Substituted thiazines as GPR65 agonists

Abstract

The disclosures herein relate to novel compounds of Formula (1): (1); or a salt thereof, wherein X, R1, R2 and R10 are defined herein, and their use in treating, preventing, ameliorating, controlling or reducing the risk of disorders associated with GPR65.

Description

[0001] SUBSTITUTED THIAZINES AS GPR65 AGONISTS

[0002] 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 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.

[0003] BACKGROUND OF THE INVENTION

[0004] 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 Gas- and Gai2 / i3-mediated pathways and its downstream effects have been associated with a wide range of chronic inflammatory 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.

[0005] Inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis, is a 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*lle231Leu (I231L) as a prevalent risk factor for IBD development (Immunity 2016, 44, 1392-1405). These studies associate 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 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).

[0006] Introduction of the GPR65*lle231Leu allele into mice has shown how this less active protein might be linked to inflammation. GPR65*lle231Leu knock-in mice were shown to be highly susceptible to both bacterial infection-induced and T cell-driven colitis. Mechanistically, GPR65231 Leu elicits a cytokine imbalance through impaired helper type 17 T cell (Th17 cell) and Th22 cell differentiation and interleukin (IL)-22 production in association with altered cellular metabolism controlled through the cAMP-CREB-DGATI 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. Immunol. 2022, 23(7), 1063-1075).

[0007] 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 (lEC)-intrinsic GPR65 signalling 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 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).

[0008] THE INVENTION

[0009] The present invention provides compounds having activity as GPR65 agonists. Provided is a compound of Formula (1): or a salt thereof, wherein:

[0010] X is NR3or CR3R3a;

[0011] R1is H or a Ci-e alkyl group which is optionally substituted with 1 to 3 fluorine atoms, NR1aR1band / or OR1a; or R1is a group -(CR1aR1 b)mQ, where m is 0-3 and Q is a 3 to 10-membered carbocyclic or heterocyclic ring system which is optionally substituted with one or more R4groups;

[0012] R2is a 4 to 6-membered carbocyclic or heterocyclic ring which is optionally substituted with one or more R5groups;

[0013] R3and R3aare independently H, a C1.3 alkyl 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 which is optionally substituted with 1 to 3 fluorine atoms; each R4is independently H, halo, CN, OR4a, a C1.3 alkyl 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 C1.3 alkyl group which is optionally substituted with 1 to 3 fluorine atoms;

[0014] R1a, R1b, R4aand R5aare independently H or a C1.3 alkyl group which is optionally substituted with 1 to 3 fluorine atoms, NH2 and / or OH; and

[0015] R10is H or a C1.3 alkyl group which is optionally substituted with 1 to 3 fluorine atoms; provided that when R1is CH3, X is NCH3 and R10is H, R2is not: or cr ci .

[0016] 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. 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, 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.

[0017] Compounds of the present invention may be useful 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.

[0018] DETAILED DESCRIPTION OF THE INVENTION

[0019] 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. Provided is a compound of Formula (1): or a salt thereof, wherein:

[0020] X is NR3or CR3R3a;

[0021] R1is H or a C1.6 alkyl group which is optionally substituted with 1 to 3 fluorine atoms, NR1aR1band / or OR1a; or R1is a group -(CR1aR1 b)mQ, where m is 0-3 and Q is a 3 to 10-membered carbocyclic or heterocyclic ring system which is optionally substituted with one or more R4groups;

[0022] R2is a 4 to 6-membered carbocyclic or heterocyclic ring which is optionally substituted with one or more R5groups;

[0023] R3and R3aare independently H, a C1.3 alkyl 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 which is optionally substituted with 1 to 3 fluorine atoms; each R4is independently H, halo, CN, OR4a, a C1.3 alkyl 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 C1.3 alkyl group which is optionally substituted with 1 to 3 fluorine atoms;

[0024] R1a, R1b, R4aand R5aare independently H or a C1.3 alkyl group which is optionally substituted with 1 to 3 fluorine atoms, NH2and / or OH; and

[0025] R10is H or a C1.3 alkyl group which is optionally substituted with 1 to 3 fluorine atoms; provided that when R1is CH3, X is NCH3and R10is H, R2is not:

[0026] In the compounds herein, X is NR3or CR3R3a. X can be NR3. X can be CR3R3a. X can be NCH3, NCH2CH3, NCD3, N-cyclopropyl, NCH2CH2F or CHCH3. X can be NCH3.

[0027] In the compounds herein, R3and R3aare independently H, a Ci-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 which is optionally substituted with 1 to 3 fluorine atoms.

[0028] R3can be H, a C1.3 alkyl 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, CH3, CH2CH3, CD3, cyclopropyl or CH2- CFH2. R3can be joined with R3ato form a cyclopropyl ring.

[0029] R3acan be H, a C1.3 alkyl 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 carbocyclic ring which is optionally substituted with 1 to 3 fluorine atoms. R3acan be H, CH3, CH2CH3, CD3, cyclopropyl or CH2- CFH2. R3acan be joined with R3to form a cyclopropyl ring.

[0030] R3can be selected from: CH3, CH2CH3, CD3, cyclopropyl and CH2CFH2. R3can be joined with R3ato form a cyclopropyl ring.

[0031] In the compounds herein, R1is H or a C-i-e alkyl group which is optionally substituted with 1 to 3 fluorine atoms, NR1aR1band / or OR1a; or R1is a group -(CR1aR1b)mQ, where m is 0-3 and Q is a 3 to 10-membered carbocyclic or heterocyclic ring system which is optionally substituted with one or more R4groups. R1can be H or a Ci-e alkyl group which is optionally substituted with 1 to 3 fluorine atoms, NR1aR1band / or OR1a. R1can be H. R1can be a CI-B alkyl group which is optionally substituted with 1 to 3 fluorine atoms, NR1aR1 band / or OR1a. R1can be a Ci-e alkyl group. R1can be CH3. R1can be a group -(CR1aR1 b)mQ, where m is 0-3 and Q is a 3 to 10-membered carbocyclic or heterocyclic ring system which is optionally substituted with one or more R4groups. R1can be a group -(CR1aR1b)mQ, where m is 0-3 and Q is a phenyl or pyridyl ring which is optionally substituted with one or more R4groups.

[0032] R1can be selected from the group consisting of:

[0033]

[0034] In the compounds herein, each R4is independently H, halo, CN, OR4a, a C1.3 alkyl 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, OCH2CH2NH2 and morpholinyl.

[0035] In the compounds herein, R2is 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 or pyridyl ring which is optionally substituted with one or more R5groups.

[0036] R2can be selected from:

[0037] R2can be selected from the group consisting of:

[0038] In the compounds herein, each R5is independently H, halo, CN, NO2, OR5aor a C1-3 alkyl 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 and CFH2.

[0039] In the compounds herein, R1a, R1b, R4aand R5aare independently H or a Ci.3alkyl group which is optionally substituted with 1 to 3 fluorine atoms, NH2 and / or OH.

[0040] In the compounds herein, R10is H or a C1.3 alkyl 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.

[0041] In the compounds herein, when R1is CH3, X is NCH3and R10is H, R2is not:

[0042] Also included are compounds wherein, when R1is CH3and X is NCH3, R2is not:

[0043] Also included are compounds wherein, when R1is CH3, R2is not:

[0044] Also included are compounds wherein, when X is NCH3, R2is not: Also included are compounds wherein, R2is not:

[0045] Accordingly, the following compounds are not included within the scope of the present invention:

[0046] The compound can be a compound of Formula (2a), (2b), (2c) or (2d): or a salt thereof.

[0047] The compound can be a compound of Formula (3a), (3b), (3c) or (3d): or a salt thereof.

[0048] The compound can be a compound of Formula (4a), (4b), (4c) or (4d): or a salt thereof.

[0049] The co or a salt thereof. The compound can be a compound of Formula (6a), (6b) or (6c): or a salt thereof.

[0050] The compound can be a compound of Formula (7a), (7b) or (7c): or a salt thereof.

[0051] The compound can be a compound of Formula (8a) or (8b): or a salt thereof. The compound can be a compound of Formula (9a) or (9b): or a salt thereof. The compound can be selected from any one of Examples 1 to 99 as shown in Table 1 or a salt thereof. The compound can be selected from any one of Examples 1 to 98 as shown in Table 1 or a salt thereof.

[0052] The compound can be selected from the group consisting of:

[0053] 3-[(4-bromo-2-chlorophenyl)methylsulfanyl]-1 ,6-dimethylpyridazino[4,5-e][1 ,3,4]thiadiazin-5- one;

[0054] 3-[(2-chloro-4-nitrophenyl)methylsulfanyl]-1,6-dimethylpyridazino[4,5-e][1 ,3,4]thiadiazin-5-one;

[0055] 3-chloro-4-[(1 ,6-dimethyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl)sulfanylmethyl]benzonitrile;

[0056] 3-[(2-chloro-4-iodophenyl)methylsulfanyl]-1,6-dimethylpyridazino[4,5-e][1 ,3,4]thiadiazin-5-one;

[0057] 5-bromo-2-[(1-methyl-5-oxo-6H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl)sulfanylmethyl]benzonitrile;

[0058] 3-[(4-bromo-2-chlorophenyl)methylsulfanyl]-1-methyl-6H-pyridazino[4,5-e][1,3,4]thiadiazin-5- one;

[0059] 3-chloro-4-[(1-methyl-5-oxo-6H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl)sulfanylmethyl]benzonitrile;

[0060] 3-[(2-chloro-4-nitrophenyl)methylsulfanyl]-1-methyl-6H-pyridazino[4,5-e][1 ,3,4]thiadiazin-5- one;

[0061] 3-[(4-bromo-2-methylphenyl)methylsulfanyl]-1-methyl-6H-pyridazino[4,5-e][1 ,3,4]thiadiazin-5- one;

[0062] 3-[[2-chloro-4-(trifluoromethyl)phenyl]methylsulfanyl]-1-methyl-6H-pyridazino[4,5- e][1 ,3,4]thiadiazin-5-one;

[0063] 3-[(4-iodo-2-methylphenyl)methylsulfanyl]-1-methyl-6H-pyridazino[4,5-e][1 ,3,4]thiadiazin-5- one;

[0064] 1-methyl-3-[[3-methyl-5-(trifluoromethyl)pyridin-2-yl]methylsulfanyl]-6H-pyridazino[4,5- e][1 ,3,4]thiadiazin-5-one;

[0065] 5-iodo-2-[(1-methyl-5-oxo-6H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl)sulfanylmethyl]benzonitrile; 3-[[3-chloro-5-(trifluoromethyl)pyridin-2-yl]methylsulfanyl]-1-methyl-6H-pyridazino[4,5- e][1 ,3,4]thiadiazin-5-one;

[0066] 2-[(1-methyl-5-oxo-6H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)sulfanylmethyl]-5- (trifluoromethyl)benzonitrile;

[0067] 2-[(1-ethyl-5-oxo-6H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-iodobenzonitrile;

[0068] 2-[(1,6-dimethyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)sulfanylmethyl]-5- (trifluoromethyl)benzonitrile;

[0069] 2-[(1,6-dimethyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)sulfanylmethyl]-5- iodobenzonitrile;

[0070] 2-[(1-methyl-5-oxo-6H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-

[0071] (trifl uoromethoxy) benzonitri le ;

[0072] 2-[[1-methyl-5-oxo-6-(trideuteriomethyl)pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl]sulfanylmethyl]-

[0073] 5-(trifluoromethyl)benzonitrile;

[0074] 3-[[4-iodo-2-(trifluoromethyl)phenyl]methylsulfanyl]-1-methyl-6H-pyridazino[4,5- e][1 ,3,4]thiadiazin-5-one;

[0075] 5-bromo-2-[(1 ,6-dimethyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl)sulfanylmethyl]benzonitrile;

[0076] 5-bromo-2-[[1-methyl-5-oxo-6-(trideuteriomethyl)pyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethyl]benzonitrile;

[0077] 2-[[6-(2-methoxyethyl)-1-methyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-

[0078] (trifluoromethyl)benzonitrile;

[0079] 5-iodo-2-[[1-methyl-5-oxo-6-(trideuteriomethyl)pyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethyl]benzonitrile;

[0080] 5-(difluoromethyl)-2-[(1-methyl-5-oxo-6H-pyridazino[4,5-e][1,3,4]thiadiazin-3- yl)sulfanylmethyl]benzonitrile;

[0081] 5-iodo-2-[(1-methyl-5-oxo-6-pyridin-2-ylpyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl)sulfanylmethyl]benzonitrile;

[0082] 2-[[6-(2-hydroxyethyl)-1-methyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile;

[0083] 3-[[2,6-difluoro-4-(trifluoromethyl)phenyl]methylsulfanyl]-1-methyl-6H-pyridazino[4,5- e][1 ,3,4]thiadiazin-5-one;

[0084] 2-[(6-ethyl-1-methyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)sulfanylmethyl]-5- iodobenzonitrile;

[0085] 4,5-dichloro-2-[(1-methyl-5-oxo-6H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl)sulfanylmethyl]benzonitrile;

[0086] 3-[(3-chloro-5-iodo-2-pyridinyl)methylsulfanyl]-1-methyl-6H-pyridazino[4,5-e][1 ,3,4]thiadiazin- 5-one;

[0087] 5-iodo-2-[(1-methyl-5-oxo-6-pyridin-4-ylpyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl)sulfanylmethyl]benzonitrile; 3-[(4-bromo-2-chlorophenyl)methylsulfanyl]-1-methyl-6-(trideuteriomethyl)pyridazino[4,5- e][1 ,3,4]thiadiazin-5-one;

[0088] 5-iodo-2-[(1-methyl-5-oxo-6-pyridin-3-ylpyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl)sulfanylmethyl]benzonitrile;

[0089] 5-iodo-2-[[1-methyl-5-oxo-6-(2,2,2-trifluoroethyl)pyridazino[4,5-e][1,3,4]thiadiazin-3- yl]sulfanylmethyl]benzonitrile;

[0090] 3-[(2-chloro-4-iodophenyl)methylsulfanyl]-1-methyl-6H-pyridazino[4,5-e][1 ,3,4]thiadiazin-5- one;

[0091] 5-iodo-2-[[1-methyl-5-oxo-6-(1 H-pyrazol-5-yl)pyridazino[4,5-e][1,3,4]thiadiazin-3- yl]sulfanylmethyl]benzonitrile;

[0092] 3-[(2-chloro-4-iodophenyl)methylsulfanyl]-1-methyl-6-(trideuteriomethyl)pyridazino[4,5- e][1 ,3,4]thiadiazin-5-one;

[0093] 2-[(1-methyl-5-oxo-6-pyrrolidin-3-ylpyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-

[0094] (trifluoromethyl)benzonitrile;

[0095] 3-[[2,4-bis(trifluoromethyl)phenyl]methylsulfanyl]-1-methyl-6H-pyridazino[4,5- e][1 ,3,4]thiadiazin-5-one;

[0096] 2-[[6-(4-methoxyphenyl)-1-methyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl]sulfanylmethyl]-

[0097] 5-(trifluoromethyl)benzonitrile;

[0098] 5-chloro-2-[(1-methyl-5-oxo-6H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl)sulfanylmethyl]benzonitrile;

[0099] 2-[[6-(6-methoxy-2-pyridinyl)-1-methyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0100] 2-[[1-methyl-6-(3-methyl-2-pyridinyl)-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0101] 2-[(1-methyl-5-oxo-6-pyrazin-2-ylpyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-

[0102] (trifluoromethyl)benzonitrile;

[0103] 2-[[5-oxo-1 ,6-bis(trideuteriomethyl)pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile;

[0104] 2-[(6-cyclobutyl-1-methyl-5-oxopyridazino[4,5-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5- (trifluoromethyl)benzonitrile;

[0105] 2-[[1-methyl-5-oxo-6-(pyridin-2-ylmethyl)pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl]sulfanylmethyl]-

[0106] 5-(trifluoromethyl)benzonitrile;

[0107] 2-[[6-(2-fluorophenyl)-1-methyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile;

[0108] 2-[[6-(2-ethoxyethyl)-1-methyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile;

[0109] 2-[[6-(4-cyanophenyl)-1-methyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile;

[0110] 3-[(2-chloro-6-fluoro-4-iodophenyl)methylsulfanyl]-1-methyl-6H-pyridazino[4,5- e][1 ,3,4]thiadiazin-5-one; 2-[(4,7-dimethyl-8-oxo-4H-pyridazino[4,5-e][1 ,3]thiazin-2-yl)sulfanylmethyl]-5-iodobenzonitrile;

[0111] 3-fluoro-5-iodo-2-[(1-methyl-5-oxo-6H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl)sulfanylmethyl]benzonitrile;

[0112] 2-[[1-methyl-6-(6-methyl-2-pyridinyl)-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0113] 5-(difluoromethyl)-2-[(1,6-dimethyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl)sulfanylmethyl]benzonitrile;

[0114] 2-[(1-cyclopropyl-5-oxo-6H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)sulfanylmethyl]-5- (trifluoromethyl)benzonitrile;

[0115] 2-[[6-[2-(dimethylamino)ethyl]-1-methyl-5-oxopyridazino[4,5-e][1,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0116] 2-[(1-methyl-5-oxo-6-pyridin-2-ylpyridazino[4,5-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5- (trifluoromethyl)benzonitrile;

[0117] 5-(difluoromethyl)-2-[(1-methyl-5-oxo-6-pyridin-2-ylpyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl)sulfanylmethyl]benzonitrile;

[0118] 2-[[1-methyl-5-oxo-6-(pyrrolidin-3-ylmethyl)pyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0119] 2-[[1-methyl-6-[(1-methylpyrrolidin-3-yl)methyl]-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0120] 2-[[1-methyl-6-(oxan-4-yl)-5-oxopyridazino[4,5-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile;

[0121] 2-[[1-methyl-6-(oxan-3-yl)-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile;

