHz, DMSO-d6): δ 8.07 (s, 1H), 5.75 - 5.65 (m, 1H), 4.95 - 4.87 (m, 2H), 4.63 - 4.57 (m, 2H). 96 To a solution of 4-bromo-3-chloro-6-(oxetan-3-yloxy)pyridazine (140 mg, 0.527 mmol) in MeOH (1.4 mL) was added methyl hydrazine (0.42 g, 3.65 mmol, 480.00 μL). The mixture was stirred at rt for 3 h. The mixture was concentrated under reduced pressure and purified by prep TLC (0-100% EtOAc in petroleum ether) to afford 3-chloro-4-(1-methylhydrazineyl)-6- 5 (oxetan-3-yloxy)pyridazine (100 mg, 80%) as a white solid. 1H NMR (400 MHz, DMSO-d6): δ 6.86 (s, 1H), 5.67 - 5.58 (m, 1H), 4.91 - 4.86 (m, 2H), 4.81 - 4.71 (m, 2H), 4.60 - 4.53 (m, 2H), 3.17 (s, 3H). To a solution of 3-chloro-4-(1-methylhydrazineyl)-6-(oxetan-3-yloxy)pyridazine (80 mg, 0.347 10 mmol) in NMP (1.6 mL) was added KOH (5 M, 208.11 μL) and the mixture was stirred at rt for 10 min. Carbon disulfide (158.45 mg, 2.08 mmol, 125.46 μL) and 18-crown-6 (91.68 mg, 0.347 mmol) were added and the mixture was stirred at rt for 2 h. 2-(bromomethyl)-5- (trifluoromethyl)benzonitrile (137.37 mg, 0.520 mmol) was added and the mixture was stirred at rt for 2 h. The mixture was poured into water (10 mL) and extracted with EtOAc (3 x 4 mL). 15 The combined organic layers were washed with brine (3 x 3 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by prep HPLC (Method A) to afford 2-[[1-methyl-7-(oxetan-3-yloxy)pyridazino[4,3- e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (67.03 mg, 42%) as a yellow solid. 20 Analytical data for Example 37 can be found in Table 15. Route O Typical procedure for the preparation of spiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazin]-3'-amines as exemplified by 2-[[3'-(dimethylamino)spiro[cyclopropane- 25 1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 38) To a stirred solution of 2-(((3'-chlorospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'- yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.6 g, 1.403 mmol) in EtOH (6 mL) was added 30 2 M dimethyl amine in THF (6.0 mL). The mixture was stirred at 70 °C for 16 h. The reaction 97 mixture was concentrated under reduced pressure. The crude material was purified by flash column chromatography (40% EtOAc in n-hexane), then purified by reverse-phase column chromatography (50% MeCN in [0.05% formic acid in water]) to afford2-[[3'- (dimethylamino)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]- 5 5-(trifluoromethyl)benzonitrile (0.05 g, 0.114 mmol, 8%). Analytical data for Example 38 can be found in Table 16. Route P Typical procedure for the preparation of 1-methyl-1H-pyridazino[4,3-10 e][1,3,4]thiadiazine-7-carboxamides as exemplified by 3-[[2-cyano-4- (trifluoromethyl)phenyl]methylsulfanyl]-N,1-dimethylpyridazino[4,3- e][1,3,4]thiadiazine-7-carboxamide (Example 39) To a solution of 3-((2-cyano-4-(trifluoromethyl)benzyl)thio)-1-methyl-1H-pyridazino[4,3- 15 e][1,3,4]thiadiazine-7-carboxylic acid (Intermediate 6, 0.1 g, 0.235 mmol) in DMF (1 mL) was added DIPEA (91.14 mg, 0.705 mmol, 122.83 μL) and HATU (134.07 mg, 0.353 mmol). MeNH2.HCl (15.87 mg, 0.235 mmol) was added and the mixture was stirred at rt for 1 h. The reaction mixture was filtered and the filtrate was purified by prep HPLC (Method A) to afford 1-methyl-1H-pyridazino[4,3-e][1,3,4]thiadiazine-7-carboxamides as exemplified by 3-[[2-20 cyano-4-(trifluoromethyl)phenyl]methylsulfanyl]-N,1-dimethylpyridazino[4,3- e][1,3,4]thiadiazine-7-carboxamide (13.1 mg, 0.029 mmol, 12%) as a yellow solid. Analytical data for Example 39 can be found in Table 17. Route Q 25 Procedure for the preparation of 7'-[[2-cyano-4- (trifluoromethyl)phenyl]methylsulfanyl]spiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazine]-3'-carbonitrile (Example 41) 98 To a solution of 5-(1-aminocyclopropyl)-6-chloropyridazine-3-carbonitrile (200 mg, 0.648 mmol, Intermediate 7) in DMF (2 mL) was added DIPEA (251.25 mg, 1.94 mmol, 338.61 μL) and CS2(986.78 mg, 12.96 mmol, 781.30 μL). The mixture was stirred at rt for 2 h.2- 5 (bromomethyl)-5-(trifluoromethyl)benzonitrile (225.39 mg, 0.854 mmol) was added and the mixture was stirred for 1 h. The solution was filtered and purified by prep-HPLC (Method E) to afford 7'-[[2-cyano-4-(trifluoromethyl)phenyl]methylsulfanyl]spiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazine]-3'-carbonitrile (53.9 mg, 0.046 mmol, 19%) as a white solid. Analytical data for Example 41 can be found in Table 18. 10 Route R Procedure for the preparation of 2-[[1-methyl-7-(1,3,4-oxadiazol-2-yl)pyridazino[4,3- e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 42) 15 To a stirred solution of methyl 6-oxo-1,6-dihydropyridazine-3-carboxylate (15 g, 64.37 mmol) in EtOH (150 mL) was added hydrazine monohydrate (30 mL) and the mixture was stirred at rt for 16 h. The reaction mixture was poured into cold water (300 mL). The precipitate formed was collected by vacuum filtration and dried under reduced pressure to afford 5-bromo-6-oxo- 1,6-dihydropyridazine-3-carbohydrazide (15 g, 64.37 mmol, 100%). 20 LCMS: 0.458 min, 230.9 [M-H]-, Method D. 99 A stirred solution of 5-bromo-6-oxo-1,6-dihydropyridazine-3-carbohydrazide (15 g, 57.46 mmol) in formic acid (150 mL) was stirred at 80°C for 30 min. The resulting reaction mixture was concentrated under reduced pressure. The crude material was purified by flash column 5 chromatography (5% MeOH in DCM) to afford 5-bromo-N'-formyl-6-oxo-1,6- dihydropyridazine-3-carbohydrazide (10 g, 38.30 mmol, 59%). LCMS: 0.482 min, 258.9 [M-56]-, Method D. A stirred solution of 5-bromo-N'-formyl-6-oxo-1,6-dihydropyridazine-3-carbohydrazide (5 g, 10 19.15 mmol) in POCl3(50 mL) was stirred 80 °C for 16 h. The reaction mixture was diluted with sat. aq. NaHCO3solution (500 mL) and extracted with EtOAc (3 x 250 mL). The combined organic layers were dried over Na2SO4and concentrated under reduced pressure. The crude material was purified by flash column chromatography (25% EtOAc in hexane) to afford 2- (5,6-dichloropyridazin-3-yl)-1,3,4-oxadiazole (0.9 g, 4.14 mmol, 21%). 15 ¹H NMR (400 MHz, DMSO-d6): δ 9.63 (s, 1H), 8.87 (s, 1H). To a stirred solution of 2-(5,6-dichloropyridazin-3-yl)-1,3,4-oxadiazole (0.35 g, 1.61 mmol) in MeOH (3.5 mL) was added methylhydrazine (0.051 g, 1.12 mmol) and the reaction mixture was stirred at 0 °C to rt for 15 min. To the solution, DMF (1 mL) was added and the mixture20 was concentrated under reduced pressure remove the MeOH. A solution of 2-(6-chloro-5-(1- methylhydrazinyl)pyridazin-3-yl)-1,3,4-oxadiazole (0.35 g, 1.54 mmol, quantitative yield) in DMF (1 mL) was carried directly into the next step. LCMS: 0.629 min, 227.1 [M+H]+, Method D. 25 To a stirred solution of 2-(6-chloro-5-(1-methylhydrazinyl)pyridazin-3-yl)-1,3,4-oxadiazole (0.35 g, 1.54 mmol) in DMF (8.75 mL) was added 2 M NaOH (0.7 mL) at rt and the mixture was stirred for 20 min. Carbon disulfide (0.35 mL) was added and the mixture was stirred for 2 h.2-(Bromomethyl)-5-(trifluoromethyl)benzonitrile (0.448 g, 1.70 mmol) was added and the mixture was stirred at rt for 2 h. The reaction mixture was poured into cold water (100 mL) and 30 extracted with EtOAc (2 x 75 mL). The combined organic layers were dried over Na2SO4, filtered and concentrated under reduced pressure to afford crude material. The crude material was purified by prep HPLC (Method F) to afford 2-[[1-methyl-7-(1,3,4-oxadiazol-2- 100 yl)pyridazino[4,3-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (0.011 g, 0.024 mmol, 2%). Analytical data for Example 42 can be found in Table 19. 5 Route S Typical procedure for the preparation of 2-(((3'-aminospiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5-(trifluoromethyl)benzonitriles as exemplified by 2-[[3'-(3-oxa-8-azabicyclo[3.2.1]octan-8-yl)spiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile 10 (Example 43) To a solution of 2-(((3'-bromospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'- yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (50 mg, 0.106 mmol, Intermediate 8) and 3-oxa- 8-azabicyclo[3.2.1]octane (36.01 mg, 0.318 mmol) in NMP (4 mL) was added DIPEA (41.13 15 mg, 0.318 mmol, 55.43 μL). The mixture was stirred at 140 °C for 0.5 h.27 separate reaction mixtures on this scale were combined and filtered. The filter cake was washed with DCM (20 mL) and the filtrate was concentrated under reduced pressure. The residue was purified by prep-HPLC (Method G), then purified by prep-HPLC (Method H) to afford 2-[[3'-(3-oxa-8- azabicyclo[3.2.1]octan-8-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'- 20 yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (158.8 mg, 11%) as pale brown solid. Analytical data for Example 43 can be found in Table 20. Route T Typical procedure for the preparation of 2-(((3'-hydroxyspiro[cyclopropane-1,5'- 25 pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5-(trifluoromethyl)benzonitriles as exemplified by 2-[[3'-(2-hydroxyethoxy)spiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 47) 101 To a stirred solution of 2-(((3'-chlorospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'- yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.3 g, 0.704 mmol, Example 24) in THF (3 mL) was added 2-((tert-butyldimethylsilyl)oxy)ethan-1-ol (0.37 g, 2.112 mmol) followed by LiHMDS 5 (1 M in THF; 2.1 mL, 2.112 mmol) at rt. The reaction mixture was stirred at 60 °C for 16 h. The reaction mixture was diluted with water (50 mL) and extracted with EtOAc (3 x 50 mL). The combined organic layers were dried over Na2SO4, filtered, and concentrated under reduced pressure. The crude material was purified by flash column chromatography (10% EtOAc in n- hexane) to afford 2-(((3'-(2-((tert-butyldimethylsilyl)oxy)ethoxy)spiro[cyclopropane-1,5'- 10 pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.13 g, 0.229 mmol, 25%). LCMS: 2.04 min, 567.2 [M+H]+, Method D. To a stirred solution of 2-(((3'-(2-((tert-butyldimethylsilyl)oxy)ethoxy)spiro[cyclopropane-1,5'- 15 pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.13 g, 0.229 mmol) in THF (5 mL) was added TBAF dropwise (0.13 mL) at 0 °C. The reaction mixture was stirred at rt for 1 h. The reaction mixture was diluted with water (50 mL) and extracted with EtOAc (3 x 50 mL). The combined organic layers were dried over Na2SO4, filtered, and concentrated under reduced pressure. The crude material was purified by prep HPLC (Method20 I) to afford 2-(((3'-(2-hydroxyethoxy)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'- yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.010 g, 0.022 mmol, 10%). Analytical data for Example 47 can be found in Table 21. Route U 25 Typical procedure for the preparation of 2-[[3'-(1H-triazol-4-yl)spiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitriles as exemplified by 2-[[3'-(1H-triazol-4-yl)spiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 49) 102 To a solution of 2-(((3'-bromospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'- yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (1 g, 2.12 mmol, Intermediate 8) in tetrahydrofuran (30 mL) was added ethynyl (trimethyl silane (416.78 mg, 4.24 mmol, 587.84 5 μL), CuI (40.41 mg, 0.212 mmol), Pd(PPh3)2Cl2(74.46 mg, 0.106 mmol) and TEA (1.07 g, 10.61 mmol, 1.48 mL). The mixture was stirred at rt for 1 h. The reaction was repeated as two further batches on the same scale. The reaction mixtures were combined, diluted with water (90 mL) and extracted with ethyl acetate (3 x 90 mL). The combined organic layers were washed with brine (90 mL), dried over sodium sulfate, filtered, and concentrated under 10 reduced pressure. The crude material was purified by flash column chromatography (25% EtOAc in petroleum ether) to afford 5-(trifluoromethyl)-2-(((3'- ((trimethylsilyl)ethynyl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'- yl)thio)methyl)benzonitrile (2.2 g, 71%) as a yellow solid. 1H NMR (400 MHz, CDCl3): δ 7.89 (s, 1H), 7.82 - 7.78 (m, 1H), 7.74 - 7.70 (m, 1H), 6.79 (s, 15 1H), 4.44 (s, 2H), 1.58 - 1.53 (m, 2H), 1.44 - 1.39 (m, 2H), 0.28 (s, 9H). To a solution of 5-(trifluoromethyl)-2-(((3'-((trimethylsilyl)ethynyl)spiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)benzonitrile (2.2 g, 4.50 mmol) in MeOH (20 mL) was added K2CO3(1.24 g, 9.00 mmol). The mixture was stirred at rt for 20 min. The 20 reaction mixture was diluted with water (50 mL) and extracted with ethyl acetate (3 x 20 mL). The combined organic layers were washed with brine (30 mL), dried over sodium sulfate, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (50% EtOAc in petroleum ether) to afford 2-(((3'- ethynylspiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5- 25 (trifluoromethyl)benzonitrile (1.5 g, 72%) as a yellow solid. 1H NMR (400 MHz, CDCl3): δ 7.89 (s, 1H), 7.85 - 7.79 (m, 1H), 7.75 - 7.69 (m, 1H), 6.83 (s, 1H), 4.44 (s, 2H), 3.40 (s, 1H), 1.60 - 1.55 (m, 2H), 1.45 - 1.38 (m, 2H). 103 To a solution of 2-(((3'-ethynylspiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'- yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (1.1 g, 2.64 mmol) in acetone (10 mL) and water (5 mL) was added copper sulfate (105.40 mg, 0.660 mmol, 101.34 μL), sodium L-ascorbate 5 (130.82 mg, 0.660 mmol) and azido(trimethyl)silane (608.63 mg, 5.28 mmol, 694.78 μL). The mixture was stirred at 60 °C for 4 h. After cooling to rt, the reaction mixture was diluted with water (15 mL) and extracted with ethyl acetate (3 x 15 mL). The combined organic layers were washed with brine (15 mL), dried over sodium sulfate, filtered, and concentrated under reduced pressure. The crude material was purified by prep HPLC (Method J) to afford 2-[[3'-10 (1H-triazol-4-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (208 mg, 17%) as a brown solid. Analytical data for Example 49 can be found in Table 22. Route V 15 Procedure for the preparation of 2-[[3'-(1,3,4-oxadiazol-2-yl)spiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 50) To a stirred solution of 7'-((2-cyano-4-(trifluoromethyl)benzyl)thio)-N'- 20 formylspiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-3'-carbohydrazide (0.2 g, 0.418 mmol, Intermediate 10) in MeCN (5.0 mL) was added trimethylamine hydrochloride (0.012 g, 0.125 mmol) followed by TEA (0.2 mL) and p-toluenesulfonyl chloride (0.12 g, 0.627 mmol) at rt. The reaction mixture was stirred at 50 °C for 1 h. The reaction mixture was concentrated under reduced pressure and purified by flash column chromatography (30-35% EtOAc in n-25 hexane) to afford 2-(((3'-(1,3,4-oxadiazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazin]-7'-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.05 g, 0.108 mmol, 26%). Analytical data for Example 50 can be found in Table 23. 104 Route W Typical procedure for Stille Couplings on Intermediate 8 as exemplified by 2-[[3'-(1,3- oxazol-4-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'- yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 52) 5 To a solution of 4-(trimethylstannyl)oxazole (156.7 mg, 0.088 mmol, Intermediate 8) in dioxane (3 mL) was added Pd(PPh3)2Cl2(35.74 mg, 0.051 mmol) and 2-(((3'-bromospiro[cyclopropane- 1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (120 mg, 0.255 mmol) at rt under a nitrogen atmosphere. The mixture was stirred at 80 °C for 12 h. The10 mixture was filtered and the filtrate was purified by prep HPLC (Method J) to afford 2-[[3'-(1,3- oxazol-4-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (32.5 mg, yield 27%) as an off-white solid. Analytical data for Example 52 can be found In Table 24. 15 Route X Procedure for the preparation of 2-[(3'-ethoxyspiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazine]-7'-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 53) 105 To a stirred solution of 3-chloro-6-ethoxypyridazine (2.5 g, 15.82 mmol) and 1-((tert- butoxycarbonyl)amino)cyclopropane-1-carboxylic acid (4.77 g, 142.8 mmol) in water (62.5 mL) was added AgNO3(0.26 g, 1.582 mmol) at rt. The reaction mixture was stirred and heated to 55 °C. After reaching 55 °C, (NH4)2S2O8(7.22 g, 31.64 mmol) was added slowly. The 5 reaction mixture was stirred at 70 °C for 4 h. The reaction mixture was diluted with water (200 mL) and extracted with extracted with EtOAc (2 x 200 mL). The combined organic layers were dried over Na2SO4and concentrated under reduced pressure. The crude material was purified by flash column chromatography (10% EtOAc in hexane) to afford tert-butyl (1-(3-chloro-6- ethoxypyridazin-4-yl)cyclopropyl)carbamate (1.0 g, 3.19 mmol, 37%). 10 LCMS: 2.17 min, 314.2 [M+H]+, Method D. To a stirred solution of tert-butyl (1-(3-chloro-6-ethoxypyridazin-4-yl)cyclopropyl)carbamate (1.0 g, 3.19 mmol) in DCM (10 mL) was added TFA (3 mL, 3.0 vol) at 0 °C and the mixture was stirred at rt for 2 h. The reaction mixture was poured onto 2 M NaOH (50 mL) and extracted 15 with EtOAc (50 mL). The combined organic layers were dried over Na2SO4, filtered, and concentrated under reduced pressure to afford 1-(3,6-dibromopyridazin-4-yl)cyclopropan-1- amine (0.3 g, 1.408 mmol, 28%). LCMS: 1.23 min, 214.1 [M+H]+, Method D. 20 To a stirred solution of 1-(3,6-dibromopyridazin-4-yl)cyclopropan-1-amine (0.3 g, 1.408 mmol) in DMF (1.5 mL) was added carbon disulfide (0.6 mL, 2 vol) and the mixture was stirred at rt for 4 h. DIPEA (0.74 mL, 4.224 mmol) and 2-(bromomethyl)-5-(trifluoromethyl)benzonitrile (0.40 g, 1.549 mmol) were added and the mixture was stirred at rt for 1 h. The reaction mixture was diluted with water (30 mL) and extracted with EtOAc (2 x 30 mL). The combined organic 25 layers were dried over Na2SO4, filtered, and concentrated under reduced pressure. The crude material was purified by flash column chromatography (10% EtOAc in hexane) to afford 2- (((3'-ethoxyspiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5- (trifluoromethyl)benzonitrile (0.02 g, 0.045 mmol, 10%). Analytical data for Example 53 can be found in Table 25. 30 106 Route Y Procedure for the preparation of 2-[[3'-(1,3,4-thiadiazol-2-yl)spiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 54) 5Intermediate 10 To a stirred solution of 7'-((2-cyano-4-(trifluoromethyl)benzyl)thio)-N'- formylspiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-3'-carbohydrazide (0.1 g, 0.106 mmol, Intermediate 10) in toluene (5 mL) was added Lawesson’s reagent (0.1 g, 0.127 mmol). The reaction mixture was stirred under microwave irradiation at 140 °C for 2 h. The reaction 10 mixture was diluted with water (50 mL) and extracted with EtOAc (2 x 50 mL). The combined organic layers were dried over Na2SO4, filtered, and concentrated under reduced pressure. The crude material was purified by prep HPLC (Method I) to afford 2-(((3'-(1,3,4-thiadiazol-2- yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5- (trifluoromethyl)benzonitrile (0.007 g, 0.014 mmol, 3%). 15 Analytical data for Example 54 can be found in Table 26. Route Z Typical procedure for the preparation of 5-(spiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazin]-3'-yl)-1,2,4-oxadiazoles as exemplified by 2-[[3'-(1,2,4-oxadiazol-5-20 yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (Example 55) 107 To a solution of 1-(3-chloro-6-(1,2,4-oxadiazol-5-yl)pyridazin-4-yl)cyclopropan-1- amine;trifluoroacetic acid (140 mg, 0.589 mmol) in DMF (1.5 mL) was added DIPEA (513.05 μL, 2.95 mmol) and CS2(672.83 mg, 8.84 mmol) under a nitrogen atmosphere. The reaction mixture was stirred at rt for 1 h.2-(bromomethyl)-5-(trifluoromethyl)benzonitrile (152.34 mg, 5 0.577 mmol) at 0 °C. The mixture was stirred at rt for 10 min. The reaction mixture was diluted with water (10 mL) and extracted with ethyl acetate (3 x 3 mL). The combined organic phases were washed with brine (3 mL), dried over sodium sulfate, filtered and concentrated under reduced pressure. The crude material was purified by prep HPLC (Method J) to afford 2-[[3'- (1,2,4-oxadiazol-5-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'- 10 yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (17.3 mg, 0.040 mmol, 7%) as a white solid. Analytical data for Example 55 can be found in Table 27. Route AA Typical procedure for the preparation of 3-(spiro[cyclopropane-1,5'-pyridazino[4,3-15 e][1,3]thiazin]-3'-yl)-1,2,4-oxadiazoles as exemplified by 2-[[3'-(1,2,4-oxadiazol-3- yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (Example 56) To a solution of 1-(3-chloro-6-(1,2,4-oxadiazol-3-yl)pyridazin-4-yl)cyclopropan-1-amine (283.4 20 mg, 0.716 mmol) in DMF (5 mL) was added CS2(653.76 mg, 8.59 mmol, 517.63 μL) and DIPEA (462.38 mg, 3.58 mmol, 623.15 μL) under nitrogen atmosphere. The mixture was stirred at rt for 1 h.2-(Bromomethyl)-5-(trifluoromethyl)benzonitrile (132.23 mg, 0.501 mmol) was added at 0 °C. Then the mixture was warmed to rt and stirred for 10 min. The reaction mixture was diluted with water (10 mL), extracted with ethyl acetate (3 × 10 mL). The combined 25 organic phases were washed with brine (10 mL), dried over sodium sulfate, filtered, and concentrated under reduced pressure. The crude material was purified by prep HPLC (Method D) to afford 2-[[3'-(1,2,4-oxadiazol-3-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]- 108 7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (64 mg, 0.143 mmol, 28%) as an off-white solid. Analytical data for Example 56 can be found in Table 28. 5 Route AB Procedure for the preparation of 2-[[3'-(oxolan-3-yl)spiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 57) 10 In a glovebox under an argon atmosphere, a solution of tetrahydrofuran-3-ol (91.60 mg, 1.04 mmol, 84.03 μL) and NHC-1-BF4(375.69 mg, 0.951 mmol) in t-BuOMe (0.6 mL) was stirred at rt for 5 min. Pyridine (75.19 mg, 0.951 mmol, 76.72 μL) in t-BuOMe (0.6 mL) was added dropwise, and the mixture was stirred at rt for 10 min. The mixture was filtered, and the filtrate was added to a solution of (Ir(ppy)2(dtbbpy)PF6(8.14 mg, 0.009 mmol), NiBr2.dtbbpy (14.4615 mg, 0.030 mmol), quinuclidine (115.59 mg, 1.04 mmol) and 2-(((3'-bromospiro[cyclopropane- 1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (280 mg, 0.594 mmol) in DMA (1.2 mL). The reaction mixture was sealed in a threaded culture tube and stirred at rt for 12 h under blue LED light (450 nm). The reaction mixture was filtered, and the filtrate was diluted with water (10 mL) and extracted with EtOAc (10 mL × 3). The combined 20 organic phases were washed with brine (3 x 20 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-50% EtOAc in petroleum ether), then further purified by prep HPLC (Method D) to afford 2-[[3'-(oxolan-3-yl)spiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (64.5 mg, 0.139 mmol, 25 23%) as a white solid. Analytical data for Example 57 can be found in Table 29. 109 Route AC Typical procedure for the preparation of 3'-(4H-1,2,4-triazol-3-yl)spiro[cyclopropane- 1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-thiols as exemplified by 2-[[3'-(4H-1,2,4-triazol-3- yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5- 5 (trifluoromethyl)benzonitrile (Example 58) To a solution of 1-(3-bromo-6-(4H-1,2,4-triazol-3-yl)pyridazin-4-yl)cyclopropan-1- amine;trifluoroacetic acid (530.00 mg, 1.04 mmol, Intermediate 14) and DIPEA (672.65 mg, 5.20 mmol, 906.54 μL) in DMF (5 mL) was added CS2(1.09 g, 14.25 mmol, 859.25 μL) and10 the mixture was stirred at rt for 1.5 h under a nitrogen atmosphere. 2-(Bromomethyl)-5- (trifluoromethyl)benzonitrile (274.23 mg, 1.04 mmol) was added and the reaction mixture was stirred at rt for 30 min. The mixture was poured into water (50 mL) and the solids formed were collected by vacuum filtration. The solids were purified by flash column chromatography (20- 35% EtOAc in petroleum ether) to afford 2-[[3'-(4H-1,2,4-triazol-3-yl)spiro[cyclopropane-1,5'- 15 pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (109.8 mg, 0.237 mmol, 23%) as a white solid. Analytical data for Example 58 can be found in Table 30. Route AD 20 Typical procedure for performing Buchwald-Hartwig cross couplings using 2-(((3'- bromospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5- (trifluoromethyl)benzonitrile (Intermediate 8) as exemplified by 2-[[3'-(triazol-2- yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (Example 64) and 2-[[3'-(triazol-1-yl)spiro[cyclopropane- 25 1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 65) 110 To a stirred solution of 1H-1,2,3-triazole (1.5 mL, 5 vol) and 2-(((3'-bromospiro[cyclopropane- 1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.3 g, 0.636 mmol) in THF (2.5 mL) was added Cs2CO3(0.62 g, 1.910 mmol) at rt and the mixture 5 was purged with nitrogen gas for 10 min. BrettPhos Pd G3 was added and the mixture was stirred at 100 °C for 3 h. The reaction mixture was diluted with water (40 mL) and extracted with EtOAc (3 x 40 mL). The combined organic layers were dried over Na2SO4and concentrated under reduced pressure. The crude material was purified by flash chromatography (20% EtOAc in hexane) to afford 2-(((3'-(2H-1,2,3-triazol-2-10 yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5- (trifluoromethyl)benzonitrile (0.015 g, 0.278 mmol, Example 64) as an off-white solid. The fractions containing Example 65 were repurified by reverse-phase flash column chromatography (89% MeCN in 0.05% formic acid in water) to afford 2-(((3'-(1H-1,2,3-triazol- 1-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5-15 (trifluoromethyl)benzonitrile (0.03 g, 0.278 mmol, Example 65, 20% overall yield) as an off- white solid. Analytical data for Examples 64 and 65 can be found in Table 31. Route AE 20 Typical procedure for a nucleophilic aromatic substitution reaction using 3'- fluorospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-thiols as exemplified by 2-[[3'-(2,2-difluoroethoxy)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'- yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 67) 111 To a solution of 2-(((3'-fluorospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'- yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (40 mg, 97.46 μmol, Intermediate 16) in THF (5 mL) was added Cs2CO3(95.27 mg, 292.39 μmol) and 2,2-difluoroethan-1-ol (79.97 mg, 974.63 μmol) at rt. The mixture was stirred at 50 °C for 3 h. The mixture was diluted with water 5 (10 mL) and extracted with ethyl acetate (3 × 10 mL). The combined organic phases were washed with brine (10 mL), dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by prep-HPLC (Method J) to afford 2-[[3'-(2,2- difluoroethoxy)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (9.3 mg, 20%) as an off-white solid. 10 Analytical data for Example 67 can be found in Table 32. Route AF Typical procedure for the preparation of 7'-(l1-sulfaneyl)-3'-(1,3,5-triazin-2- yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]s as exemplified by 2-[[3'-15 (1,3,5-triazin-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'- yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 72) To a solution of 7'-(((2-(trimethylsilyl)ethoxy)methyl)thio)spiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazine]-3'-carbonitrile (400 mg, 1.10 mmol, Intermediate 36) in MeOH 20 (5 mL) was added sodium methoxide (197.58 mg, 1.10 mmol) at rt. The mixture was stirred at rt for 0.5 h. The reaction mixture was concentrated under reduced pressure to afford methyl 7'-(((2-(trimethylsilyl)ethoxy)methyl)thio)spiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazine]-3'-carbimidate (435.1 mg, 1.10 mmol, 99%) as a brown solid. LCMS: 0.57 min, 397.1 [M+H]+, Method G. 112 To a solution of methyl 7'-(((2-(trimethylsilyl)ethoxy)methyl)thio)spiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazine]-3'-carbimidate (435.1 mg, 1.10 mmol) in MeOH (5 mL) was added NH4Cl (586.84 mg, 10.97 mmol) at rt. The mixture was stirred at rt for 2 h. The reaction 5 mixture was filtered to remove the solids and the filtrate was collected to afford 7'-(((2- (trimethylsilyl)ethoxy)methyl)thio)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-3'- carboximidamide (1.10 mmol, 99%) in MeOH (5 mL) as a yellow liquid. The product was used directly in the next step. LCMS: 1.54 min, 382.2 [M-H]-, Method E. 10 To the solution of 7'-(((2-(trimethylsilyl)ethoxy)methyl)thio)spiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazine]-3'-carboximidamide (418.6 mg, 1.10 mmol, 1 eq) in MeOH (5 mL) telescoped through from the previous step was added 1,3,5-triazine (88.94 mg, 1.10 mmol) at rt. The mixture was stirred at rt for 12 h. The reaction mixture was diluted with water 15 (10 mL) and extracted with ethyl acetate (3 × 10 mL). The combined organic phases were washed with brine (10 mL), dried over sodium sulfate, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (20-35% EtOAc in hexane) to afford 3'-(1,3,5-triazin-2-yl)-7'-(((2- (trimethylsilyl)ethoxy)methyl)thio)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine] (235 20 mg, 51%) as a yellow solid. 1H NMR (400 MHz, DMSO-d6): δ 9.56 (s, 2H), 7.94 (s, 1H), 5.32 - 5.26 (m, 2H), 3.64 - 3.57 (m, 2H), 1.78 - 1.72 (m, 2H), 1.60 - 1.52 (m, 2H), 0.90 – 0.87 (m, 2H), 0.01 - 0.02 (m, 9H). A solution of 3'-(1,3,5-triazin-2-yl)-7'-(((2- 25 (trimethylsilyl)ethoxy)methyl)thio)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine] (235 mg, 561.38 μmol) in DCM (3 mL) and TFA (1 mL) was stirred at rt for 10 min. The reaction mixture was concentrated under reduced pressure to afford 3'-(1,3,5-triazin-2- yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-thiol (161.8 mg, 74%) as a black oil. 30 LCMS: 0.36 min, 289.1 [M+H]+, Method G. 113 To a solution of 3'-(1,3,5-triazin-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'- thiol (161.8 mg, 415.23 μmol in DMF (2 mL) was added DIPEA (268.33 mg, 2.08 mmol, 361.63 μL) and 2-(bromomethyl)-5-(trifluoromethyl)benzonitrile (131.57 mg, 498.28 μmol) at rt. The mixture was stirred at rt for 30 min. The reaction mixture was diluted with water (10 mL) and 5 extracted with ethyl acetate (3 × 10 mL). The combined organic phases were washed with brine (3 × 10 mL), dried over sodium sulfate, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (20-100% EtOAc in petroleum ether), then purified by prep-HPLC (Method J) to afford 2-[[3'-(1,3,5-triazin-2- yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5- 10 (trifluoromethyl)benzonitrile (11.9 mg, 6%, Example 72) as an off-white solid. Analytical data for Example 72 can be found in Table 33. Route AG Procedure for the preparation of 2-[[3'-(4-methoxy-1,3-oxazol-2-yl)spiro[cyclopropane- 15 1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 82) To a solution of 4-methoxyoxazole (50 mg, 504.60 μmol, Intermediate 33) in THF (2 mL) was added LDA (2 M, 165.68 μL, 331.36 μmol at -78 °C dropwise over 3 min. The reaction mixture 20 was stirred at -70 °C for 0.5 h., then ZnCl2(1 M, 555.06 μL, 555.06 μmol) was added dropwise at -70 °C over 3 min. The resulting mixture was stirred at 15 °C for 1.5 h. Pd(PPh3)4(19.44 mg, 16.82 μmol) in THF (1 mL) and 2-(((3'-iodospiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazin]-7'-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (87.18 mg, 168.20 μmol, Intermediate 32) in THF (1 mL) were added. The resulting mixture was stirred at 60 °C for 3 25 h. The reaction mixture was diluted with water (10 mL) and extracted with ethyl acetate (3 × 2 mL). The combined organic layers were washed with brine (5 mL), dried over sodium sulfate, filtered and the filtrate was concentrated under reduced pressure. The crude material was 114 purified by prep-HPLC (Method N) to afford 2-[[3'-(4-methoxy-1,3-oxazol-2- yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (20 mg 24%, Example 82) as a white solid. Analytical data for Example 82 can be found in Table 34. 5 Route AH Procedure for the preparation of 2-[[3'-(4-aminotriazol-2-yl)spiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazine]-7'-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 90) 10 To a solution of 2-[(3'-fluorospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'- yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (300 mg, 730.97 μmol, Intermediate 16) in MeCN (3 mL) was added K2CO3(303.07 mg, 2.19 mmol) and 4-nitro-2H-triazole (416.89 mg, 3.65 mmol). The mixture was stirred at 80 °C for 48 h. The reaction mixture was diluted with 15 water (5 mL) and extracted with ethyl acetate (3 x 5 mL). The combined organic layers were washed with brine (10 mL), dried over Na2SO4, filtered and concentrated under reduced pressure to give a residue, which was purified by prep-HPLC (Method N) to afford 2-(((3'-(4- nitro-2H-1,2,3-triazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'- yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (55 mg, 14%) as a white solid. 201H NMR (400 MHz, DMSO-d6): δ 9.16 (s, 1H), 8.36 (s, 1H), 8.11 – 8.05 (m, 1H), 7.90 – 7.86 (m, 1H), 7.76 (s, 1H), 4.58 (s, 2H), 1.84 - 1.76 (m, 2H), 1.57 - 1.50 (m, 2H). To a solution of 2-(((3'-(4-nitro-2H-1,2,3-triazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazin]-7'-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (50 mg, 99.11 μmol) in ethanol 25 (0.8 mL) and water (0.2 mL) was added Fe (27.68 mg, 495.57 μmol) and NH4Cl (53.02 mg, 991.14 μmol). The mixture was stirred at 80 °C for 2 h. After cooling to room temperature, the reaction mixture was diluted with water (5 mL) and extracted with ethyl acetate (3 x 5 mL). The combined organic layers were washed with brine (10 mL), dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by prep-HPLC (Method 115 N) to afford 2-(((3'-(4-amino-2H-1,2,3-triazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazin]-7'-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (11.6 mg, 25%, Example 90) as a white solid. Analytical data for Example 90 can be found in Table 35. 5 Route AI Typical procedure for the preparation of 3'-(2H-1,2,3-triazol-2-yl)spiro[cyclopropane- 1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-thiols via final step cyclisation as exemplified by 5-[[3'-(triazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'- 10 yl]sulfanylmethyl]-2-(trifluoromethyl)pyrimidine-4-carbonitrile (Example 92) To a solution of 1-[3-bromo-6-(triazol-2-yl) pyridazin-4-yl] cyclopropanamine (103 mg, 262.32 μmol, Intermediate 39) in DMF (3 mL) was added CS2(199.73 mg, 2.62 mmol, 158.14 μL) and DIPEA (508.53 mg, 3.93 mmol, 685.36 μL) under a nitrogen atmosphere. The mixture was 15 stirred at rt for 1 h and used directly in the next step without workup. LCMS: 0.41 min, 277.1 [M+H]+, Method G. To the solution of 3'-(triazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'-thiol (72.49 mg, 262.32 μmol) in DMF (5 mL) was added 5-(bromomethyl)-2- 20 (trifluoromethyl)pyrimidine-4-carbonitrile (69.78 mg, 262.32 μmol, Intermediate 38) at 0 °C under a nitrogen atmosphere. The mixture was stirred at 0 °C for 20 min. The reaction mixture was diluted with water (10 mL) and extracted with ethyl acetate (3 × 10 mL). The combined organic phases were washed with brine (10 mL), dried over sodium sulfate, filtered and the filtrate was concentrated under reduced pressure. The crude material was purified by prep-25 HPLC (Method N) to afford 5-(((3'-(2H-1,2,3-triazol-2-yl)spiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-2-(trifluoromethyl)pyrimidine-4-carbonitrile (21.2 mg, 17%, Example 92) as off-white solid. 116 Analytical data for Example 92 can be found in Table 36. Route AJ Typical procedure for the preparation of 2-(7'-mercaptospiro[cyclopropane-1,5'- 5 pyridazino[4,3-e][1,3]thiazin]-3'-yl)-1,2-dihydro-3H-pyrazol-3-ones as exemplified by 2- [[3'-(3-oxo-1H-pyrazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'- yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 93) To a solution of 2-(((3'-fluorospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'- 10 yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (400 mg, 974.63 μmol, Intermediate 16) in EtOH (5 mL) was added N2H4-H2O (243.95 mg, 4.87 mmol, 236.39 μL, 100% purity). The mixture was stirred at rt for 8 h. The reaction mixture was concentrated under reduced pressure to afford 2-(((3'-hydrazineylspiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'- yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (340 mg, 82%) as white solid. 15 LCMS: 1.48 min, 423.1 [M+H]+, Method E. To a solution of 2-[(3'-hydrazinospiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'- yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (300 mg, 710.14 μmol) in a mixture of EtOH (3 mL) and AcOH (0.6 mL) was added ethyl (E)-3-(dimethylamino)prop-2-enoate (111.85 mg, 20 781.16 μmol). After heating to 90 °C, the mixture was stirred at 90 °C for 0.5 h. After cooling to room temperature, the reaction mixture was concentrated under reduced pressure. The residue was diluted with EtOAc (10 mL), adjusted to pH 7-8 with saturated aqueous sodium carbonate and extracted with EtOAc (3 × 10 mL). The combined organic layers were washed with brine (30 mL), dried over anhydrous sodium sulfate, filtered and concentrated under25 reduced pressure to give a residue, which was purified by flash column chromatography (0- 30% ethyl acetate in hexane) to afford ethyl (Z)-3-(2-(7'-((2-cyano-4- (trifluoromethyl)benzyl)thio)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-3'- yl)hydrazineylidene)propanoate (280 mg, 75%) as a yellow solid. 117 1H NMR (400 MHz, DMSO-d6): δ 8.35 (s, 1H), 8.07 (br d, J = 8.0 Hz, 1H), 7.85 (d, J = 8.0 Hz, 1H), 7.44 (t, J = 5.6 Hz, 1H), 6.77 (s, 1H), 4.52 (s, 2H), 4.21 - 4.01 (m, 2H), 3.38 (d, J = 5.6 Hz, 2H), 1.56 - 1.51 (m, 2H), 1.37 - 1.33 (m, 2H), 1.20 (t, J = 7.2 Hz, 3H). 5 To a solution of ethyl (Z)-3-(2-(7'-((2-cyano-4-(trifluoromethyl)benzyl)thio)spiro[cyclopropane- 1,5'-pyridazino[4,3-e][1,3]thiazin]-3'-yl)hydrazineylidene)propanoate (100.00 mg, 192.10 μmol,) in EtOH (2 mL) was added t-BuOK (21.56 mg, 192.10 μmol). The mixture was stirred at rt for 5 min. The reaction mixture was diluted with water (8 mL) and extracted with EtOAc (3 × 10 mL). The combined organic layers were washed with brine (30 mL), dried over sodium 10 sulfate, filtered and concentrated under reduced pressure to give a residue, which was purified by prep-HPLC (Method N) to afford 2-(((3'-(5-oxo-2,5-dihydro-1H-pyrazol-1- yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)-5- (trifluoromethyl)benzonitrile (32 mg, 35%, Example 93) as white solid. Analytical data for Example 93 can be found in Table 37. 15 Route AK Typical procedure for the preparation of 3'-(oxazol-2-yl)spiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazine]-7'-thiols via final step cyclisation as exemplified by 5- chloro-2-[[3'-(1,3-oxazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3-e][1,3]thiazine]-7'- 20 yl]sulfanylmethyl]benzonitrile (Example 96) To a solution of 1-(3-chloro-6-(oxazol-2-yl)pyridazin-4-yl)cyclopropan-1-amine (70 mg, 256.30 μmol, Intermediate 40) and DIPEA (165.62 mg, 1.28 mmol, 223.21 μL) in DMF (1 mL) was added CS2(195.14 mg, 2.56 mmol, 154.51 μL) and the mixture was stirred at rt for 25 1 h under a nitrogen atmosphere. The reaction mixture was used directly in the next step without workup. LCMS: 0.40 min, 277.1 [M+H]+, Method G. 118 To the above solution of 3'-(oxazol-2-yl)spiro[cyclopropane-1,5'-pyridazino[4,3- e][1,3]thiazine]-7'-thiol (70 mg, 253.31 μmol) in DMF (1 mL) was added 2-(bromomethyl)-5- chlorobenzonitrile (58.39 mg, 253.31 μmol) and the mixture was stirred at rt for 10 min under5 a nitrogen atmosphere. The reaction mixture was filtered and the filtrate was purified by prep- HPLC (Method N) to afford 5-chloro-2-(((3'-(oxazol-2-yl)spiro[cyclopropane-1,5'- pyridazino[4,3-e][1,3]thiazin]-7'-yl)thio)methyl)benzonitrile (51 mg, 47%, Example 96) as white solid. Analytical data for Example 96 can be found in Table 38.

