Pyridazine alkynes and their uses

Abstract

The present invention provides a novel compound that effectively inhibits the activity of CD73, which is a compound represented by Formula I, its tautomer, stereoisomer, hydrate, solvate, pharmaceutically acceptable salt or prodrug, its preparation method, and its use in the preparation of drugs.

Description

[0001] Priority Information

[0002] This application claims the priority and benefits of the patent application with the patent application number 202011224592.7, which was filed with the China National Intellectual Property Administration on November 5, 2020, and the entire text thereof is incorporated herein by reference. Technical Field

[0003] The present invention belongs to the field of medicinal chemistry. Specifically, the present invention relates to pyridazine alkynes compounds. More specifically, the present invention relates to a pyridazine alkyne compound and its preparation method, as well as its use in the preparation of drugs. Background Art

[0004] CD73, also known as extracellular 5'-nucleotidase, belongs to the exonuclease of the metallophosphatase superfamily and is a peripheral glycoprotein. Its main form is anchored to the plasma membrane through glycosylphosphatidylinositol (GPI), with a molecular weight of 70 KD and encoded by the NT5E gene. CD73 is widely expressed on the cell surface of different tissues, including the brain, lung, heart, spleen, lymph nodes, kidney, colon, vascular endothelium, and bone marrow; various immune cells also express it, including macrophages, neutrophils, myeloid-derived suppressor cells (MDSCs), dendritic cells (DC), natural killer cells (NK), and regulatory T cells (Treg) (Soleimani A et al., Biochimie, 2020, 176: 21-30.); CD73 is also highly expressed in a variety of tumor cells, such as melanoma, breast cancer, pancreatic cancer, ovarian cancer, colon cancer, and prostate cancer, etc. (Gao Z et al., Biomed Res Int, 2014, 2014: 460654.). CD73 also exists in biological fluids including serum in a soluble form (sCD73) and retains the full enzyme activity.

[0005] CD73 mainly exerts physiological and pathological effects by hydrolyzing AMP (adenosine monophosphate) to produce extracellular adenosine (ADO). ADO exerts its effects through four G protein-coupled receptors (GPCRs): A1 adenosine receptor (A1AR), A2A adenosine receptor (A2AR), A2B adenosine receptor (A2BR), and A3 adenosine receptor (A3AR), among which A2AR plays a major role (Linden J et al., Annu. Rev. Immunol., 2019, 37: 325-347.). Adenosine receptors (ARs) are not only expressed in tumor cells but also on the cell surface of immune cells and vascular endothelial cells infiltrating the tumor microenvironment. After ADO binds to the receptor, it produces a variety of immunosuppressive and pro-tumor effects.

[0006] CD73 is closely related to tumor growth, angiogenesis and metastasis. Under normal physiological conditions, the extracellular ADO level is between 20 and 300 nM, but in the tumor microenvironment, it increases and maintains at the micromolar level (30 - 100 μM), and the high extracellular ADO concentration is mainly affected by the hydrolysis of AMP by CD73. Studies have shown that the level of soluble CD73 (sCD73) in the plasma of cancer patients is increased compared with that of healthy people (Klemens M R et al., Biochem. Biophys. Res. Commun., 1990, 172: 1371 - 7..). In gastrointestinal stromal tumors, tumor-infiltrating NK cells express higher levels of CD73, and the absence of A2AR signaling in NK cells can improve CD73 + tumor metastasis and enhance the anti-tumor immune response (Young A et al., Cancer Cell. 2016; 30(3): 391 - 403.). Compared with normal pancreatic tissue, CD73 is up-regulated in pancreatic ductal carcinoma (PDAC) and is associated with tumor size, metastasis and poor prognosis (Harvey Jerry B et al., Front Immunol, 2020, 11: 508.). In the preclinical study of ORIC company, the CD73 selective inhibitor ORIC-533 significantly reduced the ADO concentration in the tumor microenvironment and at the same time reduced the tumor volume. These research results all indicate that CD73 is up-regulated in a variety of tumors, and inhibiting CD73 may reduce the ADO concentration, thereby inhibiting tumor growth and metastasis.

[0007] In addition to being used alone, CD73 inhibitors can block tumor growth by relieving immunosuppression and can also be combined with other targeted therapies and / or immunotherapies and radiotherapy to enhance the anti-tumor effect. In several mouse tumor models, combination therapy with anti-CD73 and anti-PD-1 / L1 (programmed death receptor 1 / ligand 1) and / or anti-CTLA-4 (cytotoxic T lymphocyte-associated protein 4) antibodies is more effective than treatment with anti-PD-L1 and / or anti-CTLA-4 antibodies alone (Allard B et al., Clin. Cancer Res., 2013, 19:5626 - 35.); the CD73 level was found to be upregulated in melanoma patients receiving anti-PD-1 antibody immunotherapy, and a unique population of CD73-highly expressing macrophages persisted in glioblastoma patients after anti-PD-1 treatment. CD73 deficiency enhanced the efficacy of anti-PD-1 and anti-CTLA-4 in a mouse glioblastoma model (Goswami S et al., Nat. Med., 2020, 26:39 - 46.); radiotherapy causes partial destruction of tumor cells, releasing a large amount of intracellular ATP into the extracellular space, which is converted into adenosine under the action of CD73 on the tumor cell surface or in the free state, producing an immunosuppressive effect, which is considered to be one of the reasons for the poor prognosis of some patients after radiotherapy. Therefore, the combination of CD73 inhibitors and radiotherapy may produce a synergistic effect (Wennerberg E et al., Cancer Immunol Res, 2020, 8:465 - 478.).

[0008] Currently, some anti-CD73 monoclonal antibodies (MEDI9447, BMS986179, SRF373 / NZV930, CPI-006 / CPX-006, TJ004309) and selective small molecule inhibitors (LY3475070, AB680) have entered the clinical stage, and some clinical trials have achieved encouraging early results (NCT02754141). CD73 inhibition may be a promising approach for treating tumors. Summary of the Invention

[0009] The present invention aims to provide a new CD73 inhibitor that can be used to prepare drugs for treating tumor-related diseases.

[0010] In a first aspect of the present invention, a compound is provided, which is a compound represented by formula I, its tautomer, stereoisomer, hydrate, solvate, pharmaceutically acceptable salt or prodrug:

[0011]

[0012] Wherein,

[0013] m is 0, 1, 2, 3 or 4;

[0014] R in 1 is independently selected from hydrogen, halogen, hydroxyl, cyano, amino, unsubstituted or R a -substituted C1-C6 alkyl, or, unsubstituted or R a -substituted C1-C6 alkoxy; in the R a -substituted C1-C6 alkyl, or, in the R a -substituted C1-C6 alkoxy, the R a -substitution may be one or more substitutions, and each of the R a is independently one of the following substituents: halogen, hydroxyl, cyano, amino, C1-C6 alkyl, C1-C6 alkoxy, -COOH, -C(=O)NH2; when there are multiple substituents, the substituents are the same or different; when m is not 0 or 1, the R 1 are independently the same or different; n is 0, 1, 2 or 3;

[0015] R 2 is selected from hydrogen, unsubstituted or R b -substituted C1-C6 alkyl, unsubstituted or R b -substituted C3-C6 cycloalkyl, unsubstituted or R b -substituted 5- to 8-membered aryl, unsubstituted or R b -substituted 5- to 8-membered heteroaryl, unsubstituted or R b -substituted 4- to 8-membered heterocycloalkyl, or, unsubstituted or R b -substituted 4- to 8-membered heterocycloalkenyl; in the R b -substituted C1-C6 alkyl, the R b -substituted C3-C6 cycloalkyl, the R b -substituted 5- to 8-membered aryl, the R b -substituted 5- to 8-membered heteroaryl, the R b -substituted 4- to 8-membered heterocycloalkyl, or, in the R b -substituted 4- to 8-membered heterocycloalkenyl, the R b -substitution may be one or more substitutions, and each of the R b is independently one of the following substituents: halogen, hydroxyl, cyano, amino, carboxyl, C3-C6 cycloalkyl, C1-C6 alkyl, C1-C6 alkyl substituted with 1 to 5 identical or different halogens, or, C1-C6 alkoxy; when there are multiple substituents, the substituents are the same or different;

[0016] In the unsubstituted or R b -substituted 5- to 8-membered heteroaryl, the heteroatoms are selected from one or more of N, S, O and P, and the number of heteroatoms is 1 to 3; in the unsubstituted or Rb In the substituted 4- to 8-membered heterocycloalkyl group, the heteroatoms are selected from one or more of N, S, O, and P, and the number of heteroatoms is 1 to 3; the unsubstituted or R b In the substituted 4- to 8-membered heterocycloalkenyl group, the heteroatoms are selected from one or more of N, S, O, and P, and the number of heteroatoms is 1 to 3.

[0017] In a preferred embodiment of the present invention, the compound represented by formula I, its tautomer, stereoisomer, hydrate, solvate, pharmaceutically acceptable salt or prodrug is:

[0018]

[0019] Wherein,

[0020] m is 0, 1, 2, 3, or 4;

[0021] Among them, R 1 Independently selected from hydrogen, halogen, hydroxyl, cyano, amino, unsubstituted or R a Substituted C1-C6 alkyl, or, unsubstituted or R a Substituted C1-C6 alkyl-O-; the substituted C1-C6 alkyl, or, the substituted C1-C6 alkyl-O- by R a Substituted C1-C6 alkyl, or, the substituted C1-C6 alkyl-O- by R a In the substituted C1-C6 alkyl, or, the substituted C1-C6 alkyl-O-, the substitution each independently refers to substitution by one or more of the following substituents: halogen, hydroxyl, cyano, amino, C1-C6 alkyl, C1-C6 alkyl-O-, -COOH, -C(=O)NH2; when there are multiple substituents, the substituents are the same or different; when m is not 0 or 1, R 1 Independently are the same or different;

[0022] n is 0, 1, 2, or 3;

[0023] R 2 Selected from hydrogen, unsubstituted or R b Substituted C1-C6 alkyl, unsubstituted or R b Substituted C3-C6 cycloalkyl, unsubstituted or R b Substituted 5- to 8-membered aryl, unsubstituted or R b Substituted 5- to 8-membered heteroaryl, unsubstituted or R b Substituted 4- to 8-membered heterocycloalkyl, or, unsubstituted or R b Substituted 4- to 8-membered heterocycloalkenyl; the substituted C1-C6 alkyl, the substituted C3-C6 cycloalkyl, the substituted 5- to 8-membered aryl, the substituted by R b Substituted C1-C6 alkyl, the substituted C3-C6 cycloalkyl by R b Substituted 5- to 8-membered aryl, the substituted by R b Substituted 5- to 8-membered aryl, the substituted by Rb Substituted 5- to 8-membered heteroaryl, said R-substituted b Substituted 4- to 8-membered heterocycloalkyl, or, said R-substituted b In the substituted 4- to 8-membered heterocycloalkenyl, each of the substitutions independently refers to one or more substitutions selected from the following substituents: halogen, hydroxy, cyano, amino, C3-C6 cycloalkyl, C1-C6 alkyl, C1-C6 alkyl substituted with 1 to 5 identical or different halogens, or, C1-C6 alkoxy-; when there are multiple substituents, the substituents are the same or different;

[0024] Said unsubstituted or R-substituted b In the 5- to 8-membered heteroaryl, the heteroatoms are selected from one or more of N, S, O, and P, and the number of heteroatoms is 1 to 3; said unsubstituted or R-substituted b In the 4- to 8-membered heterocycloalkyl, the heteroatoms are selected from one or more of N, S, O, and P, and the number of heteroatoms is 1 to 3; said unsubstituted or R-substituted b In the 4- to 8-membered heterocycloalkenyl, the heteroatoms are selected from one or more of N, S, O, and P, and the number of heteroatoms is 1 to 3.

[0025] In a preferred embodiment of the present invention, when R 2 is unsubstituted or R-substituted b C1-C6 alkyl, said C1-C6 alkyl is C1-C4 alkyl, preferably methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl.

[0026] In a preferred embodiment of the present invention, when R 2 is unsubstituted or R-substituted b C1-C6 alkyl, the number of said substituents R b is 1 to 3, preferably 1.

[0027] In a preferred embodiment of the present invention, when R 2 is unsubstituted or R-substituted b C3-C6 cycloalkyl, said C3-C6 cycloalkyl is cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl, preferably cyclopropyl or cyclobutyl.

[0028] In a preferred embodiment of the present invention, when R 2 is unsubstituted or R-substituted b 5- to 8-membered aryl, said 5- to 8-membered aryl is independently phenyl or naphthyl, preferably phenyl.

[0029] In a preferred embodiment of the present invention, when R 2 is unsubstituted or R-substituted bWhen it is a substituted 5- to 8-membered heteroaryl group, the 5- to 8-membered heteroaryl group is independently pyrrole, pyrazole, triazole, furan, oxazole, thiophene, thiazole, pyridine, pyrazine or pyrimidine, preferably pyrazole, furan, thiophene, pyridine.

[0030] In a preferred embodiment of the present invention, when R 2 is an unsubstituted or R b substituted 4- to 8-membered heterocycloalkyl group, the 4- to 8-membered heterocycloalkyl group is independently azetidine, oxetane, pyrrolidinyl, tetrahydrofuryl, hexahydropyran or tetrahydro-2H-thiopyran 1,1-dioxide, preferably azetidine or oxetane.

[0031] In a preferred embodiment of the present invention, when R 2 is an unsubstituted or R b substituted 4- to 8-membered heterocycloalkenyl group, the 4- to 8-membered heterocycloalkenyl group is independently dihydropyridyl, tetrahydropyridyl, tetrahydropyrimidinyl, pyrrolinyl, imidazolinyl, pyrazolinyl, dihydroimidazolyl, dihydropyrazolyl, dihydrooxazolyl, dihydrooxadiazolyl, dihydrothiazolyl, dihydroisothiazolyl, dihydrothienyl, dihydropyrrolyl, 3,4-dihydro-2H-pyranyl, dihydrofuryl, dihydropyrazinyl, dihydropyrimidinyl or fluorodihydrofuryl, preferably 1,2,3,4-tetrahydropyridyl, 1,2-dihydropyridyl, 1,4-dihydropyridyl, 1,2,3,6-tetrahydropyridyl, 3,4-dihydro-2H-pyranyl or dihydrofuryl.

[0032] In a preferred embodiment of the present invention, R b is hydroxyl.

[0033] In a preferred embodiment of the present invention, when R b is a C1-C6 alkyl group, the C1-C6 alkyl group is a C1-C4 alkyl group, preferably methyl, ethyl, n-propyl or isopropyl.

[0034] In a preferred embodiment of the present invention, when R b is a halogen, the halogen is F, Cl, Br, I, preferably F or Cl.

[0035] In a preferred embodiment of the present invention, is preferably

[0036] In a preferred embodiment of the present invention, when R 1 is a halogen, the halogen is F, Cl, Br or I, preferably F or Cl.

[0037] In a preferred embodiment of the present invention, when R 1When R is a halogen, m is 0, 1 or 2.

