TW201841896A - Heterocyclic compound serving as pd-l1 inhibitor - Google Patents

Abstract

The present invention relates to the field of medical chemistry, and relates to a heterocyclic compound serving as a PD-L1 inhibitor. Specifically, the present invention relates to a compound represented by formula A, or an isomer, pharmaceutically acceptable salt, solvate or prodrug thereof, preparation methods therefor, a pharmaceutical composition containing these compounds, and a use of these compounds or composition in treating cancers or infectious diseases.

Description

Heterocyclic compounds as PD-L1 inhibitors

The present invention belongs to the field of medicinal chemistry, and relates to a class of heterocyclic compounds as PD-L1 inhibitors and uses thereof. In particular, the present invention relates to a compound of the formula A or an isomer thereof, a pharmaceutically acceptable salt thereof, Solvates or prodrugs, processes for their preparation, and pharmaceutical compositions containing such compounds and the use of such compounds or compositions for the treatment of cancer or infectious diseases.

Programmed Cell Death-1 (PD-1) and its ligand PD-L1 (B7·H1) belong to the CD28/B7 superfamily. PD-1 is mainly expressed on the membrane surface of T cells, B cells, and natural killer cells (NK cells). PD-L1 is mainly expressed on mature CD4 T cells, CD8 T cells, B cells, monocytes, Hematopoietic cells such as dendritic cells (DCs), macrophages, and some non-hematopoietic cells, such as membrane surfaces of endothelial cells, islet cells, mast cells, and the like. Among them, PD-L1 is highly expressed in various tumors, such as lung cancer, gastric cancer, multiple bone marrow, melanoma and breast cancer. The expression of PD-L1 on the surface of tumor cells interacts with the ligand on the surface of T cells, which can induce apoptosis of T cells or reduce the reactivity of T cells, thereby inhibiting the tumor immune response and allowing tumor cells to escape immune attack. Therefore, blocking the antagonist of the PD1-PDL1 signal pathway can promote the activation of T cells, reverse the tumor immune microenvironment, and enhance the endogenous anti-tumor immune effect. Target PD-1/PD-L1 inhibitors have broad application prospects in the field of tumor immunotherapy.

Currently, anti-PD-1/PD-L1 antibody therapy has been shown to have a clinical advantage, however, biomacromolecules also have some disadvantages such as immunogenicity and limitations of the route of administration. Therefore, there is still a need to develop targeted PD-1/PD-L1 inhibitors with better pharmacodynamics. The inventors of the present invention have found that a class of small molecule drugs can specifically modulate and/or mediate the transduction of PD-L1 and its related protein kinases for the treatment of diseases associated with PD-1/PD-L1.

It is an object of the present invention to provide a compound of the formula A or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, (A) wherein: X and Y are each independently selected from N, O and S, and when X is N, Y is selected from O and S; when X is O or S, Y is N; when Y is N, X is selected From O and S; when Y is O or S, X is N; when X is N, Y is selected from O and S or Y is O or S, and X is N, the group for When X is O or S, Y is N or Y is N, and X is selected from O and S, the group for R _{1 is} selected from the side chain of the amino acids Ser and Thr; R _{2 is} selected from the amino acid Ser and Thr residues; R _{3 is} selected from H, -(CH ₂ ) _m C(O)OR ₄ , -(CH ₂ ) _m C (O)N(R ₅ )(R ₆ ) and —(CH ₂ ) _m CN, wherein R ₄ , R ₅ , R ₆ are each independently selected from H and alkyl, and m is 0, 1, 2, 3 or 4; and n is 1, 2, 3 or 4.

In some preferred embodiments, a compound of Formula A, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, which is represented by Formula I or II a compound or a stereoisomer thereof, a pharmaceutically acceptable salt, a solvate, a crystal or a prodrug: (I), (II), wherein: Q is selected from O and S; and R ₁ , R ₂ , and R ₃ are as defined in Formula A.

In some embodiments, a compound of Formula A, Formula I or II, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, according to the invention, wherein: R ₁ a side chain selected from the group consisting of the amino acids Ser and Thr; R _{2 is} selected from the group consisting of the amino acid Ser and Thr residues; R _{3 is} selected from the group consisting of H, -(CH ₂ ) _m C(O)OR ₄ , -(CH ₂ ) _m C(O) N(R ₅ )(R ₆ ) and —(CH ₂ ) _m CN, wherein R ₄ , R ₅ , R ₆ are each independently selected from H and C _1-6 alkyl, and m is 1, 2, 3 or 4 ; and n is 1, 2, 3 or 4.

In some embodiments, a compound of Formula A, Formula I or II, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, according to the invention, wherein: R ₁ Selected from with ; R _{2 is} selected from with ; R _{3 is} selected from the group consisting of H, -(CH ₂ ) _m C(O)OR ₄ , -(CH ₂ ) _m C(O)N(R ₅ )(R ₆ ) and -(CH ₂ ) _m CN, wherein R ₄ , R ₅ and R ₆ are each independently selected from H and C _1-6 alkyl, m is 1, 2, 3 or 4; and n is 1, 2, 3 or 4.

In some embodiments, a compound of Formula A, Formula I or II, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, according to the invention, wherein: R ₁ Selected from with ; R _{2 is} selected from with ; R _{3 is} selected from H, , , , , , with ; and n is 1, 2, 3 or 4. In some embodiments, the compound of Formula A, Formula I or II above, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof thereof, according to the invention, wherein Selected from , , , , , , with .

In some embodiments, a compound of Formula A, Formula I or II, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, according to the invention, wherein: R ₁ Selected from with ; R _{2 is} selected from with ;and Selected from , , , , , , with .

A compound having the formula A or a stereoisomer thereof, a pharmaceutically acceptable salt, a solvate, a crystal or a prodrug thereof, non-limiting examples of which include: , , , , , , , , , , , , with .

Another object of the present invention is to provide a compound of the formula B or a stereoisomer thereof, a pharmaceutically acceptable salt, a solvate, a crystal or a prodrug thereof, (B) wherein: X and Y are each independently selected from N, O and S, and when X is N, Y is selected from O and S; when X is O or S, Y is N; when Y is N, X is selected From O and S; when Y is O or S, X is N; when X is N, Y is selected from O and S or Y is O or S, and X is N, the group for When X is O or S, Y is N or Y is N, and X is selected from O and S, the group for ; R _{7 is} selected from the side chain of the amino acids Asn, Gln, Asp, Glu; R _{8 is} selected from the group consisting of the amino acid Ser and Thr residues; R ₉ and R ₁₀ are each independently selected from H, an alkyl group and an alkylhydroxy group, R ₉ , R _{10 is} not H at the same time, and R ₉ or R ₁₀ together with the amino group attached to the α carbon position form a nitrogen heterocycloalkyl group or a nitrogen heterocycloalkyl group, and the nitrogen heterocycloalkyl group or the nitrogen oxyheterocycloalkyl group Optionally substituted with one or more substituents selected from the group consisting of hydroxyl, hydroxyalkyl, cyano, amino, halogen, nitro; or R ₉ , R ₁₀ together with the C atom to which they are attached form a cycloalkyl or oxygen Heterocycloalkyl, the cycloalkyl or oxacycloalkyl is optionally substituted by one or more substituents selected from the group consisting of hydroxy, hydroxyalkyl, cyano, amino, halo, nitro.