[0002] 1H HdH1 7 8 ( – 1 = ( 1) z , . .H1 sHz 1 .2H1 sH8H1, , JN93 36N,17.N, . 4N,1) .3,.2H0, 14 3 3 ,30 3 9H14 5 dH413 z0 2 (), 0 . 6H 0. 5 z.0 9,) 0(s,H,) (d1 M H m,802.M9(s,),M27(s,1 8 0 ( J,0H M s, =8.M3H, 4 d,HH)) z , 310)H9H(s, 1H6H .z(s , H, 1), zH2H 809H ..3 J , 7 ,C.2 ), – z,33H) ,, 2C 3 HH) 7 ,1z, ).,2( zd ,1H. N f NoMorRm.T1 9 7 2 1Exable Saltte1 8A( H 6.13H=M4MH7M1H8, (d ,MH7 6NM 3),2.R.5 –(s)4R 087 ,R, )8, ) .5(m,.3 JR, 4 9(3s,R (s7 (4(s .9 1H( . (4 6.=( . (1(3=.s3D5 78. D4(D, .4H D3H , D( 8, .8(.0M)..s).4 6 ),M. zJM 23CsH ,(d 3l,0733(S 4,C.O51H3l 45 (d 8. S 2 ,O61 =8SO )2 ,),. J: δH ()s m (,, -d s,) ), : δ( ,s J06 -(d s H,),.2-d30 = 7 . 1 16.H2 8 . H H):2H5.4 7 ,. 2 = (H 8 dd6 ):3H6. H69z ):9z, .3 42),), δ), 7 53),.3 ,J δ). 5 , δ346 38 47 4M M M M M1e [tM90 3. . 0. 2. 0. 2. 3. 3. 6. 2.9 53et043et12 et92 et07ho +H / ho[Mh[M 3ho[M2h[M 4d ] 39 m d mod m d mod mC , + 2.i9n +,B Hin +Hin +Hin +Hin], B , C , A ,, + ], + ], + ], +LCMS data