[0038] In a preferred embodiment of the present invention, when R 1 is an unsubstituted or R a substituted C1-C6 alkyl group, or, an unsubstituted or R a substituted C1-C6 alkoxy group, the C1-C6 alkyl groups are independently C1-C4 alkyl groups, preferably methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl.

[0039] In a preferred embodiment of the present invention, when R 1 is an unsubstituted or R a substituted C1-C6 alkyl group, or, an unsubstituted or R a substituted C1-C6 alkoxy group, m is 1 or 2, preferably m is 1.

[0040] In a preferred embodiment of the present invention, when R 1 is an R a substituted C1-C6 alkyl group, or, an R a substituted C1-C6 alkoxy group, the number of substitutions is independently 1-3, preferably 2.

[0041] In a preferred embodiment of the present invention, when R 1 is an R a substituted C1-C6 alkyl group, or, an R a substituted C1-C6 alkoxy group, the substitutions are each independently a C1-C6 alkyl group, or a C1-C6 alkoxy group, and the C1-C6 alkyl groups in the substitutions are independently C1-C4 alkyl groups, preferably methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl.

[0042] In a preferred embodiment of the present invention, when R a is a halogen, the halogen is F, Cl, Br or I, preferably F or Cl.

[0043] In a preferred embodiment of the present invention, when is , the is

[0044] In a preferred embodiment of the present invention, when is , the is

[0045] In a preferred embodiment of the present invention, when is When is

[0046] In a preferred embodiment of the present invention, when is When is

[0047] In a preferred embodiment of the present invention, is

[0048] In a preferred embodiment of the present invention, R 2 is

[0049] In a preferred embodiment of the present invention, is

[0050] In a preferred embodiment of the present invention, the compound represented by Formula I, its tautomer, stereoisomer, hydrate, solvate, pharmaceutically acceptable salt or prodrug is:

[0051]

[0052] Wherein,

[0053] R 1 is independently selected from hydrogen, halogen, hydroxyl, cyano, amino, unsubstituted or substituted by R a substituted C1-C6 alkyl, or, unsubstituted or substituted by R a substituted C1-C6 alkyl-O-; the substituted C1-C6 alkyl, or, the substituted C1-C6 alkyl-O- by R a substituted C1-C6 alkyl, or, the substituted C1-C6 alkyl-O- by R a substituted C1-C6 alkyl-O-, the substitution each independently refers to substitution by one or more of the following substituents: halogen, hydroxyl, cyano, amino, C1-C6 alkyl, C1-C6 alkyl-O-, -COOH, -C(=O)NH2; when there are multiple substituents, the substituents are the same or different;

[0054] R 2 is selected from hydrogen, unsubstituted or substituted by R b substituted C1-C6 alkyl, unsubstituted or substituted by R b substituted C3-C6 cycloalkyl, unsubstituted or substituted by R b substituted 5-8 membered aryl, unsubstituted or substituted by R b substituted 5-8 membered heteroaryl, unsubstituted or substituted by R b substituted 4-8 membered heterocycloalkyl, or, unsubstituted or substituted by R bSubstituted 4- to 8-membered heteroalkenyl; the R b substituted C1-C6 alkyl, the R b substituted C3-C6 cycloalkyl, the R b substituted 5- to 8-membered aryl, the R b substituted 5- to 8-membered heteroaryl, the R b substituted 4- to 8-membered heteroalkyl, or, the R b substituted 4- to 8-membered heteroalkenyl, each of the substitutions independently refers to one or more substitutions by the following substituents: halogen, hydroxy, cyano, amino, C3-C6 cycloalkyl, C1-C6 alkyl, C1-C6 alkyl substituted by 1 to 5 identical or different halogens, or, C1-C6 alkyl-O-; when there are multiple substituents, the substituents are the same or different;

[0055] The unsubstituted or R b substituted 5- to 8-membered heteroaryl, the heteroatoms are selected from one or more of N, S, O, and P, and the number of heteroatoms is 1 to 3; the unsubstituted or R b substituted 4- to 8-membered heteroalkyl, the heteroatoms are selected from one or more of N, S, O, and P, and the number of heteroatoms is 1 to 3; the unsubstituted or R b substituted 4- to 8-membered heteroalkenyl, the heteroatoms are selected from one or more of N, S, O, and P, and the number of heteroatoms is 1 to 3.

[0056] In a preferred embodiment of the present invention, the compound of formula I, its hydrate, solvate, pharmaceutically acceptable salt or prodrug is wherein, R 1 and R 2 have the definitions as described above.

[0057] In a preferred embodiment of the present invention, R 1 is selected from difluoromethyl, trifluoromethyl, dichloromethyl, trichloromethyl or isopropyl; R 2 is selected from methyl, ethyl or cyclopropyl.

[0058] In a preferred embodiment of the present invention, the compound of formula I, its tautomer, stereoisomer, hydrate, solvate, pharmaceutically acceptable salt or prodrug is selected from any of the following compounds:

[0059]

[0060] In a second aspect of the present invention, there is provided a pharmaceutical composition comprising a therapeutically effective dose of the above compound, its tautomer, stereoisomer, hydrate, solvate, pharmaceutically acceptable salt or prodrug, and a pharmaceutically acceptable excipient.

[0061] According to specific embodiments of the present invention, the pharmaceutical composition of the present invention may comprise a therapeutically effective dose of the above compound, its tautomer, stereoisomer, hydrate, solvate, pharmaceutically acceptable salt or prodrug, and a pharmaceutically acceptable pharmaceutical carrier, diluent or excipient, and be mixed to prepare a pharmaceutical preparation suitable for oral or parenteral administration. The administration methods include, but are not limited to, intradermal, intramuscular, intraperitoneal, intravenous, subcutaneous, intranasal and oral routes. The preparation can be administered by any route, for example, by infusion or bolus injection, and by routes of absorption through epithelial or skin mucosa (such as oral mucosa or rectum, etc.). The administration can be systemic or local. Examples of orally administered preparations include solid or liquid dosage forms, specifically, tablets, pills, granules, powders, capsules, syrups, emulsions, suspensions, etc. The preparation can be prepared by methods known in the art and contains carriers, diluents or excipients commonly used in the field of pharmaceutical preparations.

[0062] In a third aspect of the present invention, there is provided the use of the above compound, or its tautomer, stereoisomer, hydrate, solvate, pharmaceutically acceptable salt or prodrug, the pharmaceutical composition in combination with a PD-1 antibody, a PD-L1 antibody, a CTLA-4 antibody, or a PD-1 inhibitor, a PD-L1 inhibitor, a CTLA-4 inhibitor in the preparation of a medicament for the treatment of a CD73-related disease, and the medicament can be used for the treatment of cancer. These cancers include, for example, bladder cancer, breast cancer, cholangiocarcinoma, rectal cancer, colon cancer, gastric cancer, gallbladder cancer, glioblastoma, head and neck cancer, liver cancer, lung cancer, lymphoma, medulloblastoma, melanoma, ovarian cancer, pancreatic cancer, prostate cancer or kidney cancer.

[0063] In a fourth aspect of the present invention, there is provided the use of the above compound, its tautomer, stereoisomer, hydrate, solvate, pharmaceutically acceptable salt or prodrug, or the above pharmaceutical composition in the preparation of a medicament for the treatment of a CD73-related disease.

[0064] Use of the above compound or its tautomer, stereoisomer, hydrate, solvate, pharmaceutically acceptable salt or prodrug or the above pharmaceutical composition in the preparation of a drug for treating a CD73-related disease, wherein the drug can be used for treating cancer. These cancers include, for example, bladder cancer, breast cancer, cholangiocarcinoma, colorectal cancer, colon cancer, gastric cancer, gallbladder cancer, glioblastoma, head and neck cancer, liver cancer, lung cancer, lymphoma, medulloblastoma, melanoma, ovarian cancer, pancreatic cancer, prostate cancer or kidney cancer.

[0065] Terms and definitions

[0066] Unless otherwise specified, the terms and definitions used in the present invention application, including those described in the specification and claims of the present application, are as follows.

[0067] Those skilled in the art can understand that, according to the convention used in the art, in the structural formula of the present application, is used to depict a chemical bond, which is the point where the chemical bond is connected to the core structure or the backbone structure by a moiety or a substituent.

[0068] The term "pharmaceutically acceptable" refers to those compounds, materials, compositions and / or dosage forms that are within the scope of reliable medical judgment, suitable for contact with human and animal tissues, without excessive toxicity, irritation, allergic reaction or other problems or complications, and commensurate with a reasonable benefit / risk ratio.

[0069] The term "pharmaceutically acceptable salt" refers to a non-toxic salt of a pharmaceutically acceptable acid or base, including salts of inorganic acids and bases, organic acids and bases.

[0070] In addition to pharmaceutically acceptable salts, the present invention also contemplates other salts. They can act as intermediates in the purification of the compound or in the preparation of other pharmaceutically acceptable salts or can be used for the identification, characterization or purification of the compounds of the present invention.

[0071] The term "pharmaceutical composition" refers to a mixture of one or more of the compounds described in the text or their physiologically / pharmaceutically acceptable salts or prodrugs with other chemical components, such as physiologically / pharmaceutically acceptable carriers and excipients. The purpose of the pharmaceutical composition is to facilitate the administration of the compound to an organism.

[0072] The term "excipient" refers to a pharmaceutically inert ingredient. Non-limiting examples of the types of "excipients" include binders, disintegrants, lubricants, glidants, stabilizers, fillers and diluents, etc. Excipients can enhance the handling characteristics of pharmaceutical formulations, that is, make the formulations more suitable for direct compression by increasing fluidity and / or adhesiveness.

[0073] The term "prodrug" refers to a compound that can be converted into a biologically active compound of the present invention under physiological conditions or by solvolysis. The prodrugs of the present invention are prepared by modifying the functional groups in the compound, and such modification can be removed by conventional operations or in vivo to obtain the parent compound. Prodrugs include compounds formed by connecting a hydroxyl group or an amino group in the compound of the present invention to any group. When the prodrug of the compound of the present invention is administered to a mammalian individual, the prodrug is cleaved to form a free hydroxyl group and a free amino group, respectively.

[0074] The term "stereoisomer" refers to isomers generated by different arrangements of atoms in space within a molecule, including cis-trans isomers, enantiomers, diastereoisomers, and conformational isomers.

[0075] Depending on the choice of starting materials and methods, the compounds of the present invention may exist in the form of one or a mixture of possible isomers, for example, as pure enantiomers, or as a mixture of isomers, such as a racemic and diastereoisomer mixture, depending on the number of asymmetric carbon atoms. When describing an optically active compound, the prefixes D and L or R and S are used to indicate the absolute configuration of the molecule with respect to the chiral center(s) in the molecule. The prefixes D and L or (+) and (–) are symbols used to specify the rotation of plane-polarized light caused by the compound, where (–) or L indicates that the compound is levorotatory. A compound with the prefix (+) or D is dextrorotatory. For a given chemical structure, these stereoisomers are identical except that these stereoisomers are mirror images of each other. Specific stereoisomers may also be referred to as enantiomers, and a mixture of the isomers is generally referred to as a mixture of enantiomers. A 50:50 mixture of enantiomers is called a racemic mixture or racemate, and such a racemic mixture or racemate may occur when there is no stereoselectivity or stereospecificity in a chemical reaction or method. Many geometric isomers of alkenes, C=N double bonds, etc. may also exist in the compounds described herein, and all such stable isomers are contemplated in the present invention. When the compounds described herein contain an alkene double bond, unless otherwise specified, such a double bond includes E and Z geometric isomers. If the compound contains a disubstituted cycloalkyl group, the substituents on the cycloalkyl group may be in the cis- or trans- configuration.

[0076] When depicting the bonds to a chiral carbon in the formula of the present invention as straight lines, it should be understood that both the (R) and (S) configurations of the chiral carbon and the resulting enantiomerically pure compounds and mixtures thereof are included within the scope of the general formula. The graphical representation of racemates or enantiomerically pure compounds herein is from Maehr, J. Chem. Ed. 1985, 62: 114-120. Unless otherwise specified, the absolute configuration of a stereocenter is represented by a wedge bond and a dashed bond.

[0077] The optically active (R)- or (S)-isomers can be prepared using chiral synthons or chiral preparations, or resolved using conventional techniques. The compounds of the present invention containing asymmetrically substituted carbon atoms can be isolated in optically active form or racemic form. The resolution of the racemic mixtures of the compounds can be carried out by any of a number of methods known in the art. Exemplary methods include fractional crystallization using a chiral resolving acid, which is an optically active salt-forming organic acid. Suitable resolving agents for the fractional crystallization method are, for example, optically active acids such as tartaric acid, diacetyltartaric acid, dibenzoyltartaric acid, mandelic acid, malic acid, lactic acid or various optically active camphorsulfonic acids such as the D and L forms of β-camphorsulfonic acid. Other resolving agents suitable for the fractional crystallization method include stereoisomerically pure forms of α-methyl-benzylamine (e.g., the S and R forms or diastereomerically pure forms), 2-phenylglycol, norephedrine, ephedrine, N-methylephedrine, cyclohexylethylamine, 1,2-diaminocyclohexane, etc. The resolution of the racemic mixture can also be carried out by elution on a chromatographic column packed with an optically active resolving agent (e.g., dinitrobenzoyl-phenylglycine). High performance liquid chromatography (HPLC) or supercritical fluid chromatography (SFC) can be employed. The choice of the specific method, as well as the elution conditions and the choice of the chromatographic column, can be selected by those skilled in the art according to the structure of the compound and the test results. Further, any enantiomer or diastereomer of the compounds described in the present invention can be obtained by stereoselective organic synthesis using optically pure starting materials or reagents of known configuration.

[0078] The term "tautomer" refers to functional group isomers resulting from the rapid migration of an atom within a molecule between two positions. The compounds of the present invention may exhibit tautomerism. Tautomeric compounds can exist in two or more interconvertible species. Prototropic tautomers result from the migration of a hydrogen atom covalently bonded between two atoms. Tautomers generally exist in an equilibrium form, and attempting to isolate a single tautomer usually results in a mixture whose physical and chemical properties are consistent with those of a mixture of compounds. The position of the equilibrium depends on the chemical characteristics within the molecule. For example, in many aliphatic aldehydes and ketones such as acetaldehyde, the keto form predominates; while in phenols, the enol form predominates. The present invention encompasses all tautomeric forms of the compounds.

[0079] The compounds of the present invention may contain non-natural proportions of atomic isotopes on one or more atoms constituting the compound. For example, the compounds can be labeled with radioactive isotopes such as deuterium ( 2 H), tritium ( 3 H), iodine-125 ( 125 I) or C-14 ( 14C). All isotopic variations of the compounds of the present invention, whether radioactive or not, are included within the scope of the present invention.

[0080] For a drug or a pharmacological active agent, the term "effective amount" or "therapeutically effective amount" refers to a sufficient amount of the drug or agent that is non-toxic but can achieve the desired effect. For the oral dosage forms in the present invention, the "effective amount" of an active substance in the composition refers to the amount required to achieve the desired effect when used in combination with another active substance in the composition. The determination of the effective amount varies from person to person, depending on the age and general condition of the recipient, and also depends on the specific active substance. In a specific case, the appropriate effective amount can be determined by those skilled in the art through routine tests.