[0122] 5-bromo-2-[(1 ,6-dimethyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)sulfanylmethyl]pyridine-

[0123] 3-carbonitrile;

[0124] 2-[[1-methyl-6-(1-methylpyrrolidin-3-yl)-5-oxopyridazino[4,5-e][1,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0125] 2-[(6-ethyl-1-methyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)sulfanylmethyl]-5- (trifluoromethyl)benzonitrile;

[0126] 2-[[1-methyl-6-[(1-methylpyrrolidin-2-yl)methyl]-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0127] 2-[[1-methyl-5-oxo-6-(pyrrolidin-2-ylmethyl)pyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0128] 2-[(6-cyclopropyl-1-methyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)sulfanylmethyl]-5- (trifluoromethyl)benzonitrile;

[0129] 2-[[1-methyl-5-oxo-6-(oxolan-3-yl)pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile;

[0130] 2-[[5-oxo-6-pyridin-2-yl-1-(trideuteriomethyl)pyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile; 6-bromo-3-[(1 ,6-dimethyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)sulfanylmethyl]pyridine- 2-carbonitrile;

[0131] 2-[[6-[2-(2-hydroxyethoxy)ethyl]-1-methyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0132] 2-[[1-(2-fluoroethyl)-6-methyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl]sulfanylmethyl]-5- iodobenzonitrile;

[0133] 2-[(4,7-dimethyl-8-oxo-4H-pyridazino[4,5-e][1 ,3]thiazin-2-yl)sulfanylmethyl]-5- (trifluoromethyl)benzonitrile;

[0134] 2-[[1-methyl-6-(6-morpholin-4-yl-2-pyridinyl)-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0135] 2-[(1,6-dimethyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)sulfanylmethyl]-5-

[0136] (fluoromethyl)benzonitrile;

[0137] 2-[[1-methyl-6-(oxetan-3-ylmethyl)-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl]sulfanylmethyl]-

[0138] 5-(trifluoromethyl)benzonitrile;

[0139] 2-[[6-[1-(dimethylamino)-3-hydroxypropan-2-yl]-1-methyl-5-oxopyridazino[4,5- e][1 ,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile;

[0140] 2-[[6-(2-chloro-6-methyl-4-pyridinyl)-1-methyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0141] 2-[[6-(4,6-dimethyl-2-pyridinyl)-1-methyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0142] 2-[[6-(3,6-dimethyl-2-pyridinyl)-1-methyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0143] 5-bromo-2-[(1-methyl-5-oxo-6-pyridin-4-ylpyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl)sulfanylmethyl]benzonitrile;

[0144] 6-bromo-3-[(4,7-dimethyl-8-oxo-4H-pyridazino[4,5-e][1 ,3]thiazin-2-yl)sulfanylmethyl]pyridine-

[0145] 2-carbonitrile;

[0146] 5-bromo-2-[(4,7-dimethyl-8-oxo-4H-pyridazino[4,5-e][1 ,3]thiazin-2- yl)sulfanylmethyl]benzonitrile;

[0147] 2-[[7-(6-methoxy-2-pyridinyl)-4-methyl-8-oxo-4H-pyridazino[4,5-e][1,3]thiazin-2- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0148] 2-[[6-(4,6-dimethoxy-2-pyridinyl)-1-methyl-5-oxopyridazino[4,5-e][1,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0149] 2-[(1-methyl-5-oxo-6-pyridin-4-ylpyridazino[4,5-e][1,3,4]thiadiazin-3-yl)sulfanylmethyl]-5- (trifluoromethyl)benzonitrile;

[0150] 2-[[1-methyl-6-(1-methylazetidin-3-yl)-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0151] 2-[[6-[6-(2-aminoethoxy)-2-pyridinyl]-1-methyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0152] 2-[[6-(2-methoxypyrimidin-4-yl)-1-methyl-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethylj-5-(trifluoromethyl) benzonitrile; 2-[[1-cyclopropyl-6-(oxetan-3-ylmethyl)-5-oxopyridazino[4,5-e][1,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0153] 5-iodo-2-[(4-methyl-8-oxo-4,7-dihydropyridazino[4,5-e][1 ,3]thiazin-2- yl)sulfanylmethyl]benzonitrile;

[0154] 5-iodo-2-[[4-methyl-7-(oxetan-3-ylmethyl)-8-oxo-4H-pyridazino[4,5-e][1 ,3]thiazin-2- yl]sulfanylmethyl]benzonitrile;

[0155] 3-[(4-bromo-2-methylphenyl)methylsulfanyl]-1-methyl-6-(oxetan-3-ylmethyl)pyridazino[4,5- e][1 ,3,4]thiadiazin-5-one;

[0156] 2-[[1-methyl-6-[2-(oxetan-3-yl)ethyl]-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl]sulfanylmethyl]-5-(trifluoromethyl) benzonitrile;

[0157] 2-[(7'-methyl-8'-oxospiro[cyclopropane-1 ,4'-pyridazino[4,5-e][1 ,3]thiazine]-2'- yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile; or a salt thereof

[0158] 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 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 that would benefit from the modulation of GPR65.

[0159] 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 multiple sclerosis (MS) and disorders or symptoms related thereto.

[0160] 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.

[0161] 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. 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.

[0162] 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.

[0163] 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 medicament is for the prevention and / or treatment of a disorder or disease mediated by GPR65.

[0164] 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 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.

[0165] 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 (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.

[0166] 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. 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, ora 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 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 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.

[0167] DEFINITIONS

[0168] In this application, the following definitions apply, unless indicated otherwise.

[0169] 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 modulation by modalities including, but not limited to agonists.

[0170] 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 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.

[0171] 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 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 Book), unless indicated otherwise.

[0172] The term "alkyl" as used herein, means straight or branched chain, saturated alkyl groups.

[0173] The term “carbocyclic ring” as used herein, means a saturated or unsaturated carbocyclic group containing the indicated number of carbon atoms and includes, for example, phenyl, cyclobutane and cyclopropane ring systems.

[0174] 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 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, oxetane, azetidine, pyrrolidine, tetrahydrofuran, tetrahydropyran, pyrazine, pyrimidine, pyrazole, imidazo[1,2-a]pyridine, indole and 1 H-pyrrolo[2,3-c]pyridine ring systems.

[0175] The number of carbon atoms that are possible in the referenced groups herein may be indicated by subscript "Cni-nz”. Thus, for example, the term "C1.3 alkyl” represents an alkyl group having 1, 2 or 3 carbon atoms and includes methyl, ethyl, n-propyl and iso-propyl.

[0176] 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 atoms.

[0177] 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 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.

[0178] Salts or pharmaceutically acceptable salts that may be mentioned include acid addition salts 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 compound in the form of a salt with another counter-ion, for example using a suitable ion exchange resin.

[0179] 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, potassium and calcium.

[0180] 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- 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), a-oxoglutaric, glycolic, hippuric, hydrobromic, hydrochloric, hydriodic, 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.

[0181] 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 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 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. 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.

[0182] 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 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, solutions, cachets, granules, capsules and suppositories, as well as liquid preparations for injections, including liposome preparations.

[0183] 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 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 and1SO 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 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 three hydrogen atoms are in the deuterium isotopic form (a trideuteromethoxy group). The isotopes may be radioactive or non-radioactive.

[0184] Therapeutic dosages may be varied depending upon the requirements of the patient, the 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 administered in portions during the day if desired.

[0185] 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 in this art, without undue burden. In general, the daily dose range may be from about 10 pg to about 30 mg per kg body weight of a human and non-human animal, preferably from about 50 pg to about 30 mg per kg of body weight of a human and non-human animal, for example from about 50 pg to about 10 mg per kg of body weight of a human and non-human animal, for example from about 100 pg to about 30 mg per kg of body weight of a human and non-human animal, for example from about 100 pg to about 10 mg per kg of body weight of a human and non-human animal and most preferably from about 100 pg to about 1 mg per kg of body weight of a human and non-human animal.

[0186] PHARMACEUTICAL FORMULATIONS

[0187] 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).

[0188] 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 at least one pharmaceutically acceptable excipient.

[0189] 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, 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, thickening agents, flavouring agents, sweeteners, pigments, plasticizers, taste masking agents, stabilisers or any other excipients conventionally used in pharmaceutical compositions.

[0190] 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” in the sense of being compatible with the other ingredients of the formulation.

[0191] 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 form suitable for oral, parenteral, intravenous, intramuscular, intrathecal, subcutaneous, topical, intranasal, intrabronchial, sublingual, buccal, ophthalmic, otic, rectal, intra-vaginal, or transdermal administration.

[0192] Pharmaceutical dosage forms suitable for oral administration include tablets (coated or 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.

[0193] The composition may be a tablet composition or a capsule composition. Tablet compositions 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 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 do not need to be discussed in detail here.

[0194] 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 Gl tract.

[0195] 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 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, dragees, powders, tablets or capsules.

[0196] 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. 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.

[0197] 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) (depending on dose and if freeze dried). Formulations for intramuscular depots may also contain 0-99% (w / w) oils.

[0198] 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.

[0199] 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 subranges 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 (for example 1 microgram to 10 milligrams, e.g. 0.1 milligrams to 2 milligrams of active ingredient).

[0200] For oral compositions, a unit dosage form may contain from 1 milligram to 2 grams, more typically 10 milligrams to 1 gram, for example 50 milligrams to 1 gram, e.g. 100 milligrams to 1 gram, of active compound.

[0201] 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 amount). The precise amounts of compound administered may be determined by a supervising physician in accordance with standard procedures.

[0202] EXAMPLES The invention will now be illustrated, but not limited, by reference to the following examples shown in Table 1.

[0203] Table 1 - Examples

[0204]

[0205]

[0206] PREPARATION OF THE COMPOUNDS OF THE INVENTION

[0207] 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 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.

[0208] LCMS methods HPLC purification methods for Examples

[0209] Abbreviations and Acronyms Synthesis of Intermediates

[0210] Procedure for the preparation of 2-(bromomethyl)-3-methyl-5-(trifluoromethyl)pyridine (Intermediate 1)

[0211] To a stirred solution of 2,3-dichloro-5-(trifluoromethyl)pyridine (3.0 g, 13.88 mmol) and methyl boronic acid (2.07 g, 34.723 mmol) in 1 ,4-dioxane:water (24:6 mL) was added K2COs (5.75 g, 41.66 mmol) at rt and the mixture was degassed with N2gas for 10 min. PdCI2(dppf) (1.01 g, 1.388 mmol) was added and the reaction mixture was stirred at 80 °C for 16 h. The reaction mixture was cooled to rt, diluted with water (100 mL) and extracted with EtOAc (2 x 100 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 (20% EtOAc in n-hexane) to afford 2,3-dimethyl-5-(trifluoromethyl)pyridine (0.6 g, 3.448 mmol, 24%).

[0212] LCMS: 1.84 min, 176.2 [M+H]+, Method F.

[0213] To a stirred solution of 2,3-dimethyl-5-(trifluoromethyl)pyridine (0.6 g, 3.448 mmol) in DCM (5 mL) was added m-CPBA (1.48 g, 8.62 mmol) at 0 °C and the mixture was stirred at rt for 3 h. The reaction mixture was diluted with ethyl acetate (100 mL) and washed with sat. aq. NaHCOs solution (5 x 50 mL). The organic layer was dried over Na2SO4, filtered and concentrated under reduced pressure to afford 2,3-dimethyl-5-(trifluoromethyl)pyridine 1- oxide (0.37 g, 1.937 mmol, 56%).

[0214] LCMS: 1.63 min, 191.9 [M+H]+, Method F.

[0215] To a stirred solution of 2,3-dimethyl-5-(trifluoromethyl)pyridine 1 -oxide (0.35 g, 1.831 mmol) in DCM (5 mL) was added TFAA (1.15 g, 5.493 mmol) at rt and the mixture was stirred at rt for 3 h. The reaction mixture was diluted with sat. aq. NaHCOs solution (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 (20% EtOAc in n-hexane) to afford (3-methyl-5-(trifluoromethyl)pyridin-2- yl)methanol (0.15 g, 0.784 mmol, 42%). LCMS: 1.75 min, 191.9 [M+H]+, Method F.

[0216] To a stirred solution of (3-methyl-5-(trifluoromethyl)pyridin-2-yl)methanol (0.150 g, 0.785 mmol) in DCM (5 ml_) was added PBrs (0.212 g, 0.785 mmol) at 0 °C and the mixture was stirred at rt for 1 h. The reaction mixture was diluted with sat. aq. NaHCCh solution (50 ml_) and extracted with EtOAc (2 x 50 mL). The combined organic layers were dried over Na2SC>4, filtered and concentrated under reduced pressure to afford 2-(bromomethyl)-3-methyl-5- (trifluoromethyl)pyridine (0.16 g, 0.627 mmol, 75%) (Intermediate 1).

[0217] 1H NMR (400 MHz, DMSO-d6): d 8.76 (s, 1 H), 8.11 (s, 1 H), 4.78 (s, 2H), 2.41 (s, 3H).

[0218] Procedure for the preparation of 2-(bromomethyl)-5-(fluoromethyl)benzonitrile (Intermediate 2)

[0219] Intermediate 2

[0220] To a stirred solution of 5-formyl-2-methylbenzonitrile (2.0 g, 12.16 mmol) in MeOH (20 mL) was added NaBH4 (1 .0 g, 25.10 mmol) at 0 °C and the mixture was stirred at rt for 5 h. The reaction mixture was quenched with sat. aq. NaHCCh (100 mL) and extracted with ethyl acetate (2 x 100 mL). The combined organic layers were dried over Na2SO4, filtered and concentrated under reduced pressure to afford 5-(hydroxymethyl)-2-methylbenzonitrile (1.8 g, 12.23 mmol, 88%).

[0221] 1H NMR (400 MHz, DMSO-d6): 6 7.65 (s, 1 H), 7.53 (d, J = 8.0 Hz, 1 H), 7.43 (d, J = 8.0 Hz, 1 H), 5.36 (t, J = 5.6 Hz, 1 H), 4.58 (d, J = 5.2 Hz, 2H), 2.46 (s, 3H).

[0222] To a stirred solution of 5-(hydroxymethyl)-2-methylbenzonitrile (1.8 g, 12.23 mmol) in DCM (20 mL) was added DAST (3.9 g, 24.44 mmol) at 0 °C and the mixture was stirred at rt for 16 h. The reaction mixture was diluted with a sat. aq. NaHCOs (100 mL) and extracted with ethyl acetate (2 x 100 mL). The combined organic layers were dried over Na2SC>4 and concentrated under reduced pressure. The crude was purified by flash column chromatography (10% EtOAc in n-hexane) to afford 5-(fluoromethyl)-2-methylbenzonitrile (0.8 g, 5.360 mmol, 44%).1H NMR (400 MHz, DMSO-d6): 6 7.84 (s, 1 H), 7.64 (d, J = 8.0 Hz, 1 H), 7.52 (d, J = 8.0 Hz, 1 H), 5.43 (d, J = 47.6 Hz, 2H), 2.50 (s, 3H). To a stirred solution of 5-(fluoromethyl)-2-methylbenzonitrile (0.8 g, 3.357 mmol) in triflurotoluene (5.0 mL) was added NBS (0.9 g, 5.00 mmol) and Al BN (0.06 g, 0.335 mmol) at rt and the reaction was stirred at 80 °C for 30 min. The reaction mixture was diluted with water (50 mL) and extracted with ethyl acetate (2 x 50 mL). The combined organic layers were dried over Na2SO4 and concentrated under reduced pressure to afford 2-(bromomethyl)-5- (fluoromethyl)benzonitrile (0.5 g, 2.13 mmol, 60%) (Intermediate 2). Product used crude.

[0223] Procedure for the preparation of 6-bromo-3-(bromomethyl)picolinonitrile (Intermediate 3)

[0224] Intermediate 3

[0225] To a stirred solution of 6-bromo-3-methylpicolinonitrile (0.5 g, 2.53 mmol) in CCI4 (5 mL) were added NBS (0.485 g, 2.79 mmol) followed by benzylperoxide (0.153 g, 0.634 mmol) at rt and the reaction was stirred at 800C 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 Na2SC>4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-10% EtOAc in n-hexane) to afford 6-bromo-3- (bromomethyl)picolinonitrile (0.180 g, 0.657 mmol, 26%) (Intermediate 3).

[0226] 1H NMR (400 MHz, DMSO-de): 68.16 - 8.05 (m, 3H), 7.92 (s, 1H), 4.82 (s, 2H).

[0227] Procedure for the preparation of 5-(1-aminocyclopropyl)-4-chloro-2-methylpyridazin- 3(2H)-one;trifluoroacetic acid (Intermediate 4)

[0228] Intermediate 4

[0229] In a nitrogen-filled glovebox, 4-chloro-5-iodo-2-methylpyridazin-3(2H)-one (500 mg, 1.85 mmol), 1 ,3-dioxoisoindolin-2-yl 1-((tert-butoxycarbonyl)amino)cyclopropane-1-carboxylate (736.32 mg, 2.13 mmol), manganese (609.40 mg, 11.09 mmol, 603.96 pL), dichloronickel; 1 ,2- dimethoxyethane (121.86 mg, 0.554 mmol) and pyridine-2- carboxamidine;hydrochloride (291.36 mg, 1.85 mmol) were dissolved in DMA (15 ml_). The reaction was stirred at rt. Eleven batches were worked up together. The mixture was filtrated and the filtrate was diluted with water (1000 mL) and extracted with EtOAc (3 x 500 ml_). The combined organic layers were washed with water (2 x 300 mL), brine (200 mL), dried over Na2SC>4, filtered and concentrated under reduced pressure. The crude material was purified by prep-HPLC (Method H). The product-containing fractions was concentrated under reduced pressure to remove the organic solvent. The resulting aqueous mixture was extracted with EtOAc (3 x 300 mL). The combined organic layers were washed with brine (80 mL), dried over Na2SO4, filtered and concentrated under reduced pressure to afford tert-butyl (1-(5-chloro-1-methyl-6-oxo-1,6-dihydropyridazin- 4-yl)cyclopropyl)carbamate (700 mg, 2.27 mmol, 11%) as light yellow solid.