[0003] 126 ( P ( P P P0he0%FMCe reMer (eMer (eMerex ia nCtptptptpn nE he- tO( oHhP oHhP oHhP oHP )A0 d d d dc - AL L L L )C A) C A) C A) C6. 7 15 .9 8. ¹H(m H)8.H1 7H1 62 .4N. 7H1H= 73 . .6Nz 1 8 18H 9 (4 3s(7N, s (M4 , , 8 7.1H. 6N H 0M45M,1.60M),(mR( (RH, (dNM 1, s1 ,R59 ), 9 (d,R3.3 ,s(, m1, ( ),8.1,JR H1)H (6 -J 3414 6=,)H(4s4, 7 ), 0,80 2.88.H50 =(4 00H(0H H075 0 s) 3 .9H(4,,0),6M4 ),0M.2 6 z109(,.6 03.H5 .9 7 .M(d.9 M 3.H3 .4 7Hs 1 H M). (6 1s2H),,(t z 3, (mJ,HHH3z ) 5 z,H)1 .6(s , HH (1 z,, 1H), z, z2,-H J 8, .=.0 D26= 1zH,M1, ,(D2s C . s,D,- 7C 37DH)(5, .)HM.41C2 .5C) 4 315H,)DM ),6 6Ss ., 9, ) S 6HlH 3l..3 ( ,7 S38. ( O 3 H76m Hz . ,9 8.O (s),, 34 ) ): , 3 ) 8 d .δ 3(m: δ( ,J71O.2,, -d) , 4 36-d 3.3 .3 ,s, =-d7 1 1( H6 ). 1 -6 )H 07. 1 27. 2 (d6 )sH,),) :H,δ)7,. (9 s,:δ). (s 4 (, 9 s H 6 H 8 d:,),6),.1 ,J δ2 - -4 M4 38 2M8 1M4 30 3M8 42M8 2e . . 22 e . .8 e [M5 . 24 e . . 33 e . .t2o8t1t . t0t08h[h8h + 06h7h3d M mo[d M mod H / 4 mo[d M mo[M mD+Hin +Hin], + 07in +Hind+Hin], B , C .0 , B , B ,, + ], + ], + ], +33292 T42037. 8 ¹H¹ 2 1 4 1 1 1 sH19 .3H) ., 80H.0 4 75.5 . 89 .3H.4 7 8H. 3H,4 .4 .2 07.4 )1 Ns, 1 H(2() 403H s, ((m40H H 9 H(() 4H0)Hm,0)1 0), ),m,0,6 H(4H H (() 0 8 4)s,00), , 8M, 3m,0), ,2H,M1 3 , 8M. , 8M0 22 -H 7. M31..H1 )3H.4 ,1.4HH0 .21.H1 3 20HH61.H07H.6 .60 ),86H 3),-z, 6 .3 ), z 4 7, -(),-z,). (s),-z 4, -(s2.(zm,C1 EHxlt N. f noMorRm.able Sate2 (B74 7 7N N.6 -17 (sM6., R(s 8 -07M(. m7 5 6N(-(7Rs, 7 sM(8 5Ns,R,- 7(sM(,Rm H, 4Hz, . )4 ,M 7 R (.9 1,( 2,1 2 .8 1 2 .4 1,2 18 .7 (0(78 D (s9 7.D 0 s,68 D ,68 D 0 ,8s..0M, (5M. 3..0M3..0M. 33 ,D ,1336 3 s59(SH , 8 H63 H74 73 H(H( 2- S ) 7(S ), 8(S ) t2t, HC )3l)s mO)7 O (. , 1, -m,( mOd.H .- 2s,, - 2.(s m O (,, -m,0J,6 ): δH1)H6 ) ,5316d, .)4 13 1H 1 d4H6 )5 1H 1 d, .H6 )2 9 =6 6.70 7),) :,δ .2 (9 m:H)) :(,δ ). -,,δ s,),) :H,δ).- .6 ., (s 9, 24 M5 40 2M .[M2M2 42 1M54 2M[M1e . e . e . . e . . e .t16 t 4 32910 4 9ho[d M 0mh +oH172th[ 8th[ 6th + 2.moM moM moH24. mD+Hind]+1ind+ ind+ ind]+2in], D , , B H D H] , ] , B , ,, + , + , +LCMS dataT ,] rt ih d loi[ th ea,tn]t i ,d y el tn] pt y e ea,tn]t id yl mrb ]t p uh y lf th 2-aaz3.yl h- yylmhiaz-7 hyylmhirid th hyylmhiaz -7en on iarid any clyd ii n 2.a o 17]- l( )8b-e eatd in- ia op ly )be eatd aia z yi lal)boe eatd in -mia ooNametalitr di i aa z yi l)]-pah noz [4 on hz [4 rrn hz n mn hz [4r ple zi no 1- en -4 37 (.H1 ( 1 ¹ 1H(sH1 1H(sH1 18 d ., 7 s s5, ,H8.3H) ,13. ) , 7. 89 .3H 1J( 1H NM31H), 6N, 4H N6M1 41H NM4 7 6N(b =m)R.2 ) 7.(sM.4 ), .R- 4 )R.6 -(sM r2,,1, 7 ( 7 , 4 92,R5 7. (35.(7. 07. ,R d.3 H.JH8 4(s.5 (1((s7 45 s8 (4(s 90 1H(=z ), 4 05 -0 ,5 dH,4M3H ( J), 0,2 00(2 0 3 ,26 00 ,H -7 () 40M(m H- 7M 2H m,801,2.67 s.H), =8.Ms, ).8H, ).7) , .M2. H488)z , 12 808H6, 36z43.5H z,( 0, .H .4( zH.(,H8(,z, .41,D(3Hz, JM(,2D3. -3,D 1H NMR,31.H13H ) -zH4s, (m C93 ), d ,D).28m C) 7m C26 ,8,D(7..0M 25H 1CsH ( ,.4 ,=Ss, HC28. 27 HCs,425S)s),H3l)411H 8 O 3) 3l)( 9) 3l3 ( (mO,,4 ). , :H (s).4-H,5 :s, (5 ):H s,, -325 7 δ. ). ,4, 6d), .6 δ3 m.7 δ ). 1 16d.2 H8)0 7, (b 9 7.9 H5. Hz): 38 7. H,4 7 7. H H):r- 1)9, 1 , δ .13 (s 9, 0).H ()s 9, 1),),δ49 45 42 46 4M3 1M1 2M5 3M7 3M0 3et .h2.9 et .2.0 et .0.1 et .1. 70 e .0.2o[M5mho[M 3mho[M0mho[M 5tho[M 0dB+Hind+ ind+ ind+min], D H , C H , C H ,LCMS datadC+mHin,, + ], + ], + ], + ], +T T rifluoym rl e]Erxifluy e p] hErxifluyo)s [mu 1 eth 2p olle ro)s [1 en 2p oe rlo]suef,a3, y4 l -p [(7rim mulef,a3, y -4 lp [(1 rim mlefa 7. ( 1R ineteargmeneotdsriam atnedsdat77 sH.5 7H . R ineteargmenetdsia atnedsdaa tafo fr or Salt fut ue tE Salt formeD 12H(s3,1(mH N 19N), ,M( 0M m(23R.0H,),R,m4 ),2H 17.8 (4H3,3(4 - 3.)H,) 9 0 ),H)H00 13,.21.3 6 -03 , 6 ),M(m94(2 .07 M.4 .1.8H6 7 d.H,(d30z.), 319 88 z)4 ) ) ,(m):12 m,(s, (s (m,CH NMR(s, (s- ,7CH NMRH, J).2 =3 ,H 1,D3H , 1 .DH7C)2)H 1C.Hl ). H 53l ,13.8,1., :497 δ 4..8 750, δ 9228- .4( 0 .9 ( H .0 1. Hs, - 4 s,),1 8- 1z,45 4M e0t . 3M5h2. 8 31 e . .3o[ 1d MtmC+HinLCMS datah0o[d M 8+m, C Hin],, + ], +LCMS data271h5FMr (Mrx ia nCtnnE h thpe - tO(5 oHdP oHdP)A0c - AL )C AL )C2H, 8) .N 1,, 1 -1, 7 ) 908MH H.. R), ) 9 ,4 8 -.39 N4 84 1 N.M.59(s ( HM ,m),R 7-73.5 24 , 7 - 715R( 1,17. (4.37 8.9( 0 ((m4 .0 52 .57m 82. -9 8 (m(4s, H H92) 0) 80(,0 (1 M s 0 ., - 37 ( 2, 010 H, 6 , -MM) .6 7.7.H P Su M Earixlefti.tc fh noaoortdim.onT310able ( ee%Ce epe esisedviaRouteF (m2H8 1¹ ( (H1 9 6 7 (sH1, ) .78Hs,m)H.1H1 .9 .7 ,(s,,2 mHH2 . m3 H, )H, zH 4,( Hm,)H3 5 2591z,)).,14H8 , ). ,4 1, , 8 z .4- -( M4D3(m H 1. ,. )C06. 7 me6 ,1 8 2M.3 , ),H71( 6 .2,O-S 617 ),Ds, 3 4 2HD (.s0,18 O H..8 8 -83C3 (m (- 3-(86d s,), 9 .0.NH) )6- 9 65) ).,m, :1,17 δ27 ():3H .9 7 ( (:δ H H.7 8H).,9 m δ4, ). 9 .8 s5 , m),,)5 .,- 124 M5 42M5 42M4e 9t .h2. 95 e .1. 8 30 e .0.2o[M2tmho[M1tmho[M 3dD+mHind+,B Hind+,C Hin]+ ] ] ,, , + , +LC 1HM NSM dRata181ne t, ep). (s,)2,-z68,3 .H),0b zr ,toe.T5 Ex. na Tb 1le2d ly3 .H),4( zd ,.. D0) 3H d D)3H , DH)9, 78M..2 z,M..2 zJM (S 5 ,1 J=S 5 ,1 =S3.(2s m O,-(s H O (s H 8 O.6 1,16d ,),8-d ,)4-d( Hs)36.06 ,)36H6 ),)H,) :H .,δ)8 H:H .7, 7zδz :,), 1 , δ40 4 4M6 2 2M2.M0 2 8 3e . e . . e . .t1307 t02ho[d M 1tho[M 8ho[M 6m mB+dHin + inLCMS datad+min], B H , C H ,, + ], + ], +LC E RMxo.Su n dtoeRa.taable Roudanay Sa nat lyi ti 4.6 7. 8 1 (9 .3Hs 1,H8.3 1 (s 1 8 17H,H.3H 9 (4 7N 1s-( H),( N 1H), 6NsM) 7.sM) 7.(M ,1 7 ,R, 9H.9 1( 4. 3, 1R, 92s,R (H( 4. (1()2 H4 2 59 d ), 4 2 5 dH4,(), 0 .1,8 0 .5 8,) 04m802(s J.05( J, 803H.5 ,91.H1M0 H(s , =0M s, =.M, 2H 89(H 1H NMR(s, 2H 808H 1H NM2A) C4. 7. 8H1Salett fh nooordm.T4 Ex.ab 2 Tle3v Aia ) CuteJ (bmbrH 55 8 .9 35Nrs, sN(s-(sM,1 1H , 1M 1.5, 7. ,R2H)),HR )12H 8 1(H, 7 , (4-1)3 H4,(m), 00) 6, . .8 7. 0.1 3 5 0 90., 8.M.3 1-3MS M Eaxlet.t fh nooordm.able RoutendRoutendanaanly aly MviaRoRoute(1I( 387(71H10H m-,1),-z8,D2 .67H3.5.0M 2H 1,)H 1H6d1H NMR9(b 7 (( r .7 s,H sz,s3 , 4 11 (m H,)CD 13SH H), ,7C ). (m (s (m O).,42H.8 3l),,- .4 ) 7 δ):9,, )(7-7 8,),δ s .1 ., 2 8 .61 44 M4[M2M8 2e 4 .5 e . .t 2o8t15h +Hd7mB]+.1LCMS dataho[d M 4m,in +,B Hin]+ ,,LC 1HM NSM dRata L SC 1 EaHMxlt N.S f noM dorRam.taTab 3le0260s, b,rRHz, 27. ,8 1R (s 1 1 s,H H, H H ,(42)9) (42)H, )10H,6 ,H 0), 3(.m, 8 0.0), . 79 . ),M3 1 2 , 1M34 9. 1 8.HH.2 71( H0- H 35-3 z ).2s) z6- 7 ,.7 ( D(t,,8, 36..0,D(s 8 .8 s, 4 5 ,MJ H74M 3( 1H m (S=), 7(mSmH O 72(s,O)., )1,H1, -7 6d .6.74, 1 1H-6d)H., )9),7:H ( Hδzq,),), )-, J 7:δ-44 4M2M1e 8t .h2. 0 30 e .1.1o[d M 3tmho[ 1M mB+HindC+Hin], ,, + ], +LC 1 EHMx N.S nM doRa.taT5able ou ot ueSalt formtLe17 4 8K73. .9 . 1 = . .3H5 .9 3H114 820N7.8.( ( 6 (5 5Nm(Ms-(sM