[0081] The terms "active ingredient", "therapeutic agent", "active substance" or "active agent" refer to a chemical entity that can effectively treat a target disorder, disease or condition.

[0082] The term "substituted" means that any one or more hydrogen atoms on a specific atom are replaced by substituents, including deuterium and variants of hydrogen, as long as the valence state of the specific atom is normal and the resulting compound is stable. When the substituent is a keto group (i.e., =O), it means that two hydrogen atoms are replaced. Keto substitution does not occur on an aromatic group. The term "optionally substituted" means that it can be substituted or not substituted. Unless otherwise specified, the type and number of substituents can be arbitrary based on what is chemically achievable.

[0083] The term "C1-C6 alkyl" should be understood to represent a straight-chain or branched-chain saturated monovalent hydrocarbon group having 1, 2, 3, 4, 5 or 6 carbon atoms. Examples of such alkyl groups are methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1-methylbutyl, 1-ethylpropyl, 1,2-dimethylpropyl, neopentyl, 1,1-dimethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 2-ethylbutyl, 1-ethylbutyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 2,3-dimethylbutyl, 1,3-dimethylbutyl or 1,2-dimethylbutyl, etc. or their isomers. In particular, the group has 1, 2 or 3 carbon atoms ("C1-C3 alkyl"), such as methyl, ethyl, n-propyl or isopropyl.

[0084] The term "C1-C6 alkyl-O-" should be understood to mean that the alkyl group is connected to the rest of the molecule through an oxygen atom, where "C1-C6 alkyl" has the above definition. Such as methyl-O-, ethyl-O-.

[0085] The term "C3-C6 cycloalkyl" is understood to denote a saturated monocyclic or bicyclic hydrocarbon ring having 3 to 6 carbon atoms, including fused or bridged polycyclic systems, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl.

[0086] The term "4- to 8-membered heterocyclic group" or "4- to 8-membered heterocycloalkyl" is understood to denote a saturated, unsaturated or partially saturated monocyclic, bicyclic or tricyclic ring having 4 to 8 atoms, wherein 1, 2, 3, 4 or 5 ring atoms are selected from N, O and S, and which, unless otherwise specified, may be attached through carbon or nitrogen, where the -CH 2- group is optionally replaced by -C(O)-; and wherein, unless otherwise stated to the contrary, the ring nitrogen atom or ring sulfur atom is optionally oxidized to form an N-oxide or S-oxide or the ring nitrogen atom is optionally quaternized; wherein -NH in the ring is optionally substituted by acetyl, formyl, methyl or methanesulfonyl; and the ring is optionally substituted by one or more halogens. It should be understood that when the total number of S and O atoms in the heterocyclic group exceeds 1, these heteroatoms are not adjacent to each other. If the heterocyclic group is bicyclic or tricyclic, at least one ring may optionally be a heteroaromatic ring or an aromatic ring, provided that at least one ring is non-heteroaromatic. If the heterocyclic group is monocyclic, it must not be aromatic. Examples of heterocyclic groups include, but are not limited to, piperidinyl, N-acetylpiperidinyl, N-methylpiperidinyl, N-formylpiperazinyl, N-methanesulfonylpiperazinyl, homopiperazinyl, piperazinyl, azetidinyl, oxetanyl, morpholinyl, tetrahydroisoquinolinyl, tetrahydroquinolinyl, dihydroindolyl, tetrahydropyranyl, dihydro-2H-pyranyl, tetrahydrofuryl, tetrahydrothiopyranyl, tetrahydrothiopyran-1-oxide, tetrahydrothiopyran-1,1-dioxide, 1H-pyridin-2-one and 2,5-dioxoimidazolidinyl.

[0087] The term "4- to 8-membered heteroalkenyl" should be understood as a non-aromatic monocyclic or polycyclic group containing 4 to 8 ring atoms, preferably 5 to 6 ring atoms, wherein the 4- to 8-membered heteroalkenyl contains 1 to 3 heteroatoms selected from N, O, S, and P and contains at least one carbon-carbon double bond or carbon-nitrogen double bond. The aza, oxa, or thia included in the group name means that at least one nitrogen, oxygen, or sulfur atom, respectively, is a ring atom. The nitrogen or sulfur atom of the 4- to 8-membered heteroalkenyl can be optionally oxidized to the corresponding N-oxide, S-oxide, or S-dioxide. Preferred 4- to 8-membered heteroalkenyls include, but are not limited to, 1,2,3,4-tetrahydropyridinyl, 1,2-dihydropyridinyl, 1,4-dihydropyridinyl, 1,2,3,6-tetrahydropyridinyl, 1,4,5,6-tetrahydropyrimidinyl, 2-pyrrolinyl, 3-pyrrolinyl, 2-imidazolinyl, 2-pyrazolinyl, dihydroimidazolyl, dihydrooxazolyl, dihydrooxadiazolyl, dihydrothiazolyl, 3,4-dihydro-2H-pyranyl, dihydrofuranyl, fluorodihydrofuranyl and its oxides, etc. The "4- to 8-membered heteroalkenyl" may also include that two available hydrogen atoms on the same carbon atom of the ring are simultaneously replaced by a single group =O (i.e., a carbonyl group is formed).

[0088] The term "5- to 8-membered aryl" should be understood as a monocyclic, bicyclic, or tricyclic hydrocarbon ring that is monovalent aromatic or partially aromatic and has 5 to 8 carbon atoms, especially a ring having 6 carbon atoms ("C6 aryl"), such as phenyl; when the 5- to 8-membered aryl is substituted, it can be mono-substituted or multi-substituted. And there is no restriction on its substitution site, for example, it can be ortho-substituted, para-substituted, or meta-substituted.

[0089] The term "5- to 8-membered heteroaryl" should be understood as a monovalent monocyclic, bicyclic, or tricyclic aromatic ring group having 5 to 8 ring atoms, especially 5 or 6 carbon atoms, and containing 1 to 5 heteroatoms independently selected from N, O, and S. Preferably, it is a monovalent monocyclic, bicyclic, or tricyclic aromatic ring group having 1 to 3 heteroatoms independently selected from N, O, and S, and in each case, it can be benzo-fused. In particular, the heteroaryl is selected from thienyl, furanyl, pyrrolyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, isoxazolyl, isothiazolyl, oxadiazolyl, triazolyl, thiadiazolyl, etc.; or pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, etc.; or cinnolinyl, phthalazinyl, quinazolinyl, quinoxalinyl, naphthyridinyl, pteridinyl, carbazolyl, acridinyl, phenazinyl, phenothiazinyl, phenoxazinyl, etc.

[0090] The term "halogen" or "halo" is fluorine, chlorine, bromine, and iodine.

[0091] In addition, it should be noted that, unless otherwise explicitly indicated, the description method "…… independently" adopted in the present invention should be understood in a broad sense, which means that the described individuals are independent of each other and can independently be the same or different specific groups. More specifically, the description method "…… independently" can either mean that among different groups, the specific options expressed between the same symbols do not affect each other, or it can mean that within the same group, the specific options expressed between the same symbols do not affect each other.

[0092] Beneficial effects

[0093] According to the embodiments of the present invention, the present invention provides CD73 inhibitors with novel structures, excellent pharmacokinetic properties, and good pharmacodynamic or drug-likeness, which can be used to effectively treat CD73-related diseases and disorders.

[0094] The compounds of the present invention have good inhibitory effects on CD73 enzyme and good in vitro pharmacodynamic effects. In addition, the results of mouse experiments show that the compounds of the present invention exhibit excellent pharmacokinetic properties and good drug-likeness.

[0095] In addition, the compounds of the present invention alone or in combination with PD-1 / L1 antibodies both have significant effects on inhibiting the growth of CT-26 colorectal cancer and E.G7-OVA T cell lymphoma.

[0096] The additional aspects and advantages of the present invention will be partly given in the following description, partly will become obvious from the following description, or will be understood through the practice of the present invention. Detailed implementation manners

[0097] The solutions of the present invention will be explained below in conjunction with embodiments. Those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. For those not specified in the embodiments regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the art or according to the product specifications. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0098] Unless otherwise specified, the structures of the compounds of the present invention are determined by nuclear magnetic resonance (NMR) and / or mass spectrometry (MS). The unit of NMR shift is 10 -6 (ppm). The solvents for NMR measurement are deuterated dimethyl sulfoxide, deuterated chloroform, deuterated methanol, etc., and the internal standard is tetramethylsilane (TMS).

[0099] The abbreviations in the present invention are defined as follows:

[0100] M: Molar concentration. For example, 1M hydrochloric acid means 1 mol / L hydrochloric acid solution

[0101] DCM: Dichloromethane

[0102] DMP: Dess-Martin periodinane

[0103] DMF: N,N-dimethylformamide

[0104] DAST: diethylaminosulfur trifluoride

[0105] DMSO: dimethyl sulfoxide

[0106] dioxane: 1,4-dioxane

[0107] TEA: triethylamine

[0108] THF: tetrahydrofuran

[0109] TEMPO: 2,2,6,6-tetramethylpiperidine 1-oxyl

[0110] LC-MS: liquid chromatography-mass spectrometry

[0111] IC 50 : half maximal inhibitory concentration, referring to the concentration when the maximum inhibitory effect reaches half.

[0112] Control Example 1: Preparation of Positive Control Compound 1

[0113] 5-(5-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-methylpyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (Control Compound 1)

[0114]

[0115] Prepared according to the method of reference patent WO2019168744Al.

[0116] 1 1H NMR (400 MHz, DMSO-d6) δ 11.51 (s, 2H), 8.27 (s, 1H), 7.77 (s, 1H), 6.17 - 5.85 (m, 1H), 2.69 (s, 3H), 2.32 - 2.29 (m, 1H), 1.77 - 1.70 (m, 1H), 1.32 - 1.18 (m, 2H).

[0117] LC-MS, M / Z (ESI): 295.0 [M + H] + .

[0118] "Control Compound 1" mentioned below all refers to the compound described in Control Example 1.

[0119] Control Example 2: Preparation of Positive Control Compound 2

[0120] 5-(5-((1S,2R)-2-Isopropylcyclopropyl)-6-methylpyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (Control Compound 2)

[0121]

[0122] Prepared according to the method of reference patent WO2019168744A1.

[0123] 1 H NMR (400 MHz, CD3OD) δ 8.65 (s, 1H), 8.22 (s, 1H), 2.89 (s, 3H), 2.07 - 2.10 (m, 1H), 1.33 - 1.45 (m, 4H), 1.10 (d, 6H).

[0124] LC-MS, M / Z (ESI): 287.0 [M+H] + 。

[0125] "Control Compound 2" mentioned below refers to the compound described in Control Example 2.

[0126] Preparation 1: Preparation of Intermediate A

[0127] 3-Chloro-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (Intermediate A)

[0128]

[0129] The synthetic route of Intermediate A is shown below:

[0130]

[0131] Step 1: Synthesis of ethyl (1S,2S)-2-((benzyloxy)methyl)cyclopropane-1-carboxylate (A-3)

[0132]

[0133] Under nitrogen protection, sodium hydride (58.5 g, 1.46 mol, 60% content) was suspended in toluene (3000 mL), and then triethyl phosphonoacetate (327.7 g, 1.46 mol) was added dropwise at 0 °C. After the addition was completed, the mixture was stirred at 25 °C for 1 hour. Then, (S)-(+)-glycidyl benzyl ether (200 g, 1.22 mol) was added to the reaction solution, and the temperature was raised to 130 °C and reacted for 12 hours. The reaction mixture was diluted with water (5000 mL), and then extracted with ethyl acetate (2000 mL × 2). The organic layers were combined, washed with saturated brine (2000 mL), dried over sodium sulfate, and concentrated to obtain the crude product. The crude product was separated and purified by silica gel column chromatography (petroleum ether: ethyl acetate (V / V) = 50:1 - 10:1, gradient elution) to obtain the red oil (1S,2S)-ethyl 2-((benzyloxy)methyl)cyclopropane-1-carboxylate (A-3) (180 g, yield 63%).

[0134] 1 1H NMR (400 MHz, CDCl3) δ 7.18 - 7.25 (m, 5H), 4.42 (s, 2H), 4.00 - 4.04 (m, 2H), 3.33 - 3.37 (m, 1H), 3.24 - 3.28 (m, 1H), 1.62 - 1.66 (m, 1H), 1.46 - 1.49 (m, 1H), 1.06 - 1.16 (m, 4H), 0.75 - 0.78 (m, 1H).

[0135] Step 2: Synthesis of (1S,2S)-ethyl 2-(hydroxymethyl)cyclopropane-1-carboxylate (A-4)

[0136]

[0137] (1S,2S)-Ethyl 2-((benzyloxy)methyl)cyclopropane-1-carboxylate (A-3) (120 g, 512.2 mmol) was dissolved in ethanol (1200 mL). Under nitrogen protection, palladium on carbon (30.0 g, 10% content) was added, and then the mixture was purged with hydrogen three times. Then, the reaction was carried out at 50 Psi pressure and 50 °C for 24 hours. After cooling to room temperature, the palladium on carbon was filtered off through diatomaceous earth, and the filter cake was washed with ethanol three times. The filtrate was concentrated to obtain the yellow oil (1S,2S)-ethyl 2-(hydroxymethyl)cyclopropane-1-carboxylate (A-4) (65.0 g, yield 85%).

[0138] Step 3: Synthesis of (1S,2S)-ethyl 2-formylcyclopropane-1-carboxylate (A-5)

[0139]

[0140] Dissolve ethyl (1S,2S)-2-(hydroxymethyl)cyclopropane-1-carboxylate (A-4) (100 g, 693.6 mmol) in dichloromethane (1500 mL). Slowly add Dess-Martin periodinane (353.0 g, 832.4 mmol) at 0 °C, and then react at 25 °C for 12 hours. After completion of the reaction, pour the reaction solution into an aqueous sodium carbonate solution (500 mL) and an aqueous sodium sulfite solution (500 mL), then extract with dichloromethane (2000 mL × 2). Combine the organic phases, wash with saturated brine (500 mL), dry over sodium sulfate, filter, and concentrate to obtain yellow oil ethyl (1S,2S)-2-formylcyclopropane-1-carboxylate (A-5) (67.0 g, yield 68%).

[0141] 1 H NMR (400 MHz, CDCl3) δ 9.31 (d, 1H), 4.18 (q, 2H), 2.40 - 2.46 (m, 1H), 2.24 - 2.28 (m, 1H), 1.59 - 1.64 (m, 1H), 1.50 - 1.54 (m, 1H), 1.35 - 1.20 (m, 3H).