In a preferred embodiment, a compound of the formula B, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, is a compound of the formula III or IV. Or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof: (III), (IV) wherein: Q is selected from the group consisting of O and S, and R ₇ , R ₈ , R ₉ and R ₁₀ are as defined in the formula B.

In some embodiments, the compound of Formula B, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, according to the present invention, wherein: R _{7 is} selected from the group consisting of amino acid Asn a side chain of Gln, Asp, Glu; R _{8 is} selected from the group consisting of amino acid Ser and Thr residues; R ₉ and R ₁₀ are each independently selected from H, C _1-6 alkyl and C _1-6 alkyl hydroxy, R ₉ And R _{10 is} not H at the same time, and R ₉ or R ₁₀ together with the amino group attached to the α carbon position form an aza C _3-6 cycloalkyl group or a nitrogen oxa C _3-6 cycloalkyl group, the aza C _{3 -6} cycloalkyl or oxa C _3-6 cycloalkyl is optionally substituted by one or more substituents selected from the group consisting of hydroxy, hydroxy C _1-6 alkyl, cyano, amino, halogen, nitro Or R ₉ , R ₁₀ together with the C atom to which they are attached form a C _3-6 cycloalkyl or oxa C _3-6 cycloalkyl group, the C _3-6 cycloalkyl or oxa C _3-6 ring The alkyl group is optionally substituted with one or more substituents selected from the group consisting of a hydroxyl group, a hydroxy C _1-6 alkyl group, a cyano group, an amino group, a halogen, and a nitro group.

In another preferred embodiment, a compound of the formula B, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, wherein R ₉ is H, R ₁₀ is is formed on the α-carbon position aza amino linked together C _3-6 cycloalkyl, C _3-6 cycloalkyl which aza optionally substituted with one or more substituents selected from hydroxy, hydroxy C _1-6 alkyl, cyano Substituted by a substituent of a group, an amino group, a halogen or a nitro group.

In another preferred embodiment, a compound of the formula B, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, wherein R _{9 is} selected from C _1-3 alkyl group, R ₁₀ is selected from C _1-3 alkyl, R _9, R ₁₀ together with the C atom to which they are attached, C _3-6 cycloalkyl, C _3-6 cycloalkyl which is optionally substituted with one or A plurality of substituents selected from the group consisting of a hydroxyl group, a hydroxyalkyl group, a cyano group, an amino group, a halogen, and a nitro group are substituted.

In another preferred embodiment, a compound of the formula B, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, wherein R _{9 is} selected from C _1-3 An alkyl group, R _{10 is} selected from a C _1-3 hydroxyalkyl group, and R ₉ and R ₁₀ together with the C atom to which they are attached form an oxa C _3-6 cycloalkyl group, the oxa C _3-6 cycloalkyl group Optionally, it is substituted with one or more substituents selected from the group consisting of hydroxyl, hydroxyalkyl, cyano, amino, halogen, nitro.

A compound having the formula B or a stereoisomer thereof, a pharmaceutically acceptable salt, a solvate, a crystal or a prodrug thereof, non-limiting examples of which include: , , , , , , , , , , , , , , , , with .

Another object of the present invention is to provide a compound of the formula C or a stereoisomer thereof, a pharmaceutically acceptable salt, a solvate, a crystal or a prodrug, (C) wherein: X and Y are each independently selected from N, O and S, and when X is N, Y is selected from O and S; when X is O or S, Y is N; when Y is N, X is selected From O and S; when Y is O or S, X is N; when X is N, Y is selected from O and S or Y is O or S, and X is N, the group for When X is O or S, Y is N or Y is N, and X is selected from O and S, the group for ; R _{11 is} selected from the side chain of the amino acids Ser and Thr; R _{12 is} selected from the amino acid Asn, Gln, Asp, Glu side chain; R _{15 is} selected from H and alkyl; R ₁₃ and R ₁₄ are each independently selected from H, alkane a group, R ₁₃ and R _{14 are} not simultaneously H, and R ₁₃ and R ₁₄ together with the C atom to which they are attached form a cycloalkyl group; or R ₁₃ or R ₁₄ together with an imino group to which the α carbon position is bonded to form a nitrogen heterocycle An alkyl group, or R _{14 ,} together with R ₁₅ and the atom to which they are attached, form an optionally substituted lactone cycloalkyl group.

The cycloalkyl, azacycloalkyl or lactone cycloalkyl is optionally substituted with one or more substituents selected from the group consisting of hydroxyl, hydroxyalkyl, cyano, amino, halogen, nitro.

In a preferred embodiment, a compound of the formula C, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, is a compound of the formula V or VI. Or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof: (V), (VI), wherein: Q is selected from the group consisting of O and S; and R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ and R ₁₅ are as defined in the formula C.

In a preferred embodiment, a compound of the formula C, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, wherein R ₁₃ , R ₁₄ and The attached C atoms together form a C _3-6 cycloalkyl group.

In another preferred embodiment, a compound of the formula C, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, wherein R ₁₄ and its alpha carbon position The attached imino groups together form an aza C _3-6 cycloalkyl group.

In another preferred embodiment, a compound of the formula C, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, wherein R ₁₄ and R ₁₅ and The attached atoms together form a lactone C _3-6 cycloalkyl group, the lactone cycloalkyl group being substituted by one or more substituents selected from the group consisting of hydroxyl, oxo, hydroxyalkyl, cyano, amino, halogen, nitro Replaced.

A compound having the formula C or a stereoisomer thereof, a pharmaceutically acceptable salt, a solvate, a crystal or a prodrug thereof, non-limiting examples of which include: , , , , with .

Another object of the present invention is to provide a process for the preparation of a compound of the formula I, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, which process comprises the steps of: (1) a compound of the formula ia is reacted with a compound of the formula ib to form a compound of the formula ic; (2) a compound of the formula ic is cyclized to give a compound of the formula id; (3) a compound of the formula id is reacted with an amine compound to give a compound of the formula IE; a compound of the formula IE is subjected to a nucleophilic substitution reaction with a compound of the formula i to give a compound of the formula ig; (5) a hydrolysis reaction of the compound of the formula ig under acidic conditions to give a compound of the formula I; wherein: Pg ₁ represents a protecting group for R ₁ ; ₂ represents a protecting group for R ₂ ; as described in Formula I, R ₁ and R ₂ are each selected from the group consisting of the amino acid Ser and Thr side chains, and in order to avoid further reaction of the amino acid Ser or Thr side chain during the reaction, conventional The hydroxy protecting group protects the amino acid Ser or Thr side chain, Pg ₁ , Pg _{2 is} preferably tert-butyl (tBu); Pg ₃ represents a protecting group of R ₃ or is absent; as described in Formula I, R _{3 is} selected from H , -(CH ₂ ) _m C(O)OR ₄ , -(CH ₂ ) _m C(O)N(R ₅ )(R ₆ ) and -(CH ₂ ) _m CN; when R ₃ is a hydroxyl group or an amino group When a group which is liable to change in a further reaction, it can be protected by a conventional protecting group; Pg ₄ and Pg ₅ represent an amino protecting group.