[0004] T yll)m iba )pyl yllmiariden7-yllmia zi .2l-7e en thdi ya r- i7 )d-b(e etdia az t (a 1)-be etdi n .a o 1-(zyol z]- i a 2,n hzyl zi in no yn hzyl z [i 4 ]o, c -o,1 H8H), . ¹3H.N1 sH8 ¹HH=H7 (s.26.0 =2 8.0M6 .HH45, 1 =8.0M (H,4 s,),.4dNameen p arodidaa ny-yl)cy3tal pz zi l]-ph an5 n- zi 2 o ]- n5 -p an in n 1 e- o[ - ny o-3 [4 la o ]- n5 - 3 t3 - a xarooi 7- 4 l] 4- (s 1 3 ( 1 1 ¹MH3 ( 1 J 19 ,1), .3Ht,H= 2Nz, 1 ), .9 ,N. ¹H)J ), 8 3), 7 72 5 .9(sM( H7 6M20.4 21HM,Rs,), .9(sRH 8.5 (d )R3 = 6.7..107NH (sM R H.0 2,)9 (,-d1 35 1,H(,4H.8 () 0 ), 7 d1),H6 ,H(,4 3 z) 0 .2 , -J, 08 (24. 4 3.21.=08 00 (s H (sz,,1z, H(411H) 035 J, 802(s J, 80(m6H 52 8(M ,23,H) , 803( H1mH ,H ,3,H , D , 1, 4H , D.),4H 1 8D 4. ).5,860-d.H6 0s,),.4-d -2 2 , δ1H)4), , 7 .M.36H (s (m .09( z )d ,. (s H).48( zd ,H 3.)H4 zJz9 , ,=,CH NMR).,2H4.5 z ., 5 92(sz,26 (, DH 2z,JMH.5 zJM1 (d )H .4C0H (sd, 1HM ). H),1 =SH8 O) ,, 521 =S .(H 8 O9,7J,=3 ),.Hl-), J) S6 6 3. z ):2.4,532.2H =,O)88. -d)4 27H61 10 ( 8 1H 8 ( 8,.4086(.5s, 1z,:δ (s H .5,), 4z ),:.δ 87 .8 d, (sJ ,),.3 m (37,s . H):,74z( δ, d,48 4e 0 6 4 4M t. 2M M9M81. 37 et . 22. 31 e . 22. 31 e . 22.1ho[d M2h[ 2th[ 3th[ 2+moM moM mid+ id+LCMS dataod M+mD Hn, D HnD HinD Hin]] , ] , ] ,, + , + , + , +3z 2, 7=4 H .272( .) ( zHq, d ,D).J H.=z 0 zJM ,5 ,1 =S.4=,6, 6 6H NMoR.T8 Ex. na Tb 3le7nateH z1 (s 1H8 ¹H(H1 . 1252 (( H,1 m), zH, 8 ,D, 43H , s,),1.34 ) 1H. ,H2M 54 ), SJ( H 8 O) 7 .9 6 -8O4 s).2-d. -40 .-42 .0- 46dH 7 H . Hz):.3 4 ( ():z., 2)5, 2 , δ 9 .8 s2 , m,δ4 M5e [tM2M 4. 4 33 e . .h + 3oHd67t011mD]+.2,inLCMS dataho[d M+m, C Hin],, +LC EHMxlt N.S f noM dorRam.taable aanly at lyic tic Salt formouSaoutOe1 8N,.6 , ) .3m,),H38H 2H31H, 7 8N 25 ), -N)- ) .(sM(H.6 78M ,1 , 85,Rm) 4 .9.3R J1 .6 4= .3 0 .5 (d1H(4 , ,24 - 6.5 - 4((47 0.2-(q1,) 0H51, ( J,0)Js, =8.M, 7.53( 6 7. m090,01 MH.2 80H 1.s, (m HH 1