[0230] 1H NMR (400 MHz, CDCI3): 68.00 (s, 1 H), 5.48 (br s, 1H), 3.83 (s, 3H), 1.41 (s, 9H), 1.30 - 1.26 (m, 2H), 1.18 - 1.11 (m, 2H).

[0231] To a solution of tert-butyl (1-(5-chloro-1-methyl-6-oxo-1,6-dihydropyridazin-4- yl)cyclopropyl)carbamate (200 mg, 0.667 mmol) in DCM (2 mL) was added TFA (760.78 mg, 6.67 mmol, 495.62 pL). The reaction mixture was stirred at rt for 2 h. The reaction was concentrated under reduced pressure to afford 5-(1-aminocyclopropyl)-4-chloro-2- methylpyridazin-3(2H)-one;trifluoroacetic acid (285 mg, 0.666 mmol, 99%, Intermediate 4) as yellow oil.

[0232] LCMS: 0.114 min, 200.0 [M+H]+, Method J.

[0233] Synthesis of Examples

[0234] Route A

[0235] Typical procedure for the preparation of 1,6-dimethyl-1 H-pyridazino[4,5- e][1,3,4]thiadiazin-5(6H)-ones as exemplified by the preparation of 3-((4-bromo-2- chlorobenzyl)thio)-1,6-dimethyl-1H-pyridazino[4,5-e][1,3,4]thiadiazin-5(6H)-one

[0236] (Example 1)

[0237] Example 1

[0238] To a stirred solution of 4,5-dichloro-2-methylpyridazin-3(2H)-one (10 g, 55.86 mmol) in MeOH (55 mL) was added methyl hydrazine (85% aqueous solution; 9.08 g, 167.59 mmol) at rt and the mixture was stirred for 4 h. The reaction mixture was concentrated under reduced pressure. The crude was purified by recrystallization with ethanol (150 mL) by cooling to 0 °C. The resulting off-white solid was filtered and dried under reduced pressure to afford 4-chloro- 2-methyl-5-(1-methylhydrazinyl)pyridazin-3(2H)-one. (6.0 g, 31.91 mmol, 57%).

[0239] LCMS: 0.864 min, 189.3 [M+H]+, Method F

[0240] To a stirred solution of 4-chloro-2-methyl-5-(1-methylhydrazinyl)pyridazin-3(2H)-one (0.5 g, 2.65 mmol) in DMF (5 ml_) was added NaOH (0.266 g, 6.64 mmol) in water (0.8 mL) at rt and the mixture was stirred for 10 min. Carbon disulfide (0.202 g, 2.65 mmol) was added and the reaction mixture was stirred at rt for 2 h. 4-bromo-1-(bromomethyl)-2-chlorobenzene (0.831 g, 2.92 mmol) was added at rt and the mixture was stirred at rt for 1 h. The reaction mixture was poured into cold water (100 mL) and extracted with EtOAc (2 x 25 mL). The combined organic layers were dried over NazSC , filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (25-30% EtOAc in n-hexane) to afford 3-((4-bromo-2-chlorobenzyl)thio)-1 ,6-dimethyl-1 H-pyridazino[4,5-e][1 ,3,4]thiadiazin-5(6H)- one. (0.150 g, 0.348 mmol, 13%) (Example 1).

[0241] Analytical data for Example 1 is in Table 2.

[0242] Route B

[0243] Typical procedure for the preparation of 1-methyl-1 H-pyridazino[4,5-e][1,3,4]thiadiazin- 5(6H)-ones as exemplified by the preparation of 5-bromo-2-(((1-methyl-5-oxo-5,6- dihydro-1 H-pyridazino[4,5-e][1,3,4]thiadiazin-3-yl)thio)methyl)benzonitrile (Example 5)

[0244] Example 5

[0245] To a stirred solution of 4,5-dichloropyridazin-3(2H)-one (15.0 g, 90.90 mmol) in IPA (250 mL) was added methylhydrazine (8.78 g, 190.0 mmol) at rt and the mixture was stirred at 90 °C for 16 h. The reaction mixture was cooled to 0 °C. The precipitate formed was collected by vacuum filtration and dried under reduced pressure. The product was stirred in MeOH (50 mL), then the solids collected by vacuum filtration and dried under reduced pressure to afford 4-chloro-5-(1-methylhydrazinyl)pyridazin-3(2H)-one. (12.0 g, 68.96 mmol, 76%).

[0246] LCMS: 1.22 min, 175.1 [M+H]+, Method I To a stirred solution of 4-chloro-5-(1-methylhydrazinyl)pyridazin-3(2H)-one (0.14 g, 0.799 mmol) in DMF (2 mL) was added 5 M aq. KOH solution (0.5 mL) at rt and the mixture was stirred for 20 min. Carbon disulfide (0.2 mL) was added at rt and the mixture was stirred for 2 h. 5-bromo-2-(bromomethyl)benzonitrile ( 0.2 g, 0.722 mmol) was added and the mixture was stirred at rt for 16 h. The reaction mixture was poured into cold water (30 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 was purified by flash column chromatography (8-10% MeOH in DCM) to afford -bromo-2-(((1-methyl-5-oxo-5,6-dihydro-1 H- pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)thio)methyl)benzonitrile (0.1 g, 0.245 mmol, 34%) (Example 5).

[0247] Analytical data for Example 5 can be found in Table 3.

[0248] Route C

[0249] Typical procedure for the preparation of 6-CD3 and 6-Et 1-methyl-1 H-pyridazino[4,5- e][1,3,4]thiadiazin-5(6H)-ones as exemplified by the preparation of 2-(((1-methyl-6- (methyl-d3)-5-oxo-5,6-dihydro-1 H-pyridazino[4,5-e][1,3,4]thiadiazin-3-yl)thio)methyl)-5-

[0250] (

[0251] To a stirred solution of 4,5-dichloropyridazin-3(2H)-one (1.0 g, 6.06 mmol) in MeCN (10 ml) at rt were added K2CO3 (2.09 g, 15.15 mmol) and CD3I (0.878 g, 6.06 mmol) and the mixture was stirred at 80 °C for 16 h. The reaction mixture was poured onto cold water (60 mL) and extracted with EtOAc (2 x 60 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 (70% EtOAc in hexane) to afford 4,5-dichloro-2-(methyl- d3)pyridazin-3(2H)-one. (0.70 g, 3.86 mmol, 63% yield).

[0252] LCMS: 1.68 min, 181.9 [M+H]+, Method F

[0253] To a stirred solution of 4,5-dichloro-2-(methyl-d3)pyridazin-3(2H)-one (0.6 g, 3.31 mmol) in I PA (10 ml) at rt was added methyl hydrazine (85% in water) (0.269 mL, 4.97 mmol) and the mixture was stirred at 80 °C for 3 h. The reaction mixture was concentrated under reduced pressure. The crude material was purified by flash column chromatography (10% MeOH in DCM) to afford 4-chloro-2-(methyl-d3)-5-(1-methylhydrazinyl)pyridazin-3(2H)-one. (0.320 g, 1.67 mmol, 50%).

[0254] LCMS: 0.80 min, 191.9 [M+H]+, Method F

[0255] To a stirred solution of 4-chloro-2-(methyl-d3)-5-(1-methylhydrazinyl)pyridazin-3(2H)-one (0.1 g, 0.523 mmol) in DMF (5 ml_) was added NaOH (0.048 g, 1 .204 mmol) in water (0.2 ml_) and the mixture was stirred at rt for 10 min. Carbon disulfide (0.1 ml_) was added at rt and the mixture was stirred at rt for 2 h. 2-(bromomethyl)-5-(trifluoromethyl)benzonitrile (0.151 g, 0.575 mmol) was added at rt and the mixture was stirred at rt for 16 h. The reaction mixture was poured onto cold water (15 mL). The precipitate formed was collected by vacuum filtration and dried under reduced pressure. The crude material was purified by flash column chromatography (27-30% EtOAc in n-hexane) to afford 2-(((1-methyl-6-(methyl-d3)-5-oxo-5,6- dihydro-1 H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.055 g, 0.132 mmol, 25%) (Example 20).

[0256] Analytical data for Example 20 can be found in Table 4.

[0257] Route D

[0258] Typical procedure for N-alkylation in 6-position of 1-methyl-1 H-pyridazino[4,5- e][1,3,4]thiadiazin-5(6H)-ones as exemplified by 2-(((6-(2-methoxyethyl)-1-methyl-5- oxo-5,6-dihydro-1H-pyridazino[4,5-e][1,3,4]thiadiazin-3-yl)thio)methyl)-5- (trifluoromethyl)benzonitrile (Example 24)

[0259] Example 15 Example 24

[0260] To a stirred solution of 2-(((1-methyl-5-oxo-5,6-dihydro-1 H-pyridazino[4,5-e][1 ,3,4]thiadiazin- 3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.130 g, 0.327 mmol) in DMF (3 mL), K2CO3 (0.135 g, 0.982 mmol) was added followed by 1-bromo-2-methoxyethane (0.068 g, 0.130 g, 0.982 mmol) at 0 °C. The reaction mixture was stirred at rt for 9 h. The reaction mixture was poured into cold water (150 mL) and extracted with EtOAc (2 x250 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 (27-30% EtOAc in n-hexane) to afford 2-(((6-(2-methoxyethyl)-1-methyl-5-oxo-5,6-dihydro-1 H-pyridazino[4,5- e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile. (0.031 g, 0.068 mmol, 20%) (Example 24).

[0261] Analytical data for Example 24 can be found in Table 5.

[0262] Route E

[0263] Typical procedure for N-alkylation in 6-position of 1-methyl-1 H-pyridazino[4,5- e][1,3,4]thiadiazin-5(6H)-ones followed by O-deprotection on R1 as exemplified by 2- (((6-(2-hydroxyethyl)-1-methyl-5-oxo-5,6-dihydro-1H-pyridazino[4,5-e][1,3,4]thiadiazin-

[0264] 3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (Example 28)

[0265] To a stirred solution of 2-(((1-methyl-5-oxo-5,6-dihydro-1 H-pyridazino[4,5-e][1 ,3,4]thiadiazin- 3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.150 g, 0.377 mmol) in DMF (3 ml_), K2CO3 (0.156 g, 1.133 mmol) and tert-butyl(2-iodoethoxy)dimethylsilane (0.162 g, 0.566 mmol) were added at 0 °C. The reaction mixture was stirred at rt for 16 h. The reaction mixture was poured into cold water (50 ml_) and extracted with EtOAc (2 x 50 ml_). The combined organic layers were dried over anhydrous Na2SC>4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (50-55% EtOAc in n-hexane) to afford 2-(((6-(2-((tert-butyldimethylsilyl)oxy)ethyl)-1-methyl-5-oxo-5,6-dihydro-1 H- pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.150 g, 0.269 mmol, 71%).

[0266] LCMS: 3.05 min, 555.8 [M+H]+, Method F

[0267] To a stirred solution of 2-(((6-(2-((tert-butyldimethylsilyl)oxy)ethyl)-1-methyl-5-oxo-5,6-dihydro- 1 H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.1 g, 0.179 mmol) in THF (3 ml_) was added TBAF (1.0 M in THF, 0.1 ml_) at 0 °C and the mixture was stirred at rt for 1 h. The reaction mixture was poured into 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 flash column chromatography (30-35% EtOAc in n-hexane) to afford 2-(((6-(2-hydroxyethyl)-1- methyl-5-oxo-5,6-dihydro-1 H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5- (trifluoromethyl)benzonitrile (0.03 g, 0.068 mmol, 38%) (Example 28).

[0268] Analytical data for Example 28 can be found in Table 6. Route F

[0269] Typical procedure for N-alkylation in 6-position of 1-methyl-1 H-pyridazino[4,5- e][1,3,4]thiadiazin-5(6H)-ones followed by N-deprotection on R1 as exemplified by 2- (((1-methyl-5-oxo-6-(pyrrolidin-3-yl)-5,6-dihydro-1H-pyridazino[4,5-e][1,3,4]thiadiazin-3- yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (Example 40)

[0270] To a stirred solution of 2-(((1-methyl-5-oxo-5,6-dihydro-1 H-pyridazino[4,5-e][1 ,3,4]thiadiazin-

[0271] 3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.3 g, 0.75 mmol) in DMF (5 mL) was added CS2CO3 (0.491 g, 1.50 mmol) and tert-butyl 3-iodopyrrolidine-1 -carboxylate (0.448 g, 1.50 mmol) at rt and the mixture was stirred for 2 h. The reaction mixture was poured in water (100 mL) and extracted with EtOAc (2 x 50 mL). The combined organic layers were dried over Na2SO4, filtered and concentrated under reduced pressure to afford tert-butyl 3-(3-((2-cyano-

[0272] 4-(trifluoromethyl)benzyl)thio)-1-methyl-5-oxo-1,5-dihydro-6H-pyridazino[4,5- e][1 , 3, 4]thiadiazin-6-yl)pyrrolidine-1 -carboxylate (0.12 g, 0.21 mmol, 28%).

[0273] LCMS: 2.71 min, [M+H-56]4, Method F

[0274] To a stirred solution of tert-butyl 3-(3-((2-cyano-4-(trifluoromethyl)benzyl)thio)-1-methyl-5-oxo- 1 ,5-dihydro-6H-pyridazino[4,5-e][1 , 3, 4]thiadiazin-6-yl)pyrrolidine-1 -carboxylate (0.1 g, 0.17 mmol) in DCM (5 mL) was added TFA (0.3 mL) at 0 °C and the mixture was stirred at rt for 3 h. The reaction mixture was poured in saturated NaHCOa solution (100 mL) and extracted with EtOAc (2 x 30 mL). The combined organic layers were dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by prep HPLC (Method A) to afford 2-(((1-methyl-5-oxo-6-(pyrrolidin-3-yl)-5,6-dihydro-1 H-pyridazino[4,5- e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.030 g, 0.064 mmol, 36%) (Example 40).

[0275] Analytical data for Example 40 can be found in Table 7.

[0276] Route G

[0277] Typical procedure for N-alkylation in 6-position of 1-methyl-1 H-pyridazino[4,5- e][1,3,4]thiadiazin-5(6H)-ones followed by N-deprotection and methylation on R1 as exemplified by 2-[[1-methyl-6-[(1-methylpyrrolidin-3-yl)methyl]-5-oxopyridazino[4,5- e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 63)

[0278] To a solution of 2-(((1-methyl-5-oxo-6-(pyrrolidin-3-ylmethyl)-5,6-dihydro-1 H-pyridazino[4,5- e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (230 mg, 0.478 mmol) in MeOH (2 mL) was added CH2O (388.42 mg, 4.79 mmol, 356.35 pL), AcOH (28.74 mg, 0.478 mmol, 27.40 pL) and NaBH(OAc)3 (1.01 g, 4.79 mmol) at 00C. The mixture was stirred at rt for 1h. The reaction mixture was quenched with water (5 mL) and extracted with ethyl acetate (3 x 5 mL). The organic layers were combined, washed with brine (10 mL), dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by prep-HPLC (Method B) to afford 2-[[1-methyl-6-[(1-methylpyrrolidin-3- yl)methyl]-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (90.8 mg, 0.175, 37%) (Example 63) as a red solid.

[0279] Analytical data for Example 63 can be found in Table 8.

[0280] Route H

[0281] Typical procedure for the preparation of 1-methyl-1 H-pyridazino[4,5-e][1,3,4]thiadiazin- 5(6H)-ones via a cyclisation using (E)-2,3-dibromo-4-oxobut-2-enoic acid as exemplified by 5-iodo-2-(((1 -methyl-5-oxo-6-(pyridin-2-yl)-5,6-dihydro-1 H-pyridazino[4,5- e][1,3,4]thiadiazin-3-yl)thio)methyl)benzonitrile (Example 27)

[0282] To a stirred solution of 2-hydrazinylpyridine (0.4 g, 3.66 mmol) in 4 M aq. HCI (10 mL) was added (E)-2,3-dibromo-4-oxobut-2-enoic acid (0.154 g, 3.35 mmol) and the reaction mixture was stirred at 80 °C for 3 h. The reaction mixture was poured into cold water (50 mL) and extracted with DCM (3 x 50 mL). The combined organic layers were dried over Na2SC>4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (30-35% EtOAc in n-hexane) to afford 4,5-dibromo-2-(pyridin-2-yl)pyridazin- 3(2H)-one (0.75 g, 2.26 mmol, 61%). LCMS: 1.76 min, 331.9 [M+H]+, Method F

[0283] To a stirred solution of 4,5-dibromo-2-(pyridin-2-yl)pyridazin-3(2H)-one (0.75 g, 2.26 mmol) in I PA (15 mL) was added methylhydrazine (0.218 g, 4.75 mmol) and the reaction mixture was stirred at 80 °C for 1 h. The reaction mixture was concentrated under reduced pressure. The crude material was purified by flash column chromatography (1-2% MeOH in DCM) to afford 4-bromo-5-(1-methylhydrazinyl)-2-(pyridin-2-yl)pyridazin-3(2H)-one. (0.5 g, 1.68 mmol, 74%). LCMS: 1.49 min, 295.7 [M+H]+, Method F

[0284] To a stirred solution of 4-bromo-5-(1-methylhydrazinyl)-2-(pyridin-2-yl)pyridazin-3(2H)-one (0.17 g, 0.574 mmol) in DMF (3.4 mL) was added 10% aq. KOH (0.5 mL) at rt and th mixture was stirred for 20 min. Carbon disulfide (0.046 g, 0.574 mmol) was added at rtand the mixture was stirred for 2 h. 2-(bromomethyl)-5-iodobenzonitrile (0.202 g, 0.631 mmol) was added and the mixture was stirred at rt for 16 h. The reaction mixture was poured into cold water (100 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 was purified by flash column chromatography (70-75% EtOAc in n-hexane) to afford 5-iodo-2-(((1-methyl-5-oxo-6- (pyridin-2-yl)-5,6-dihydro-1 H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)thio)methyl)benzonitrile (0.052 g, 0.097 mmol, 17%) (Example 27).