Another object of the present invention is to provide a process for the preparation of a compound of the formula II, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, which process comprises the steps of: (1) a compound of the formula ia is reacted with a compound of the formula iib to form a compound of the formula iic; (2) a compound of the formula iic is cyclized to give a compound of the formula iid; (3) a compound of the formula iid is reacted with an amine compound to give a compound of the formula iie; a compound of the formula iie and a compound of the formula if subjected to nucleophilic substitution to give a compound of the formula iig; (5) a hydrolysis reaction of the compound of the formula iig under acidic conditions to give a compound of the formula II; wherein: Pg ₁ represents a protecting group for R ₁ ; ₂ represents a protecting group for R ₂ ; as described in Formula II, R ₁ and R ₂ are each selected from the group consisting of the amino acid Ser and Thr side chains, and in order to avoid further reaction of the amino acid Ser or Thr side chain during the reaction, conventional The hydroxy protecting group protects the hydroxy group, Pg ₁ and Pg _{2 are} preferably tert-butyl (tBu); Pg ₃ represents the protection or absence of R ₃ ; as described in the general formula II, R _{3 is} selected from H, -(CH ₂ ) _m C(O)OR ₄ , -(CH ₂ ) _m C(O)N(R ₅ )(R ₆ ) and -(CH ₂ ) _m CN; when R ₃ is a hydroxyl group or an amino group, etc. The changing group can be protected by a conventional protecting group; Pg ₄ and Pg ₅ represent an amino protecting group.

Another object of the present invention is to provide a compound of Formula B, Formula C, Formula III, Formula IV, Formula V or Formula VI or a stereoisomer thereof, a pharmaceutically acceptable salt, a solvate thereof, The preparation method of the crystallization or prodrug, according to the preparation method of the compound of the general formula I and the general formula II provided above, the person skilled in the art can obtain the general formula B, the general formula C, and the conventional raw material according to the conventional knowledge in the field of organic synthesis. Formula III, Formula IV, Formula V or Formula VI.

Another object of the present invention is to provide a pharmaceutical composition comprising, for example, Formula A, Formula B, Formula C, Formula I, Formula II, Formula III, Formula IV, Formula V Or a compound of the formula VI or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, and a pharmaceutically acceptable carrier.

Another object of the present invention is to provide a compound of the formula A, formula B, formula C, formula I, formula II, formula III, formula IV, formula V, formula VI or The use of a stereoisomer, a pharmaceutically acceptable salt, a solvate, a crystal or a prodrug thereof or a pharmaceutical composition comprising the same for the preparation of a medicament for the treatment of cancer or an infectious disease.

In a preferred embodiment, a compound of Formula A, Formula B, Formula C, Formula I, Formula II, Formula III, Formula IV, Formula V or Formula VI Or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof or a pharmaceutical composition comprising the same, for use in the manufacture of a medicament for treating cancer or an infectious disease, wherein the cancer includes Not limited to melanoma, brain tumors (gliomas with malignant astroglia and oligodendroglioma), esophageal cancer, stomach cancer, liver cancer, pancreatic cancer, colorectal cancer (colon cancer, rectal cancer, etc.) ), lung cancer (non-small cell lung cancer, small cell lung cancer, primary or metastatic squamous cell carcinoma, etc.), kidney cancer, breast cancer, ovarian cancer, prostate cancer, skin cancer, neuroblastoma, sarcoma, osteochondroma, Osteosarcoma, osteosarcoma, seminoma, testicular tumor, uterine cancer (cervical cancer, endometrial cancer, etc.), head and neck cancer (maxillary cancer, laryngeal cancer, pharyngeal cancer, tongue cancer, intraoral cancer, etc.), Multiple myeloma, malignant lymphoma (reticular sarcoma, lymphosarcoma) , Hodgkin's lymphoma, etc., polycythemia vera, leukemia (acute myeloid leukemia, chronic myeloid leukemia, acute lymphocytic leukemia, chronic lymphocytic leukemia, etc.), thyroid neoplasms, ureteral tumors, bladder tumors, gallbladder cancer, Cholangiocarcinoma, chorionic epithelial cancer, or pediatric tumor (Ewing familial sarcoma, Wilms' sarcoma, rhabdomyosarcoma, angiosarcoma, embryonic testicular cancer, neuroblastoma, retinoblastoma, hepatic blastoma, nephroblast A tumor, etc.) and a combination of the cancer.

In another preferred embodiment, a formula of formula A, formula B, formula C, formula I, formula II, formula III, formula IV, formula V or formula VI Use of a compound, or a stereoisomer thereof, a pharmaceutically acceptable salt, a solvate, a crystal or a prodrug thereof, or a pharmaceutical composition comprising the same, for the preparation of a medicament for treating cancer or an infectious disease, wherein the infectivity Diseases include, but are not limited to, bacterial, viral, and fungal infections.

In a specific embodiment, a compound pair of Formula A, Formula B, Formula C, Formula I, Formula II, Formula III, Formula IV, Formula V, or Formula VI Colon cancer has a significant inhibitory effect.

Explanation of terms:

Terms used in the specification and patent claims have the following meanings unless stated to the contrary.

"Hydrogen" and "carbon" in the compounds of the present invention include all isotopes thereof. Isotopes are understood to include those atoms having the same number of atoms but having different mass numbers, such as isotopes of hydrogen including lanthanum and cerium, and isotopes of carbon including ¹³ C and ¹⁴ C.

The term "stereoisomer" refers to a molecule having the same atomic composition and attachment in the same manner, but having a three-dimensional arrangement differently, including optical isomers, geometric isomers (also known as cis-trans isomers), "chiral" It is a molecule that has properties that cannot overlap with its mirror image; "non-chiral" refers to a molecule that can overlap with its mirror image. Optical isomers are divided into enantiomers and diastereomers. "Enantiomer" refers to two isomers of a compound that are not superimposable but are mirror images of each other. "Diastereomer" refers to a stereoisomer that has two or more chiral neutralities and whose molecules are not mirror images of each other. Diastereomers have different physical properties such as melting point, boiling point, spectral properties and reactivity. The mixture of diastereomers can be separated by high resolution analytical procedures such as electrophoresis and chromatography, such as HPLC.

All stereoisomeric forms of the compounds of the invention include, but are not limited to, diastereomers, enantiomers, cis and trans isomers, and mixtures thereof, such as racemic mixtures. Many organic compounds exist in optically active forms, that is, they have the ability to rotate planes of plane polarized light. In describing an optically active compound, the pre-D, L or R, S is used to indicate the absolute configuration of the molecular chiral center. The front D, L or (+), (-) is used to name the symbol of the plane polarization of the compound, (-) or L means that the compound is left-handed, and the front (+) or D means that the compound is right-handed. . The chemical structures of these stereoisomers are the same, but their stereostructures are different. A particular stereoisomer can be an enantiomer, and a mixture of isomers is often referred to as a mixture of enantiomers. The 50:50 mixture of enantiomers is referred to as a racemic mixture or a racemate, which may result in no stereoselectivity or stereospecificity during the chemical reaction. The terms "racemic mixture" and "racemate" refer to a mixture of two enantiomers of the same molar, lacking optical activity.