[0005] s, .17 sH2 . sH H1HM),3 2H.4H.8 4 6 . 4, 3s., ( C31 m, D.0s8, (m CRouteT PP danaLil HSytt MS eit pDe1 7( 1 7 ( 1 1. 4 (s 1 1 4 ( 14,N H7 ,N90 .38,1 H8H), . ¹3H.5 3 4 7 sH 5N4 .5 .1 6 .8 .0270,1H N)(m3(mM2H- 1() 7(M - 1- -( (M ,)4 ,2,R 7. ),R (3 ,17 ( ),. m8, , 4 .85s,R.5 314 2.51(0 . 4 m m)4.5,2, ,R 17. (49 7 0( H87 0 .( H7 (dH4( 1 4 H H8 0()s,,7 -0 s.17 M ,)33,H7 -03m.7 M8-, ),23- ,) 0.4 J,.=80 m,(m (m), ) 3, -0.M22, , 4. 67 M2 .8HH1.8H1 H550H H 1 27 .3.7H H81z ), 81z1H.63 87HH H1538z)(, ).3(,1,D NMR3),.0z ).), ) ) ,(1 -(m.63 m. H(d5, z,,D1J M. ,4 2 , -. 44 (s (0.4.6 , m C1,D 6H)1C- H 1C, 41 3H,=S 3 2 47 H 1C (s,H5) 3l):3.),H3l4 ) ):2H- 1( 1m)H 8 O- 1(s (s (m),H)3l),3.6 ,7 δ0. , δ )., )..24 7.61,0- 24 , 6d .37 , 1 , 2, 4 , :2.97 δH8 8 7 (m 8.7 7 H.46H)H H H 0.7 7). (b 0 .9 ( 8 .9 (m 4 .8z :(mr - 3,s, - 3) )4 .8,),- 5 ,δ,, ,),– - 94 M2e 5t . 2.M[M2M .[M2.M[M3.h05o[d M 3et 43 63et 46 35et 47 28+mh +oHd9]+.0 mLCMS datah +oHd7]+.2 mh +oHd9].1 mB Hin inDin]A+ in+, B , , , , , ,,4odPicaoti.onT2 Ex. na Tb 4le1edodPPu Erixfi.c naoti.onable RoutendRoutendanaanly aly PurifeFL )CMethodv EL ia ) CMethoddviaR R.(3H s,M Salt formoute(s (s (sM 2z,1HR1.,R 2, 1 ,(s, 1) (4 52H H 1H(41H, 8 00- ), ), ), 0Salt formoute19R QH= .) 5 ¹, 8 2H4. 75 . 88 .3H17.4 N5 8 5N(s,H), .) 3, 7. 7M 1.41. 7 807.9 .0M3H4 9)..6 5(H sz2 ((d,s , 1,),.3409 -d1H NMR6(3m-0-9H z HD 1 7 -8,M,.6 .8 . D0M ,J 22 =), SH 4 3 5SH88.O). (m (m (m O, .H (6 )3:2,H1, -dH 1H6 ):7zd, , J δ), ), ),δ4 M5 4e 0M1t . 2. 8 2.h22 e .09o[d M8tmD+HinLCMS datah8o[d M mG+Hin], ] ,, + , +LC 1HM NSM dRata59484J 1 (6 ¹H2 s 1 δ 1 2 7 (sH1H2 3 4 7 8 1.45N1 ), ,Hs7 3N-3,( HM1 - ( 7 4N(M.6 3 ), . 4M1 H3m) .61 (mb -(M z,R 13 .- 6 4 8(5.7 4s,R.5) ., 83 , ,R 17 ( 6-.9,rs 7 s.R 8, 1(s,d, D ). 2H,m4,H(d ,D1.46 H s, (m M)e.2H1 -. ,93 (s68,.D, 1M),H 1z, .8z1,O).4 ,.70M JH=) S, 1 )H,JM3H,2 H 1D,1 16 203S8O. ,- 3 3 )1 =S -. ,H 8 O 1z,H),H. -) 4 ), ): 31 (m H),(s (m O8.4.0 6d4-064. )5 , 6.0-.d 36 2H, 3 .5 7. δ 4.- 82,,231,1-6dH 7z():δ 1. (s 1( .5 H6,d, 21 , sz ): (m). 1 8 8 1,1 ( 8 .0 . (m H.63 H)H)) :δ, 1 ,,0 s, - 8 26, ), - ,,50 4 4M e4. 2.M66 22 e . .M94 23 e . .M e[M5 2.t2 7t0 5t04 t 0 7ho[d M mho[M mho[M 8mho +H44. mD+Hind+,B HindB+Hind ]B , + 11in]] , ] , ,, + , + , +LC EMx.S n doa.taT543able 32S=H)H,H8 1 .6 (H.8 , ) .0 . .5 .H 8.1 ,1H) .H0 s, )2 1 N, 0 566 8 .3,1 H(H4) 01. -2 (d1 2H( 24(m.5 (t,H.9 4) 6 00 1 2 2 ,. (m H 2 3 H(40) ,, 80(m 50 3. - ,4 4 J), 00, 6(J, 6 -M(m58, ),H (3),m),807.. 3M85H,2 (m9 .6 =68.0M2H 2Ht,=6.57.9H,(m 2H.5 4 , .M.11H 4((zH,m 8( .06H z).),J9=.8 ( 1z,2H, ), 2 51H0)-z1H NMR