[0285] Analytical data for Example 27 can be found in Table 9.

[0286] Route I

[0287] Typical procedure for the preparation of 1-methyl-1 H-pyridazino[4,5-e][1,3,4]thiadiazin- 5(6H)-ones via a cyclisation using (E)-2,3-dichloro-4-oxobut-2-enoic acid as exemplified by 5-iodo-2-(((1 -methyl-5-oxo-6-(pyridin-4-yl)-5,6-dihydro-1 H-pyridazino[4,5- e][1,3,4]thiadiazin-3-yl)thi°)methyl)benzonitrile (Example 33)

[0288] To a stirred solution of 4-hydrazinylpyridine (5.0 g, 45.87 mmol) and (E)-2,3-dichloro-4-oxobut- 2-enoic acid (7.70 g, 45.83 mmol) in EtOH (250 mL) and water (250 ml) was added cone. HCI (1 mL) at rt, then the mixture was stirred at 80 °C for 4 h. The reaction mixture was filtered and the filtrate was extracted with 25% I PA in chloroform (2 x 50 mL). The combined organic layers were dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by trituration using diethyl ether to afford 4,5-dichloro-2-(pyridin-4- yl)pyridazin-3(2H)-one (1.0 g, 4.14 mmol, 9%).

[0289] LCMS: 1.59 min, 242.0 [M+H]+, Method F

[0290] To a stirred solution of 4,5-dichloro-2-(pyridin-4-yl)pyridazin-3(2H)-one (0.830 g, 3.45 mmol) in MeOH (45 ml_) was added methylhydrazine (80% in water, 0.4 ml_, 10.37 mmol) at 0°C and the mixture was stirred at rt for 16 h. The reaction mixture was concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-32% EtOAc in n-hexane) to afford 4-chloro-5-(1-methylhydrazinyl)-2-(pyridin-4-yl)pyridazin-3(2H)-one (0.365 g, 1.45 mmol, 42%).

[0291] LCMS: 0.72 min, 251.9 [M+H]+, Method F

[0292] To a stirred solution of 4-chloro-5-(1-methylhydrazinyl)-2-(pyridin-4-yl)pyridazin-3(2H)-one (0.200 g, 0.796 mmol) in DMF (2.0 mL) and water (0.2 mL), NaOH (0.080 g, 1.99 mmol) was added at 0 °C, then the mixture was stirred at 0 °C for 20 min. Carbon disulfide (0.2 mL) was added at 0 °C and the mixture was stirred at rt for 2 h. 2-(bromomethyl)-5-iodobenzonitrile (0.255 g, 0.796 mmol) was added at 0 °C and the mixture was stirred at rt 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 (0-50% EtOAc in n-hexane) to afford 5-iodo-2-(((1-methyl-5-oxo-6-(pyridin-4-yl)-5,6-dihydro-1 H-pyridazino[4,5- e][1 ,3,4]thiadiazin-3-yl)thio)methyl)benzonitrile. (0.090 g, 0.169 mmol, 21 %) (Example 33). Analytical data for Example 33 can be found in Table 10.

[0293] Route J

[0294] Typical procedure for the preparation of 1-methyl-1 H-pyridazino[4,5-e][1,3,4]thiadiazin- 5(6H)-ones via hydrazine formation using sodium nitrite and tin(ll) chloride, followed by a cyclisation using (E)-2,3-dichloro-4-oxobut-2-enoic acid as exemplified by 5-iodo-2-

[0295] (((1 -methyl-5-oxo-6-(1 H-pyrazol-5-yl)-5,6-dihydro-1 H-pyridazino[4,5-e][1 ,3,4]thiadiazin- 3-yl)thio)methyl)benzonitrile (Example 38) meth

[0296] Example 38

[0297] To a stirred solution of 1 H-pyrazol-5-amine (1.5 g, 18.052 mmol) in cone. HCI (15 mL) cooled to 0 °C was added dropwise a solution of NaNC>2 (1.24 g, 18.052 mmol) in water (1.5 mL) and the mixture was stirred at 0 °C for 15 min. SnCI2(4.07 g, 18.052 mmol) in water (1.5 mL) was added dropwise at 0 °C and the reaction mixture was stirred at rt for 2 h. The reaction mixture was diluted with water (200 mL) and ethyl acetate (2 x 100 mL). The combined organic layers were dried over Na2SC>4 and concentrated under reduced pressure. The crude material was purified by trituration using diethyl ether to afford 5-hydrazinyl-1 H-pyrazole (1.5 g, 15.29 mmol, 84%).

[0298] LCMS: 0.244 min, 98.9 [M+H]+, Method F

[0299] To a stirred solution of 5-hydrazinyl-1 H-pyrazole (1.5 g, 11.189 mmol) and (E)-2,3-dichloro-4- oxobut-2-enoic acid (1.89 g, 11.189 mmol) in EtOH (30 mL) and water (30 mL) was added cone. HCI (3 mL) at rt and the mixture was stirred at 90 °C for 16 h. The reaction mixture was diluted with sat. aq. NaHCOs (250 mL) and extracted with ethyl acetate (2 x 250 mL). The combined organic layers were dried over Na2SO4 and concentrated under reduced pressure. The crude material was purified by trituration using diethyl ether to afford 4,5-dichloro-2-(1 H- pyrazol-5-yl)pyridazin-3(2H)-one (0.3 g, 1.304 mmol, 12%).

[0300] LCMS: 1.69 min, 230.8 [M+H]+, Method F

[0301] To a stirred solution of 4,5-dichloro-2-(1 H-pyrazol-5-yl)pyridazin-3(2H)-one (0.26 g, 1.130 mmol) in MeOH (5 mL) was added methylhydrazine (80% in water, 0.2 mL, 3.391 mmol) at 0 °C and the mixture was stirred at rt for 16 h. The reaction mixture was concentrated under reduced pressure. The crude was purified by trituration using DCM / n-pentane to afford 4- chloro-5-(1-methylhydrazinyl)-2-(1 H-pyrazol-5-yl)pyridazin-3(2H)-one (0.35 g, 0.145 mmol, 13%).

[0302] LCMS: 1.21 min, 241.2 [M+H]+, Method F

[0303] To a stirred solution of 4-chloro-5-(1-methylhydrazinyl)-2-(1 H-pyrazol-5-yl)pyridazin-3(2H)- one (0.33 g, 1.387 mmol) in DMF (8.3 mL) and water (0.6 mL), NaOH (0.11 g, 2.777 mmol) was added at 0 °C and the mixture was stirred at 0 °C for 20 min. Carbon disulfide (0.3 mL) was added at 0 °C and the mixture was stirred at rt for 2 h. 2-(bromomethyl)-5-iodobenzonitrile (0.421 g, 1.314 mmol) was added at 0 °C and the reaction mixture was stirred at rt 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 NazSC , filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-50% EtOAc in n-hexane) to afford 5-iodo-2-(((1 -methyl- 5-oxo-6-(1 H-pyrazol-5-yl)-5,6-dihydro-1 H- pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)thio)methyl)benzonitrile (0.15 g, 0.289 mmol, 21%) (Example 38).

[0304] Analytical data for Example 38 can be found in Table 11.

[0305] Route K

[0306] Typical procedure for the preparation of 1-methyl-1 H-pyridazino[4,5-e][1,3,4]thiadiazin-

[0307] 5(6H)-ones via reductive amination using tert-butyl hydrazinecarboxylate followed by a cyclisation using (E)-2,3-dichloro-4-oxobut-2-enoic acid as exemplified by 2-(((1- methyl-5-oxo-6-(tetrahydro-2H-pyran-3-yl)-5,6-dihydro-1 H-pyridazino[4,5- e][1,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (Example 65)

[0308] Example 65 To the solution of dihydro-2H-pyran-3(4H)-one (5 g, 49.94 mmol) and tert-butyl hydrazinecarboxylate (6.60 g, 49.94 mmol) in DCE (30 mL) was added AcOH (15.00 g, 249.71 mmol, 14.29 mL), then the mixture was stirred at rtfor 2 h. NaBH(OAc)s (14.82 g, 69.92 mmol) was then added at rt and the mixture was stirred for 12 h. The mixture was poured into water (50 mL), extracted with DCM (3 x 20 mL) and separated. The combined organic layers were washed with brine (20 mL), dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure to afford tert-butyl 2-(tetrahydro-2H-pyran-3-yl)hydrazine-1 -carboxylate (11.1 g, quantitative, crude) as yellow solid.

[0309] 1H NMR: (400 MHz, DMSO-d6) 6 8.19 (br s, 1 H), 4.29 (t, J = 3.9 Hz, 1 H), 3.75 - 3.68 (m, 1H), 3.65 (td, J = 3.8, 11.0 Hz, 1 H), 3.24 (dt, J = 2.7, 10.7 Hz, 1H), 3.01 (dd, J = 8.7, 11.0 Hz, 1 H), 2.74 (dt, J = 4.2, 8.4 Hz, 1H), 1.82 - 1.71 (m, 1H), 1.67 - 1.57 (m, 1H), 1.46 - 1.35 (m, 10H), 1.26 - 1.20 (m, 1 H).

[0310] Tert-butyl 2-(tetrahydro-2H-pyran-3-yl)hydrazine-1-carboxylate (2 g, 9.25 mmol) was added to a solution of HCI (4 M, 10 mL) in water (10 mL). The reaction mixture was stirred at rt for 2 h. The reaction mixture, ~10 mL of (tetrahydro-2H-pyran-3-yl)hydrazine hydrogen chloride as an aq. solution, was obtained as a yellow liquid and used directly in the next step without purification.

[0311] The solution of (tetrahydro-2H-pyran-3-yl)hydrazine hydrogen chloride obtained in the previous step (~7.5 mL, 6.55 mmol) and (E)-2,3-dichloro-4-oxobut-2-enoic acid (1.11 g, 6.55 mmol) in water (10 mL) was stirred at 100 °C for 4 h. The solids formed in the reaction mixture were collected by vacuum filtration, washed with ice water (5 ml) and dried under reduced pressure to afford 4,5-dichloro-2-(tetrahydro-2H-pyran-3-yl)pyridazin-3(2H)-one (1.3 g, 5.17 mmol, 79%) as white solid.

[0312] 1H NMR: (400 MHz, CDCh) 3 7.80 (s, 1 H), 4.93-5.13 (m, 1 H), 3.88-4.07 (m, 2H), 3.60 (t, J = 10.3 Hz, 1 H), 3.43 (td, J = 10.7, 4.1 Hz, 1 H), 1.96-2.13 (m, 2H), 1.78-1.92 (m, 2H).

[0313] To a mixture of 4,5-dichloro-2-(tetrahydro-2H-pyran-3-yl)pyridazin-3(2H)-one (1.1 g, 4.42 mmol) in MeOH (15 mL) was added methylhydrazine (2.14 g, 18.55 mmol, 2.44 mL, 40% purity) at rt, then the mixture was stirred at rt for 12 h. The reaction mixture was concentrated under reduced pressure and purified by flash column chromatography (0-100% EtOAc in petroleum ether) to afford 4-chloro-5-(1-methylhydrazineyl)-2-(tetrahydro-2H-pyran-3- yl)pyridazin-3(2H)-one (0.8 g, 3.09 mmol, 70%) as yellow solid.

[0314] 1H NMR: (400 MHz, CDCI3) 5 8.25 (s, 1 H), 5.02 (tt, J = 10.0, 4.9 Hz, 1 H), 3.88-4.03 (m, 2H), 3.58 (t, J = 10.4 Hz, 1 H), 3.43-3.47 (m, 3H), 3.38-3.42 (m, 1 H), 1.93-2.08 (m, 2H), 1.72-1.90 (m, 2H). To a solution of 4-chloro-5-(1-methylhydrazineyl)-2-(tetrahydro-2H-pyran-3-yl)pyridazin- 3(2H)-one (0.25 g, 0.966 mmol) in 1-methylpyrrolidin-2-one (3.2 ml_) was added 1 ,4,7,10,13,16-hexaoxacyclooctadecane (255.42 mg, 0.966 mmol), followed by a solution of KOH (5 M, 579.81 pL) in water (0.58 ml_) at rt. The mixture was stirred for 20 min. Carbon disulfide (735.79 mg, 9.66 mmol, 582.57 pL) was added at rt and the mixture was stirred for 2 h. 2-(bromomethyl)-5-(trifluoromethyl)benzonitrile (255.16 mg, 0.966 mmol) was added and the mixture was stirred at rt for 12 h. The reaction mixture was quenched by addition water (30 mL) at 0 °C, then diluted with EtOAc (10 mL) and extracted with EtOAc (3 x 30 mL). The combined organic layers were washed with brine (30 mL), dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by prep HPLC (Method B). The product-containing fractions were lyophilized directly to afford 2-[[1-methyl-6- (oxan-3-yl)-5-oxopyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (58.19 mg, 0.119 mmol, 12%) as brown solid ((Example 65).

[0315] Analytical data for Example 65 can found in Table 12.

[0316] Route L

[0317] Typical procedure for the preparation of 1-methyl-1 H-pyridazino[4,5-e][1,3,4]thiadiazin- 5(6H)-ones via SNAP of hydrazine hydrate into an aryl chloride followed by a cyclisation using (E)-2,3-dichloro-4-oxobut-2-enoic acid as exemplified by 2-(((6-(4,6- dimethylpyridin-2-yl)-1 -methyl-5-oxo-5,6-dihydro-1 H-pyridazino[4,5-e][1 ,3,4]thiadiazin- 3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (Example 83)

[0318] Example 83

[0319] A mixture of 2-chloro-4,6-dimethylpyridine (1.0 g, 7.092 mmol) in hydrazine monohydrate (10 mL) was stirred at 180 °C for 3 h. The reaction mixture was cooled to rt, diluted with water (50 mL) and extracted with EtOAc (5 x 100 mL). The combined organic layers were dried over Na2SO4, filtered and concentrated under reduced pressure to afford 2-hydrazinyl-4,6- dimethylpyridine (0.8 g, 5.839 mmol, 82%). The crude material was triturated with DCM / n- pentane to afford 2-hydrazinyl-4,6-dimethylpyridine

[0320] LCMS: 0.629 min, 138.1 [M+H]+, Method G

[0321] To a stirred solution of 2-hydrazinyl-4,6-dimethylpyridine (0.8 g, 5.839 mmol) and (E)-2,3- dichloro-4-oxobut-2-enoic acid (0.91 g, 5.839 mmol) in EtOH (10 ml_) and water (10 mL) was added cone. HCI (2.0 mL) at rt, then the mixture was stirred at 100 °C for 3 h. The reaction mixture was quenched with sat. aq. NaHCCh (100 mL) and extracted with ethyl acetate (2 x 100 mL). The combined organic layers were dried over Na2SO4 and concentrated under reduced pressure. The crude was purified by trituration with diethyl ether to afford 4,5-dichloro- 2-(4,6-dimethylpyridin-2-yl)pyridazin-3(2H)-one (1.0 g, 3.717 mmol, 62%)

[0322] 1H NMR: (400 MHz, DMSO-d6) 58.32 (s, 1 H), 7.26 (d, J = 10.4 Hz, 2H), 2.46 (s, 3H), 2.37 (s, 3H).

[0323] LCMS: 1.92 min, 270.1 [M+H]+, Method G

[0324] To a stirred solution of 4,5-dichloro-2-(4,6-dimethylpyridin-2-yl)pyridazin-3(2H)-one (1.0 g, 3.717 mmol) in MeOH (10 mL) was added methylhydrazine (3.3 mL) at rt and the mixture was stirred for 16 h. The reaction mixture was concentrated under reduced pressure and triturated with diethyl ether to afford 4-chloro-2-(4,6-dimethylpyridin-2-yl)-5-(1- methylhydrazinyl)pyridazin-3(2H)-one (0.6 g, 2.150 mmol, 57%).

[0325] LCMS: 1.59 min, 280.1 [M+H]+, Method G

[0326] To a stirred solution of 4-chloro-2-(4,6-dimethylpyridin-2-yl)-5-(1-methylhydrazinyl)pyridazin- 3(2H)-one (0.1 g, 0.358 mmol) in DMF (5 mL) was added KOH (0.04 g, 0.716 mmol) and water (0.2 mL) at rt and the mixture was stirred for 20 min. Carbon disulfide (0.1 mL) was added at rt and the mixture was stirred for 2 h. 2-(bromomethyl)-5-(trifluoromethyl)benzonitrile (0.103 g, 0.394 mmol) was added and the mixture was stirred at rt for 16 h. The reaction mixture was poured into cold water (100 mL) and extracted with EtOAc (2 x 50 mL). The combined organic layers were dried over Na2SO4 and concentrated under reduced pressure. The crude material was purified by flash column chromatography (33% EtOAc in n-hexane) to afford 2-(((6-(4,6- dimethylpyridin-2-yl)-1-methyl-5-oxo-5,6-dihydro-1H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.025 g, 0.049 mmol, 13%) (Example 83).