Depending on the choice of starting materials and methods, the compounds of the invention may be one of the possible isomers or a mixture thereof, such as a mixture of racemates and diastereomers (depending on the number of asymmetric carbon atoms). The form exists. Optically active (R)- or (S)-isomers can be prepared using chiral synthons or chiral reagents, or isolated using conventional techniques.

The resulting mixture of any stereoisomers can be separated into pure or substantially pure geometric isomers, enantiomers, diastereomers, for example, by virtue of differences in physicochemical properties of the components. Chromatography and/or fractional crystallization.

The "pharmaceutically acceptable salt" of the present invention means an acid and/or a basic salt of a compound with an inorganic and/or organic acid and a base form, and also a zwitterionic salt (internal salt). The compound of the present invention contains an amino acid side chain and an amino acid residue, and thus it can form an internal salt or a salt corresponding to other inorganic and/or organic acid and base forms.

The "solvate" of the present invention means a form of the compound of the present invention which forms a solid or liquid complex by coordination with a solvent molecule. Hydrates are a special form of solvates in which coordination occurs with water. The solvate is preferably a hydrate within the scope of the invention.

"Crystalline" as used in the present invention refers to various solid forms formed by the compounds of the present invention, including crystalline forms and amorphous forms.

The "prodrug" of the present invention means a compound which is converted into a compound of the present invention by reaction with an enzyme, gastric acid or the like under physiological conditions of a living body, that is, a compound which is converted into an invention by oxidation, reduction, hydrolysis or the like of an enzyme and/or A compound which is converted into a compound of the invention by a hydrolysis reaction such as gastric acid or the like.

The "alkyl group" of the present invention means a linear or branched saturated hydrocarbon group, preferably a C _1-8 alkyl group, more preferably a C _1-6 alkyl group. Non-limiting examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, n-pentyl, 1,1-dimethylpropane 1,1,2-dimethylpropyl, 2,2-dimethylpropyl, 1-ethylpropyl, 2-methylbutyl, 3-methylbutyl, n-hexyl, 1-ethyl -2-methylpropyl, 1,1,2-trimethylpropyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 2,2-dimethylbutyl, 1,3-Dimethylbutyl, 2-ethylbutyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 2,3-dimethylbutyl, n-glycol Base, 2-methylhexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 2,2- Dimethylpentyl, 3,3-dimethylpentyl, 2-ethylpentyl, 3-ethylpentyl, n-octyl, 2,3-dimethylhexyl, 2,4-dimethyl Hexyl, 2,5-dimethylhexyl, 2,2-dimethylhexyl, 3,3-dimethylhexyl, 4,4-dimethylhexyl, 2-ethylhexyl, 3-ethylhexyl, 4-ethylhexyl, 2-methyl-2-ethylpentyl, 2-methyl-3-ethylpentyl.

The "cycloalkyl group" of the present invention means a saturated or partially unsaturated monocyclic or polycyclic substituent which includes 3 to 20 carbon atoms, preferably 4 to 13 carbon atoms. Non-limiting examples of monocycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, cyclohexadienyl, cycloheptyl, cycloheptatriene The group, the cyclooctyl group and the like are preferably a cyclopentyl group or a cyclohexyl group. Polycycloalkyl groups include spiro, fused, and bridged cycloalkyl groups.

The "azacycloalkylene group" of the present invention means a saturated ring comprising a nitrogen atom and a plurality of carbon atoms, and the azacycloalkyl group is preferably aza C _3-20 cycloalkyl group, more preferably aza C. _4-13 cycloalkyl. More preferably, it is aza C _3-6 cycloalkyl. Non-limiting examples of azacycloalkyl groups include pyrrolidinyl and acridinyl groups.

The "oxyheterocycloalkyl group" of the present invention means a saturated ring composed of one oxygen and a plurality of carbon atoms. The oxacycloalkyl group is preferably an oxa C _3-20 cycloalkyl group, more preferably an oxa C _4-13 cycloalkyl group. More preferably, it is an oxa C _3-6 cycloalkyl group.

The "lactone cycloalkyl group" of the present invention means an ester group ( And a saturated ring composed of multiple carbon atoms. The lactone cycloalkyl group is preferably a lactone C _3-20 cycloalkyl group, more preferably a lactone C _4-13 cycloalkyl group. More preferably, it is a lactone C _3-6 cycloalkyl group.

The "alkyl hydroxy group" of the present invention means -alkyl-OH.

The "halogen" of the present invention means fluorine, chlorine, bromine or iodine.

The "amino group" of the present invention means -NH ₂ , -NH(alkyl), -N(alkyl)(alkyl).

The "nitro group" of the present invention means -NO ₂ .

The "cyano group" of the present invention means -CN.

The hydroxy "hydroxy group" of the present invention means -OH.

The "benzyl group" of the present invention means -CH ₂ -phenyl group, abbreviated as " Bn ".

The "tert-butoxycarbonyl group" of the present invention means -(O)CO(tBu), abbreviated as " Boc ".

The "Fmoc-" of the present invention means a fluorenylmethoxycarbonyl group.

The "amino acid" of the present invention means an amino group-containing carboxylic acid, and the amino group attached to the α-carbon is an α-amino acid, and the structural formula is represented by a CH(COOH)(NH ₂ )- side chain. The "L-amino acid" of the present invention means that the α-carbon atom of the α-amino acid is left-handed; conversely, the "D-amino acid" refers to the α of the general structure CH(COOH)(NH ₂ )-side chain - The carbon atom is right-handed. In addition to glycine, the α-carbon atoms of other protein amino acids are asymmetric carbon atoms (ie, the four substituents bonded to the α-carbon atom are different), so the amino acids may have stereoisomers, ie, may be different Configuration (D-type and L-type two configurations).

Non-limiting examples of amino acids include alanine (Ala), arginine (Arg), aspartame (Asn), aspartic acid (Asp), cysteine (Cys), glutamine ( Gln), glutamic acid (Glu), glycine (Gly), histidine (His), isoleucine (Ile), leucine (Leu), lysine (Lys), methionine (Met), benzene Alanine (Phe), proline (Pro), serine (Ser), threonine (Thr), tryptophan (Trp), tyrosine (Tyr), valine (Val).

The "amino acid side chain" of the present invention means a component of an amino acid, and the amino acid structural formula is represented by CH(COOH)(NH ₂ )-R, and R represents an amino acid side chain, for example, the structure of alanine is CH (COOH). (NH ₂ )-CH ₃ , the amino acid side chain is -CH ₃ ; the structure of serine is CH(COOH)(NH ₂ )-CH ₂ OH, the amino acid side chain is -CH ₂ OH; the structure of threonine is CH(COOH)(NH ₂ )-CH(OH)(CH ₃ ), the amino acid side chain is -CH(OH)(CH ₃ ).