[0006] T ri yfluloy o rif p drl e 1 x l a r–rify 2-uyl e n oxEluyl eo]smu ][ ,lf1 5, ' ) [3 - s [o]s ] e- yp p 3r'- omu [lf1, 1, ex o5thp re o]smu ][lf1,eay ir(1ea3 ' o 2riea3 , y 3h p P nt3ty e T (l n riMr ht e e ee tta ( u thnhpe en-ratr / ioH1.4 8, 12-1 H), 0 10. 63 44.8 dH40PurificationsisdP)d oie n IL )C2H, 7 8 80N 2, 4H), 35NS MethodedviaRou(s 2 J 1 (,H m H(s 1) = 2. ¹H, ) ,1 H8. ¹Halt formte2T(1sH(m,2), 6), .5.2 (MH.4 ), 7.(M,H.61 3H s,R), 1 0 4 84s,R2H), 9.6(sz,1H(4 . - .8 (1( ) 3, .1(s,6 - 34 - , J),01. 51( 1 Hm.6) ), , 87 .3M 1 4H(m .6 (m.8 =828.0M3H H,),11H =) S2O H38,8 . )1 =S- )O14(s H- ,),,77 .8 5 z ,1,( .6 zH1), D H m H H DH NMR1 352(m.1 8(s,2 ( 2 m 2(d ,.3 H.) 09.,2 ((st, 1J HM) ,,., ),1M1,Hz,J (m1.(s,6, 2,74 ,4H)8.-24-H.4),.2.0 6d1-.5 ,26d H 1),34. H 7): .3 3 36. H- 5z ): ). .644z(, d δ 9 . 8, - 70 (s, 7 , δ 1 .5247 4M2M5e 5t . . 3 24 e . .0h2o[d M 6tmh2o[M 9mD+dHin + in], D H ,, + ], +LCMS data51.44. 885 8(7sz(, 1,D(m s ,,,2 2 J H).14 86.)1H N nMoR.T0 Ex.ab 4 Tle906-1(0 5sz4,- 7(s,,D(dM. 2 .M ), S0 H 84 1HO ()() SOH H =),88..0 -m,d, 1m,2.7, 861.1-d16 )7H (:6zd δ H- H-:δ, ,).), M4 46 61 2M0 2e .t 4 e . .7h.o[M 8th0[d+M 3mD HiLCMS dataod+mi ]n+, B Hn,, ], +LC 1 EHMx N.S nM doRa.taable anaanly at lyic tic a aRoRuouH= .5 ¹HSalt formte. 7 8. 8H1( ), 8 4 66.6 03.5Salt formt1 J 9VeU 1s, 7.4 ( NM(0N(92.H79H s, m (s m (M s )1R,R ,(1sz,H( ,42,,H 1H 1 1(4., 151 H), 02H) 80), )H,)H,), 00), .3M1. 4. 7 8M-, 7. 6H5 5 .9 .3H6261671(s ()m, , –8 8.8M2(7. – 767 (M1.7(s (2m(sM2H),1H 1H=M 1 R .5, 2, .0 3.477Rm3, 9.9 sR4,8 , 1-1,1 ,R 1), 4. )4 , 7 ),.0(m ,1- 2.6 7., .1 8 ,.D- 517 7.8.,D).2H , s,31 7 , D (1(7Cm), .9D H8 5 11 45H– 6M S.4 (s90M)H .,18S ,18 1Mm.6H5 9S , 9 , 7.C ). (m (m), 88.–8O 6( 2H–(7 mO. )4 ,4(m),O 2H-18 (1H5 d,3l),2, .9 09 .4-6d m,),.8,2-6d9-.5 , 8.1-6d)..5), 7-7 J:=δH1H 0 ( 2):217 H):1 6 1 2)7 . . 8),),– m,(m δ H . ()δ . (s H –:δ ( 3 7 1 .5,).75 m,4,5 ,),m4 8,.0 044 4 4M70 2M7 6 6. 6 2M .0 2M0 3e . 7 e . e . . e . .t2 3t27 t24 t04ho[d M mho[M 5mho[M 5mho[M 7mD+Hind+ ind+ ind+ in], D H , D H , C H ,, + ], + ], + ], +LC EMx.S n doa.taT052able 88 24 8 1 . ¹ - 1H. ¹H7 8 (8 ¹ s (H(dH1.5 .8 1H75H) 7H1N.7 ) 0 8, 2 .3HN), .6 .5 08.4H,m,N1H, z, JN0H 2-((42 (s H(41 H H H(4 1 6 7H4)H,) –s (8 , m0H , (0)1 m), 00 .7), ), ), 00.5 .7 .5(6 9 00 z01.41 , 7. 1, ,H, 8 (m17. 7 8s, -,1 M7.7 .579 H)1H M1H.4 ),1H.0MH,(m56 .9 .3M -H1 2H 7 (s, HH (1-8(m,8 ), z 9 4. ), 920 6.-zH,(s–(z5).,70 1H), z,1H NMR

[0007] 2H7), . 86 .H1 (s 14 41,H92), .0H1 (s 1,H9 22), .2H1H)2 8,H.1 9 21 . ¹0H H7) ., 9 82 . ¹3H1.7(s ( NmMH7 7) .6( NsMH7 5) .( N1 )s M. , – 6N47 7 –M. - 7N7 (M 8,R, 5,R, 64,R0 .68. 9R58. sR -1,21.( 11.( 1- 907 .0 ( 8 ,6 11 H H(4 1 7s H(4 7s H(41– (4s H(4(.m6)7, 7 ), 00.4 7, 1), 0 10.3 4, 1), 00(.6 7 (m1(0, (0 2 m), 00,2 (m.5 86 .2M 6- 1H8) .5M 5- 1H8) .9M m7 .7 H(m.6, 2H(m.6, 4H,2 ( 6m 5,m1(,Ms,H, 8)4.M( H 2H2,H11H H,9777m)H H1 )). 2 (H s,– z, ,2 (.5(sz ,,,2 (.5(sz,H,)2, , z7 ), , )..7 , 7 – z,),1 8. D H m6D H m6, D.HM),( 1M) ,( 1M)11H 2 H.9 8D8M(.58. D0M .),5S. 2H s H, 1), S.2H s H, 1), S , .1 ) 0 3,s7-7 S, 72-(S4 4(mO)H8O)H8O.5 47 ( O H 7 mO8 -.5 , -d, . -d, . -d0 .5. s-d .4, -d1 9 1. H6 1 )) .5, 4 1 )416 ) .4, 4426 )-1 7 86 , 1H6 )) , 18 1H6 )3(s:2 . (,),δ - 60 s:3 . (, δ - 7 s:,δ .4 (s (:,m), δ .5 (m) :,δ6 1 8,1,4 4 4 4 5M60 2M6. 0 3M6M7M1. 0 3. 1 2. 0 2e . 6 e . e . e . e . .th9o[d M 7tmh92o[ 5th925th333th180d M mo[d M mo[d M mo[M mA+Hin, C+Hin +,C HinD+HindD+Hin]] ] , , ,, + , + , + ], + ], +

[0008] LC 1H NMa NSmM deRataT T en ylmiaacy[(tla )b ez 3e on ylmia zinpiz r rimlen in cl '-pn thyer] o o[ pr15(.3 (m61 (d1H(4Namentaitlrli)lep ezyin o opirtihye [4] ,3 adninozo l]- -5 7 4 o' ,3 pprodi ln ]- -2 7' - e -- 2 ConditionsmpleConditionsm0 iopl h°Cx ta eps es , 1ne 1ss2 , :13 Slt frmeY Slt frme2XH(s) , 1,1 H8. ¹H1. 275 (tH9, ) .H11.H)) , 37 5N, 0NM- J 8 86 ,( 1= .5(M 44 .8s,R.63 43sR -. 5. ,8 (s 1H(4s,), 0(0 m H , 1), 00,, J=8 , z5(m 2H,H)8.0M22,H9HH H 1H), .0MH .H,.447( z) .4H , D.3 -184 H 8 O1H NMR).), ) 7. 3 z)2d , 1 , 4 86 (d ,DM.5 .,,zJ7 6(-s JM 13 ,=S 0(, 1 =SO- .3),. 1 s0-d .4 , H 42).- 176 ,8 d. . H643 (m 8z ):δ ( Hm) 7H6 ),.6z :δ1,5 ,,6 ,44M37 2M7. 2 2e . e . .th26o[d M 8LCMS datat087mho[d M mD+Hin +,C Hin],, + ], +

[0009] odP3 .5 8s,z47 s,), SHo NuMteRT Z Rsa Y YndanI HPurificationseoH HL Methodd dP oLdPJ) CSav Lia ) C IL )CRou.7 )3, 87.42lt formte- 1 = 9Z17 = 91H.3H1 .7 4 . 8. ¹H2 .7 ¹H( 9.5 9sN1 37HN) 8.8M(7 2 ,2 (s N(m.7H , m (–(sMH4H ,M ,9 z1R 2(, ,s, 7. ,R) ., 5 z1R Hs, 1 HH) (2 2 8 1(, 4H H 6 H4 1 8 ,.( 1 HH) (, 4),1H), 8 0.30), )1 , 2(m), 08052s, 2), 8 0.01.5 ), 7 6M. . , .1M - H7 36M4.8(H 147 8212H1) .8H -H .(– z4,1 8(sz- ( , ) ,9(,,17 d1 D 1 s,, 78 D (.8 d1 D. ( , J HM.50 3H.8.09Mm0, HM S,- J), S(2 =m H 88.0O-(m) 3, 1(s (m O 2 1 =8-H .7 8.0O-, ).48d, .,,d).7 .29d2,H1). Hz(d6 ):2 76 1 16 )( (6 )δH H H:δ m Hzd:δ.79 , , J). -),),,, , J4 M3M9 42M7e [tM4 . 0. . 7 2.h + 6 3oHd11et961et .253mC]+.1,in,LCMS dataho[d M mho[M mD+HindD+Hin], ,, + ], +5.5 q z 9 4. 7. 8 1-8 11 ( H 0, 03-4),-z.m36, ),(m.812 0.07.18,.0 D(m H. ,31 2)1H(q(74M 2H.6 2).23. = 16 H 1H 1 dMR.T7 Ex. noa Tb 5le6aly18 8H 8,1u , 5 5 8 .H.6 ),.9Hin1- 3 7 34N 874 (s N(m) ,H 3 (s- M(.6H ,M 3- .5 817 (sd,z1,D.4 (s , HM ,J)mS3 2 =,8 SO ,,, (s (1 -),J,, m O (,-m H,)8..408 -dH6 )2, 6H1H (d):.5- 3 1 7.6),),): .,).75z, , J δ44M6M6e 3t . 20. 18 et . 30.4ho[d M7mB+HinLCMS dataho[d M 0mC+Hin], ] ,, + , +LC EHMx N.S nM doRa.taable ananat lyic tic A9A1(m(H3. δB- 1H= . 1A,, J )22=,.H.2738.7 , 7 (2 . s m8 ,R, 5(H 2 1 (z,1HR H(2 s 1) (4), 0.676m)(4H ,1 -, ,m), 0 ),1 H, 0.42 H - 14. , 801H), 8.0)7 3M3.0z,3. H70) 71H.1MH 1H N.5 , 4 .8 5( H 1 LC 1 EHMx N.S nM dorRam.taTab 8le65teAH).6 roHH. (, 3 p4N), 8 s, dH .-8o 14 1roNf M.(mHpM 26H1.TR76 , ), oR ), –42F ( -1814 (A 401 H. f1 T (F 40.4.5 m):97,2δ0 .9 M(m 61), 0 A7 -8)0: M(b (mH .0H,2 (m.6r2.0 δ8H s, ),8z,H,42 (zs.5,,27– D).H , (m 2 D2 H.6H), 39M .0S ),1,(M 1H 1 s,S). 1. –76 O. ),H 1 O07. (- (6 m d56 4 ),H-db 0, 61, o-.5 7 )16.9, 608. wr (s m H n .4 (s 3it,, ),e 1 , - 4 h46 4M1 2M60 2et .0.7 e . .o1t06h[d M mho[M 1mC+Hind+,B Hin]] ,, + , +L SC 1 EaHMxlt N.S f noM dorRam.taT8able Salt foe rx ea xm apmle pl ou outeD1 8 d 1 2 7 a 1AC