[0327] Analytical data for Example 83 can be found in Table 13. Route M

[0328] Typical procedure for the preparation of 1-methyl-1 H-pyridazino[4,5-e][1,3,4]thiadiazin- 5(6H)-ones via a first step Mitsunobu reaction using 4,5-dichloropyridazin-3(2H)-one as exemplified by 3-[(4-bromo-2-methylphenyl)methylsulfanyl]-1 -methyl-6-(oxetan-3- ylmethyl)pyridazino[4,5-e][1,3,4]thiadiazin-5-one (Example 97)

[0329] Example 97

[0330] To a stirred solution of oxetan-3-ylmethanol (1.0 g, 11.36 mmol) and 4,5-dichloropyridazin- 3(2H)-one (1.87 g, 11.35 mmol) in THF (10 mL) was added PPhs (4.47 g, 17.04 mmol) followed by DIAD (3.44 g, 17.07 mmol) and the mixture was stirred at rt for 1 h. The reaction mixture was poured into cold water (100 mL) and extracted with EtOAc (2 x 50 mL). The combined organic layers were dried over Na2SO4 and concentrated under reduced pressure. The crude material was purified by flash column chromatography (20% EtOAc in n-hexane) to afford 4,5- dichloro-2-(oxetan-3-ylmethyl)pyridazin-3(2H)-one (1.1 g, 4.68 mmol, 56%).

[0331] LCMS: 1.65 min, 235.1 [M+H]+, Method G

[0332] To a stirred solution of 4,5-dichloro-2-(oxetan-3-ylmethyl)pyridazin-3(2H)-one (1.0 g, 4.235 mmol) in MeOH (10 mL) was added methyl hydrazine (3 mL, 12.71 mmol) and the mixture was stirred at 80 °C for 1 h. The reaction mixture was concentrated under reduced pressure, diluted with water (30 mL) and extracted with EtOAc (2 x 30 mL). The combined organic layers were dried over Na2SO4 and concentrated under reduced pressure to afford 4-chloro-5-(1- methylhydrazinyl)-2-(oxetan-3-ylmethyl)pyridazin-3(2H)-one (0.8 g, 3.269 mmol, 45%).

[0333] LCMS: 1.34 min, 245.2 [M+H]+, Method G

[0334] To a stirred solution of 4-chloro-5-(1-methylhydrazinyl)-2-(oxetan-3-ylmethyl)pyridazin-3(2H)- one (0.2 g, 0.816 mmol) in DMF (5 mL) was added NaOH (0.065 g, 1.632 mmol) followed by water (0.4 mL) and the mixture was stirred at rt for 20 min. Carbon disulfide (0.4 mL) was added and the mixture was stirred for 2 h. 4-bromo-1-(bromomethyl)-2-methylbenzene (0.237 g, 0.901 mmol) was added and the mixture was stirred at rt for 16 h. The reaction mixture was poured into cold 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 (50% EtOAc in n-hexane) to afford 3- ((4-bromo-2-methylbenzyl)thio)-1-methyl-6-(oxetan-3-ylmethyl)-1 H-pyridazino[4,5- e][1 ,3,4]thiadiazin-5(6H)-one (0.04 g, 0.085 mmol, 17%) (Example 97).

[0335] Analytical data for Example 97 can be found in Table 14.

[0336] Route N

[0337] Typical procedure for the preparation of 4,7-dimethyl-4H-pyridazino[4,5-e][1,3]thiazin- 8(7H)-one as exemplified by 2-[(4,7-dimethyl-8-oxo-4H-pyridazino[4,5-e][1,3]thiazin-2- yl)sulfanylmethyl]-5-iodobenzonitrile (Example 54)

[0338] To a stirred solution of 4,5-dichloro-2-methylpyridazin-3(2H)-one (50.0 g, 279.32 mmol) in DMF (250 ml_) was added Nal (167.4 g, 1117.3 mmol) at rt and the mixture was stirred at 140 °C for 24 h. The reaction mixture was cooled to rt and diluted with ethyl acetate (500 ml_). The solids were removed by vacuum filtration and the resulting filtrate was concentrated under reduced pressure. The crude material was purified by trituration with ethyl acetate (100 mL) and diethyl ether (500 mL) to afford 4-chloro-5-iodo-2-methylpyridazin-3(2H)-one. (24.0 g, 88.91 mmol, 31%).

[0339] LCMS: 1.81 min, 270.7 [M+H]+, Method F

[0340] A stirred solution 4-chloro-5-iodo-2-methylpyridazin-3(2H)-one (22 g, 81.50 mmol), tributyl(1- ethoxyvinyl)stannane (29.44 g, 81.50 mmol) in DMF (50 ml_) was purged with nitrogen gas for 15 min. PdChdppf (2.97 g, 4.07 mmol) was added and the reaction was stirred at 85 °C for 16 h. The reaction mixture was cooled to rt, diluted with water (500 mL) and extracted with EtOAc (2 x 500 mL). The combined organic layers were filtered through a Celite bed, then dried over anhydrous Na2SC>4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (20-30% EtOAc in n-hexane) to afford 4-chloro- 5-(1-ethoxyvinyl)-2-methylpyridazin-3(2H)-one (10.2 g, 47.65 mmol, 58%).

[0341] LCMS: 1.86 min, 215.1 [M+H]+, Method F

[0342] To a stirred solution of 4-chloro-5-(1-ethoxyvinyl)-2-methylpyridazin-3(2H)-one (10 g, 46.71 mmol) in THF (200 mL) was added 1 N HCI (230 mL) and the mixture was stirred at rt for 2 h. The reaction mixture was diluted with water (500 mL) and extracted with EtOAc (2 x 250 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 (12-15% EtOAc in n-hexane) to afford 5-acetyl-4-chloro-2-methylpyridazin-3(2H)-one (5.5 g, 29.56 mmol, 63%).

[0343] LCMS: 1.53 min, 186.9 [M+H]+, Method F

[0344] To a stirred solution of 5-acetyl-4-chloro-2-methylpyridazin-3(2H)-one (1.5 g, 8.06 mmol) in MeOH (15 mL) was added NaBH4(0.152 g, 4.031 mmol) at rt and the mixture was stirred at rt for 30 min. The reaction mixture was concentrated under reduced pressure. Water (100 mL) was added to the residue thus obtained and extracted with EtOAc (2 x 100 mL). The combined organic layers were dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure to afford 4-chloro-5-(1-hydroxyethyl)-2-methylpyridazin-3(2H)-one (1.43 g, 7.60 mmol, 94%).

[0345] LCMS: 1.29 min, 189.1 [M+H]+, Method F

[0346] To a stirred solution of 4-chloro-5-(1-hydroxyethyl)-2-methylpyridazin-3(2H)-one (1.438 g, 7.64 mmol) in DCM (10 mL) were added TEA (1.59 mL, 11.47 mmol) and MsCI (1.30 g, 11.47 mmol) at 0 °C. The reaction mixture was then stirred at rt for 1 h. The reaction mixture was poured into water (50 mL) and extracted with DCM (2 x 50 mL). The combined organic layers were dried over anhydrous Na2SC>4, filtered and concentrated under reduced pressure to afford 1- (5-chloro-1-methyl-6-oxo-1 ,6-dihydropyridazin-4-yl)ethyl methanesulfonate (2.48 g, 9.32 mmol, quantitative yield).

[0347] LCMS: 1.63 min, 267.1 [M+H]+, Method F

[0348] To a stirred solution of 1-(5-chloro-1-methyl-6-oxo-1 ,6-dihydropyridazin-4-yl)ethyl methanesulfonate (2.486 g, 9.33 mmol) in DMSO (5 mL) was added NaNs (0.788 g, 12.13 mmol) at rt and the mixture was stirred for 2 h. The reaction mixture was poured into water (10 mL) and extracted with EtOAc (2 x 100 ml_). The combined organic layers were dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure to afford 5-(1- azidoethyl)-4-chloro-2-methylpyridazin-3(2H)-one (1.32 g, 6.19 mmol, 66%).

[0349] LCMS: 1.80 min, 214.2 [M+H]+, Method F

[0350] To a stirred solution of 5-(1-azidoethyl)-4-chloro-2-methylpyridazin-3(2H)-one (1.32 g, 6.19 mmol) in THF (10 mL) was added PPhs (1.78 g, 6.81 mmol) at rt and the mixture was stirred for 30 min. 1 M NaOH (5 mL) was added and the mixture was stirred at rt for 48 h. The reaction mixture was concentrated under reduced pressure, diluted with water (30 mL) and extracted with DCM (2 x 50 mL). The combined organic layers were dried over anhydrous Na2SC>4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (20-25% MeOH in DCM) to afford 5-(1-aminoethyl)-4-chloro-2- methylpyridazin-3(2H)-one (0.380 g, 2.03 mmol, 32%).

[0351] LCMS: 0.66 min, 188.0 [M+H]+, Method F

[0352] To a stirred solution of 5-(1-aminoethyl)-4-chloro-2-methylpyridazin-3(2H)-one (0.190 g, 1.015 mmol) in DMF (5 mL) was added 10% KOH solution (0.2 mL) at rt and the mixture was stirred for 10 min. Carbon disulfide (0.2 mL) was added at rt and the mixture was stirred for 2 h. 2- (bromomethyl)-5-iodobenzonitrile (2.26 g, 8.62 mmol) was added and the mixture was stirred at rt for 24 h. Additional 10% KOH solution (1 mL) was added and the mixture was stirred at rt for a further 16 h. The reaction mixture was poured into water (10 mL) and extracted with EtOAc (2 x 10 mL). The combined organic layers were dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crud material was purified by prep HPLC (Method C) to afford 2-(((4,7-dimethyl-8-oxo-7,8-dihydro-4H-pyridazino[4,5-e][1,3]thiazin-2- yl)thio)methyl)-5-iodobenzonitrile. (0.015 g, 0.032 mmol, 3%) (Example 54).

[0353] Analytical data for Example 54 can be found in Table 15.

[0354] Route O

[0355] Typical procedure for the preparation of 4-methyl-4H-pyridazino[4,5-e][1,3]thiazin-

[0356] 8(7H)-one as exemplified by 5-iodo-2-[(4-methyl-8-oxo-4,7-dihydropyridazino[4,5- e][1,3]thiazin-2-yl)sulfanylmethyl]benzonitrile (Example 95)

[0357] A solution of compound 4,5-dichloropyridazin-3(2H)-one (20 g, 121.23 mmol) in DMF (200 ml_) was stirred at 0° C. NaH (6.30 g, 157.60 mmol, 60% in mineral oil) was added portionwise at 0 °C. The mixture was stirred for 30 min at 0 °C. SEMCI (26.27 g, 157.60 mmol, 27.89 ml_) was added slowly at 0 °C. The resulting solution was stirred for 1 h at 0 °C. The reaction was then quenched by the addition of water (1000 mL). The resulting solution was extracted with EtOAc (2 x 200 mL) and the organic layers combined. The combined organic layers were washed with brine (200 ml_) and concentrated under reduced pressure. The crude material was purified by flash column chromatography (4% EtOAc in petroleum ether) to afford 4,5- dichloro-2-((2-(trimethylsilyl)ethoxy)methyl)pyridazin-3(2H)-one (22 g, 72.24 mmol, 60%) as a pale yellow oil.

[0358] 1H NMR: (400 MHz, CDCI3) 57.81 (s, 1 H), 5.50 (s, 2H), 3.78 - 3.66 (m, 2H), 1.02 - 0.93 (m, 2H), 0.01 (s, 9H).

[0359] A mixture of 4,5-dichloro-2-((2-(trimethylsilyl)ethoxy)methyl)pyridazin-3(2H)-one (16 g, 54.19 mmol) and Nal (40.62 g, 270.97 mmol) in DMA (80 mL) was stirred at 145 °C for 12 h. The reaction mixture was cooled to rt, poured into water (300 mL) and stirred for 5 min. The aqueous phase was extracted with ethyl acetate (3 x 100 mL). The combined organic layers were washed with brine (100 mL), dried with anhydrous Na2SC>4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-10% EtOAc in petroleum ether) to afford 4-chloro-5-iodo-2-((2- (trimethylsilyl)ethoxy)methyl)pyridazin-3(2H)-one (12.6 g, 30.01 mmol, 55%) as pale yellow oil.1H NMR: (400 MHz, CDCh) 68.02 (s, 1 H), 5.51 - 5.45 (m, 2H), 3.76 - 3.66 (m, 2H), 1.02 - 0.92 (m, 2H), 0.01 (s, 9H).

[0360] A stirred solution 4-chloro-5-iodo-2-((2-(trimethylsilyl)ethoxy)methyl)pyridazin-3(2H)-one (5.6 g, 14.48 mmol), tributyl(1-ethoxyvinyl)stannane (5.75 g, 15.93 mmol, 5.38 ml_) in DMF (56 ml_) was purged with nitrogen gas. Pd(dppf)CI2(529.83 mg, 0.724 mmol) was added and the mixture was stirred at 85 °C for 16 h. The reaction mixture was cooled to rt, diluted with water (200 mL) and extracted with EtOAc (2 x 70 ml_). The combined organic layers were filtered, dried over anhydrous Na2SC>4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-10% EtOAc in petroleum ether) to afford 4-chloro-5-(1-ethoxyvinyl)-2-((2-(trimethylsilyl)ethoxy)methyl)pyridazin-3(2H)-one (3.7 g, 10.47 mmol, 72%) as a pale yellow oil.

[0361] 1H NMR: (400 MHz, CDCI3) 67.85 (s, 1 H), 5.51 (s, 2H), 4.77 (d, J = 3.4 Hz, 1 H), 4.69 (d, J = 3.4 Hz, 1 H), 3.93 (q, J = 7.0 Hz, 2H), 3.78 - 3.69 (m, 2H), 1.41 (t, J = 7.0 Hz, 3H), 1.02 - 0.95 (m, 2H), 0.01 (s, 9H).

[0362] To a stirred solution of 4-chloro-5-(1-ethoxyvinyl)-2-((2-(trimethylsilyl)ethoxy)methyl)pyridazin- 3(2H)-one (5.7 g, 17.23 mmol) in THF (57 mL) was added HCI (3 M, 86.13 mL) and stirred at rt for 14 h. The reaction mixture was diluted with water (5 mL) and adjusted to pH 8 with sat aq. NaHCOs. The aqueous phase was 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 flash column chromatography (0-10% EtOAc in petroleum ether) to afford 5-acetyl-4-chloro-2-((2-(trimethylsilyl)ethoxy)methyl)pyridazin- 3(2H)-one (4.5 g, 14.75 mmol, 85%) as a pale yellow oil.

[0363] 1H NMR: (400 MHz, CDCh) 67.84 (s, 1 H), 5.52 (s, 2H), 3.78 - 3.69 (m, 2H), 2.71 (s, 3H), 1.04

[0364] - 0.93 (m, 2H), 0.01 (s, 9H).

[0365] To a stirred solution of 5-acetyl-4-chloro-2-((2-(trimethylsilyl)ethoxy)methyl)pyridazin-3(2H)- one (4 g, 13.21 mmol) in MeOH (10 mL) and THF (30 mL) was added NaBH4(299.81 mg, 7.93 mmol) at 0 °C and the mixture was stirred at rt for 1 h. The reaction mixture diluted with water (100 mL) and extracted with EtOAc (2 x 60 mL). The combined organic layers were dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure to afford 4- chloro-5-(1-hydroxyethyl)-2-((2-(trimethylsilyl)ethoxy)methyl)pyridazin-3(2H)-one (4.03 g, 13.2 mmol, quantitative yield) as a brown solid.

[0366] 1H NMR: (400 MHz, CDCh) 6 8.07 (s, 1H), 5.57 - 5.48 (m, 2H), 5.20 (q, J = 6.5 Hz, 1H), 3.78

[0367] - 3.70 (m, 2H), 1.51 (d, J = 6.6 Hz, 3H), 1.03 - 0.94 (m, 2H), 0.01 (s, 9H). To a stirred solution of 4-chloro-5-(1-hydroxyethyl)-2-((2- (trimethylsilyl)ethoxy)methyl)pyridazin-3(2H)-one (4 g, 13.12 mmol) in DCM (40 mL) were added TEA (1.99 g, 19.68 mmol, 2.74 mL) and MsCI (2.38 g, 20.78 mmol, 1.61 mL) at 0 °C and the mixture was stirred at rt for 1 h. The reaction mixture was poured into water (50 mL) and extracted with DCM (2 x 40 mL). The combined organic layers were dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure to afford 1-(5-chloro-6-oxo-1-((2- (trimethylsilyl)ethoxy)methyl)-1 ,6-dihydropyridazin-4-yl)ethyl methanesulfonate (5 g, crude, quantitative yield) as a brown solid.

[0368] 1H NMR: (400 MHz, CDCI3) 6 7.93 (s, 1 H), 5.96 (q, J = 6.7 Hz, 1 H), 5.60 - 5.44 (m, 2H), 3.82 - 3.71 (m, 2H), 3.08 (s, 3H), 1.70 (d, J = 6.6 Hz, 3H), 1.05 - 0.90 (m, 2H), 0.01 (s, 9H).

[0369] To a stirred solution of 1-(5-chloro-6-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1 ,6- dihydropyridazin-4-yl)ethyl methanesulfonate (5 g, 13.06 mmol) in DMSO (18 mL) was added NaNs (1.18 g, 18.15 mmol) at rt and the mixture was stirred for 2 h. The reaction mixture was poured into water (100 mL) and extracted with EtOAc (2 x 50 mL). The combined organic layers were dried over anhydrous Na2SC>4, filtered and concentrated under reduced pressure to afford 5-(1-azidoethyl)-4-chloro-2-((2-(trimethylsilyl)ethoxy)methyl)pyridazin-3(2H)-one (4.2 g, crude, quantitative yield) as a brown solid.

[0370] 1H NMR: (400 MHz, CDCh) 5 7.89 (s, 1 H), 5.52 (s, 2H), 5.05 (q, J = 6.8 Hz, 1 H), 3.82 - 3.70 (m, 2H), 1.54 (d, J = 6.9 Hz, 3H), 1.09 - 0.92 (m, 2H), 0.01 (s, 9H).