The "amino acid residue" of the present invention means that a part of the structure is absent compared to the structure of the parent amino acid, and is an incomplete amino acid. For example, a hydrogen atom on the amino group of the amino acid is replaced by a chemical bond to bond with another atom, or an amino acid. -OH is replaced by a chemical bond to bond with other atoms. Such as the structure of alanine , then its amino acid residue can be Can also be .

The "protecting group" of the present invention is such that the nitrogen atom and the oxygen atom remain unchanged in the reaction of other parts of the molecule, and are protected by a group which is easily removed. The protecting group of the present invention includes an amino protecting group and a hydroxy protecting group, and the amino protecting group of the present invention means a group which prevents or prevents the amino group from participating in the next reaction until the protecting group is removed, and a non-limiting example includes a formazan group and an alkane. Carbocarbonyl, alkoxycarbonyl, benzhydryl, aralkylcarbonyl, aralkoxycarbonyl, triphenylmethyl, phthalic acid, N,N-dimethylaminomethylene, substituted Carboxyalkyl, tert-butoxycarbonyl, benzyloxycarbonyl, and the like. The hydroxy protecting group of the present invention means a group which prevents or prevents the hydroxyl group from participating in the next reaction until the protecting group is removed. Examples of the hydroxy protecting group include etidinyl, allyl, benzhydryl, benzyl, β-methoxyethoxymethyl, methoxymethyl, dimethoxytrityl [two -(4-methoxyphenyl)phenylmethyl], methoxytriphenyl[(4-methoxyphenyl)diphenylmethyl], p-methoxybenzyl ether, methyl sulfide Methyl, trimethylethenyl, tetrahydropyranyl, triphenylmethyl, decyl (eg trimethyl decyl, tert-butyldimethyl decyl, tert-butyl diphenyl fluorenyl) , triisopropyl methoxymethyl and triisopropyl decyl). Other examples include alkyl groups such as methyl and t-butyl groups, as well as other ethers such as ethoxyethyl groups.

The organic solvents used in the following examples are abbreviated as follows: NMM: N-methylmorpholine; HATU: 2-(7-oxobenzotriazole)-N,N,N',N'-tetramethylurea Hexafluorophosphate; TPP: triphenylphosphine; HOBT: 1-hydroxybenzotriazole; EDC: 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride; DAST: Diethylaminosulfur trifluoride; TBDMSCl: tert-butyldimethylchloromethane; Fmoc-Asn(Trt)-OH: N-fluorenylmethoxycarbonyl-L-aspartate.

Example 1: ((1-(5-((1S,2S)-1-Amino-2-hydroxypropyl)-1,3,4-oxadiazol-2-yl)-3-(carboxymethyl) Preparation of cyclobutyl)carbamoyl)-L-serine

Step 1:1 - Preparation of ((tert-Butoxycarbonyl)amino)-3-oxocyclobutane-1-carboxylic acid

Ethyl 1-((tert-butoxycarbonyl)amino)-3-oxocyclobutanecarboxylate (50 mg, 0.19 mmol) was dissolved in methanol (1 mL), water (0.5 mL) (9.3 mg, 0.23 mmol), reacted at room temperature for half an hour, and the reaction was monitored by TLC plate (iodine, bromocresol green color development), and the reaction was complete. Methanol was distilled off under reduced pressure, and the remaining liquid was adjusted to pH 4 with 1 M citric acid. Layered with EA and water, the organic phase was washed with brine, dried over anhydrous Na ₂ SO _4. Distillation under reduced pressure, separation and purification on a silica gel column (0-50% EA in PE) gave a white solid 40 mg, yield 90%.

Step 2: Preparation of benzyl 1-((tert-butoxycarbonyl)amino)-3-oxocyclobutane-1-carboxylate

1-((tert-Butoxycarbonyl)amino)-3-oxocyclobutane-l-carboxylic acid (2 g, 8.73 mmol) was dissolved in DMF (20 mL) and K ₂ CO ₃ (1.81 g, 13.09 mmol), BnCl (1.32 g, 10.48 mmol). Place on a 65 ^o C oil bath, heat the reaction for 2 h, monitor the reaction on the TLC plate (iodine smoked color), and complete the reaction. Layered with EA and water, the organic phase was washed with brine, dried over anhydrous Na ₂ SO _4. The mixture was evaporated under reduced pressure and purified (yield: 0-10% EA in EtOAc)

Step 3: Preparation of benzyl 1-((tert-butoxycarbonyl)amino)-3-(2-ethoxy-2-oxoethylidene)cyclobutane-1-carboxylate

Benzyl 1-((tert-butoxycarbonyl)amino)-3-oxocyclobutane-1-carboxylate (1 g, 3.13 mmol) was dissolved in toluene (15 mL). Ethyl acetate (1.53 g, 4.38 mmol) was heated under reflux for 4 h, and the reaction was monitored by TLC plate (yield of iodine) and the reaction was completed. Layered with EA and water, the organic phase was washed with brine, dried over anhydrous Na ₂ SO _4. The mixture was evaporated under reduced pressure, and purified (yield: 0-10% EA in EtOAc)

Step 4: Preparation of benzyl 1-amino-3-(2-ethoxy-2-oxoethylidene)cyclobutane-1-carboxylate

Benzyl 1-((tert-butoxycarbonyl)amino)-3-(2-ethoxy-2-oxoethylidene)cyclobutane-1-carboxylate (40 mg, 0.1 mmol) was dissolved in two In a mixed solvent of methyl chloride (1 mL) and trifluoroacetic acid (1 mL), the mixture was reacted at room temperature for 2 h, and the reaction was monitored by TLC plate (iodine smoked color), and the reaction was completed. The excess trifluoroacetic acid was distilled off under reduced pressure, and a 20% aqueous Na ₂ CO ₃ solution was added and stirred for 15 min. EA and water layer were applied, and the organic phase was washed with brine and dried over anhydrous Na ₂ SO ₄ . Distillation under reduced pressure gave a pale yellow oil (30 mg).

Step 5: 1-(((9H-芴-9-yl)methoxy)carbonyl)amino)-3-(2-ethoxy-2-oxoethylidene)cyclobutane-1-carboxylic acid Preparation of benzyl ester

Benzyl 1-amino-3-(2-ethoxy-2-oxoethylidene)cyclobutane-1-carboxylate (50 mg, 0.17 mmol) was dissolved in 1,4-dioxane (1) Add Na ₂ CO ₃ (22 mg, 0.21 mmol,) to a mixed solvent of water (0.2 mL), and place in an ice bath, add FmocCl (53.7 mg, 0.21 mmol), add and gradually increase to room temperature. . After 1 h of reaction, the reaction was monitored by TLC plate (iodine smoked color development) and the reaction was completed. Layered with EA and water, the organic phase was washed with brine, dried over anhydrous Na ₂ SO _4. Distillation under reduced pressure, separation and purification (0-10% EA in PE) to give a colorless oil of 64 mg, yield 72%.