[0142] Step 4: Synthesis of ethyl (1S,2S)-2-(difluoromethyl)cyclopropane-1-carboxylate (A-6)

[0143]

[0144] Dissolve ethyl (1S,2S)-2-formylcyclopropane-1-carboxylate (A-5) (95 g, 668.3 mmol) in dichloromethane (1200 mL). Dropwise add diethylaminosulfur trifluoride (237.0 g, 194 mL, 1.47 mol) at 0 °C, and then stir and react at 25 °C for 2 hours. Quench the reaction mixture with saturated aqueous sodium bicarbonate solution (1000 mL), then extract with dichloromethane (500 mL × 2). Combine the organic layers, wash the organic phase with saturated brine (1000 mL), dry over sodium sulfate, and concentrate to obtain yellow oil ethyl (1S,2S)-2-(difluoromethyl)cyclopropane-1-carboxylate (A-6) (95 g, crude product), which is directly used in the next step.

[0145] 1 H NMR (400 MHz, CDCl3) δ 5.62 - 5.91 (m, 1H), 4.16 (q, 2H), 1.88 - 1.96 (m, 2H), 1.26 - 1.30 (m, 4H), 1.12 - 1.16 (m, 1H).

[0146] Step 5: Synthesis of (1S,2S)-2-(difluoromethyl)cyclopropane-1-carboxylic acid (A-7)

[0147]

[0148] Ethyl (1S,2S)-2-(difluoromethyl)cyclopropane-1-carboxylate (A-6) (95.0 g, 578.7 mmol) was dissolved in methanol (500 mL) and water (100 mL), and then sodium hydroxide (69.5 g, 1.74 mmol) was added. The reaction was carried out at 25 °C for 12 hours. After the reaction was completed, the reaction solution was concentrated, water (500 mL) was added, and the mixture was extracted with methyl tert-butyl ether (500 mL × 2). The aqueous phase was collected, adjusted to pH = 3 with 1 M hydrochloric acid, and then extracted with ethyl acetate (500 mL × 3). The organic phases were combined, washed with saturated brine (500 mL), dried over anhydrous sodium sulfate, filtered, and concentrated to obtain a yellow oil, (1S,2S)-2-(difluoromethyl)cyclopropane-1-carboxylic acid (A-7) (47.0 g, yield 60%).

[0149] 1 H NMR (400 MHz, CDCl3) δ 9.52 (br.s, 1H), 5.65 - 5.94 (m, 1H), 1.89 - 1.94 (m, 2H), 1.34 - 1.37 (m, 1H), 1.23 - 1.27 (m, 1H).

[0150] Step 6: Synthesis of 3,6-dichloro-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)pyridazine (A-9)

[0151]

[0152] 3,6-Dichloropyridazine (6.60 g, 44.3 mmol) and (1S,2S)-2-(difluoromethyl)cyclopropane-1-carboxylic acid (6.03 g, 44.3 mmol) were dissolved in water (150 mL), and then concentrated sulfuric acid (6.74 mL) was added. The temperature was raised to 70 °C under nitrogen protection. Then an aqueous solution of silver nitrate (4.20 g, 24.7 mmol, 7.5 mL) was quickly added, and then an aqueous solution of ammonium persulfate (30.3 g, 132.9 mmol, 75 mL) was slowly added dropwise. The reaction was continued at 70 °C for 2 hours. The reaction solution was adjusted to pH about 9 with ammonia water, and then extracted with ethyl acetate (500 mL × 2). The organic layers were combined, washed with saturated brine (500 mL), dried over sodium sulfate, and concentrated to obtain a crude product. Purification by silica gel column chromatography (petroleum ether:ethyl acetate (V / V) = 20:1 - 3:1, gradient elution) gave a yellow oil, 3,6-dichloro-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)pyridazine (A-9) (5.00 g, yield 46.4%).

[0153] 11H NMR (400 MHz, CDCl3) δ 7.10 (s, 1H), 5.79 - 6.08 (m, 1H), 2.39 - 2.45 (m, 1H), 1.68 - 1.75 (m, 1H), 1.51 - 1.54 (m, 1H), 1.22 - 1.25 (m, 1H).

[0154] LC-MS, M / Z (ESI): 239.1 [M + H] + 。

[0155] Step 7: Synthesis of 3-chloro-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (A)

[0156]

[0157] Dissolve 3,6-dichloro-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)pyridazine (5.00 g, 20.9 mmol) and 2,4-dimethoxypyrimidine-5-boronic acid (3.85 g, 20.9 mmol) in 1,4-dioxane (50 mL) and water (10 mL). Under nitrogen protection, add sodium carbonate (6.65 g, 62.7 mmol) and [1,1-bis(diphenylphosphino)ferrocene]dichloropalladium (1.53 g, 2.09 mmol), and heat the mixture to 70 °C for reaction for 1 hour. Dilute the reaction mixture with water (50 mL), then extract it with ethyl acetate (100 mL × 3). Combine the organic phases, wash the organic phases with saturated brine (100 mL), dry over sodium sulfate, and concentrate to obtain the crude product. Purify it by silica gel column chromatography (petroleum ether:ethyl acetate (V / V) = 10:1 - 2:1, gradient elution) to obtain 3-chloro-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (A) as a yellow oil (4.5 g, yield 48%).

[0158] LC-MS, M / Z (ESI): 343.1 [M + H] + 。

[0159] Preparation 2: Preparation of Intermediate B

[0160] 3-chloro-6-(2,4-dimethoxypyrimidin-5-yl)-4-((1S,2S)-2-(fluoromethyl)cyclopropyl)pyridazine (Intermediate B)

[0161]

[0162] The synthetic route of Intermediate B is as follows:

[0163]

[0164] Step 1: Synthesis of tert-butyl (1S,2S)-2-((benzyloxy)methyl)cyclopropane-1-carboxylate (B-3)

[0165]

[0166] Under nitrogen protection, sodium hydride (14.6 g, 365.4 mmol, 60% content) was suspended in toluene (500 mL), and then tert-butyl diethylphosphonoacetate (92.2 g, 365.4 mmol) was added dropwise. After the addition, the mixture was stirred at 25 °C for 30 minutes, and then (S)-(+)-glycidyl benzyl ether (50.0 g, 304.5 mmol) was added to the reaction solution. The temperature was raised to 130 °C and the reaction was carried out for 8 hours. The reaction mixture was diluted with water (100 mL), and then extracted with ethyl acetate (100 mL × 2). The organic layers were combined, washed with saturated brine (50 mL), dried over sodium sulfate, and concentrated to obtain a crude product. The crude product was separated and purified by silica gel column chromatography (petroleum ether:ethyl acetate (V / V) = 50:1 - 10:1, gradient elution) to obtain yellow oily compound tert-butyl (1S,2S)-2-((benzyloxy)methyl)cyclopropane-1-carboxylate (B-3) (55 g, yield 68.8%).

[0167] Step 2: Synthesis of tert-butyl (1S,2S)-2-(hydroxymethyl)cyclopropane-1-carboxylate (B-4)

[0168]

[0169] tert-Butyl (1S,2S)-2-((benzyloxy)methyl)cyclopropane-1-carboxylate (B-3) (55 g, 209.6 mmol) was dissolved in ethanol (500 mL). Under nitrogen protection, palladium on carbon (20.0 g, 10% content) was added, and then the mixture was purged with hydrogen three times. Then the reaction was carried out at 50 °C under 50 Psi pressure for 24 hours. After cooling to room temperature, the palladium on carbon was filtered off through diatomaceous earth, and the filter cake was washed three times with ethanol. The filtrate was concentrated to obtain yellow oily substance tert-butyl (1S,2S)-2-(hydroxymethyl)cyclopropane-1-carboxylate (B-4) (36.0 g, yield 99.7%).

[0170] 1 H NMR (400 MHz, CDCl3) δ 3.50–3.63 (m, 2H), 1.67–1.72 (m, 1H), 1.47 (s, 9H), 1.38 (t, 1H), 1.14–1.89 (m, 1H), 0.78 - 0.84 (m, 1H).

[0171] Step 3: Synthesis of tert-butyl (1S,2S)-2-(fluoromethyl)cyclopropane-1-carboxylate (B-5)

[0172]

[0173] (1S,2S)-tert-Butyl 2-(fluoromethyl)cyclopropane-1-carboxylate (B-5) was synthesized by dissolving (1S,2S)-tert-Butyl 2-(hydroxymethyl)cyclopropane-1-carboxylate (B-4) (2.5 g, 14.5 mmol) in dichloromethane (25 mL), adding diethylaminosulfur trifluoride (4.68 g, 3.84 mL, 29.0 mmol) dropwise at 0 °C, and then stirring the reaction at 0 °C for 1 h. The reaction mixture was quenched with saturated aqueous sodium bicarbonate (100 mL), then extracted with dichloromethane (100 mL × 2). The combined organic layers were washed with saturated brine (50 mL), dried over sodium sulfate, and concentrated to obtain the crude product. Purification by silica gel column chromatography (petroleum ether:ethyl acetate (V / V) = 50:1 - 10:1, gradient elution) gave (1S,2S)-tert-Butyl 2-(fluoromethyl)cyclopropane-1-carboxylate (B-5) as a yellow oil (2.0 g, yield 79%).

[0174] 1 1H NMR (400 MHz, CDCl3) δ 4.19 - 4.42 (m, 2H), 1.75–1.82 (m, 1H), 1.55 - 1.59 (m, 1H), 1.46 (s, 9H), 1.18–1.23 (m, 1H), 0.83 - 0.88 (m, 1H).

[0175] Step 4: Synthesis of (1S,2S)-2-(fluoromethyl)cyclopropane-1-carboxylic acid (B-6)

[0176]

[0177] (1S,2S)-tert-Butyl 2-(fluoromethyl)cyclopropane-1-carboxylate (B-5) (2.0 g, 11.5 mmol) was dissolved in 1,4-dioxane (10 mL) solution of hydrogen chloride (4 M), and stirred at 20 °C for 1 h. The reaction mixture was concentrated to obtain (1S,2S)-2-(fluoromethyl)cyclopropane-1-carboxylic acid (B-6) as a yellow oil (1.3 g, yield 95%).

[0178] 1 1H NMR (400 MHz, CDCl3) δ 4.16 - 4.52 (m, 2H), 1.88 - 1.94 (m, 1H), 1.67 - 1.71 (m, 1H), 1.34–1.37 (m, 1H), 1.01 - 1.05 (m, 1H).

[0179] Step 5: Synthesis of 3,6-dichloro-4-((1S,2S)-2-(fluoromethyl)cyclopropyl)pyridazine (B-8)

[0180]

[0181] Dissolve 3,6-dichloropyridazine (630 mg, 4.23 mmol) and (1S,2S)-2-(fluoromethyl)cyclopropane-1-carboxylic acid (B-6) (500 mg, 4.23 mmol) in water, then add concentrated sulfuric acid (0.5 mL), and heat to 70 °C under nitrogen protection. Then quickly add an aqueous solution of silver nitrate (359.6 mg, 2.12 mmol, 5 mL), and then slowly dropwise add an aqueous solution of ammonium persulfate (2.90 g, 12.7 mmol, 10 mL). Continue the reaction at 70 °C for 1 hour. Adjust the pH of the reaction solution to about 9 with ammonia water, then extract with ethyl acetate (100 mL × 2). Combine the organic layers, wash the organic phase with saturated brine (50 mL), dry over sodium sulfate, and concentrate to obtain the crude product. Purify by silica gel column chromatography (petroleum ether:ethyl acetate (V / V) = 10:1 - 3:1, gradient elution) to obtain 3,6-dichloro-4-((1S,2S)-2-(fluoromethyl)cyclopropyl)pyridazine (B-8) as a yellow oil (500 mg, yield 26%).

[0182] Step 6: Synthesis of 3-chloro-6-(2,4-dimethoxypyrimidin-5-yl)-4-((1S,2S)-2-(fluoromethyl)cyclopropyl)pyridazine (B)

[0183]

[0184] Dissolve 3,6-dichloro-4-((1S,2S)-2-(fluoromethyl)cyclopropyl)pyridazine (300 mg, 1.36 mmol) and 2,4-dimethoxypyrimidine-5-boronic acid in 1,4-dioxane (10 mL) and water (2 mL). Under nitrogen protection, add sodium carbonate (359.6 mg, 3.39 mmol) and [1,1-bis(diphenylphosphino)ferrocene]dichloropalladium (99.3 mg, 135.7 μmol), and heat to 70 °C for 2 hours. Dilute the reaction mixture with water (50 mL), then extract with ethyl acetate (50 mL × 2). Combine the organic layers, wash the organic phase with saturated brine (50 mL), dry over sodium sulfate, and concentrate to obtain the crude product. Separate the crude product by silica gel column chromatography (petroleum ether:ethyl acetate (V / V) = 5:1 - 1:1, gradient elution) to obtain 3-chloro-6-(2,4-dimethoxypyrimidin-5-yl)-4-((1S,2S)-2-(fluoromethyl)cyclopropyl)pyridazine (B) as a yellow solid (150 mg, yield 34%).

[0185] 11H NMR (400 MHz, CDCl3) δ 9.06 (s, 1H), 7.55 (s, 1H), 4.45 - 4.58 (m, 2H), 4.10 (s, 3H), 4.08 (s, 3H), 2.24 - 2.29 (m, 1H), 1.65 - 1.69 (m, 1H), 1.31 - 1.35 (m, 1H), 1.19 - 1.23 (m, 1H).

[0186] LC-MS, M / Z (ESI): 324.9 [M + H] + 。

[0187] Example 1: Preparation of Target Compound 1

[0188] 5-(5-((1S,2S)-2-(Difluoromethyl)cyclopropyl)-6-(prop-1-yn-1-yl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (Target Compound 1)

[0189]

[0190] The synthetic route of Target Compound 1 is as follows:

[0191]

[0192] The First Step: Synthesis of 4-((1S,2S)-2-(Difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)-3-(prop-1-yn-1-yl)pyridazine (1B)

[0193]

[0194] Under nitrogen protection, 3-chloro-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (500 mg, 1.46 mmol), tributyl(prop-1-yn-1-yl)stannane (960.3 mg, 2.92 mmol), 1,1-bis(diphenylphosphino)ferrocene palladium chloride (102.4 mg, 0.146 mmol) were dissolved in 1,4-dioxane (10 mL), and then reacted at 80 °C for 3 hours under nitrogen protection. After the reaction was completed, the reaction mixture was concentrated to obtain a crude product. It was separated and purified by silica gel column chromatography (petroleum ether: ethyl acetate (V / V) = 5:1 - 1:1, gradient elution) to obtain 4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)-3-(prop-1-yn-1-yl)pyridazine (1B) as a yellow oil (600 mg, yield 98%).

[0195] LC-MS, M / Z (ESI): 347.0 [M + H]+ .

[0196] Step 2: 5-(5-((1S,2S)-2-(Difluoromethyl)cyclopropyl)-6-(prop-1-yn-1-yl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (1)

[0197]

[0198] Dissolve 4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)-3-(prop-1-yn-1-yl)pyridazine (600 mg, 1.73 mmol) in aqueous hydrochloric acid solution (1 M, 10 mL), heat up to 70 °C and react for 10 hours. Concentrate the reaction solution, and then separate it by reverse-phase high performance liquid chromatography. The separation method is (column: Waters Xbridge 150×25 mm×5 μm; mobile phase: A = water + ammonium bicarbonate (10 mM), B = acetonitrile; gradient: 12%-48% B, 10 minutes), to obtain the yellow solid 5-(5-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(prop-1-yn-1-yl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (1) (80 mg, yield 14.5%).