[0371] To a solution of 5-(1-azidoethyl)-4-chloro-2-((2-(trimethylsilyl)ethoxy)methyl)pyridazin-3(2H)- one (3.6 g, 9.10 mmol) in THF (36 mL) was added HCI (3 M, 9.10 mL) and SnCI2.2H2O (6.16 g, 27.31 mmol) at 0 °C, then the mixture was stirred at rt for 1 h. The mixture was adjusted to ~pH 9 with sat. aq. Na2COs at 0 °C, then sat. aq. KF solution (30 mL) was added and the mixture was stirred for 10 min. The aqueous phase was extracted with ethyl acetate (3 x 40 mL). The combined organic layers were washed with brine (50 mL), dried with anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-100% EtOAc in petroleum ether) to afford 5-(1- aminoethyl)-4-chloro-2-((2-(trimethylsilyl)ethoxy)methyl)pyridazin-3(2H)-one (2.4 g, 7.45 mmol, 81 %) as pale yellow solid.

[0372] 1H NMR: (400 MHz, CDCh) 5 8.10 (s, 1 H), 5.52 (d, J = 1.4 Hz, 2H), 4.54 (q, J = 6.8 Hz, 1 H), 3.73 (dd, J = 7.8, 8.9 Hz, 2H), 1.81 (br, 3H), 1.41 (d, J = 6.8 Hz, 3H), 1.02 - 0.92 (m, 2H), 0.01 (s, 9H).

[0373] To a stirred solution of 5-(1-aminoethyl)-4-chloro-2-((2-(trimethylsilyl)ethoxy)methyl)pyridazin- 3(2H)-one (0.86 g, 2.83 mmol) in DMF (17 mL) was added DIPEA (731.58 mg, 5.66 mmol, 985.95 pL) and CS2 (2.59 g, 33.96 mmol, 2.05 mL) at rt and the mixture was stirred for 3 h. 2- (bromomethyl)-5-iodobenzonitrile (1.18 g, 3.40 mmol) and DI PEA (731.58 mg, 5.66 mmol, 985.95 pL) was added and the mixture was stirred at rt for 2 h. The mixture was poured into water (60 mL). The aqueous phase was extracted with ethyl acetate (3 x 20 mL). The combined organic layers were washed with brine (30 mL), dried with anhydrous Na2SC>4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-25% EtOAc in petroleum ether) to afford 5-iodo-2-(((4-methyl-8- oxo-7-((2-(trimethylsilyl)ethoxy)methyl)-7,8-dihydro-4H-pyridazino[4,5-e][1 ,3]thiazin-2- yl)thio)methyl)benzonitrile (1.3 g, crude, quantitative yield) as pale yellow solid.

[0374] 1H NMR: (400 MHz, CDCI3) 5 7.95 (d, J = 1.8 Hz, 1 H), 7.86 (dd, J = 1.7, 8.3 Hz, 1 H), 7.66 (s, 1 H), 7.33 (d, J = 8.4 Hz, 1 H), 5.49 (s, 2H), 4.78 (q, J = 6.9 Hz, 1H), 4.51 - 4.36 (m, 2H), 3.74 - 3.66 (m, 2H), 1.50 (d, J = 7.0 Hz, 3H), 1.02 - 0.92 (m, 2H), 0.05 (s, 8H).

[0375] A solution of 5-iodo-2-(((4-methyl-8-oxo-7-((2-(trimethylsilyl)ethoxy)methyl)-7,8-dihydro-4H- pyridazino[4,5-e][1,3]thiazin-2-yl)thio)methyl)benzonitrile (0.06 g, 0.067 mmol) in TFA (3.00 mL) was stirred at rt for 1 h. The mixture was concentrated under reduced pressure. The crude product was purified by prep HPLC (Method B) to afford 5-iodo-2-[(4-methyl-8-oxo-4,7- dihydropyridazino[4,5-e][1 ,3]thiazin-2-yl)sulfanylmethyl]benzonitrile (18.61 mg, 39.87 pmol, 59% yield) as a pale yellow solid (Example 95).

[0376] Analytical data for Example 95 can be found in Table 16.

[0377] Route P

[0378] Typical procedure for the preparation of 7-alkyl 4-methyl-4H-pyridazino[4,5- e][1,3]thiazin-8(7H)-ones as exemplified by 5-iodo-2-[[4-methyl-7-(oxetan-3-ylmethyl)-8- oxo-4H-pyridazino[4,5-e][1 ,3]thiazin-2-yl]sulfanylmethyl]benzonitrile (Example 96)

[0379] To a solution of 5-iodo-2-[(4-methyl-8-oxo-4,7-dihydropyridazino[4,5-e][1,3]thiazin-2- yl)sulfanylmethyl]benzonitrile (0.12 g, 0.264 mmol) in DMF (2.2 mL) was added K2CO3 (109.52 mg, 0.792 mmol), Nal (39.59 mg, 0.264 mmol) and 3-(bromomethyl)oxetane (47.86 mg, 0.316 mmol). The mixture was stirred at rt for 8 h. The solids formed in the reaction mixture were collected by vacuum filtration and purified by prep HPLC (Method B) to afford 5-iodo-2-[[4- methyl-7-(oxetan-3-ylmethyl)-8-oxo-4H-pyridazino[4,5-e][1 ,3]thiazin-2- yl]sulfanylmethyl]benzonitrile (10.74 mg, 0.020 mmol, 8%) (Example 96) as a pale pink solid.

[0380] Analytical data for Example 96 can be found in Table 17.

[0381] Route Q

[0382] Typical procedure for the preparation of 1,6-bis(methyl-d3)-1 H-pyridazino[4,5- e][1,3,4]thiadiazin-5(6H)-ones as exemplified by 2-(((1,6-bis(methyl-d3)-5-oxo-5,6- dihydro-1 H-pyridazino[4,5-e][1, 3, 4]thiadiazin-3-yl)thio)methyl)-5-

[0383] (tr

[0384] To a stirred solution of 4,5-dichloropyridazin-3(2H)-one (20 g, 121.9 mmol) in THF (200 mL) was added DHP (81.97 g, 975.9 mmol) and PTSA (4.63 g, 24.39 mmol) at rt and the mixture was stirred at 80 °C for 16 h. The reaction mixture was cooled to rt, then poured into cold water (400 mL) and extracted with EtOAc (3 x 200 mL). The combined organic layers were dried over NazSO^ filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (20-26% EtOAc in n-hexane) to afford 4,5-dichloro- 2-(tetrahydro-2H-pyran-2-yl)pyridazin-3(2H)-one (0.19 g, 76.92 mmol, 63%).

[0385] LCMS: 2.07 min, 248.8 [M+H]+, Method F

[0386] To a stirred solution of (4-methoxybenzyl) hydrazine hydrochloride (28.81 g, 153.2 mmol) in IPA (190 mL) was added DIPEA (30.53 mL, 229.1 mmol) at rt and the mixture was stirred for 20 min. 4,5-dichloro-2-(tetrahydro-2H-pyran-2-yl)pyridazin-3(2H)-one (19 g, 76.60 mmol) was added and the mixture was stirred at 80 °C for 16 h. The reaction mixture was cooled to rt, then poured into cold water (300 mL) and extracted with EtOAc (3 x 150 mL). The combined organic layers were dried over NazSC , filtered and concentrated under reduced pressure. The crude was purified by flash column chromatography (20-30% EtOAc in n-hexane) to afford 4-chloro-5-(1-(4-methoxybenzyl)hydrazinyl)-2-(tetrahydro-2H-pyran-2-yl)pyridazin-3(2H)-one (9.0 g, 24.62 mmol, 32%).

[0387] LCMS: 2.07 min, 364.8 [M+H]+, Method F

[0388] To a stirred solution of 4-chloro-5-(1-(4-methoxybenzyl)hydrazinyl)-2-(tetrahydro-2H-pyran-2- yl)pyridazin-3(2H)-one (9.0 g, 24.68 mmol) in DMF (90 ml_) was added 10% aq. KOH solution (9 ml_) at rt and the mixture was stirred for 20 min. Carbon disulfide (9 ml_) was added at rt and the mixture was stirred for 3 h. 2-(bromomethyl)-5-(trifluoromethyl)benzonitrile (7.14 g, 27.12 mmol) was added and the mixture was stirred at rt for 16 h. The reaction mixture was poured into cold water (250 ml_) and extracted with EtOAc (3 x 150 mL). The combined organic layers were dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (15-20% EtOAc in n-hexane) to afford 2-(((1-(4-methoxybenzyl)-5-oxo-6-(tetrahydro-2H-pyran-2-yl)-5,6-dihydro-1 H-pyridazino[4,5- e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (4.0 g, 24.67 mmol, 27%). LCMS: 2.64 min, 588.3 [M+H]+, Method F

[0389] A solution of 32-(((1-(4-methoxybenzyl)-5-oxo-6-(tetrahydro-2H-pyran-2-yl)-5,6-dihydro-1 H- pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (4.0 g, 6.81 mmol) in TFA (40 mL) was stirred at rt for 16 h. The reaction mixture was quenched with sat. aq. NaHCOs solution (100 mL) and extracted with EtOAc (2 x 100 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 (60-70% EtOAc in n-hexane) to afford 2-(((5-oxo-5,6-dihydro-1 H-pyridazino[4,5-e][1,3,4]thiadiazin-3-yl)thio)methyl)-5- (trifluoromethyl)benzonitrile (1.9 g, 4.96 mmol, 72%) LCMS: 2.01 min, 384.2 [M+H]+, Method F

[0390] To a stirred solution of 2-(((5-oxo-5,6-dihydro-1 H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (1.0 g, 2.61 mmol) in DMF (15 mL) was added CS2CO3 (0.848 mL, 2.61 mmol) at 0 °C and the mixture was stirred for 10 min. CD3I (3.7 g, 26.1 mmol) was added and the mixture was stirred at rt for 16 h. The reaction mixture was quenched with cold water (50 mL) and extracted with EtOAc (3 x 30 mL). The combined organic layers were dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (15-20% EtOAc in n-hexane) to afford 2-(((1 ,6-bis(methyl-d3)-5-oxo-5,6-dihydro-1 H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.02 g, 0.047 mmol, 2%) (Example 47). Analytical data for Example 47 can be found in Table 18. Route R

[0391] Typical procedure for the preparation of 1-(methyl-d3)-6-(pyridin-2-yl)-1 H- pyridazino[4,5-e][1,3,4]thiadiazin-5(6H)-ones as exemplified by 2-(((1 -(methyl-d3)-5- oxo-6-(pyridin-2-yl)-5,6-dihydro-1H-pyridazino[4,5-e][1,3,4]thiadiazin-3-yl)thio)methyl)- 5-(trifluoromethyl)benzonitrile (Example 73)

[0392] To a stirred solution of 2-hydrazinylpyridine (15.0 g, 137.40 mmol) in 4 M HCI (150 mL) was added (E)-2,3-dichloro-4-oxobut-2-enoic acid (CAS: 87-56-9; 23.21 g, 137.40 mmol) and stirred at 80 °C for 3 h. The reaction mixture was poured into cold water (500 mL) and the resultant solid was collected by vacuum filtration and dried under reduced pressure. The crude material was purified by trituration using diethyl ether (150 mL) to afford 4,5-dichloro-2- (pyridin-2-yl)pyridazin-3(2H)-one (15.0 g, 61.96 mmol, 45%).

[0393] LCMS: 1.75 min, 242.1 [M+H]+, Method G

[0394] To a stirred solution of (4-methoxybenzyl)hydrazine hydrochloride (17.53 g, 92.95 mmol) in IPA (150 mL) was added DIPEA (27.7 mL, 154.92 mmol) at rt and the mixture was stirred for 20 min. 4,5-dichloro-2-(pyridin-2-yl)pyridazin-3(2H)-one (15.0 g, 61.96 mmol) was added and the mixture was stirred at 80 °C for 16 h. The reaction mixture was poured into cold water (300 mL) and extracted with EtOAc (3 x 150 mL). The combined organic layers were dried over Na2SCU, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (65-70% EtOAc in n-hexane) to afford 4-chloro-5-(1-(4- methoxybenzyl)hydrazinyl)-2-(pyridin-2-yl)pyridazin-3(2 / 7)-one (10.0 g, 27.94 mmol, 45%). LCMS: 1.84 min, 358.2 [M+H]+, Method G

[0395] To a stirred solution of 4-chloro-5-(1-(4-methoxybenzyl)hydrazinyl)-2-(pyridin-2-yl)pyridazin- 3(2 / 7)-one (9.5 g, 26.61 mmol) in DMF (95.0 mL) and water (9.5 mL) was added NaOH (2.66 g, 66.52 mmol) at 0 °C and the mixture was stirred for 20 min. Carbon disulfide (9.5 mL) was added at rt and the mixture was stirred for 2 h. 2-(bromomethyl)-5-(trifluoromethyl)benzonitrile (8.31 g, 29.27 mmol) was added and the mixture was stirred at rt for 16 h. The reaction mixture was poured into cold water (100 mL) and extracted with EtOAc (3 x 150 ml_). The combined organic layers were dried over Na2SC>4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (95-100% EtOAc in n- hexane) to afford 2-(((1-(4-methoxybenzyl)-5-oxo-6-(pyridin-2-yl)-5,6-dihydro-1H- pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (5.6 g, 1.722 mmol, 36%).

[0396] LCMS: 2.57 min, 581.2 [M+H]+, Method G

[0397] A stirred solution of 2-(((1-(4-methoxybenzyl)-5-oxo-6-(pyridin-2-yl)-5,6-dihydro-1H- pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (5.6 g, 9.645 mmol) in TFA (56 mL) was stirred at rt for 16 h. The reaction mixture was quenched with sat. aq. NaHCOs solution (300 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 was purified by flash column chromatography (75-80% EtOAc in n-hexane) to afford 2-(((5-oxo-6-(pyridin-2-yl)-5,6-dihydro-1 / 7-pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)thio)methyl)- 5-(trifluoromethyl)benzonitrile (3.0 g, 6.515 mmol, 67%) LCMS: 2.25 min, 461.2 [M+H]+, Method G

[0398] To a stirred solution of 2-(((5-oxo-6-(pyridin-2-yl)-5,6-dihydro-1H-pyridazino[4,5- e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.3 g, 0.651 mmol) and 02003 (0.254 g, 0.781 mmol) in DMF (15 mL) was added CD3I (0.094 g, 0.651 mmol) and stirred at rt for 16 h. The reaction mixture was diluted with cold water (50 mL) and extracted with EtOAc (3 x 30 mL). The combined organic layers were dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by prep HPLC (Method D) to afford 2-(((1-(methyl-<d3)-5-oxo-6-(pyridin-2-yl)-5,6-dihydro-1H- pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.06 g, 0.013 mmol, 2%) (Example 73).

[0399] Analytical data for Example 73 can be found in Table 19.

[0400] Route S

[0401] Typical procedure for the preparation of 1-(2-fluoroethyl)-6-methyl-1 H-pyridazino[4,5- e][1,3,4]thiadiazin-5(6H)-ones as exemplified by 2-[[1-(2-fluoroethyl)-6-methyl-5- oxopyridazino[45-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-iodobenzonitrile (Example

[0402] To a stirred solution of 4,5-dichloro-2-methylpyridazin-3(2H)-one (1.0 g, 5.586 mmol) in MeOH (10 mL) was added 2-hydrazinylethan-1-ol (0.9 g, 11.17 mmol) and the mixture was stirred at 80 °C for 3 h. The reaction mixture was concentrated under reduced pressure, then triturated with MeOH and diethyl ether to afford 4-chloro-5-(1-(2-hydroxyethyl)hydrazinyl)-2- methylpyridazin-3(2 / - / )-one (0.450 g, 2.06 mmol, 37%).

[0403] LCMS: 0.86 min, 219.2 [M+H]+, Method G

[0404] To a stirred solution of 4-chloro-5-(1-(2-hydroxyethyl)hydrazinyl)-2-methylpyridazin-3(2H)-one (0.45 g, 2.064 mmol) in DMF (5 mL) was added 10% aq. KOH (1.0 mL ) at rt and the mixture was stirred for 20 min. Carbon disulfide (0.4 mL) was added at rt and the mixture was stirred for 2 h. 2-(bromomethyl)-5-iodobenzonitrile (0.600 g, 2.064 mmol) was added and the mixture was stirred at rt for 16 h. The reaction mixture was poured into cold water (100 mL) and extracted with EtOAc (2 x 50 mL). The combined organic layers were dried over Na2SO4 and concentrated under reduced pressure. The crude was purified by flash column chromatography (60% EtOAc in n-hexane) to afford 2-(((1-(2-hydroxyethyl)-6-methyl-5-oxo- 5,6-dihydro-1H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-iodobenzonitrile (0.120 g, 0.24 mmol, 11%).

[0405] LCMS: 2.40 min, 500.0 [M+H]+, Method G

[0406] To a stirred solution of 2-(((1-(2-hydroxyethyl)-6-methyl-5-oxo-5,6-dihydro-1 / 7-pyridazino[4,5- e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-iodobenzonitrile (0.020 g, 0.040 mmol) in DCM (1.0 mL) was added DAST (0.015 g, 0.081 mmol) at 0 °C and the mixture was stirred at rt for 16 h. The reaction mixture was poured into sat. aq. Na2CO3 (50 mL) and extracted with EtOAc (2 x 50 mL). The combined organic layers were dried over Na2SO4 and concentrated under reduced pressure. The crude material was purified by flash column chromatography (60% EtOAc in n- hexane) to afford 2-(((1-(2-fluoroethyl)-6-methyl-5-oxo-5,6-dihydro-1 / -pyridazino[4,5- e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-iodobenzonitrile (0.010 g, 0.019 mmol, 20%) (Example 76).