Step 6: 1-(((9H-芴-9-yl)methoxy)carbonyl)amino)-3-(2-ethoxy-2-oxoethyl)cyclobutane-1-carboxylic acid preparation

Benzyl 1-((((9H-芴-9-yl)methoxy)carbonyl)amino)-3-(2-ethoxy-2-oxoethylidene)cyclobutane-1-carboxylate (800 mg, 1.56 mmol) was dissolved in methanol (10 mL). Pd/C (80 mg, 10%, w/w) was added and hydrogenated for 2 h. The reaction was monitored by TLC plate. The Pd/C was removed by filtration through celite, and the filtrate was evaporated under reduced pressure to afford 496 mg of colorless oil.

Step 7: 2-(3-(((9H-芴-9-yl)methoxy)carbonyl)amino)-3-(2-(N-(tert-butoxy)-O-(tert-butyl) Preparation of ethyl-L-betathreonyl)nonyl-1-carbonyl)cyclobutyl)acetate

1-((((9H-芴-9-yl)methoxy)carbonyl)amino)-3-(2-ethoxy-2-oxoethyl)cyclobutane-1-carboxylic acid (790 mg) , 1.86 mmol) was dissolved in DMF (15 mL) and ((2S,3S)-3-(tert-butoxy)-1-indol-1-yloxy-2-yl)carbamic acid tert-butyl The ester (539 mg, 1.86 mmol), NMM (188.6 mg, 4.65 mmol), HATU (710 mg, 1.86 mmol), reacted for 2 h at room temperature, and the reaction was monitored by TLC plate. The reaction solution was poured slowly into ice water, and a white solid was precipitated.

Step 8: 2-(3-(((9H-芴-9-yl)methoxy)carbonyl)amino)-3-(5-((1S,2S)-2-(tert-butoxy)- Preparation of ethyl 1-((tert-butoxycarbonyl)amino)propyl)-1,3,4-oxadiazol-2-yl)cyclobutyl)acetate

2-(3-(((9H-芴-9-yl)methoxy)carbonyl)amino)-3-(2-(N-(tert-butoxy)-O-(tert-butyl)- Ethyl L-subthreonyl) decyl-1-carbonyl)cyclobutyl)acetate (660 mg, 0.95 mmol) was dissolved in DMF (8 mL), THF (2 mL) bath, was added TPP (997 mg, 3.8 mmol) , I 2 (966 mg, 3.8 mmol), stirred for 30 min until complete dissolution of I _2, was added _{Et 3 N (768 mg, 7.6} mmol). After the addition, the ice bath was removed and reacted at room temperature for 3 h. The reaction was monitored by TLC plate and the reaction was complete. Layered with EA and water, the organic phase was washed with saturated sodium thiosulfate, brine, dried over anhydrous Na ₂ SO _4. Distillation under reduced pressure, separation and purification (0-25% EA in PE) to afford 418 mg of colorless oil.

Step 9: 2-(3-Amino-3-(5-((1S,2S)-2-(tert-butoxy)-1-((tert-butoxycarbonyl)amino)propyl)-1,3 Of 4-(oxadiazol-2-yl)cyclobutyl)acetate

2-(3-(((9H-芴-9-yl)methoxy)carbonyl)amino)-3-(5-((1S,2S)-2-(tert-butoxy)-1-) ((tert-Butoxycarbonyl)amino)propyl)-1,3,4-oxadiazol-2-yl)cyclobutyl)acetate (606 mg, 0.9 mmol) dissolved in DCM (5 mL) Add Et ₂ NH (355 mg, 4.85 mmol), react at room temperature for 6 h, and the reaction is complete. The mixture was evaporated under reduced pressure and purified (yield: -30% EA in PE) to afford 270 mg as colorless oil.

Step 10: Preparation of O-(tert-butyl)-N-((4-nitrophenoxy)carbonyl)-L-serine tert-butyl ester

The O- (tert-butyl) - L- serine tert-butyl ester (10 g, 0.046 mol, 1.0 eq) was dissolved in DCM (200 mL), ice-bath cooling at 0 ℃ successively added dropwise Et ₃ N (9.32 g , 0.092 mol 2.0 eq) and a solution of phenyl 4-nitrochloroformate (9.25 g, 0.046 mol, 1.0 eq) in DCM (60 mL). The reaction was monitored by TLC plate (iodine) and the reaction was complete. The organic layer was washed three times with saturated Na ₂ CO ₃ , and then adjusted to pH 4 with EtOAc. Dry with anhydrous Na ₂ SO ₄ . Distilled under reduced pressure, washed with petroleum ether, the product was dissolved in petroleum ether, filtered, and the filtrate was evaporated under reduced pressure to yield 10.5 g of colorless oil.

Step 11: N-((1-(5-((1S,2S)-2-(tert-butoxy)-1-((tert-butoxycarbonyl)amino)propyl)-1,3,4-oxole Preparation of tert-butyl 2-oxazol-2-yl)-3-(2-ethoxy-2-oxoethyl)cyclobutyl)carbamoyl-O-(tert-butyl)-L-serine

2-(3-Amino-3-(5-((1S,2S)-2-(tert-butoxy)-1-((tert-butoxycarbonyl)amino)propyl)-1,3,4 - oxadiazol-2-yl) cyclobutyl) acetic acid ethyl ester (2.11 g, 4.64 mmol) was dissolved in DMF (20 mL), was added _{Et 3 N (0.93 g, 9.28} mmol), placed in 0 ℃, was added O-(tert-butyl)-N-((4-nitrophenoxy)carbonyl)-L-serine tert-butyl ester (2.13 g, 5.57 mmol). After the addition, the temperature was raised to room temperature, and reacted at room temperature for 10 h. The reaction was monitored by TLC plate (iodine), and the reaction was completed. Distillation under reduced pressure, separation and purification (0-50% EA in PE) to give a colorless oil of 2.2 g, yield 68%.

Step 12: N-((1-(5-((1S,2S)-2-(tert-butoxy)-1-((tert-butoxycarbonyl)amino)propyl)-1,3,4-oxole Preparation of oxazol-2-yl)-3-(carboxy)cyclobutyl)carbamoyl-O-(tert-butyl)-L-serine

N-((1-(5-((1S,2S)-2-(tert-butoxy)-1-((tert-butoxycarbonyl)amino)propyl)-1,3,4-oxadiazole 2-yl)-3-(2-ethoxy-2-oxoethyl)cyclobutyl)carbamoyl-O-(tert-butyl)-L-serine tert-butyl ester (1 g, 1.43 mmol) was dissolved in THF (15 mL), mixed solvents of water (5 mL) and set in an 0 ^o C, was added LiOH (240 mg, 5.73 mmol) . addition was completed, warmed to room temperature, room temperature for 5 h, The TLC plate was monitored for reaction (iodine), and the reaction was completed. The excess THF was distilled off under reduced pressure, acidified to pH 4 with 1 M citric acid, extracted with dichloromethane and dried over anhydrous Na ₂ SO ₄ . Isolation and purification (0-5% MeOH in DCM)