[0199] 1 H NMR (400 MHz, CD3OD) δ 8.43 (s, 1H), 8.01 (s, 1H), 5.76 - 6.05 (m, 1H), 2.54 - 2.60 (m, 1H), 2.22 (s, 3H), 1.86 - 1.88 (m, 1H), 1.42 - 1.46 (m, 1H), 1.31 - 1.33 (m, 1H).

[0200] LC-MS, M / Z (ESI): 318.9 [M+H] + .

[0201] Example 2: Preparation of the target compound 2

[0202] 5-(6-(But-1-yn-1-yl)-5-((1S,2S)-2-(difluoromethyl)cyclopropyl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (target compound 2)

[0203]

[0204] The synthetic route of the target compound 2 is as follows:

[0205]

[0206] Step 1: Synthesis of 3-(but-1-yn-1-yl)-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (2B)

[0207]

[0208] Dissolve 3-chloro-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (200 mg, 0.583 mmol) in N,N-dimethylformamide (5 mL). Under nitrogen protection, add copper(I) iodide (11.1 mg, 58.4 μmol), triethylamine (236.2 mg, 2.33 mmol) and bis(triphenylphosphine)palladium(II) dichloride (40.9 mg, 58.4 μmol), then introduce but-1-yne (15 psi), and heat the reaction mixture to 80 °C for 2 hours. Dilute the reaction mixture with water (25 mL), then extract with ethyl acetate (25 mL × 2). Combine the organic layers, wash the organic phase with saturated brine (25 mL), dry over sodium sulfate, and concentrate to obtain the crude product. Purify by silica gel column chromatography (petroleum ether:ethyl acetate (V / V) = 10:1 - 1:1, gradient elution) to obtain 3-(but-1-yn-1-yl)-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (2B) as a yellow oil (200 mg, 95%).

[0209] LC-MS, M / Z (ESI): 361.1 [M+H] + 。

[0210] Step 2: Synthesis of 5-(6-(but-1-yn-1-yl)-5-((1S,2S)-2-(difluoromethyl)cyclopropyl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (2)

[0211]

[0212] 3-(Cyclopropylethynyl)-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (200 mg, 0.555 mmol) was dissolved in aqueous hydrochloric acid (1 M, 5 mL), and the temperature was raised to 50 °C and reacted for 0.5 h. The reaction solution was concentrated and then separated by reverse-phase high performance liquid chromatography (column: 3_Phenomenex Luna C18 75×30 mm×3 μm; mobile phase: A = water + 0.05% by volume HCl (36.5%), B = acetonitrile; gradient: 25%-45% B, 8 min) to obtain the yellow solid 5-(6-(but-1-yn-1-yl)-5-((1S,2S)-2-(difluoromethyl)cyclopropyl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (2) (70.7 mg, yield 38%).

[0213] 1 H NMR (400 MHz, CD3OD) δ 8.49 (s, 1H), 8.08 (s, 1H), 5.78 - 6.08 (m, 1H), 2.59 - 2.65 (m, 3H), 1.88 - 1.95 (m, 1H), 1.46 - 1.52 (m, 1H), 1.37 - 1.43 (m, 1H), 1.32 (t, 3H).

[0214] LC-MS, M / Z (ESI): 332.9 [M+H] + 。

[0215] Example 3: Preparation of target compound 3

[0216] 5-(6-(Cyclopropylethynyl)-5-((1S,2S)-2-(difluoromethyl)cyclopropyl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (target compound 3)

[0217]

[0218] The synthetic route of the target compound 3 is shown as follows:

[0219]

[0220] The first step: Synthesis of 3-(cyclopropylethynyl)-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (3B)

[0221]

[0222] 3-Chloro-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (200 mg, 583.5 μmol) and cyclopropylethyne were dissolved in N,N-dimethylformamide (5 mL). Under nitrogen protection, copper(I) iodide (11.1 mg, 58.4 μmol), triethylamine (236.2 mg, 2.33 mmol) and bis(triphenylphosphine)palladium(II) dichloride (40.9 mg, 58.4 μmol) were added. The reaction was heated to 80 °C and reacted for 2 hours. The reaction mixture was diluted with water (25 mL), then extracted with ethyl acetate (25 mL × 2). The organic layers were combined, washed with saturated brine (25 mL), dried over sodium sulfate, and concentrated to obtain the crude product. The crude product was separated and purified by silica gel column chromatography (petroleum ether:ethyl acetate (V / V) = 10:1 - 1:1, gradient elution) to obtain 3-(cyclopropylethynyl)-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (3B) as a yellow oil (200 mg, yield 92%).

[0223] LC-MS, M / Z(ESI): 373.2[M+H] + 。

[0224] Step 2: Synthesis of 5-(6-(cyclopropylethynyl)-5-((1S,2S)-2-(difluoromethyl)cyclopropyl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (3)

[0225]

[0226] 3-(Cyclopropylethynyl)-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (200 mg, 537.1 μmol) was dissolved in hydrochloric acid aqueous solution (1 M, 10 mL). The reaction was heated to 75 °C and reacted for 2 hours. The reaction solution was concentrated, and then separated by reversed-phase high performance liquid chromatography. The separation method was (column: Phenomenex Gemini-NX C18 75×30 mm×3 μm; mobile phase: A = water + ammonium bicarbonate (10 mM), B = acetonitrile; gradient: 15% - 45% B, 8 minutes) to obtain 5-(6-(cyclopropylethynyl)-5-((1S,2S)-2-(difluoromethyl)cyclopropyl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (3) as a yellow solid (50 mg, yield 27%).

[0227] 11H NMR (400 MHz, CD3OD) δ 8.43 (s, 1H), 7.99 (s, 1H), 5.78 - 6.07 (m, 1H), 2.50 - 2.55 (m, 1H), 1.81 - 1.87 (m, 1H), 1.62 - 1.69 (m, 1H), 1.41 - 1.46 (m, 1H), 1.32 - 1.36 (m, 1H), 1.15 - 1.01 (m, 2H), 0.98 - 0.85 (m, 2H).

[0228] LC - MS, M / Z (ESI): 345.2 [M + H] + 。

[0229] Example 4: Preparation of Target Compound 4

[0230] 5-(5-((1S,2S)-2-(Difluoromethyl)cyclopropyl)-6-(3-hydroxy-3-methylbut-1-yn-1-yl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (Target Compound 4)

[0231]

[0232] The synthetic route of Target Compound 4 is as follows:

[0233]

[0234] The first step: Synthesis of 4-(4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazin-3-yl)-2-methyl-3-yn-2-ol (4B)

[0235]

[0236] Under the protection of nitrogen, 3-chloro-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (200.0 mg, 583.6 μmol) and 2-methylbut-3-yn-2-ol (73.6 mg, 875.3 μmol) were dissolved in N,N-dimethylformamide (5.00 mL). Then, copper(I) iodide (11.1 mg, 58.4 μmol), triethylamine (236.2 mg, 2.33 mmol) and bis(triphenylphosphine)palladium(II) dichloride (40.9 mg, 58.4 μmol) were added thereto, and the reaction was carried out at 80 °C for 2 hours. After the reaction was completed, the reaction solution was added to water (10 mL), extracted with ethyl acetate (20 mL × 2), the organic phase was washed twice with saturated brine (50 mL), and then the organic phase was dried over anhydrous sodium sulfate. The organic phase was concentrated to obtain a yellow oil, 4-(4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazin-3-yl)-2-methyl-3-yn-2-ol (4B) (140.0 mg, yield 68.6%).

[0237] LC-MS, M / Z(ESI): 391.2[M+H] + 。

[0238] Step 2: Synthesis of 5-(5-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(3-hydroxy-3-methylbut-1-yn-1-yl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (target product 4)

[0239]

[0240] 4-(4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazin-3-yl)-2-methyl-3-yn-2-ol (140.0 mg, 358.6 μmol) was dissolved in hydrochloric acid (1 M, 3.59 mL), and then the reaction was carried out at 50 °C for 12 hours. After the reaction was completed, the reaction solution was directly lyophilized to obtain a crude product. The crude product was separated by reverse-phase high performance liquid chromatography. The separation method was (chromatographic column: 3_Phenomenex Luna C18 75×30 mm×3 μm; mobile phase: A = water + 0.05% by volume HCl (36.5%), B = acetonitrile; gradient: 16% - 36% B, 7 minutes), to obtain a yellow solid, 5-(5-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(3-hydroxy-3-methylbut-1-yn-1-yl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (4) (17.5 mg, yield 13.2%).

[0241] 1 1H NMR (400 MHz, CDCl3) δ 8.46 (s, 1H), 8.04 (s, 1H), 5.82 - 6.11 (m, 1H), 2.57 - 2.62 (m, 1H), 1.64 - 1.92 (m, 1H), 1.64 (s, 6H), 1.47 - 1.51 (m, 1H), 1.35 - 1.37 (m, 1H).

[0242] LC - MS, M / Z (ESI): 363.2 [M + H] + 。

[0243] Example 5: Preparation of Target Compound 5

[0244] 5-(5-((1S,2S)-2-(Difluoromethyl)cyclopropyl)-6-(3-methylbut-1-yn-1-yl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (Target Compound 5)

[0245]

[0246] The synthetic route of Target Compound 5 is as follows:

[0247]

[0248] The first step: Synthesis of 4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)-3-(3-methylbut-1-yn-1-yl)pyridazine (5B)

[0249]

[0250] Under the protection of nitrogen, 3-chloro-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (253.2 mg, 583.6 μmol) and 3-methylbut-1-yne (59.6 mg, 875.3 μmol) were dissolved in N,N-dimethylformamide (5.00 mL). Then copper(I) iodide (11.1 mg, 58.4 μmol), triethylamine (236.2 mg, 2.33 mmol) and bis(triphenylphosphine)palladium(II) dichloride (40.9 mg, 58.4 μmol) were added thereto, and the reaction was carried out at 80 °C for 2 hours. After the reaction was completed, the reaction solution was added to water (10 mL), and then extracted with ethyl acetate (30 mL × 2). The organic phase was washed twice with saturated brine (50 mL), and then the organic phase was dried over anhydrous sodium sulfate. The organic phase was concentrated to obtain a yellow oily compound 4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)-3-(3-methylbut-1-yn-1-yl)pyridazine (5B) (180.0 mg, yield 76.6%).

[0251] LC-MS, M / Z(ESI): 375.3[M+H] + 。

[0252] Step 2: Synthesis of 5-(5-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(3-methylbut-1-yn-1-yl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (target compound 5)

[0253]

[0254] 4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)-3-(3-methylbut-1-yn-1-yl)pyridazine (80.0 mg, 213.7 μmol) was dissolved in hydrochloric acid (1 M, 2.14 mL), and then the reaction was carried out at 40 °C for 12 hours. After the reaction was completed, the reaction solution was directly lyophilized to obtain a yellow solid 5-(5-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(3-methylbut-1-yn-1-yl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (5) (40.5 mg, yield 50.4%).

[0255] 11H NMR (400 MHz, CDCl3) δ 8.67 (s, 1H), 8.23 (s, 1H), 5.84 - 6.13 (m, 1H), 2.99 - 3.03 (m, 1H), 2.69 - 2.71 (m, 1H), 2.03 - 2.05 (m, 1H), 1.56 - 1.59 (m, 2H), 1.35 - 1.37 (m, 6H).

[0256] LC-MS, M / Z (ESI): 347.2 [M + H] + 。

[0257] Example 6: Preparation of Target Compound 6

[0258] 5-(5-((1S,2S)-2-(Difluoromethyl)cyclopropyl)-6-((1-methyl-1H-pyrazol-4-yl)ethynyl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (Target Compound 6)

[0259]

[0260] The synthetic route of the target compound 6 is as follows:

[0261]

[0262] The first step: Synthesis of 4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)-3-((1-methyl-1H-pyrazol-4-yl)ethynyl)pyridazine (6B)

[0263]

[0264] Under the protection of nitrogen, 3-chloro-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (200.0 mg, 583.6 μmol) and 4-ethynyl-1-methyl-pyrazole (154.8 mg, 1.46 mmol) were dissolved in N,N-dimethylformamide (5.00 mL). Then copper(I) iodide (22.2 mg, 116.7 μmol), triethylamine (236.2 mg, 2.33 mmol) and bis(triphenylphosphine)palladium(II) dichloride (81.9 mg, 116.7 μmol) were added thereto, and the reaction was carried out at 80 °C for 2 hours. After the reaction was completed, the reaction solution was added to water (10 mL), extracted with ethyl acetate (30 mL × 2), the organic phase was washed twice with saturated brine (50 mL), and then the organic phase was dried over anhydrous sodium sulfate. The organic phase was concentrated to obtain a yellow oil, 4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)-3-((1-methyl-1H-pyrazol-4-yl)ethynyl)pyridazine (6B) (160.0 mg, yield 66.5%).

[0265] LC-MS, M / Z(ESI): 413.2[M+H] + 。

[0266] Step 2: Synthesis of 5-(5-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-((1-methyl-1H-pyrazol-4-yl)ethynyl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (Target Compound 6)

[0267]

[0268] 4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)-3-((1-methyl-1H-pyrazol-4-yl)ethynyl)pyridazine (160.0 mg, 450.9 μmol) was dissolved in hydrochloric acid (1 M, 3.88 mL), and then the reaction was carried out at 50 °C for 12 hours. After the reaction was completed, the reaction solution was directly lyophilized to obtain a crude product. The crude product was separated by reversed-phase high performance liquid chromatography. The separation method was (column: 3_Phenomenex Luna C18 75×30 mm×3 μm; mobile phase: A = water + 0.05% by volume HCl (36.5%), B = acetonitrile; gradient: 18% - 38% B, 7 minutes) to obtain a yellow solid, 5-(5-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-((1-methyl-1H-pyrazol-4-yl)ethynyl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (6) (66.8 mg, yield 43.4%).

[0269] 1 1H NMR (400 MHz, DMSO-d6) δ 11.65 (s, 1H), 11.56 (s, 1H), 8.40 (d, 1H), 8.23 (s, 1H), 7.96 (s, 1H), 7.82 (s, 1H), 5.91 - 6.21 (m, 1H), 3.90 (s, 3H), 2.50 - 2.56 (m, 1H), 1.89 - 1.93 (m, 1H), 1.43 - 1.46 (m, 1H), 1.31 - 1.33 (m, 1H).