[0407] Analytical data for Example 76 can be found in Table 20. Route T

[0408] Typical procedure for the preparation of 1-methyl-6-(6-morpholinopyridin-2-yl)-1H- pyridazino[4,5-e][1,3,4]thiadiazin-5(6H)-ones as exemplified by 2-(((1-methyl-6-(6- morpholinopyridin-2-yl)-5-oxo-5,6-dihydro-1H-pyridazino[4,5-e][1,3,4]thiadiazin-3- yl)thios)methyl)-5-(trifluoromethyl)benzonitrile (Example 78)

[0409] To a stirred solution of 2,6-dichloropyridine (15.0 g, 101.35 mmol) in DMF (100 mL) was added (19.42 g, 222.98 mmol) and K2COs (30.7 g 222.98 mmol) at rt and the mixture was stirred at 100 °C for 16 h. The reaction mixture was cooled to rt and diluted with water (500 mL) and extracted with EtOAc (2 x 500 mL). The combined organic layers were dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (45-50% EtOAc in n-hexane) to afford 4-(6-chloropyridin-2-yl) morpholine (17.0 g, 85.83 mmol, 84%).

[0410] LCMS: 2.39 min, 199.2 [M+H]+, Method G

[0411] A solution of 4-(6-chloropyridin-2-yl)morpholine (7.0 g, 35.34 mmol) in NH2-NH2. H2O (70 mL) was stirred at 150 °C for 16 h. The reaction mixture was cooled to rt, diluted with water (100 mL) and extracted with EtOAc (2 x 100 mL). The combined organic layers were dried over Na2SCU, filtered and concentrated under reduced pressure to afford 4-(6-hydrazinylpyridin-2- yl)morpholine. (3.36 g, 17.30 mmol, 49%).

[0412] LCMS: 1.06 min, 195.3 [M+H]+, Method G

[0413] To a stirred solution of 4-(6-hydrazinylpyridin-2-yl)morpholine (1.68 g, 8.65 mmol) in EtOH (30 mL) and water (30 mL) were added (E)-2,3-dichloro-4-oxobut-2-enoic acid (1 .45 g, 8.63 mmol) and HCI (1.68 mL) at rt and the mixture was stirred at 100 °C for 1 h. The reaction mixture was concentrated under reduced pressure. The crude material was purified by trituration with DCM and n-hexane to afford 4,5-dichloro-2-(6-morpholinopyridin-2-yl)pyridazin-3(2 / - / )-one. (1.68 g, 5.15 mmol, 59%).

[0414] LCMS: 2.01 min, 327.1 [M+H]+, Method G

[0415] To a stirred solution of 4,5-dichloro-2-(6-morpholinopyridin-2-yl)pyridazin-3(2H)-one (0.700 g, 2.14 mmol) in MeOH (10 mL) was added methylhydrazine (0.7 mL) at 0 °C and the mixture stirred at rt for 4 h. The reaction mixture was concentrated under reduced pressure. The crude material was purified by flash chromatography (0-70% EtOAc in n-hexane) to afford 4-chloro- 5-(1-methylhydrazinyl)-2-(6-morpholinopyridin-2-yl)pyridazin-3(2 / 7)-one. (0.560 g, 1.66 mmol, 78%).

[0416] LCMS: 1.62 min, 337.2 [M+H]+, Method G

[0417] To a stirred solution of 4-chloro-5-(1-methylhydrazinyl)-2-(6-morpholinopyridin-2-yl)pyridazin- 3(2 / 7)-one (0.200 g, 0.5952 mmol) in DMF (2.0 mL) and water (0.4 mL), NaOH (0.060 g, 1.48 mmol) was added at 0 °C and the mixture was stirred for 20 min. Carbon disulfide (0.4 mL) was added and the mixture was stirred at rt for 2 h. 2-(bromomethyl)-5- (trifluoromethyl)benzonitrile (0.155 g, 0.589 mmol) was added at 0 °C and the mixture was stirred at rt 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 (68-70% EtOAc in n-hexane) to afford 2-(((1-methyl-6-(6-morpholinopyridin- 2-yl)-5-oxo-5,6-dihydro-1 / - / -pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5- (trifluoromethyl)benzonitrile (0.062 g, 0.110 mmol, 19%) (Example 78).

[0418] Analytical data for Example 78 can be found in Table 21 .

[0419] Route U

[0420] Typical procedure for the preparation of 7-(6-methoxypyridin-2-yl)-4-methyl-4H- pyridazino[4,5-e][1,3]thiazin-8(7H)-ones as exemplified by 2-(((7-(6-methoxypyridin-2- yl)-4-methyl-8-oxo-7,8-dihydro-4H-pyridazino[4,5-e][1,3]thiazin-2-yl)thio)methyl)-5-

[0421] (trifluoromethyl)benzonitrile (Example 88)

[0422] A solution of 2-chloro-6-methoxypyridine (5.0 g, 34.82 mmol) in hydrazine hydrate (15 mL) was stirred at 100 °C for 16 h. The reaction mixture was cooled to rt and diluted with ethyl acetate (100 mL) and washed with sat. aq. NaHCOs (2 x 50 mL). The organic layer was dried over Na2SC>4, filtered, and concentrated under reduced pressure to afford 2-hydrazinyl-6- methoxypyridine (4.6 g, 33.07 mmol, 94%).

[0423] LCMS: 0.44 min, 140.1 [M+H]+, Method F

[0424] To a stirred solution of 2-hydrazinyl-6-methoxypyridine (2.0 g, 14.38 mmol) and (E)-2,3- dichloro-4-oxobut-2-enoic acid (2.42 g, 14.38 mmol) in EtOH (20 mL) and water (20 ml), cone. HCI (4 mL) was added at rt. The mixture was stirred at 80 °C for 1 h. The reaction mixture was diluted with sat. aq. NaHCOs (100 mL) and extracted with ethyl acetate (2 x 100 mL). The combined organic layers were dried over Na2SO4 and concentrated under reduced pressure. The crude material was purified by trituration with diethyl ether to afford 4,5-dichloro-2-(6- methoxypyridin-2-yl)pyridazin-3(2 / 7)-one (2.2 g, 8.11 mmol, 56%).

[0425] LCMS: 1.94 min, 272.1 [M+H]+, Method F

[0426] To a stirred solution of 4,5-dichloro-2-(6-methoxypyridin-2-yl)pyridazin-3(2H)-one (150.0 g, 551.3 mmol) in DMF (1.5 mL) was added Nal (161.7 g, 1102 mmol) at rt and the mixture was at 140 °C for 4 h. Nal (161.7 g, 1102 mmol) and the mixture was stirred at 140 °C for a further 16 h. The reaction mixture was cooled to rt, diluted with cold water (2 L) and ethyl acetate (1 L), passed through Celite bed and washed with ethyl acetate (2 x 100 mL). The organic phase was collected and the aqueous phase was extracted with ethyl acetate (2 x 500 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 (0-15 % EtOAc in n-hexane) to afford 4-chloro-5-iodo-2-(6-methoxypyridin-2-yl)pyridazin-3(2H)-one (85 g, 233.8 mmol, 42%).

[0427] LCMS: 2.06 min, 264.1 [M+H]+, Method G

[0428] A stirred solution 4-chloro-5-iodo-2-(6-methoxypyridin-2-yl)pyridazin-3(2H)-one (21 g, 79.86 mmol) and tributyl(1-ethoxyvinyl)stannane (43.37 g, 119.80 mmol) in DMF (150 mL) was purged with nitrogen gas for 15 min. PdChdppf (5.843 g, 7.986 mmol) was added and the mixture was stirred at 100 °C for 8 h. The reaction mixture was mixed and cooled to rt, diluted with cold water (1 L) and extracted with EtOAc (2 x 500 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 (15-17 % EtOAc in n-hexane) to afford 4-chloro-5-(1-ethoxyvinyl)-2-(6-methoxypyridin-2-yl)pyridazin-3(2 / 7)-one (42.5 g, 138.1 mmol, 59%).

[0429] LCMS: 2.21 min, 308.16 [M+H]+, Method G

[0430] To a stirred solution of 4-chloro-5-(1-ethoxyvinyl)-2-(6-methoxypyridin-2-yl)pyridazin-3(2 / 7)- one (42.5 g, 138.1 mmol) in THE (425 mL) was added 1 N HCI (2.125 L) and the mixture was stirred at rt for 2 h. The reaction mixture was diluted with water (500 mL) and extracted with EtOAc (2 x 500 mL). The combined organic layers were dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure to afford 5-acetyl-4-chloro-2-(6-methoxypyridin-2- yl)pyridazin-3(2H)-one (38.5 g, 137.6 mmol, 99%).

[0431] LCMS: 1.85 min, 280.1 [M+H]+, Method G

[0432] To a stirred solution of 5-acetyl-4-chloro-2-(6-methoxypyridin-2-yl)pyridazin-3(2H)-one (38.5 g, 137.6 mmol) in MeOH (385 mL) was added NaBH4(7.829 g, 206.9 mmol) at rt and the mixture was stirred for 30 min. The reaction mixture was concentrated under reduced pressure, diluted with water (400 mL) and extracted with EtOAc (2 x 300 mL). The combined organic layers were dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure to afford 4-chloro-5-(1-hydroxyethyl)-2-methylpyridazin-3(2H)-one (35.0 g, 124.2 mmol, 90%).

[0433] LCMS: 1.69 min, 282.1 [M+H]+, Method G

[0434] To a stirred solution of 4-chloro-5-(1-hydroxyethyl)-2-methylpyridazin-3(2H)-one (35.0 g, 124.2 mmol) in DCM (350 mL) were added TEA (33.57 mL, 248.4 mmol) and MsCI (19.27 mL, 248.4 mmol) at 0 °C and the mixture was stirred at rt for 1 h. The reaction mixture was poured into water (500 mL) and extracted with DCM (3 x 500 ml_). The combined organic layers were dried over anhydrous Na2SC>4, filtered and concentrated under reduced pressure to afford 1-(5- chloro-1-(6-methoxypyridin-2-yl)-6-oxo-1,6-dihydropyridazin-4-yl)ethyl methanesulfonate (50 g, 138.9 mmol, quantitative yield).

[0435] LCMS: 1.89 min, 360.2 [M+H]+, Method G

[0436] To a stirred solution of 1-(5-chloro-1-(6-methoxypyridin-2-yl)-6-oxo-1,6-dihydropyridazin-4- yl)ethyl methanesulfonate (50.0 g, 138.9 mmol) in DMSO (500 mL) was added NaN3(18.1 g, 278.5 mmol) at rt and the mixture was stirred for 2 h. The reaction mixture was poured into water (500 mL) and extracted with diethyl ether (2 x 300 mL). The combined organic layers were dried over anhydrous NazSCU, filtered and concentrated under reduced pressure to afford 5-(1-azidoethyl)-4-chloro-2-(6-methoxypyridin-2-yl)pyridazin-3(2 / )-one (25.0 g, 81.51 mmol, 58%).

[0437] LCMS: 2.09 min, 279.0 [M+H]+, Method G

[0438] To a stirred solution of 5-(1-azidoethyl)-4-chloro-2-(6-methoxypyridin-2-yl)pyridazin-3(2 / 7)-one (25.0 g, 81.51 mmol) in THF (250 mL) was added PPh3(32.2 g, 122.5 mmol) at rt and the mixture was stirred at rt for 30 min. 1 M NaOH solution (775 mL) was added and the mixture was stirred at rt for 48 h. The reaction mixture was concentrated under reduced pressure. The reaction mixture was diluted with water (200 mL) and extracted with DCM (2 x 400 mL). The combined organic layers were dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by reverse-phase flash column chromatography (10% MeCN in 0.1% formic acid) to afford 5-(1-aminoethyl)-4-chloro-2-(6- methoxypyridin-2-yl)pyridazin-3(2 / - / )-one (20 g, 71.25 mmol, 87%).

[0439] LCMS: 1.38 min, 281.1 [M+H]+, Method G

[0440] To a stirred solution of 5-(1-aminoethyl)-4-chloro-2-(6-methoxypyridin-2-yl)pyridazin-3(2H)- one (0.50 g, 1.78 mmol) in DMF (5 mL) was added 10% aq. KOH solution (0.5 mL) at rt and the mixture was stirred for 10 min. Carbon disulfide (0.5 mL) was added at rt and the mixture was stirred for 2 h. 2-(bromomethyl)-5-(trifluoromethyl)benzonitrile (0.563 g, 2.142 mmol) was added and the mixture was stirred at rt for 24 h. The reaction mixture was poured into water (80 mL) and extracted with EtOAc (3 x 50 mL). The crude material was purified by flash column chromatography (32-35 % EtOAc in n-hexane) to afford 2-(((7-(6-methoxypyridin-2-yl)-4- methyl-8-oxo-7,8-dihydro-4H-pyridazino[4,5-e][1 ,3]thiazin-2-yl)thio)methyl)-5- (trifluoromethyl)benzonitrile (Example 88).

[0441] Analytical data for Example 88 can be found in Table 22. Route V

[0442] Typical procedure for the preparation of 6-(6-(2-aminoethoxy)pyridin-2-yl)-1-methyl-1 H- pyridazino[4,5-e][1,3,4]thiadiazin-5(6H)-ones as exemplified by 2-(((6-(6-(2- aminoethoxy)pyridin-2-yl)-1-methyl-5-oxo-5,6-dihydro-1H-pyridazino[4,5- e][1,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (Example 92)

[0443] To a stirred solution of tert-butyl (2-hydroxyethyl)carbamate (42.48 g, 263.5 mmol) in DMF (300 mL) was added NaH (12.24 g, 306.20 mmol, 60%) at 0 °C and the mixture was stirred at rt for 1 h. 2,6-dichloropyridine (30.0 g, 202.7 mmol) was added at 0 °C and the mixture was stirred at rt for 16 h. The reaction mixture was diluted with cold water (1 L) and extracted with ethyl acetate (2 x 500 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 (5-7% EtOAc in n-hexane) to afford tert-butyl (2-((6-chloropyridin-2- yl)oxy)ethyl)carbamate (30 g, 110.0 mmol, 54%).

[0444] LCMS: 2.49 min, 217.2 [M+H]+, Method G

[0445] To a stirred solution tert-butyl (2-((6-chloropyridin-2-yl)oxy)ethyl)carbamate (20 g, 73.33 mmol) in diethylene glycol (200 mL) was added hydrazine hydrate (100 mL, 366.7 mmol) at rt and the mixture was stirred at 150 °C for 16 h. The reaction mixture was cooled to rt, diluted with cold water (500 L) and extracted with EtOAc (2 x 500 mL). The combined organic layers were filtered through a Celite bed, dried over anhydrous Na2SC>4, filtered and concentrated under reduced pressure to afford tert-butyl (2-((6-hydrazinylpyridin-2-yl)oxy)ethyl)carbamate (11.50 g, 42.86 mmol, 58%).

[0446] LCMS: 1.58 min, 269.2 [M+H]+, Method G

[0447] To a stirred solution of tert-butyl (2-((6-hydrazinylpyridin-2-yl)oxy)ethyl)carbamate (11.5 g, 42.86 mmol) in EtOH (230 mL) and water (230 mL) were added cone. HCI (23 mL) and (E)- 2,3-dichloro-4-oxobut-2-enoic acid (7.24 g, 42.86 mmol) and mixture was stirred at 80 °C for 2 h. The reaction mixture was diluted with water (200 mL) and extracted with EtOAc (2 x 200 ml_). The combined organic layers were dried over anhydrous Na2SC>4, filtered and concentrated under reduced pressure to afford 2-(6-(2-aminoethoxy)pyridin-2-yl)-4,5- dichloropyridazin-3(2H)-one (5.0 g, 16.60 mmol, 38%).

[0448] LCMS: 1.51 min, 301.0 [M+H]+, Method G

[0449] To a stirred solution of 2-(6-(2-aminoethoxy)pyridin-2-yl)-4,5-dichloropyridazin-3(2H)-one (5.0 g, 16.60 mmol) in DMF (50 mL) were added TEA (6.73 mL, 49.98 mmol) and DMAP (0.203 g, 1.666 mmol) at rt and mixture was stirred for 10 min. Boc anhydride (7.20 g, 33.32 mmol) was added and mixture was stirred at rt for 3 h. The reaction mixture was diluted with cold water (300 mL) and extracted with EtOAc (2 x 300 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 (10-12% EtOAc in n-hexane) to afford terf-butyl (2-((6-(4,5-dichloro-6-oxopyridazin-1 (6 / - / )-yl)pyridin-2-yl)oxy)ethyl)carbamate (1.1 g, 2.74 mmol, 16%.

[0450] LCMS: 2.17 min, 301.1 [M+H]+, Method G

[0451] To a stirred solution of tert-butyl (2-((6-(4,5-dichloro-6-oxopyridazin-1(6 / 7)-yl)pyridin-2- yl)oxy)ethyl)carbamate (1.1 g, 2.74 mmol) in MeOH (11 mL) was added methyl hydrazine (0.21 g, 8.24 mmol) at 0 °C and the mixture was stirred at rt for 2 h. The reaction mixture was concentrated under reduced pressure to afford tert-butyl (2-((6-(5-chloro-4-(1- methylhydrazinyl)-6-oxopyridazin-1(6H)-yl)pyridin-2-yl)oxy)ethyl)carbamate (1.1 g, 2.68 mmol, 97%).