Step 13: ((1-(5-((1S,2S)-1-Amino-2-hydroxypropyl)-1,3,4-oxadiazol-2-yl)-3-(carboxymethyl) Preparation of cyclobutyl)carbamoyl)-L-serine

N-((1-(5-((1S,2S)-2-(tert-butoxy)-1-((tert-butoxycarbonyl)amino)propyl)-1,3,4-oxadiazole -2-yl)-3-(carboxy)cyclobutyl)carbamoyl-O-(tert-butyl)-L-serine (110 mg, 0.179 mmol) dissolved in DCM (4 mL) TFA (1.2 mL), triisopropyl decane (catalytic amount), stir the reaction at room temperature for 5 h. The reaction solution was spun dry, DCM and water layer were added, the organic phase was extracted with water several times, the aqueous phase was combined, and then washed with DCM The lyophilization and the preparation were separated to give a white solid (yield: 16 mg). Yield: 22.2%. ¹ H NMR (500 MHz, D ₂ O): δ 4.73 (d, J = 6.4 Hz, 1H), 4.49 - 4.39 (m , 1H), 4.19 (t, J = 4.5 Hz, 1H), 3.89 (dd, J = 10.5, 4.5 Hz, 2H), 3.11 – 2.97 (m, 1H), 2.73 (t, J = 10.8 Hz, 2H) , 2.56 (t, J = 7.4 Hz, 4H), 1.40 (s, 3H). ESI-MS m/z: 402.2 [M+H] ⁺ .

Example 2: ((1-(5-((1S,2S)-1-Amino-2-hydroxypropyl)-1,3,4-oxadiazol-2-yl)-3-(2-B) Preparation of oxy-2-oxoethyl)cyclobutyl)carbamoyl)-L-serine

Synthetic route:

N-((1-(5-((1S,2S)-2-(tert-butoxy)-1-((tert-butoxycarbonyl)amino)propyl)-1,3,4-oxadiazole 2-yl)-3-(2-ethoxy-2-oxoethyl)cyclobutyl)carbamoyl-O-(tert-butyl)-L-serine tert-butyl ester (200 mg, 0.28 (mmol) dissolved in DCM (2 mL), TFA (2.1 mL), triisopropyl decane (catalytic amount) was added at room temperature, and the reaction was stirred at room temperature for 5 h. The reaction solution was dried, DCM, water and layered. The organic phase was extracted several times with water, the aqueous phase was combined, washed with DCM several times, lyophilized and isolated to give a white solid 60 mg, yield 48.8%. ¹ H NMR (400 MHz, D ₂ O) : δ 4.51 ( Dd, J = 8.7, 6.3 Hz, 1H), 4.22 (dd, J = 12.7, 6.4 Hz, 1H), 4.05 (q, J = 7.1 Hz, 2H), 3.97 (dt, J = 13.6, 4.7 Hz, 1H ), 3.69 (dd, J = 8.5, 4.7 Hz, 2H), 2.87 (ddd, J = 17.7, 14.4, 8.4 Hz, 1H), 2.61 – 2.51 (m, 3H), 2.48 – 2.33 (m, 1H), 2.25 - 2.13 (m, 1H), 1.19 (dd, J = 6.4, 2.7 Hz, 3H), 1.14 (t, J = 7.1 Hz, 3H). ESI-MS m/z: 430.2 [M+H] ⁺ .

Example 3: ((1-(5-((1S,2S)-1-Amino-2-hydroxypropyl)-1,3,4-oxadiazol-2-yl)-3-(2-amino) Preparation of -2-oxoethyl)cyclobutyl)carbamoyl)-L-serine

Step 1: Preparation of ethyl 3-(2-amino-2-oxoethylidene)-1-((tert-butoxycarbonyl)amino)cyclobutane-1-carboxylate

NaH (676 mg, 0.016 mol, 1.1 eq) was dissolved in 10 mL of DMF, placed in a -20 ^o C low temperature reactor, and diaminocarbamyl methylphosphonate (3 g, 0.015 mol) of DMF was added. The solution was added dropwise, stirred for 1 h, and ethyl 1-((tert-butoxycarbonyl)amino)-3-oxocyclobutanecarboxylate (3.56 g, 0.013 mol) was added dropwise dropwise, and the reaction was continued. After 4 hours, the TLC plate monitored the reaction (iodine) and the reaction was complete. The organic layer was washed twice with saturated brine and dried over anhydrous Na ₂ SO ₄ . The mixture was evaporated under reduced pressure, and then purified and purified (P/E = 1/2).

Step 2: Preparation of ethyl 3-(2-amino-2-oxoethyl)-1-((tert-butoxycarbonyl)amino)cyclobutane-1-carboxylate

The title compound was obtained according to the procedure of Step 6 in Example 1, except that the starting material was 1-((((())))))))))) Replacement of benzyl 2-oxoethylidene)cyclobutane-1-carboxylate with 3-(2-amino-2-oxoethylidene)-1-((tert-butoxycarbonyl)amino) ring Butane-1-carboxylate.

Step 3: Preparation of 3-(2-amino-2-oxoethyl)-1-((tert-butoxycarbonyl)amino)cyclobutanecarboxylic acid

Ethyl ethyl 3-(2-amino-2-oxoethyl)-1-((tert-butoxycarbonyl)amino)cyclobutanecarboxylate (3.03 g, 0.01 mol) was dissolved in THF (80 mL) Add LiOH aqueous solution (508 mg, 0.012 mol,), react at room temperature for 5 h, distill off under reduced pressure, remove excess THF, adjust pH to 2 with 1 M citric acid, freeze-dry, separate and purify the rubber column (0-10 % MeOH in DCM), the obtained product was directly poured into the next reaction.

Step 4: 3-(2-Amino-2-oxoethyl)-1-carboxycyclobutylamine hydrochloride

The crude 3-(2-amino-2-oxoethyl)-1-((tert-butoxycarbonyl)amino)cyclobutanecarboxylic acid (190 mg, 0.69 mmol) was dissolved in 2 mL of 1.5M HCl. In the solution, react at room temperature for 3 h. Distillation under reduced pressure gave a crude product (132 mg, yield: 91%).

Step 5: ((1-(5-((1S,2S)-1-Amino-2-hydroxypropyl)-1,3,4-oxadiazol-2-yl)-3-(2-amino-) Preparation of 2-oxoethyl)cyclobutyl)carbamoyl)-L-serine

The title compound was obtained according to the procedure of Steps 5, 7, 8, 9, 11, and 13 in Example 1, except that the starting material in the step 5 was 1-amino-3-(2-ethoxy-2-oxo Benzene) benzyl cyclobutane-1-carboxylate (50 mg, 0.17 mmol) was dissolved in 1,4-dioxane to 3-(2-amino-2-oxoethyl)-1- Carboxycyclobutylamine hydrochloride. ¹ H NMR (400 MHz, D ₂ O): δ 4.21 – 4.11 (m, 2H), 3.89 (d, J = 6.4 Hz, 1H), 3.81 (dd, J = 6.0, 2.4 Hz, 2H), 2.97 – 2.72 (m, 2H), 2.69 (dd, J = 11.6, 5.1 Hz, 2H), 2.58 – 2.29 (m, 2H), 2.09 (ddd, J = 31.0, 12.2, 7.5 Hz, 1H), 1.37 (t, J = 5.7 Hz, 3H). ESI-MS m/z: 401.3 [M+H] ⁺ .