[0270] LC-MS, M / Z (ESI): 385.2 [M + H] + 。

[0271] Example 7: Preparation of Target Compound 7

[0272] 5-(6-(Cyclobutylethynyl)-5-((1S,2S)-2-(difluoromethyl)cyclopropyl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (Target Compound 7)

[0273]

[0274] The synthetic route of Target Compound 7 is as follows:

[0275]

[0276] The first step: Synthesis of tributyl(cyclobutylethynyl)stannane (7A)

[0277]

[0278] At -5 °C, n-butyllithium (2.5 M, 7.03 mL) was added dropwise to tetrahydrofuran (5 mL), and the temperature was maintained below 10 °C. 6-Chloro-1-hexyne (1 g, 8.58 mmol) was added dropwise to the system at about 5 °C and stirred for 2 hours. Then tributyltin chloride (3.07 g, 9.43 mmol) was added dropwise to the system and reacted for 0.5 hour. The reaction system was quenched with potassium fluoride solution (50 mL), then extracted with ethyl acetate (50 mL × 3), the organic layers were combined, dried over sodium sulfate, and concentrated to obtain yellow oily tributyl(cyclobutylethynyl)stannane (7A) (3 g, yield 94.7%).

[0279] The second step: Synthesis of 3-(cyclobutylethynyl)-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (7B)

[0280]

[0281] 3-Chloro-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (200 mg, 583.5 μmol) and tributyl(cyclobutylethynyl)stannane (7A) (323.1 mg, 875.3 μmol) were dissolved in 1,4-dioxane (10 mL). Under nitrogen protection, bis(triphenylphosphine)palladium(II) dichloride (40.9 mg, 58.4 μmol) was added, and the temperature was raised to 80 °C and reacted for 3 hours. The reaction system was evaporated to dryness to obtain a crude product. It was separated and purified by silica gel column chromatography (petroleum ether:ethyl acetate (V / V) = 5:1–1:1, gradient elution) to obtain 3-(cyclobutylethynyl)-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (7B) as a yellow oil (200 mg, yield 88.7%).

[0282] LC-MS, M / Z (ESI): 387.2 [M+H] + 。

[0283] Step 3: Synthesis of 5-(6-(cyclobutylethynyl)-5-((1S,2S)-2-(difluoromethyl)cyclopropyl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (7)

[0284]

[0285] 3-(Cyclobutylethynyl)-4-((1S,2S)-2-(difluoromethyl)cyclopropyl)-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (3) (200 mg, 435.1 μmol) was dissolved in aqueous hydrochloric acid solution (1 M, 4.35 mL), and the temperature was raised to 50 °C and reacted for 12 hours. The reaction system was evaporated to dryness, and the crude product was separated by reverse-phase high performance liquid chromatography twice. The separation methods were (column: 3_Phenomenex Luna C18 75×30 mm×3 μm; mobile phase: A = water + 0.05% by volume HCl (36.5%), B = acetonitrile; gradient: 29% - 49% B, 7.5 minutes) and (column: Phenomenex Gemini-NX C18 75×30 mm×3 μm; mobile phase: A = water + ammonium bicarbonate (10 mmol), B = acetonitrile; gradient: 24% - 44% B, 8 minutes) to obtain 5-(6-(cyclobutylethynyl)-5-((1S,2S)-2-(difluoromethyl)cyclopropyl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (7) as a yellow solid (10.3 mg, yield 6.55%).

[0286] 11H NMR (400 MHz, CD3OD) δ 8.47 (s, 1H), 8.02 (s, 1H), 5.94 (td, 1H), 3.39 - 3.48 (m, 1H), 2.55 - 2.60 (m, 1H), 2.40 - 2.48 (m, 2H), 2.27 - 2.37 (m, 2H), 1.99 - 2.12 (m, 2H), 1.83 - 1.89 (m, 1H), 1.42 - 1.47 (m, 1H), 1.33 - 1.38 (m, 1H).

[0287] LC - MS, M / Z (ESI): 359.1 [M + H] + 。

[0288] Example 8: Preparation of Target Compound 8

[0289] 5-(6-(Cyclopropyl ethynyl)-5-((1S,2S)-2-(fluoromethyl)cyclopropyl)pyridazin - 3 - yl)pyrimidine - 2,4(1H,3H)-dione (Target Compound 8)

[0290]

[0291] The synthetic route of Target Compound 8 is as follows:

[0292]

[0293] The first step: Synthesis of 3-(cyclopropyl ethynyl)-6-(2,4 - dimethoxypyrimidin - 5 - yl)-4-((1S,2S)-2-(fluoromethyl)cyclopropyl)pyridazine (8B)

[0294]

[0295] Under the protection of nitrogen, 3-chloro-6-(2,4-dimethoxypyrimidin-5-yl)-4-((1S,2S)-2-(fluoromethyl)cyclopropyl)pyridazine (120.0 mg, 369.5 μmol) and ethynylcyclopropane (24.4 mg, 369.5 μmol) were dissolved in N,N-dimethylformamide (5.00 mL). Then copper(I) iodide (7.04 mg, 36.9 μmol), triethylamine (149.6 mg, 1.48 mmol) and bis(triphenylphosphine)palladium(II) dichloride (25.9 mg, 36.9 μmol) were added. The reaction was then carried out at 80 °C for 2 hours. After the reaction was completed, the reaction solution was added to water (10 mL), and then extracted with ethyl acetate (20 mL × 2). The organic phase was washed twice with saturated brine (50 mL), and then the organic phase was dried over anhydrous sodium sulfate. The organic phase was concentrated to obtain a yellow oil, 3-(cyclopropylethynyl)-6-(2,4-dimethoxypyrimidin-5-yl)-4-((1S,2S)-2-(fluoromethyl)cyclopropyl)pyridazine (8B) (90.0 mg, yield 39.2%).

[0296] LC-MS, M / Z(ESI): 355.2 [M+H] + 。

[0297] Step 2: Synthesis of 5-(6-(cyclopropylethynyl)-5-((1S,2S)-2-(fluoromethyl)cyclopropyl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (Target Compound 8)

[0298]

[0299] 3-(Cyclopropylethynyl)-6-(2,4-dimethoxypyrimidin-5-yl)-4-((1S,2S)-2-(fluoromethyl)cyclopropyl)pyridazine (90.0 mg, 253.9 μmol) was dissolved in hydrochloric acid (1 M, 2.54 mL), and then the reaction was carried out at 50 °C for 12 hours. After the reaction was completed, the reaction was directly lyophilized to obtain a crude product. The crude product was separated by reverse-phase high performance liquid chromatography. The separation method was (column: 3_Phenomenex Luna C18 75×30 mm×3 μm; mobile phase: A = water + 0.05% by volume HCl (36.5%), B = acetonitrile; gradient: 21% - 41% B, 7 minutes), to obtain a yellow solid, 5-(6-(cyclopropylethynyl)-5-((1S,2S)-2-(fluoromethyl)cyclopropyl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (8) (21.4 mg, yield 23.9%).

[0300] 11H NMR (400 MHz, CDCl3) δ 8.61 (s, 1H), 8.17 (s, 1H), 4.32 - 4.86 (m, 2H), 2.43 - 2.46 (m, 1H), 1.73 - 1.89 (m, 1H), 1.70 - 1.72 (m, 1H), 1.09 - 1.12 (m, 2H), 0.99 - 1.02 (m, 2H), 0.98 - 0.99 (m, 2H).

[0301] LC-MS, M / Z (ESI): 327.3 [M + H] + 。

[0302] Example 9: Preparation of Target Compound 9

[0303] 5-(6-(Cyclopropylethynyl)-5-((1R,2R)-2-(difluoromethyl)cyclopropyl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (Target Compound 9)

[0304]

[0305] The synthetic route of Target Compound 9 is as follows:

[0306]

[0307] The first step: Synthesis of 3-(2-cyclopropylethynyl)-4-[(1R,2R)-2-(difluoromethyl)cyclopropyl]-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (9A)

[0308]

[0309] Dissolve 3-chloro-4-[(1R,2R)-2-(difluoromethyl)cyclopropyl]-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (250 mg, 729 μmol) and ethynylcyclopropane (120 mg, 1.82 mmol) in N,N-dimethylacetamide (4.00 mL), then add dichlorobis(triphenylphosphine)palladium(II) (102 mg, 145 μmol), copper(I) iodide (27.7 mg, 145 μmol) and triethylamine (295 mg, 2.92 mmol) to the reaction solution, and react at 80 °C for 2 hours under nitrogen protection. After the reaction is completed, pour the reaction solution into water (5 mL), extract with ethyl acetate (20 mL × 2), wash with brine (20 mL × 2), dry over anhydrous sodium sulfate, filter, concentrate, and then separate and purify by silica gel column (petroleum ether:ethyl acetate (V / V) = 10:1 - 1:1) to obtain the yellow oily compound 3-(2-cyclopropylethynyl)-4-[(1R,2R)-2-(difluoromethyl)cyclopropyl]-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (9A) (260 mg, crude product).

[0310] LC-MS, M / Z(ESI): 373.2[M+H] + 。

[0311] Step 2: 5-[6-(2-cyclopropylethynyl)-5-[(1R,2R)-2-(difluoromethyl)cyclopropyl]pyridazin-3-yl]-1H-pyrimidine-2,4-dione (target compound 9)

[0312]

[0313] Dissolve 3-(2-cyclopropylethynyl)-4-[(1R,2R)-2-(difluoromethyl)cyclopropyl]-6-(2,4-dimethoxypyrimidin-5-yl)pyridazine (260 mg, 451 μmol) in 1M hydrochloric acid aqueous solution (3 mL), and react at 50 °C for 12 hours. After the reaction is completed, concentrate the reaction solution to obtain the product, and separate it by high performance liquid chromatography. The separation method is (chromatographic column: Phenomenex luna C18 150×40 mm×15 μm; mobile phase: A = water + 0.05% volume hydrochloric acid (36.5%), B = acetonitrile; gradient: 25% - 45%, 6.5 minutes) to obtain the yellow solid compound 5-[6-(2-cyclopropylethynyl)-5-[(1R,2R)-2-(difluoromethyl)cyclopropyl]pyridazin-3-yl]-1H-pyrimidine-2,4-dione (9) (41.0 mg, yield 17.2%).

[0314] 11H NMR (400 MHz, DMSO-d6): δ 11.59 - 11.61 (m, 1H), 11.53 (s, 1H), 8.33 - 8.35 (m, 1H), 7.88 (s, 1H), 5.89 - 6.19 (m, 1H), 2.42 - 2.44 (m, 1H), 1.81 - 1.85 (m, 1H), 1.69 - 1.70 (m, 1H), 1.39 - 1.40 (m, 1H), 1.21 - 1.26 (m, 1H), 0.99 - 1.01 (m, 2H), 0.87 - 0.89 (m, 2H).

[0315] LC-MS, M / Z (ESI): 345.1 [M + H] + 。

[0316] Example 10: Preparation of Target Compound 10

[0317] 5-[6-(2-Cyclopropyl ethynyl)-5-[(1S,2S)-2-(trifluoromethyl) cyclopropyl] pyridazin-3-yl]-1H-pyrimidine-2,4-dione (Target Compound 10)

[0318]

[0319] The synthetic route of Target Compound 10 is as follows:

[0320]

[0321] The first step: Synthesis of (1S,2S)-2-(ethoxycarbonyl) cyclopropanecarboxylic acid (10A)

[0322]

[0323] Dissolve ethyl (1S,2S)-2-(hydroxymethyl)cyclopropanecarboxylate (5.0 g, 34.7 mmol) in acetonitrile (50 mL). At 25 °C, successively add 2,2,6,6-tetramethylpiperidine N-oxide (436.3 mg, 2.8 mmol), sodium dihydrogen phosphate (6.66 g, 55.5 mmol), and disodium hydrogen phosphate (7.88 g, 55.5 mmol). Then dissolve sodium hypochlorite solution (0.5 mL) and sodium chlorite (6.27 g, 69.4 mmol) in 25 mL of water, and slowly add it dropwise to the reaction system at 0 °C. Then stir at 25 °C for 12 hours. Dilute the reaction system with water (100 mL), then extract with ethyl acetate (100 mL × 2). Combine the organic layers, add saturated aqueous sodium carbonate solution (100 mL), and stir for 10 minutes. Separate the organic phase, adjust the pH of the aqueous phase to 2 - 3 with 6 M hydrochloric acid solution, then extract with ethyl acetate (100 mL × 2). Combine the organic layers, wash the organic phase with saturated brine (100 mL), dry over anhydrous sodium sulfate, and concentrate to obtain a colorless oil, (1S,2S)-2-(ethoxycarbonyl)cyclopropanecarboxylic acid (10A) (4.8 g, yield 87.5%).

[0324] 1 H NMR (400 MHz, CDCl3) δ 10.34 (br.s, 1H), 4.14 (q, 2H), 2.11 - 2.22 (m, 2H), 1.43 - 1.50 (m, 2H), 1.25 (t, 3H).

[0325] Step 2: Synthesis of ethyl (1S,2S)-2-(trifluoromethyl)cyclopropanecarboxylate (10B)

[0326]

[0327] Add (1S,2S)-2-(ethoxycarbonyl)cyclopropanecarboxylic acid (3.0 g, 19.0 mmol) to an autoclave. Add sulfur tetrafluoride (9.0 g, 83.3 mmol) at -78 °C, then heat the reaction system to 70 °C in the autoclave and react for 16 hours. Add dichloromethane (20 mL) to the reaction system, wash the organic phase with saturated aqueous sodium bicarbonate solution (500 mL), dry over anhydrous sodium sulfate, and concentrate to obtain a yellow oil, ethyl (1S,2S)-2-(trifluoromethyl)cyclopropanecarboxylate (10B) (1.17 g, yield 33.9%).

[0328] 1 H NMR (400 MHz, CDCl3) δ 4.17 - 4.19 (m, 2H), 2.10 - 2.20 (m, 1H), 2.00 - 2.05 (m, 1H), 1.20 - 1.40 (m, 5H).

[0329] Step 3: Synthesis of (1S,2S)-2-(trifluoromethyl)cyclopropanecarboxylic acid (10C)

[0330]

[0331] Dissolve ethyl (1S,2S)-2-(trifluoromethyl)cyclopropanecarboxylate (1.1 g, 6.0 mmol) in tetrahydrofuran (10 mL) and water (5 mL), then add lithium hydroxide monohydrate (634 mg, 15.1 mmol), and react at 80 °C for 6 hours. After the reaction is completed, add water (20 mL), extract with dichloromethane (30 mL × 2), collect the aqueous phase, adjust the pH of the aqueous phase to 3 with 6M hydrochloric acid, then extract with dichloromethane (30 mL × 3), combine the organic phases, wash with saturated brine (50 mL), dry over anhydrous sodium sulfate, filter, and concentrate to obtain a brown oil, (1S,2S)-2-(trifluoromethyl)cyclopropanecarboxylic acid (10C) (500 mg, yield 53.7%).

[0332] 1 H NMR (400 MHz, CDCl3) δ 9.80 (br.s, 1H), 2.20 - 2.23 (m, 1H), 2.04 - 2.06 (m, 1H), 1.27 - 1.44 (m, 2H).