[0010] C L SCo 1aHnMltd NSitM dioRantasT m pless 14 formeAE24 (5m H9. ¹ - 11H8 9 ¹ 1 8 δ. ) 0H. ) .5 , , 4N8 , 07.0H.N7 75.6 .058 ¹.H2H7. -M17. 3M(9(36N1(s.5,) 99 (,2.0Rm83(m (,s m (,R,s m,,(sM R 32H7. -207 (( ,42 ( 2 1H s H H(42H 1H 1 ,H 1(- ) 8.8 m0, 1) ) 0 ) ) )H41,.851 ,0),H, ,0, , , ) 000. (8 t,(m 1H M1 ) 7 8, . .3M1. 4 7 ,5 .5 .9 8M(3JH.5m- =, ), z 2 4 8. 8 7H z1 7 0 .30H z,1 1. 5 H8 ,.D- 518 (d(, s,,D- 1(s,- 7(s,28 5) 0M. ( 1M.4 2 .8 , DH 0 .6, 9 S5 s J HS8 H 5 2M ). (m H7. -, z 88 O 0 ,( 2 =m H 8),O (m),( Hm) S,O2, 3.H 1 - 0- 76d, ),.48.1-6d, 12.7,18. -d)H,)7,.8 (m):2δ H1. H 0)0, ).83z, -:δ H 9).- H 16)0), -:44 46 4M e2t . 2M .0. 2M6. 0. 2.h24o[d M 0et+mh25o[d M 4et+mh24o[d M7mD Hin in + in.] , D H , D H ,, + ], + ], +

[0011] 1.8 7 8.3.8 0 9 ¹H(m(br (s (sH1 (s 1,H8.1 8.H1 1. 4 7. 8.H1 - 21H9 6.H1 2H.5 7. 8.H159.43N(m,1s , ,,1 N 3)H1HMH, 0 7 7 .7 – 5N2 5 9 3 .7 0 6N7 )4, 07 7N) 7 8 3, – 7 4N(m ( (,s m (sM,R2 H 1H), ),R), .78.–M(8–Rm (s (M 7sR(m.6(sM2, RH4.6.–(M 7s,R 2,H 1,H1 ,H 1H(H)4 ) ,, 4 ), 7. 7 . 88 . (5 4 1 90 1 .08(4s 6 .7( ,2 , 2 . ,8 1( , 81)2(s H( , 51 327 .8 1H(,, ( 34H H 5 H4H ,) 4 .( ( 34) ) ) ) 0 1 4 .8 7 80.41 ,. 4 ,7 , 80 1 m (0 )() 01, 0 4s m), 05 .5 .8 .3M.6 86(s1(– –M 7- 1H,m 0)s7 8H( .),1, ,m,0)H,M1 2. .3 , 8.1M, 802, (1H.. ), 5M - 2 m1 H,180H, .1M28 9 7H -, , .8 .5 m 741H5 912H5 4 3H.)10H - 1(s–(sz,1 2.6 H 1H 4 5z,C,72 (.5 ),Hz 3H7) ,- (s)-z, 6- .6(sz,36,1 ),H4) – z,.5 ,5 2 7H . ,8 1 DM1), )6H (1 ,(m (mDH m)7,(. ,9 8DM1. ,,8 D37.01, DM1 1M(m.70 . ,6 78. DM (m), ) Sm.7 7 , ,C .1 1l. 2H s,0 .34–6 S4 H.616S.4 (6 s H,) 9 .00,S ,2 -1– 26S, 1(m,8O, 6 7-2 H H3-7 ) ) ): ),2H 7 (s O-(m), 1( (s m O-( 2m H8O2.7, . -H .6 4 (s (m O- H9 1.16d H) 1 -, , δ77 791. ),.8 , d6 16 ,2.7 , 1,26d, ), 306d).2 . ,,d( 65 1 16).- H 2),–):δ . .6 . . 59 .6 82H)94 91 .6 51 .- 3 (6 m) :δ H 9 H H)-) ) :2δ H1.)8(s:δ m ( H)H)) :δ,,),, ).1 ,,m,, ,45 5 4 4 4 4M e9t . 2M10. 149et . 30.M73 3M725e . 3 3.M60 2M7. 2 3.t .957et .94 et .96 et .96ho[M mho[M mho[M mho[M7mho[M1ho[M7dD+ idC+dA+dC+dA+m dC+mHnHinHinHinHinHin], ] , , , , ,, + , + ], + ], + ], + ], +

[0012] 47 8 1.5 .9 .3 9H1 4.H7) .7 8H1 (s 1,H9.2H1 1.8 4H zd, 8.H1 1. 7 8. 10 ¹H705.5 5 ,2.32), 6 1 .5 , J 3 8 .8 08.(4N1 5(0N H8 –N- 71H= 6(N 32 35N(–m (M(.5m (M) .39M1 ( sM(m ( (mM 1s.7 sR1s5 ,sR, 0.R. s),84,62 . . ,Rs (sR H8,61 ,H 1H( .4 5, 2H-1 ,12 7 ,H 2( .7(s 4(2 2H74.1,,,,H H(2 1 1 1(- ),() ) 0 8 5- )H4, .3 ), ) 0 1.3 8, 2 (m40(m) 65 z ) 4, 0H)H H))H401m, ,0 1457 ,0 9-H,0, , , 80, , , ),0.1 , 8 8M .14.7 . . 7M 1 1 M223(s 1.M1 4 7 8M21 1 .41H46.83(d71 .9H(m .7),HHH H.37, H12) 7H.5 .5 .9 .3H (H0m-) –(z,0,(m - J (s (z, ,172(.6 ), z, ).),- H, 7(sz 2 8 0 7, -(–(z,,1.8,78 s. , 1 D,1. =7 , s1 , D H m8 8.9D1.53.)3, .4 8,81 D 1 s. , 7 s. , D2 1.0M2 4 H 1M).,(s5M4 .HM5 2 8 1M H5). (m56 HSH 1 7()HS2H ,S36 (d ) S6 H 7 HSs(m),8O ) ( .-. m 2, 7 ), 7O),1H–8O- 1(m2(,,O ()J8m, 1(m),O,2 , 1, .36d,H2z .6 .7-6d1. ),.9-6d .46,3 s, =.0 -86d,2.8, 8 -.16dH)H 1H 7,),),–):Hδ)2 9 6,H ()4)s -:δ 543.)H 27 (m:δ (m),H 8).(b:δ H 0 1- H 1):δ,, - 1, , ),4 r).),–45 49 3 2 4 5 4M M6.M3 2. 0 3.M04 2M59 2e . 3 e . e . e . . e . .t9 95 t92 t18 t04ho[M8tmho[M 0ho[M 5ho[M 8ho[M 9dC+dA+m dC+m d+m d mHinHinHinHinD+Hin], , , B , ,, + ], + ], + ], + ], +

[0013] 1.7 (s 1H9H1 1.7 6. = 9.H1 1.7 ( 1sH8 1. 1.H1 3.6 4 7. 8.H1 (s, 2H8H18 ,1) .5 2 2 1.23 0 , ), 0 1 8 .5 8 31) .4-H, 3N-5 6 N-2H602N2 - 3 6 5N2H, 2N18(M1 ( H(dM1.((MH 3 (–(M)6, 8 (M .), .7 93s,R. m5, z, ,JR.5), 6mb43 ,rR),.6 s, 7 s. ,RH), 4 .2 d. 7 ,R 8(.m55 (d1H(7 1 1(7.( 1 s,( 13 2 8 1H( 1 5J(,4) 0(m H)H =140(m52s, H41)1H0 .4( Hm)4) 4, 0 .5 9 ((d, =40,( J,0, , ),. 0,( H,00 ,(m801s J 8 02H 2 s9H, M 24 76 M 2 s7 ),M -,24 .M - , .4 M) 1 =1.2 2.),H4HH H.76 .0H2,)zHH H 2, .5 8 8.H1..H4 ,9109H1 2 =. H 8 HH 1).8( z,).), - 1 , z,).),H5) .7 ( 34 z,3.,4),- H)– z,42),.4z, z,4 4Hd, D1.34 (. s 1, H D1. ,3 3 9 d, (s D (14m. ,6. 8 D46. (m1.8H 1H D8.7 zJM75 1)M6 .0(s J ,M74.90MzM -1 ,1 =S9 H, 8 S 9, = 1S , 26S , 1 ,1), S1H 1 O- 1() .O- 11 H O 2-(m ( O 2-H8O. (3 s .-. m, 9 -. (s H 8) -H 1 (s m-H 1. -7,)82, 6d 26,46.516d 2 .7 ,3),3, 8 6d ). .61,2 , 1,16d)..7), 306d(m H8. H4z ):, ), 0 , δ (m H 5 (d,):, ),– J δ (mH4. Hz.1)H H H)47, ), 81 , 3:δ (m) :δ ( .6 (s):δ-, , ),), m,8 ,46 4 5 4 4M1 3M7M1 7 6. 3 3. 9 2M0 3M0 2e . e . e . . e . . e . .t00 t94 t36 t0496ho[M 2mho[M 9ho[M 5ho[M 9tho[M 8dC+dC+m dC+m dC+m d mHinHinHinHin +Hin], , , , A ,, + ], + ], + ], + ], +

[0014] T yll)mia z ob ez in p,5i o ro -tnhzyeo l] ]- , a az7 3 n in1.7(m (m (M Namee on n hityyll)mia yez ryi)d s'-p (2etn [4 p ritalrip tin a i ,2pleyrhe z ri o -dyl ]- in [cn -5 '- - e- -2ditionsroin ]-2 7' o[ y Conplessy 14( nt 15Mte h h E F h in0t Heh P n extO10CeCshe%FC oad LC pr nA0ec%(2PurificationisexaEC tO(Je) p ), in 0-S Maeltth foordmd nv eiA0-a ) cRoute1AH7) . 8 9F1 1, 86.0H1 .7 =H9. 16.54N2 3- . ), 0H 4N12, 6.5(sM 3,s,R. 17,R -1,1 2 63 5 - 11 H(.)H H(4.0( 2 H(m6) 40m67, 4 ), ), 80,Hz.2, 80,(m.5 7. .3M22,52 (.5M2, 8 9H ((z,H 11H H m2H H0 6H NMR).),H,(z).2H s ( s, )1 s,), s2 , , 1 D1 ,, DM.4 4H6.5 )1HM 1.5 ),H HS 7 ,4 ) S4 2 ), ),8O- -.0 7. -1 (s.6 ,7O9.1 d .3 , 27 .0 -d1 7 06.4 ( 0):7 (( H d 36t():8s, – – δ m),, , J s, δ47 4M e1 3M7t .h9. 4 32o[M 3e .t .02mho[M 8dLCMS datamC+Hind+Hin., C] ,, + ], +91.7(–2s (M norm.T0 Ex.ab 8 Tle2te1,.( N( (M 7sR66s, s sR -1 . ,8 1( -1 , 1 , 11 H)5 H)41 H)H H(4(.m 64, 5(m, 0.80(77, )4 , )7 , 080,(m.86 ,1.1M m0 H,(m.5 . .6 8M910H S Eaxlt. f noorm.able Salt foanaanly at lyic tic ou out2AeH7 7 8H3AH7 7G).4 . .H1) . . 8.H1, 0 89 35N, 55 97 362H),(. 2H s H,), – z),2H78,.4061 6.4 (s H 12 ,)H6 ),) :1H NMR2H,)2 (s– – z.D.H , 7 8,DM),2H .8 .6 06M 1. ), 7(S 1. ),( (S50 4(s m O-.5,- 4 3m m O- 1,d1-.8 , ,d1 2 1 16 ),δ .5 (s H H:δ1 ,),),4 M7 43M8 3e 5. . 9. .t00 e95ho[d M 5tmC+HinLCMS dataho[d M 1+m, C Hin]] ,, + , +LC 1HM NSM dRata99979 T592.7 7 (s z .HH2 .9HH. 8HH.4H 3.6 , , 4N).40N) 6 ), .3N) 41sd ,D 3.s 1,D 7. d4d ,0.,,., 8 (m,(m7, H (8, , , D (82 D50 2H .4, JM92( 1 =S ,- H),Mm2J 8 JMm2HM m),H8 S ,- = .4 =S ,-) S1 zH 1. O 2 1)-H .7,7 .6O 2H 1.7 8. H 2 O 2 1,O. H .77, , )2.8 1, 86,6d).2.6 1 -d(6 ).3 4z4-dH, 6 ).4.6 -96dH 2 H . 8):(m 8 d):(m 1 H)(m)). -),29 .4 δ,(s , δz,J,, Hz :),, δ,(s:,δ46 40 2M2 47 2M2 4M6 3M62 3e . . e . . e . . . .t060901 e00ho[d M 8tmho[M0tmho[M 5tmho[M 7mC+dHin +d, C Hin +,C Hind+,C Hin],, + ], + ], + ], +L SC EMxl.S n doa.taable 19 1 1 1 1 7H1 1 1fe=AH8 1 9Im82 14(H H (, , 9 0 ,N( sM2H4H(dM2H4(7s.7(sM2H4(sM ,s)2, 1, )7 ,,R 1) ., 6 z ,R 1,1 J) ., 4R 8, 18, 2) ., 59, 1R HH. 88 .3H(4 10 .5(s H =(4 10 .5(s H(dH(4 1H(0 .5(s) 4), ) 8 5 ),1 , 4 (-800, 2),28.4 07, 2), d )7 , , 807, 2, 080.5 .7 5 d8, 8J ..4M -H1 H).2H M -H1 H). J6=.0M -H1 H.) 30MH -34.( = 0( z4,1 9(z, z.4, 61 (24..,( z51(sz1H NMR9).), 1 )6,48 z( , z. d1,5 44 .(4mdH D,,J),52( H74m). (65,ReaHge NnMtsoR. andT6 Ex. na Tb 9le3lyal1.7 (H88 d . 1K- = (d 8 1, z 2J ,.4H4141N. 8 d .8.4, 3H J5N,45 8 zH( (b,(1 bz)r,DMs., r H2 s)s,M -721 ( =8 S,O H 1, 71SO. s H4 ,),2..0 )4 -d,H.1. ) 8H7), -d8 d):5,24. (d8.06 ):,,6 . ,4 J δ - 88 , J 8 δ4 M2 4e 6 3M7. 4 2.t .h01o[d M 5et . 6mC+HinLCMS datah9o[d M 5mC+Hin], ] ,, + , +R LeaC EHgMxe N.Sn nMt dsoRa. atandable aat lyic ticad l d =A AJ- 1=H H(dM1 H=(sM .6 0) z, ,R(mz 1,R 9.,(67mH.1 J( , ,6H =41 .8),00 11 6 1H(0.4H H),48), 0, z-7.6 2), , 7.4802H 2H,1H 7..7H MH 1(m4.5 .3H.2M7 H 1