[0452] LCMS: 1.85 min, 311.2 [M+H]+, Method G

[0453] To a stirred solution of tert-butyl (2-((6-(5-chloro-4-(1-methylhydrazinyl)-6-oxopyridazin-1(6H)- yl)pyridin-2-yl)oxy)ethyl)carbamate (1.0 g, 2.438 mmol) in DMF (10 mL) was added 10% aq. KOH solution (1.0 mL) at rt and the mixture was stirred for 10 min. Carbon disulfide (1.0 mL) was added and the mixture was stirred at rt for 2 h. 2-(bromomethyl)-5- (trifluoromethyl)benzonitrile (0.770 g, 2.925 mmol) was added and the mixture was stirred at rt for 16 h. The reaction mixture was poured into cold water (80 mL) and extracted with EtOAc (2 x 100 mL). The crude material was purified by flash column chromatography (28-30% EtOAc in n-hexane) to afford terf-butyl (2-((6-(3-((2-cyano-4-(trifluoromethyl)benzyl)thio)-1- methyl-5-oxo-1,5-dihydro-6H-pyridazino[4,5-e][1,3,4]thiadiazin-6-yl)pyridin-2- yl)oxy)ethyl)carbamate (0.33 g, 0.520 mmol, 21%). LCMS: 2.54 min, 534.2 [M+H-100]+, Method G To a stirred solution of tert-butyl (2-((6-(3-((2-cyano-4-(trifluoromethyl)benzyl)thio)-1-methyl-5- oxo-1 ,5-dihydro-6 / - / -pyridazino[4,5-e][1 ,3,4]thiadiazin-6-yl)pyridin-2-yl)oxy)ethyl)carbamate (0.3 g, 0.473 mmol) in dioxane (3 mL) was added 4 M HCI in dioxane (0.6 mL) at rt and the mixture was stirred for 3 h. The reaction mixture was concentrated under reduced pressure. The crude material was purified by prep HPLC (Method E). Product-containing factions were combind, basified with sat. aq. NaHCO3(50 mL) and extracted with ethyl acetate (3 x 100 mL). The combined organic layers were dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure to afford 2-(((6-(6-(2-aminoethoxy)pyridin-2-yl)-1-methyl-5-oxo-5,6- dihydro-1H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.05 g, 0.093 mmol, 19%) (Example 92).

[0454] Analytical data for Example 92 can be found in Table 23.

[0455] Route W

[0456] Procedure for the preparation of 2-[[6-[1-(dimethylamino)-3-hydroxypropan-2-yl]-1- methyl-5-oxopyridazino[4,5-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (Example 81) and 2-[[1-methyl-6-(1-methylazetidin-3-yl)-5- oxopyridazino[4,5-e][1,3,4]thiadiazin-3-yl]sulfanylmethyl]-5-

[0457] To a solution of benzyl 3-oxoazetidine-1 -carboxylate (2 g, 9.75 mmol) in MeOH (20 mL) was added tert-butyl hydrazinecarboxylate (1.29 g, 9.75 mmol) and AcOH (1.17 g, 19.49 mmol, 1.12 mL). The mixture was stirred at rt for 12 h. NaBH3CN (612.45 mg, 9.75 mmol) was added. The mixture was stirred at rt for 8 h. The reaction mixture was diluted with water (60 mL) and extracted with EtOAc (3 x 30 mL). The combined organic layers were washed with brine (50 mL), dried with anhydrous Na2SC>4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (50-80% EtOAc in petroleum ether) to afford compound benzyl 3-(2-(tert- butoxycarbonyl)hydrazineyl)azetidine-1 -carboxylate (2 g, 6.22 mmol, 64% yield) as white solid.

[0458] 1H NMR (400 MHz, CDCh): 6 7.38 - 7.31 (m, 5H), 6.11 (br s, 1 H), 5.10 (s, 2H), 4.13 - 4.03 (m, 2H), 3.97 - 3.88 (m, 1H), 3.83 (dd, J = 4.6, 9.2 Hz, 2H), 1.46 (s, 9H).

[0459] A solution of benzyl 3-(2-(tert-butoxycarbonyl)hydrazineyl)azetidine-1-carboxylate (1.4 g, 4.36 mmol) in 4 M HCI 14 mL) was stirred at rt for 1 h. A solution of benzyl 3-hydrazineylazetidine- 1-carboxylate (1.12 g, 4.35 mmol, quantitative) in 4 M HCI (14 mL) was used directly in the next step.

[0460] To a solution of benzyl 3-hydrazineylazetidine-1 -carboxylate (1.12 g, 4.35 mmol) in 4 M HCI (14 mL) was added mucochloric acid (807.72 mg, 4.78 mmol) and the mixture was stirred at rt for 40 h. The reaction mixture was extracted with EtOAc (4 x 20 mL). The combined organic layers were washed with brine (30 mL), dried with anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-75% EtOAc in petroleum ether) to afford benzyl 3-(4,5-dichloro-6- oxopyridazin-1(6H)-yl)azetidine-1 -carboxylate (1.2 g, 3.00 mmol, 69%) as pale yellow solid.1H NMR (400 MHz, CDCh): 5 7.91 (s, 1 H), 7.40 - 7.30 (m, 5H), 5.70 (tt, J = 5.5, 7.9 Hz, 1 H), 5.14 (s, 2H), 4.46 - 4.38 (m, 2H), 4.37 - 4.28 (m, 2H).

[0461] To a solution of benzyl 3-(4,5-dichloro-6-oxopyridazin-1(6H)-yl)azetidine-1 -carboxylate (1 g, 2.82 mmol) in MeOH (10 mL) was added methylhydrazine (1.31 g, 11.37 mmol, 1.50 mL) dropwise. The reaction mixture was stirred at rt for 4 h. The mixture was poured into water (80 mL) and extracted with EtOAc (3 x 30 mL). The combined organic layers were washed with brine (50 mL), dried with anhydrous Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-75% EtOAc in petroleum ether) to afford benzyl 3-(5-chloro-4-(1-methylhydrazineyl)-6-oxopyridazin-1(6H)- yl)azetidine-1 -carboxylate (0.8 g, 2.17 mmol, 77%) as viscous yellow oil.

[0462] 1H NMR (400 MHz, DMSO-d6): 5 8.41 (s, 1 H), 7.44 - 7.28 (m, 5H), 5.56 (tt, J = 5.3, 8.0 Hz, 1 H), 5.06 (s, 2H), 5.02 (s, 2H), 4.27 (br s, 2H), 4.11 (br s, 2H), 3.39 (s, 3H).

[0463] To a stirred solution of benzyl 3-(5-chloro-4-(1-methylhydrazineyl)-6-oxopyridazin-1(6H)- yl)azetidine-1 -carboxylate (0.85 g, 2.34 mmol) in NMP (8.5 mL) was added KOH (5 M, 1.40 mL) at rt and the mixture was stirred for 10 min. Carbon disulfide (1 .78 g, 23.36 mmol, 1.41 mL) and 18-crown-6 (617.57 mg, 2.34 mmol) was added at rt and the mixture was stirred for 2 h. 2-(bromomethyl)-5-(trifluoromethyl)benzonitrile (798.37 mg, 2.57 mmol) was added at rt and the mixture was stirred at rt for 24 h. The reaction was quenched with water (30 mL) and extracted with ethyl acetate (3 x 30 mL). The combined organic layers were combined, washed with water (30 mL), dried over anhydrous Na2SC>4, filtered and concentrated under reduced pressure. The crude material was purified by flash column chromatography (0-50% EtOAc in petroleum ether) to afford benzyl 3-(3-((2-cyano-4-(trifluoromethyl)benzyl)thio)-1-methyl-5- oxo-1 , 5-dihydro-6H-pyridazino[4,5-e][1, 3, 4]thiadiazin-6-yl)azetidine-1 -carboxylate (1 g, 1.70 mmol, 73% yield) as a red solid.

[0464] 1H NMR (400 MHz, CDCI3): 6 7.91 (s, 1 H), 7.85 - 7.80 (m, 1 H), 7.78 - 7.71 (m, 1 H), 7.62 (s, 1H), 7.40 - 7.31 (m, 5H), 5.75 - 5.64 (m, 1 H), 5.15 - 5.11 (m, 2H), 4.45 (s, 2H), 4.39 - 4.31 (m, 2H), 4.31 - 4.23 (m, 2H), 3.39 (s, 3H).

[0465] A solution of benzyl 3-(3-((2-cyano-4-(trifluoromethyl)benzyl)thio)-1-methyl-5-oxo-1,5-dihydro- 6H-pyridazino[4,5-e][1 ,3,4]thiadiazin-6-yl)azetidine-1-carboxylate (0.19 g, 0.323 mmol) in TFA (10 mL) was stirred at 70 °C for 2 h. The reaction mixture was concentrated under reduced pressure and dried under vacuum to afford 2-(((6-(azetidin-3-yl)-1-methyl-5-oxo-5,6-dihydro- 1 H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.185 g, quantitative) was obtained as a brown oil. The crude material was used directly in the next step.

[0466] To a solution of 2-(((6-(azetidin-3-yl)-1-methyl-5-oxo-5,6-dihydro-1 H-pyridazino[4,5- e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (0.185 g, 0.409 mmol) in MeOH (3 mL) was added formaldehyde (165.90 mg, 2.04 mmol, 152.20 pL) and NaBH(OAc)3(433.27 mg, 2.04 mmol) at 0 °C, then the mixture was stirred at rt for 1 h. The mixture was concentrated under reduced pressure at 30 °C. The crude product was purified by prep HPLC (Method B) to afford 2-(((1-methyl-6-(1-methylazetidin-3-yl)-5-oxo-5,6-dihydro-1 H- pyridazino[4,5-e][1 ,3,4]thiadiazin-3-yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (1.4 mg, 0.003 mmol, 0.7%) (Example 81) as a red solid and 2-(((6-(1-(dimethylamino)-3- hydroxypropan-2-yl)-1-methyl-5-oxo-5,6-dihydro-1 H-pyridazino[4,5-e][1 ,3,4]thiadiazin-3- yl)thio)methyl)-5-(trifluoromethyl)benzonitrile (10.21 mg, 0.020 mmol, 5%) (Example 91) as an orange solid.

[0467] Analytical data for Examples 81 and 91 can found in Table 24.

[0468] Route X

[0469] Procedure for the preparation of 2-[(7'-methyl-8'-oxospiro[cyclopropane-1,4'- pyridazino[4,5-e][1,3]thiazine]-2'-yl)sulfanylmethyl]-5-(trifluoromethyl)benzonitrile (Example 99)

[0470] Intermediate 4 Example 99

[0471] To a solution of 5-(1-aminocyclopropyl)-4-chloro-2-methylpyridazin-3(2H)-one;trifluoroacetic acid (285 mg, 0.666 mmol) and DIPEA (430.61 mg, 3.33 mmol, 580.34 pL) in DMF (3 ml_) was added CS2 (405.91 mg, 5.33 mmol, 321.38 pL) and the mixture was stirred at rt for 2 h under N2. 2'-mercapto-7'-methylspiro[cyclopropane-1 ,4'-pyridazino[4,5-e][1 ,3]thiazin]-8'(7'H)-one

[0472] (159.48 mg, 0.666 mmol, 100%) was used directly in the next step as a yellow solution in DMF (3 mL).

[0473] LCMS: 0.301 min, 240.0 [M+H]+, Method J. To a solution of 2'-mercapto-7'-methylspiro[cyclopropane-1 ,4'-pyridazino[4,5-e][1 ,3]thiazin]- 8'(7'H)-one (159.48 mg, 0.666 mmol) in DMF (3 mL) was added 2-(bromomethyl)-5- (trifluoromethyl)benzonitrile (175.96 mg, 0.666 mmol) at 0 °C. The mixture was warmed to rt and stirred for 1 h under N2. Water (30 mL) was added to the mixture at 0 °C and the solid formed was collected by vacuum filtration. The crude product was purified by flash column chromatography (0-25% EtOAc in petroleum ether) to afford 2-[(7'-methyl-8'- oxospiro[cyclopropane-1 ,4'-pyridazino[4,5-e][1,3]thiazine]-2'-yl)sulfanylmethyl]-5- (trifluoromethyl)benzonitrile (164.2 mg, 0.388 mmol, 58%) as white solid.

[0474] Analytical data for Example 99 can be found in Table 25.

[0475] Table 2 - Experimental procedures and analytical data for examples synthesised via Route A

[0476]

[0477] Table 3 - Experimental procedures and analytical data for examples synthesised via Route B

[0478]

[0479]

[0480]

[0481] Table 4 - Experimental procedures and analytical data for examples synthesised via Route C

[0482] Table 5 - Experimental procedures and analytical data for examples synthesised via Route D

[0483]

[0484] Table 6 - Experimental procedures and analytical data for examples synthesised via Route E

[0485] Table 7 - Experimental procedures and analytical data for examples synthesised via Route F

[0486]

[0487] Table 8 - Experimental procedures and analytical data for examples synthesised via Route G

[0488] Table 9 - Experimental procedures and analytical data for examples synthesised via Route H

[0489] Table 10 - Experimental procedures and analytical data for examples synthesised via Route I

[0490]

[0491]

[0492] Table 11 - Experimental procedures and analytical data for examples synthesised via Route J

[0493]

[0494] Table 12 - Experimental procedures and analytical data for examples synthesised via Route K

[0495] Table 13 - Experimental procedures and analytical data for examples synthesised via Route L

[0496] Table 14 - Experimental procedures and analytical data for examples synthesised via Route M

[0497] Table 15 - Experimental procedures and analytical data for examples synthesised via Route N

[0498] Table 16 - Experimental procedures and analytical data for examples synthesised via Route 0

[0499] Table 17 - Experimental procedures and analytical data for examples synthesised via Route P

[0500] Table 18 - Experimental procedures and analytical data for examples synthesised via Route Q

[0501] Table 19 - Experimental procedures and analytical data for examples synthesised via Route R

[0502] Table 20 - Experimental procedures and analytical data for examples synthesised via Route S

[0503] Table 21 - Experimental procedures and analytical data for examples synthesised via Route T

[0504] Table 22 - Experimental procedures and analytical data for examples synthesised via Route U

[0505] Table 23 - Experimental procedures and analytical data for examples synthesised via Route V

[0506] Table 24 - Experimental procedures and analytical data for examples synthesised via Route W

[0507] Table 25 - Experimental procedures and analytical data for examples synthesised via Route X

[0508] BIOLOGICAL ACTIVITY EXAMPLE A

[0509] Abbreviations and Acronyms

[0510] Serum Response Factor Response Element (SRF-RE) reporter gene assay method

[0511] For assessing GPR65 activity through G12 / 13 coupling, 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 / 13 coupling activates the Serum Response Factor inducing luciferase expression. Therefore, luciferase activity is directly proportional to Gi2 / RhoA activation.

[0512] 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 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 for 6 hours and luciferase activity was measured using One-Gio™ reagent (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 EC50 values were calculated (Table 26).

[0513] Human GPR65 cyclic adenosine monophosphate (cAMP) Homogeneous Time- Resolved Fluorescence (HTRF) assay method

[0514] 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 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.

[0515] The method is as follows: 16 hours before the assay, cells were placed in low-serum conditions (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 pl 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 concentration], 5 pl of compound solution was then added to each well of the cell plate, thereby reaching the desired final concentration (30 pM 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 RPM. Fluorescent measurements at 665 nm and 620 nm were taken using Pherastar plate reader and the HTRF ratio (signal665nm / signal62onm x 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 ECso values (Table 26).

[0516] Table 26 - SRF-RE and HTRF Data of Example A

[0517] SRF-RE pECso: Group A >8.0, Group B 7.5 to 8.0, Group C 7.0 to 7.5, Group D <7.0 HTRF cAMP pECSo: Group A >6.5, Group B 5.5 to 6.5, Group C <5.5

Claims

CLAIMS1. A compound of Formula (1):or a salt thereof, wherein:X is NR3or CR3R3a;R1is H or a Ci-e alkyl group which is optionally substituted with 1 to 3 fluorine atoms, NR1aR1band / or OR1a; or R1is a group -(CR1aR1 b)mQ, where m is 0-3 and Q is 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;R3and R3aare independently H, a C1.3 alkyl 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 which is optionally substituted with 1 to 3 fluorine atoms; each R4is independently H, halo, CN, OR4a, a C1.3 alkyl 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 C1.3 alkyl group which is optionally substituted with 1 to 3 fluorine atoms;R1a, R1b, R4aand R5aare independently H or a C1.3 alkyl group which is optionally substituted with 1 to 3 fluorine atoms, NH2and / or OH; andR10is H or a C1.3 alkyl group which is optionally substituted with 1 to 3 fluorine atoms; provided that when is H, R2is not:

2. The compound according to claim 1 , wherein X is NR3.

3. The compound according to claim 1 or claim 2, wherein R3is selected from: CH3,CH2CH3, CD3, cyclopropyl and CH2CFH2.

4. The compound according to claim 1 , wherein X is CR3R3aand R3is joined with R3ato form a cyclopropyl ring.

5. The compound according to any one of claims 1 to 4, wherein R2is selected from:

6. The compound according to claim 1 , which is a compound of Formula (2a):or a salt thereof.

7. The compound according to claim 5 or claim 6, wherein each R5is independently selected from: H, Cl, Br, F, I, CN, NO2, CH3, CF3, OCF3, CF2H and CFH2.

8. The compound according to any one of claims 1 to 4, wherein R2is selected from the group consisting of:

9. The compound according to claim 8, wherein R2is:

10. The compound according to any one of claims 1 to 9, wherein R10is H.11 . The compound according to claim 1 , which is a compound of Formula (9a):or a salt thereof.

12. The compound according to any one of claims 1 to 11 , wherein R1is selected from the group consisting of:

13. The compound according to claim 1, which is a compound selected from the group consisting of:and salts thereof.

14. A pharmaceutical composition comprising a compound according to any one of claims 1 to 13 or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable excipient.

15. A combination comprising a compound according to any one of claims 1 to 13 or a pharmaceutically acceptable salt thereof and a PDE inhibitor.

16. The compound or pharmaceutically acceptable salt thereof, composition or combination according to any one of claims 1 to 15 for use in medicine.

17. The compound or pharmaceutically acceptable salt thereof, composition or combination according to any one of claims 1 to 15 for use in the treatment of a disorder associated with GPR65 or that would benefit from the modulation of GPR65 activity.

18. The compound or pharmaceutically acceptable salt thereof, composition or combination according to any one of claims 1 to 15 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.

19. 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 15.

20. 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 15.

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