[0333] Step 4: Synthesis of 3,6-dichloro-4-((1S,2S)-2-(trifluoromethyl)cyclopropyl)pyridazine (10D)

[0334]

[0335] Dissolve 3,6-dichloropyridazine (450 mg, 3.02 mmol) and (1S,2S)-2-(trifluoromethyl)cyclopropanecarboxylic acid (465 mg, 3.02 mmol) in water (15 mL), then add concentrated sulfuric acid (0.5 mL), and heat to 70 °C under nitrogen protection. Then quickly add an aqueous solution of silver nitrate (257 mg, 1.51 mmol, 1.5 mL), and then slowly dropwise add an aqueous solution of ammonium persulfate (2.07 g, 9.06 mmol, 5 mL), and continue the reaction at 70 °C for 1 hour. Adjust the pH of the reaction solution to about 9 with ammonia water, then extract with ethyl acetate (40 mL × 2), combine the organic layers, wash the organic phase with saturated brine (50 mL), dry over sodium sulfate, and concentrate to obtain the crude product. Then separate by reverse-phase high-performance liquid chromatography, and the separation method is (chromatographic column: Phenomenex luna C18 150×40 mm×15 μm; mobile phase: A = water + 0.1% by volume of TFA, B = acetonitrile; gradient: 35% - 65% B, 10 minutes) to obtain 3,6-dichloro-4-((1S,2S)-2-(trifluoromethyl)cyclopropyl)pyridazine (10D) as a yellow oil (350 mg, yield 43.8%).

[0336] LC-MS, M / Z(ESI): 256.9[M+H] + 。

[0337] Step 5: Synthesis of 3-chloro-6-(2,4-dimethoxypyrimidin-5-yl)-4-((1S,2S)-2-(trifluoromethyl)cyclopropyl)pyridazine (10E)

[0338]

[0339] Dissolve 3,6-dichloro-4-((1S,2S)-2-(trifluoromethyl)cyclopropyl)pyridazine (350 mg, 1.32 mmol) and 2,4-dimethoxypyrimidine-5-boronic acid (343 mg, 1.32 mmol) in dioxane (5 mL) and water (1 mL), add sodium carbonate (420 mg, 3.96 mmol) and [1,1-bis(diphenylphosphino)ferrocene]dichloropalladium (97 mg, 132 μmol) under nitrogen protection, and heat to 50 °C for reaction for 12 hours. Dilute the reaction mixture with water (20 mL), then extract with ethyl acetate (20 mL × 2), combine the organic layers, wash the organic phase with saturated brine (50 mL), dry over sodium sulfate, and concentrate to obtain the crude product. Purify by silica gel column chromatography (petroleum ether:ethyl acetate (V / V) = 50:1 - 3:1, gradient elution) to obtain 3-chloro-6-(2,4-dimethoxypyrimidin-5-yl)-4-((1S,2S)-2-(trifluoromethyl)cyclopropyl)pyridazine (10E) as a yellow oil (300 mg, yield 44%).

[0340] LC-MS, M / Z (ESI): 361.0 [M+H] + 。

[0341] Step 6: Synthesis of 3-(2-Cyclopropyl ethynyl)-6-(2,4-dimethoxypyrimidin-5-yl)-4-[(1S,2S)-2-(trifluoromethyl)cyclopropyl]pyridazine (10F)

[0342]

[0343] Dissolve 3-chloro-6-(2,4-dimethoxypyrimidin-5-yl)-4-[(1S,2S)-2-(trifluoromethyl)cyclopropyl]pyridazine (500 mg, 1.39 mmol) and ethynylcyclopropane (229 mg, 3.47 mmol) in N,N-dimethylacetamide (5.00 mL). Then add dichlorobis(triphenylphosphine)palladium(II) (194 mg, 277 μmol), copper(I) iodide (52.8 mg, 277 μmol) and triethylamine (561 mg, 5.54 mmol) to the reaction solution. React at 80 °C for 2 hours under nitrogen protection. After the reaction is completed, pour the reaction solution into water (10 mL), extract with ethyl acetate (20 mL × 2), wash with brine (20 mL × 2), dry over anhydrous sodium sulfate, filter, concentrate, and then separate and purify by silica gel column (petroleum ether:ethyl acetate (V / V) = 10:1 - 1:1) to obtain the yellow oily compound 3-(2-cyclopropyl ethynyl)-6-(2,4-dimethoxypyrimidin-5-yl)-4-[(1S,2S)-2-(trifluoromethyl)cyclopropyl]pyridazine (10F) (503 mg, crude product).

[0344] LC-MS, M / Z (ESI): 391.1 [M+H] + 。

[0345] Step 7: 5-[6-(2-Cyclopropyl ethynyl)-5-[(1S,2S)-2-(trifluoromethyl)cyclopropyl]pyridazin-3-yl]-1H-pyrimidine-2,4-dione (Target Compound 10)

[0346]

[0347] 3-(2-Cyclopropylethynyl)-6-(2,4-dimethoxypyrimidin-5-yl)-4-[(1S,2S)-2-(trifluoromethyl)cyclopropyl]pyridazine (503 mg, 503 μmol) was dissolved in 1 M sulfuric acid aqueous solution (5 mL), and reacted at 50 °C for 12 hours. After the reaction was completed, the reaction solution was concentrated to obtain the product, and then separated by high performance liquid chromatography. The separation method was (chromatographic column: Phenomenex luna C18 150×40 mm×15 μm; mobile phase: A = water + 0.05% by volume hydrochloric acid (36.5%), B = acetonitrile; gradient: 30% - 50%, 12 minutes), and yellow solid compound 5-[6-(2-cyclopropylethynyl)-5-[(1S,2S)-2-(trifluoromethyl)cyclopropyl]pyridazin-3-yl]-1H-pyrimidine-2,4-dione (10) (29.0 mg, yield 15.2%) was obtained.

[0348] 1 1H NMR (400 MHz, DMSO-d6): δ 8.38 (s, 1H), 7.96 (s, 1H), 2.70 - 2.72 (m, 1H), 2.32 - 2.34 (m, 1H), 1.66 - 1.70 (m, 1H), 1.49 - 1.51 (m, 2H), 1.00 - 1.03 (m, 2H), 0.82 - 0.84 (m, 2H).

[0349] LC-MS, M / Z (ESI): 363.1 [M+H] + 。

[0350] Example 11: Preparation of target compound 11

[0351] 5-(5-((1S,2R)-2-Isopropylcyclopropyl)-6-(prop-1-yn-1-yl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (target compound 11)

[0352]

[0353] The synthetic route of target compound 11 is as follows:

[0354]

[0355] The first step: Synthesis of (S)-2-chloro-3-methylbutan-1-ol (11B)

[0356]

[0357] (S)-2-Chloro-3-methylbutyric acid (30.0 g, 0.22 mmol) was dissolved in tetrahydrofuran (300 mL), and lithium aluminum hydride (9.17 g, 0.24 mmol) was slowly added thereto at 0 - 10 °C. After the addition, the mixture was stirred at 25 °C for 1 hour, and then heated to 50 °C for reaction for 1 hour. After the reaction was completed, the reaction solution was cooled to 0 - 10 °C, and water (9 mL), 15% aqueous sodium hydroxide solution (9 mL) and water (27 mL) were added successively. Then, it was filtered through diatomaceous earth, and the filter cake was washed with tetrahydrofuran (100 mL × 3), and the filtrate was concentrated to obtain a crude product. It was separated and purified by silica gel column chromatography (petroleum ether:ethyl acetate (V / V) = 5:1 - 2:1) to obtain a yellow oil, (S)-2-chloro-3-methylbutan-1-ol (11B) (8.4 g, yield 31%).

[0358] 1 H NMR (400 MHz, CDCl3) δ 3.91 - 3.94 (m, 1H), 3.74 - 3.82 (m, 2H), 2.06 - 2.09 (m, 1H), 1.99 - 2.05 (m, 1H), 1.04 (dd, 6H).

[0359] Step 2: Synthesis of (R)-2-isopropyloxirane (11C)

[0360]

[0361] Potassium hydroxide (52.1 g, 0.93 mol) was dissolved in water (50 mL), cooled to 0 - 5 °C, and then (S)-2-chloro-3-methylbutan-1-ol (25.0 g, 0.20 mol) was added dropwise, and then the mixture was reacted at 25 °C for 1 hour. After the reaction was completed, the reaction solution was distilled at 25 °C, and the distillate was collected by cooling with a dry ice-ethanol bath to obtain a yellow oil, (R)-2-isopropyloxirane (11C) (16.0 g, yield 91.1%).

[0362] 1 H NMR (400 MHz, CDCl3) δ 2.71 - 2.74 (m, 2H), 2.52 - 2.54 (m, 1H), 1.47 - 1.53 (m, 1H), 1.04 (d, 3H), 0.97 (d, 3H).

[0363] Step 3: Synthesis of ethyl (1S,2R)-2-isopropylcyclopropane-1-carboxylate (11D)

[0364]

[0365] Triethyl phosphonoacetate (14.3 g, 63.8 mmol) was dissolved in 1,4-dioxane (20 mL), and then n-butyllithium (2.5 M, 30.2 mL) was added dropwise at 0 °C. After the addition was completed, the reaction mixture was stirred at 25 °C for 0.5 h, and then transferred to a sealed tube. Then, a solution of (R)-2-isopropyloxirane (5.00 g, 58.1 mmol) in 1,4-dioxane (10 mL) was added. The sealed tube was tightened and heated to 145 °C for reaction for 12 h. After the reaction was completed, the reaction system was cooled, then water (100 mL) was added, and the mixture was extracted with methyl tert-butyl ether (100 mL × 2). The organic phase was dried over anhydrous sodium sulfate, filtered, and concentrated to obtain a yellow oil, ethyl (1S,2R)-2-isopropylcyclopropane-1-carboxylate (11D) (7.0 g, yield 80.8%).

[0366] 1 H NMR (400 MHz, CDCl3) δ 4.09 - 4.13 (m, 2H), 1.36 - 1.39 (m, 1H), 1.19 - 1.27 (m, 5H), 1.09 - 1.13 (m, 1H), 0.96 - 0.99 (m, 6H), 0.69 - 0.75 (m, 1H).

[0367] Step 4: Synthesis of (1S,2R)-2-isopropylcyclopropane-1-carboxylic acid (11E)

[0368]

[0369] Ethyl (1S,2R)-2-isopropylcyclopropane-1-carboxylate (7.00 g, 44.8 mmol) was dissolved in 1,4-dioxane (60 mL) and water (60 mL), and then sodium hydroxide (17.9 g, 448.1 mmol) was added. The reaction was carried out at 100 °C for 7 h. After the reaction was completed, the mixture was extracted with methyl tert-butyl ether (100 mL × 2). The aqueous phase was collected, and the pH of the aqueous phase was adjusted to 1 - 2 with concentrated hydrochloric acid, and then extracted with methyl tert-butyl ether (100 mL × 2). The combined organic phases were washed with saturated brine (100 mL), dried over anhydrous sodium sulfate, filtered, and concentrated to obtain a yellow oil, (1S,2R)-2-isopropylcyclopropane-1-carboxylic acid (11E) (6.40 g, crude product), which was directly used in the next step.

[0370] 1 H NMR (400 MHz, CDCl3) δ 1.56 - 1.60 (m, 1H), 1.45 - 1.50 (m, 1H), 1.37 - 1.40 (m, 1H), 1.21 - 1.27 (m, 1H), 1.60 - 1.85 (m, 6H), 0.97 - 1.02 (m, 1H).

[0371] Step 5: Synthesis of 3,6-dichloro-4-((1S,2R)-2-isopropylcyclopropyl)pyridazine (11F)

[0372]

[0373] Dissolve 3,6-dichloropyridazine (6.27 g, 42.1 mmol) and (1S,2S)-2-(difluoromethyl)cyclopropane-1-carboxylic acid (5.39 g, 42.1 mmol) in water (100 mL), then add concentrated sulfuric acid (5.39 mL), and heat to 70 °C under nitrogen protection. Then quickly add an aqueous solution of silver nitrate (3.57 g, 21.0 mmol, 25 mL), and then slowly dropwise add an aqueous solution of ammonium persulfate (28.8 g, 126.2 mmol, 50 mL), and continue the reaction at 70 °C for 1 hour. After the reaction is completed, adjust the pH of the reaction solution to about 9 with ammonia water, then extract with ethyl acetate (200 mL × 2), combine the organic layers, wash the organic phase with saturated brine (100 mL), dry over anhydrous sodium sulfate, and concentrate to obtain the crude product. Purify by silica gel column chromatography (petroleum ether:ethyl acetate (V / V) = 10:1 - 3:1) to obtain 3,6-dichloro-4-((1S,2R)-2-isopropylcyclopropyl)pyridazine (11F) as a yellow oil (3.20 g, yield 32.9%).

[0374] LC-MS, M / Z (ESI): 231.0 [M+H] + 。

[0375] Step 6: Synthesis of 3-chloro-6-(2,4-dimethoxypyrimidin-5-yl)-4-((1S,2R)-2-isopropylcyclopropyl)pyridazine (11G)

[0376]

[0377] 3,6-Dichloro-4-((1S,2R)-2-isopropylcyclopropyl)pyridazine (2.10 g, 9.09 mmol) and 2,4-dimethoxypyrimidine-5-boronic acid (1.67 g, 9.09 mmol) were dissolved in 1,4-dioxane (10 mL) and water (3 mL). Under nitrogen protection, sodium carbonate (2.89 g, 27.3 mmol) and [1,1-bis(diphenylphosphino)ferrocene]dichloropalladium (664.8 mg, 0.91 mmol) were added, and the temperature was raised to 100 °C and reacted for 2 hours. The reaction mixture was diluted with water (100 mL), then extracted with ethyl acetate (150 mL × 2). The organic phases were combined, washed with saturated brine (100 mL), dried over anhydrous sodium sulfate, and concentrated to obtain the crude product. Purification by silica gel column chromatography (petroleum ether:ethyl acetate (V / V) = 10:1 - 2:1) gave 3-chloro-6-(2,4-dimethoxypyrimidin-5-yl)-4-((1S,2R)-2-isopropylcyclopropyl)pyridazine (11G) as a yellow oil (2.00 g, yield 65.7%).

[0378] LC-MS, M / Z(ESI): 335.1 [M+H] + 。

[0379] Step 7: Synthesis of 6-(2,4-dimethoxypyrimidin-5-yl)-4-((1S,2R)-2-isopropylcyclopropyl)-3-(prop-1-yn-1-yl)pyridazine (11H)

[0380]

[0381] 3-Chloro-6-(2,4-dimethoxypyrimidin-5-yl)-4-[(1S,2R)-2-isopropylcyclopropyl]pyridazine (1.10 g, 3.29 mmol), dichlorobis(triphenylphosphine)palladium(II) (230 mg, 328 μmol) and tributyl(prop-1-ynyl)stannane (1.30 g, 3.94 mmol) were dissolved in N,N-dimethylformamide (10 mL), and then reacted at 110 °C for 2 hours under nitrogen protection. After the reaction was completed, the reaction solution was poured into water (20 mL), and then extracted with ethyl acetate (50 mL × 2). The organic phase was washed with brine (50 mL), dried over sodium sulfate, and the reaction solution was concentrated. Purification by silica gel column chromatography (petroleum ether:ethyl acetate (V / V) = 10:1 - 5:1) gave 6-(2,4-dimethoxypyrimidin-5-yl)-4-((1S,2R)-2-isopropylcyclopropyl)-3-(prop-1-yn-1-yl)pyridazine (11H) as a yellow oil (1.00 g, yield 89.1%).