[0015] rbmoe ]t d yh a c -l [n t o [3ih itry a zzin p'-o r (1ille]pinye [ o4 p ,3r -i ]d - ,7 3 a- n oxin '- e- ae 1- , z3 5 o' l-- - 2-A K IntermSe td ei pat2e :4114( P9Merethpo-HdPJL) C-11H=2 8.H1.6 ).92,(740Hm.5 (Nd M ,5 z, ,R 1J2 (H s =(), H4,1)2001H,..4 ) 84,.M94 41HH -. z6(,10s 1z,.3 ( , D1 HM 4s, H), S(2m H), 87 .6O1-, ) .6d2,4 (6H1d):).78 (s , J δ.,4 M27. 2e .th08o[d M 9mC+Hin]+ ,, 150 BIOLOGICAL ACTIVITY EXAMPLE A Abbreviations and Acronyms 5 Serum Response Factor Response Element (SRF-RE) reporter gene assay method For assessing GPR65 activity through G12 / 13coupling, the SRF-RE reporter gene assay was used. The reporter vector contains the SRF-RE driving the transcription of the luciferase reporter gene. The activation of RhoA downstream G12 / 13coupling activates the Serum Response Factor inducing luciferase expression. Therefore, luciferase activity is directly 10 proportional to G12 / RhoA activation. HEK293 cells stably expressing human GPR65 were seeded in a 384-well plate in complete media (DMEM / 10% FBS) and 6 hours later they were transfected with 0.006 ng DNA / cell of the SRF-RE reporter vector (Promega, UK) using FuGENE®4K (Promega, UK). 24 hours 15 later, the medium was replaced to DMEM / 0.5% FBS to serum-starve the cells for 16 hours. The next day, test compounds were serially diluted (1:3) in DMSO using an automated liquid handler to produce ten intermediate concentration points, each of which was then further diluted in DMEM / 0.5% FBS, pH 7.5. The spent starving medium was aspirated and the titrated compound solutions were added to the cells. The cells were incubated with the compounds 20 for 6 hours and luciferase activity was measured using One-GloTMreagent (Promega, UK). The luminescent signal was converted to percentage values by normalising to the maximum (pH 6.5) and minimum (pH 7.5) vehicle control values. The resulting data were fitted according to the non-linear regression (variable slope) analysis model (Prism 10.1, GraphPad, San Diego, USA) and compound EC50values were calculated (Table 31). 25 Human GPR65 cyclic adenosine monophosphate (cAMP) Homogeneous Time- Resolved Fluorescence (HTRF) assay method (Examples 1-40) HEK293 cells stably expressing human recombinant GPR65 (clonal population) were cultured according to vendor’s instructions. The ability of compounds to agonise GPR65 Gsactivity was 30 assessed by measuring the intracellular concentration of cAMP following treatment, using the cAMP Gs HiRange HTRF kit (Revvity). The assay principle is based on the competition of native cAMP produced by cells with introduced d2-labelled cAMP for binding to Europium 151 Cryptate-labelled, cAMP antibody. The HTRF signal produced is inversely proportional to the concentration of cAMP in the sample. The method is as follows: 16 hours before the assay, cells were placed in low-serum conditions 5 (DMEM supplemented with 0.5% FBS). On the day of the assay, 2,000 cells were seeded in each well of a 384-well, low-volume plate in 5 µl of assay buffer (HBSS supplemented with 5 mM HEPES, 0.1% BSA (w / v) and 0.5 mM IBMX, adjusted to pH 7.5). Test compounds were serially diluted (1:3) in DMSO using an automated liquid handler to produce ten intermediate concentration points, each of which was then further diluted in assay buffer at 2 x [final assay 10 concentration].5 µl of compound solution was then added to each well of the cell plate, thereby reaching the desired final concentration (30 µM being the highest concentration tested). Following treatment for 20 minutes, lysis and detection buffer containing d2-labelled cAMP and Europium Cryptate-labelled antibodies was added to each well according to manufacturer’s instructions and the plate was incubated for 1 hour on a plate shaker at 300 15 RPM. Fluorescent measurements at 665 nm and 620 nm were taken using Pherastar plate reader and the HTRF ratio (signal665nm / signal620nmx 10,000) for each sample was calculated. The data was converted to percentage values by normalising to the maximum (pH 7.5) and minimum (pH 6) vehicle control values and concentration-response curves were fitted using non-linear, four-parameter logistic regression analysis to determine EC50values (Table 31). 20 Human GPR65 cyclic adenosine monophosphate (cAMP) Homogeneous Time- Resolved Fluorescence (HTRF) assay method (Examples 41-100) HEK293 cells stably expressing human recombinant GPR65 (mixed population) were cultured according to vendor’s instructions. The ability of compounds to agonise GPR65 Gsactivity was 25 assessed by measuring the intracellular concentration of cAMP following treatment, using the cAMP GsHiRange HTRF kit (Revvity). The assay principle is based on the competition of native cAMP produced by cells with introduced d2-labelled cAMP for binding to Europium Cryptate-labelled, cAMP antibody. The HTRF signal produced is inversely proportional to the concentration of cAMP in the sample. 30 The method is as follows: Cells were seeded in 384 well plates (2,000 cells / well) in complete media (DMEM supplemented with 10% FBS) and after settling for 5 hours, the cells were incubated with low-serum conditions (DMEM supplemented with 0.5% FBS, 25mM HEPES, pH 7.5) overnight. On the day of the assay, test compounds were serially diluted (1:3) in DMSO 35 using an automated nanoliter liquid handler to produce ten intermediate concentration points, each of which was then further diluted in assay buffer (HBSS supplemented with 5 mM HEPES, 0.1% BSA (w / v) and 0.5 mM IBMX, adjusted to pH 7.5) at the [final assay 152 concentration]. The low-serum media was fully aspirated from the well and replaced with the diluted compounds, using an automated liquid handler. Following incubation for 40 minutes at room temperature, lysis and detection buffer containing d2-labelled cAMP and Europium Cryptate-labelled antibodies was added to each well according to manufacturer’s instructions 5 and the plate was incubated for 1 hour on a plate shaker at 300 RPM. Fluorescent measurements at 665 nm and 620 nm were taken using Pherastar plate reader and the HTRF ratio (signal665nm / signal620nm x 10,000) for each sample was calculated. The data was converted to percentage values by normalising to the maximum (pH 7.5 - vehicle control) and minimum (GPR65 agonist control at 10µM) values and concentration-response curves were 10 fitted using non-linear, four-parameter logistic regression analysis to determine EC50 values (Table 31). Table 31 – SRF-RE and HTRF Data of Example A 15 SRF-RE pEC50: Group A >9.0, Group B 8.5 to 9.0, Group C 8.0 to 8.5, Group D <8.0 HTRF cAMP pEC50: Group A >7.5, Group B 6.5 to 7.5, Group C 5.5 to 6.5, Group D <5.5 153 154

Claims

155 CLAIMS 1. A compound of Formula (1):or a salt thereof, wherein: X is NR3or CR3R3a; Y is S or O; Z is S, CHR6or O; R1is a group -(CR1aR1b)mQ, -O(CR1aR1b)mQ or -NR1a(CR1aR1b)mQ where m is 0-3 and Q is H, halo, CN, NR1aR1b, OR1a, SR1a, C≡CR1a, CO2R1a, CONR1aR1b, a C1-6alkyl group which is optionally substituted with 1 to 3 fluorine atoms, or a 3 to 10-membered carbocyclic or heterocyclic ring system which is optionally substituted with 1 to 3 R4groups; R2is a 4 to 6-membered carbocyclic or heterocyclic ring which is optionally substituted with 1 to 3 R5groups; R3and R3aare independently H, a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms or a 3 to 5-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms; or R3and R3amay be joined to form a 3 to 6-membered carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms; each R4is independently H, halo, CN, OR4a, NHR4a, CH2OR4a, a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms, or a 3 to 6-membered carbocyclic or heterocyclic ring which is optionally substituted with 1 to 3 fluorine atoms; each R5is independently H, halo, CN, NO2, OR5a, a 3 to 6-membered carbocyclic or heterocyclic ring system or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms; each R1a, R1b, R4aand R5ais independently H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms; R6is H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms; and R10is H or a C1-3alkyl group which is optionally substituted with 1 to 3 fluorine atoms.

2. The compound according to claim 1, wherein Y is S.

3. The compound according to claim 1 or claim 2, wherein Z is S.

4. The compound according to any one of claims 1 to 3, wherein X is NR3.156 5. The compound according to any one of claims 1 to 4, wherein R3is selected from: CH3, CH2CH3, CD3, cyclopropyl and CH2CFH2.

6. The compound according to any one of claims 1 to 3, wherein X is CR3R3aand R3is joined with R3ato form a cyclopropyl ring.

7. The compound according to any one of claims 1 to 6, wherein R2is:.

8. The compound according to claim 1, which is a compound of Formula (5a) or (6a):or a salt thereof.

9. The compound according to claim 7 or claim 8, wherein each R5is independently selected from:

10. The compound according to any one of claims 1 to 6, wherein R2is selected from the group consisting of:157 .

12. The compound according to claim 10, wherein R2is:.

13. The compound according to any one of claims 1 to 12, wherein R10is H.

14. The compound according to claim 1, which is a compound of Formula (13):or a salt thereof.

15. The compound according to claim 1, which is a compound of Formula (15):or a salt thereof.

16. The compound according to any one of claims 1 to 15, wherein R1is selected from the group consisting of:ıĵĸ15917. The compound according to claim 1, which is a compound selected from the group consisting of:Example 13 Example 14 Example 15160Example 37 Example 38 Example 39161Example 61 Example 62 Example 63162Example 85 Example 86 Example 87163Example 100 and salts thereof.

18. A pharmaceutical composition comprising a compound according to any one of claims 1 to 17 or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable excipient.

19. A combination comprising a compound according to any one of claims 1 to 18 or a pharmaceutically acceptable salt thereof and a PDE inhibitor.

20. The compound or pharmaceutically acceptable salt thereof, composition or combination according to any one of claims 1 to 19 for use in medicine.164 21. The compound or pharmaceutically acceptable salt thereof, composition or combination according to any one of claims 1 to 19 for use in the treatment of a disorder associated with GPR65 or that would benefit from the modulation of GPR65 activity.

22. The compound or pharmaceutically acceptable salt thereof, composition or combination according to any one of claims 1 to 19 for use in the treatment of inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis, atopic dermatitis (AD), asthma, bone resorption diseases, including osteoporosis, neuroinflammatory disorders, including multiple sclerosis (MS) or disorders or symptoms related thereto.

23. A method of treating a disorder associated with GPR65 or that would benefit from the modulation of GPR65 activity in a patient, comprising administering a compound or pharmaceutically acceptable salt thereof, composition or combination according to any one of claims 1 to 19.

24. A method of treating inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis, atopic dermatitis (AD), asthma, bone resorption diseases, including osteoporosis, neuroinflammatory disorders, including multiple sclerosis (MS) or disorders or symptoms related thereto in a patient, comprising administering a compound or pharmaceutically acceptable salt thereof, composition or combination according to any one of claims 1 to 19.

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