[0382] LC-MS, M / Z(ESI): 339.1 [M+H] + 。

[0383] Step 8: Synthesis of 5-(5-((1S,2R)-2-isopropylcyclopropyl)-6-(prop-1-yn-1-yl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (11)

[0384]

[0385] Dissolve 6-(2,4-dimethoxypyrimidin-5-yl)-4-((1S,2R)-2-isopropylcyclopropyl)-3-(prop-1-yn-1-yl)pyridazine (1.00 g, 2.67 mmol) in hydrochloric acid (1 M, 5.00 mL) and react at 50 °C for 12 h. After completion of the reaction, concentrate the reaction solution and then separate it by reversed-phase high performance liquid chromatography (column: Phenomenex luna C18 150×4.0 mm×15 μm; mobile phase: A = water + 0.225% v / v formic acid (99%), B = acetonitrile; gradient: 28% - 58%, 10 min) to obtain the yellow solid compound 5-(5-((1S,2R)-2-isopropylcyclopropyl)-6-(prop-1-yn-1-yl)pyridazin-3-yl)pyrimidine-2,4(1H,3H)-dione (11) (295 mg, yield 36.7%).

[0386] 1 H NMR (400 MHz, CD3OD): δ 8.40 (s, 1H), 7.84 (s, 1H), 2.22 (s, 3H), 2.14 - 2.17 (m, 1H), 1.19 - 1.21 (m, 1H), 1.13 - 1.17 (m, 1H), 1.09 - 1.11 (m, 1H), 1.08 (s, 3H), 1.06 (s, 3H), 1.04 - 1.05 (m, 1H).

[0387] LC-MS, M / Z (ESI): 311.1 [M + H] + .

[0388] Test Example 1: In vitro inhibitory activity of the compound against recombinant human CD73 enzyme

[0389] The experiment was carried out in Tris-MgCl2 buffer containing 25 mM Tris (Biosharp; 77-86-1) and 25 mM MgCl2 (Nanjing Chemical Reagent Co., Ltd.; 7791-18-6). Human-CD73 (Novoprotein; C446) was prepared as a 3× stock solution with Tris-MgCl2 buffer and added to a 96-well white plate at 20 μL / well to give a final concentration of 0.1 μg / mL; the final concentration of the compound was diluted with Tris-MgCl2 buffer to a 3× stock solution with an appropriate concentration gradient, and the compound was added to the above-mentioned 96-well test white plate at 20 μL / well. After mixing, it was incubated at room temperature for 30 min. At the same time, a positive control group (without compound) and a negative control group (without CD73) were set; AMP (Sigma; A1752-5G) was prepared as a 3× stock solution with Tris-MgCl2 buffer and added to the above-mentioned 96-well white plate at 20 μL / well to give a final concentration of 100 μM, mixed well, and continued to incubate at 37 °C for 60 min; ATP was prepared as a 7× stock solution with Tris-MgCl2 buffer and added to the above-mentioned 96-well white plate at 10 μL / well, with a final concentration of 100 μM, mixed well, and continued to incubate for 5 min, and detected with the ATP-GLO kit (Promega; G7573).

[0390] Calculate the inhibition rate of the compound at different concentrations on Human-CD73 according to the following formula, and then use the compound concentration as the X-axis and the inhibition rate as the Y-axis to calculate the IC 50 value of the compound's inhibition of Human-CD73 through Prism software:

[0391]

[0392] Table 1 In vitro inhibitory activity of test compounds on Human-CD73 enzyme

[0393] Test compound <![CDATA[IC 50 (nM)]]> Control compound 2 27.03 1 21.61 2 9.118 3 4.638 4 83.94 5 196.2 6 34.80 7 33.74 8 60.03 9 247.6 10 11.19 11 14.71

[0394] The results of the in vitro enzyme test showed that the compounds of the present invention had good inhibitory effects on CD73 enzyme. Compared with the control compounds, some of the compounds of the present invention showed more excellent inhibitory effects on CD73 enzyme.

[0395] Test Example 2: Pharmacokinetic experiment

[0396] Mouse pharmacokinetic study: Male ICR mice, weighing 20 - 25 g, were fasted overnight. Three mice were orally administered the drug (10 mg / kg) by gavage. Blood samples were collected before dosing and at 15, 30 minutes, and 1, 2, 4, 8, 24 hours after dosing. Additionally, three mice were intravenously administered the drug (3 mg / kg), and blood samples were collected before dosing and at 15, 30 minutes, and 1, 2, 4, 8, 24 hours after dosing. The blood samples were centrifuged at 6800 g for 6 minutes at 2 - 8 °C, and the plasma was collected and stored at -80 °C. Plasma samples at each time point were mixed with 3 - 5 volumes of acetonitrile solution containing internal standard, vortexed for 1 minute, centrifuged at 13000 rpm for 10 minutes at 4 °C, the supernatant was mixed with 3 volumes of water, and an appropriate amount of the mixture was subjected to LC-MS / MS analysis. The main pharmacokinetic parameters were analyzed using the non-compartmental model with WinNonlin 7.0 software.

[0397] Rat pharmacokinetic study: Male SD rats, weighing 250 - 280 g, were fasted overnight. Three rats were orally administered the drug (10 mg / kg) by gavage. Blood samples were collected before dosing and at 15, 30 minutes, and 1, 2, 4, 8, 24 hours after dosing. Additionally, three rats were intravenously administered the drug (3 mg / kg), and blood samples were collected before dosing and at 15, 30 minutes, and 1, 2, 4, 8, 24 hours after dosing. The blood samples were centrifuged at 6800 g for 6 minutes at 2 - 8 °C, and the plasma was collected and stored at -80 °C. Plasma samples at each time point were mixed with 3 - 5 volumes of acetonitrile solution containing internal standard, vortexed for 1 minute, centrifuged at 13000 rpm for 10 minutes at 4 °C, the supernatant was mixed with 3 volumes of water, and an appropriate amount of the mixture was subjected to LC-MS / MS analysis. The main pharmacokinetic parameters were analyzed using the non-compartmental model with WinNonlin 7.0 software.

[0398] Table 2 Results of mouse pharmacokinetic study

[0399]

[0400] Note: — indicates not tested

[0401] The results of the mouse pharmacokinetic study showed that the compound of the present invention exhibited excellent pharmacokinetic properties. Compared with the control compound, the compound of the present invention had a greater exposure and good drug-likeness.

[0402] Table 3 Results of rat pharmacokinetic study

[0403]

[0404] Note: — indicates not tested

[0405] The results of the rat pharmacokinetic study showed that the compound of the present invention exhibited excellent pharmacokinetic properties. Compared with the control compound, the compound of the present invention had a greater exposure and good drug-likeness.

Claims

1. A compound of formula I, its stereoisomers or pharmaceutically acceptable salts: Wherein, m is 1; R in the middle 1 independently selected from hydrogen, halogen, unsubstituted or substituted by R a substituted C1-C6 alkyl; said being substituted by R a substitution may be one or more substitutions, said R a each independently being the following substituents: halogen, C1-C6 alkyl; when there are multiple substituents, said substituents are the same or different; n is 0; R 2 is selected from hydrogen, unsubstituted or replaced by R b Substituted C1-C6 alkyl, unsubstituted or replaced by R b Substituted C3-C6 cycloalkyl, unsubstituted or replaced by R b substituted 5-8 membered heteroaryl; said R b Substituted C1-C6 alkyl, the R b Substituted C3-C6 cycloalkyl, the R b In the substituted 5-8 membered heteroaryl, the b The substitution may be one or more substitutions, and the R b Each is independently a substituent from the following: halogen, hydroxyl, C1-C6 alkyl, C1-C6 alkyl substituted by 1-5 identical or different halogens; when there are multiple substituents, the substituents are the same or different; The unsubstituted or R-substituted 5- to 8-membered heteroaryl group, wherein the heteroatom is selected from one or more of N, S, O, and P, and the number of heteroatoms is 1 to 3. b ​ 2. The compound of formula I, its stereoisomers or pharmaceutically acceptable salts according to claim 1, characterized in that, When R 2 is an unsubstituted or R b -substituted C1-C6 alkyl, the C1-C6 alkyl is a C1-C4 alkyl; and / or, when R 2 is unsubstituted or substituted by R b which is a C1-C6 alkyl group, the number of the substituents R b is 1-3; and / or, when R 2 is unsubstituted or substituted by R b substituted C3-C6 cycloalkyl, and the C3-C6 cycloalkyl is cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl; and / or, when R 2 is unsubstituted or substituted by R b and is a 5- to 8-membered heteroaryl, the 5- to 8-membered heteroaryl is independently pyrrole, pyrazole, triazole, furan, oxazole, thiophene, thiazole, pyridine, pyrazine or pyrimidine; and / or, R b is a hydroxyl group; and / or, when R b is a C1-C6 alkyl group, the C1-C6 alkyl group is a C1-C4 alkyl group; and / or, when R b is a halogen, the halogen is F, Cl, Br, or I.

3. The compound of formula I, its stereoisomers or pharmaceutically acceptable salts according to claim 1 or 2, characterized in that, When R 2 is an unsubstituted or R b -substituted C1-C6 alkyl, the C1-C6 alkyl is methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl; and / or, when R 2 is unsubstituted or substituted by R b to form a C1-C6 alkyl group, the number of the substituent R b is 1; and / or, when R 2 is unsubstituted or substituted by R b to form a C3-C6 cycloalkyl group, where the C3-C6 cycloalkyl group is cyclopropyl or cyclobutyl; and / or, when R 2 is unsubstituted or substituted by R b and is a 5- to 8-membered heteroaryl group, the 5- to 8-membered heteroaryl group is independently pyrazole, furan, thiophene, pyridine; and / or, when R b is a C1-C6 alkyl group, the C1-C6 alkyl group is methyl, ethyl, n-propyl or isopropyl; and / or, when R b is a halogen, the halogen is F or Cl.

4. The compound of formula I, its stereoisomers or pharmaceutically acceptable salts according to claim 1 or 2, characterized in that, The and / or, when R 1 is a halogen, the halogen is F, Cl, Br or I; and / or, when R 1 is unsubstituted or substituted by R a is a C1-C6 alkyl group, said C1-C6 alkyl group is independently a C1-C4 alkyl group; and / or, when R 1 is a C1-C6 alkyl group substituted by R a , the number of said substitutions is independently 1-3; and / or, when R 1 is a C1-C6 alkyl group substituted by R a When the substituents are each independently a C1-C6 alkyl group, the C1-C6 alkyl groups in the substituents are independently C1-C4 alkyl groups; and / or, when R a is a halogen, the halogen is F, Cl, Br or I.

5. The compound of formula I, its stereoisomers or pharmaceutically acceptable salts according to claim 1 or 2, characterized in that, and / or, when R 1 is a halogen, the halogen is F or Cl; and / or, when R 1 is unsubstituted or substituted by R a is a C1-C6 alkyl group, the C1-C6 alkyl group is independently methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl; and / or, when R 1 is a C1-C6 alkyl group substituted by R a , the number of said substitutions is independently 2; and / or, when R 1 is a C1-C6 alkyl group substituted by R a each of the substitutions is independently a C1-C6 alkyl group, and the C1-C6 alkyl group in each of the substitutions is independently methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl; and / or, when R a is a halogen, the halogen is F or Cl.

6. The compound of formula I, its stereoisomers or pharmaceutically acceptable salts according to claim 1 or 2, characterized in that, When is , the said is 7. The compound of formula I, its stereoisomers or pharmaceutically acceptable salts according to claim 1 or 2, characterized in that, and / or, R 2 is 8. The compound of formula I, its stereoisomers or pharmaceutically acceptable salts according to claim 1 or 2, characterized in that, For and / or, R 2 is 9. The compound of formula I, its stereoisomers or pharmaceutically acceptable salts according to claim 1 or 2, characterized in that, It is Wherein, R 1 independently selected from hydrogen, halogen, unsubstituted or R-substituted C1-C6 alkyl; each of said substitutions independently refers to substitution by one or more of the following substituents: halogen, C1-C6 alkyl; when there are multiple substituents, said substituents are the same or different; a ​ R 2 selected from hydrogen, unsubstituted or R b substituted C1-C6 alkyl, unsubstituted or R b substituted C3-C6 cycloalkyl, unsubstituted or R b substituted 5-8-membered heteroaryl; wherein the R b substituted C1-C6 alkyl, the R b substituted C3-C6 cycloalkyl, the R b substituted 5-8-membered heteroaryl, each of the substitutions independently refers to one or more of the following substituents: halogen, hydroxy, C1-C6 alkyl, C1-C6 alkyl substituted with 1-5 identical or different halogens; when there are multiple substituents, the substituents are the same or different; The unsubstituted or R b -substituted 5- to 8-membered heteroaryl, wherein the heteroatom is selected from one or more of N, S, O, and P, and the number of heteroatoms is 1 to 3.

10. The compound of formula I or a pharmaceutically acceptable salt thereof according to claim 1 or 2, characterized in that, It is wherein, R 1 and R 2 have the definitions as described in claim 1.

11. The compound of formula I or a pharmaceutically acceptable salt thereof according to claim 10, characterized in that, R 1 selected from difluoromethyl, trifluoromethyl, dichloromethyl, trichloromethyl or isopropyl; R 2 Selected from methyl, ethyl or cyclopropyl.

12. The compound, its stereoisomer or pharmaceutically acceptable salt according to claim 1 or 2, characterized in that, The compound of formula I is selected from any of the following compounds:

13. A pharmaceutical composition, characterized in that, It comprises the compound of formula I, its stereoisomers or pharmaceutically acceptable salts according to any one of claims 1-12, and a pharmaceutically acceptable excipient.

14. The use of the compound, its stereoisomers or pharmaceutically acceptable salts according to any one of claims 1-12, or the pharmaceutical composition according to claim 13 in combination with a PD-1 antibody, a PD-L1 antibody, a CTLA-4 antibody, or a PD-1 inhibitor, a PD-L1 inhibitor, a CTLA-4 inhibitor in the preparation of a medicament for the treatment of CD73-related diseases.

15. The use of the compound, its stereoisomers or pharmaceutically acceptable salts according to any one of claims 1-12, or the pharmaceutical composition according to claim 13 in the preparation of a medicament for the treatment of CD73-related diseases.

16. The use according to claim 14 or 15, characterized in that, The CD73-related disease is cancer.

17. The use according to claim 16, characterized in that, The cancer is bladder cancer, breast cancer, cholangiocarcinoma, rectal cancer, colon cancer, gastric cancer, gallbladder cancer, glioblastoma, head and neck cancer, liver cancer, lung cancer, lymphoma, medulloblastoma, melanoma, ovarian cancer, pancreatic cancer, prostate cancer or kidney cancer.

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