Example 4: (((1S,3R)-1-(5-((1S,2S)-1-Amino-2-hydroxypropyl)-1,3,4-oxadiazol-2-yl)-) Preparation of 3-(cyanomethyl)cyclobutyl)carbamoyl)-L-serine

Preparation of ethyl 1-((tert-butoxycarbonyl)amino)-3-(cyanomethylene)cyclobutanecarboxylate

The title compound was obtained in a similar manner to the method of the step 3 in Example 1, except that the starting material (triphenylphosphine) ethyl acetate was replaced with (triphenylphosphine) acetonitrile.

Step 2: Preparation of (1S,3S)-1-((tert-butoxycarbonyl)amino)-3-(cyanomethyl)cyclobutanecarboxylate

Preparation Method The method of the step 6 in Example 1, except that the starting material benzyl 1-(((9H-fluoren-9-yl)methoxy)carbonyl)amino)-3-(2-ethoxyl) -2-oxoethylidene)cyclobutanecarboxylate is replaced by ethyl 1-((tert-butoxycarbonyl)amino)-3-(cyanomethylene)cyclobutanecarboxylate obtained in the above step 1, The title compound and its stereoisomer were obtained by column chromatography after purification.

Step 3: Preparation of (1S,3S)-1-((tert-butoxycarbonyl)amino)-3-(cyanomethyl)cyclobutanecarboxylic acid

The title compound was obtained according to the procedure of Step 3 in Example 3, except that the starting material ethyl 3-(2-amino-2-oxoethyl)-1-((tert-butoxycarbonyl)amino)cyclobutane alkyl carboxylate to replace the above step 2 was obtained (1S, 3S) - 1 - (( tert-butoxycarbonyl) amino) -3- (cyanomethyl) cyclobutane carboxylate.

Step 4: Preparation of (1S,3S)-1-cyano-3-(cyanomethyl)cyclobutylamine hydrochloride

(1S,3S)-1-((tert-Butoxycarbonyl)amino)-3-(cyanomethyl)cyclobutanecarboxylic acid (1.4 g, 5.5 mmol, 1.0 eq) was dissolved in 8 mL 1,4-diox To the six rings, 14 mL of a HCl solution of 1,4-dioxane was added, and the mixture was reacted overnight, and filtered to give a white solid, 1.04 g, yield 100%.

Step 5: (((1S,3R)-1-(5-((1S,2S)-1-Amino-2-hydroxypropyl)-1,3,4-oxadiazol-2-yl)-3 Preparation of -(cyanomethyl)cyclobutyl)carbamoyl)-L-serine

The title compound was obtained according to the procedure of Steps 5, 7, 8, 9, 11, and 13 in Example 1, except that the starting material of the first step of Example 1 was 1-amino-3-(2-ethoxy- The benzyl 2-oxoethylidenecyclobutane-1-carboxylate was replaced with the product of the above step 4 (1S,3S)-1-cyano-3-(cyanomethyl)cyclobutylamine hydrochloride. ¹ H NMR (400 MHz, D ₂ O): δ 4.75 (d, J = 6.5 Hz, 1H), 4.37 (p, J = 6.4 Hz, 1H), 4.30 (t, J = 4.3 Hz, 1H), 3.94 (dd, J = 11.7, 4.8 Hz, 1H), 3.85 (dd, J = 11.6, 4.0 Hz, 1H), 2.99 (ddt, J = 16.9, 8.1, 4.6 Hz, 2H), 2.86 (tt, J = 13.6) , 6.9 Hz, 1H), 2.77 (d, J = 6.4 Hz, 2H), 2.46 – 2.35 (m, 2H), 1.33 (d, J = 6.5 Hz, 3H). ESI-MS m/z: 383.1 [M ⁺ H] +.

Example 5: (((1R,3S)-1-(5-((1S,2S)-1-Amino-2-hydroxypropyl)-1,3,4-oxadiazol-2-yl)-) Preparation of 3-(cyanomethyl)cyclobutyl)carbamoyl)-L-serine

Another conformational isomer of ethyl (1S,3S)-1-((tert-butoxycarbonyl)amino)-3-(cyanomethyl)cyclobutanecarboxylate prepared in Step 2 of Example 4 is Starting materials, the title compound was obtained by the procedure of Step 3-5 in Example 4. ¹ H NMR (400 MHz, D ₂ O): δ 4.75 (d, J = 6.5 Hz, 1H), 4.37 (p, J = 6.4 Hz, 1H), 4.30 (t, J = 4.3 Hz, 1H), 3.94 (dd, J = 11.7, 4.8 Hz, 1H), 3.85 (dd, J = 11.6, 4.0 Hz, 1H), 2.99 (ddt, J = 16.9, 8.1, 4.6 Hz, 2H), 2.86 (tt, J = 13.6) , 6.9 Hz, 1H), 2.77 (d, J = 6.4 Hz, 2H), 2.46 – 2.35 (m, 2H), 1.33 (d, J = 6.5 Hz, 3H). ESI-MS m/z: 383.1 [M +H] ⁺ .

Example 6: ((1-(3-((R)-1-Amino-2-hydroxyethyl)-1,2,4-oxadiazol-5-yl)-3-(carboxymethyl) ring Preparation of butyl)carbamoyl)-L-pyrethine

Step 1: 1 - Preparation of ((benzyloxy)carbonyl)-3-oxocyclobutaneamine hydrochloride

The title compound was obtained according to the procedure of Step 4 in Example 4, except that starting material (1S,3S)-1-((tert-butoxycarbonyl)amino)-3-(cyanomethyl)cyclobutanecarboxylic acid Replaced with benzyl 1-((tert-butoxycarbonyl)amino)-3-oxocyclobutanecarboxylate.

Step 2: Preparation of benzyl 1-((((9H-芴-9-yl)methoxy)carbonyl)amino)-3-oxocyclobutanecarboxylate

The title compound was obtained according to the procedure of Step 5 in Example 1, except that the starting material of the starting material of Example 1 was 1-amino-3-(2-ethoxy-2-oxoethylidene)cyclobutane. The benzyl alkoxyl-1-carboxylate was replaced with the 1-((benzyloxy)carbonyl)-3-oxocyclobutaneamine hydrochloride obtained in the above step 1.

Step 3: Benzyl 1-(((9H-fluoren-9-yl)methoxy)carbonyl)amino)-3-(2-(tert-butoxy)-2-oxoethylidene)cyclobutane Preparation of alkacrylate

Benzyl 1-(((((9(-)-9-yl)))carbonyl)amino)-3-oxocyclobutanecarboxylate (300 mg, 0.68 mmol) was dissolved in toluene (5 mL) , was added (tert-butoxycarbonyl methylene) triphenylphosphonium (282 mg, 0.74 mmol), placed in an oil bath at 50 ^o C, the reaction 24 h, evaporated under reduced pressure, water and EA layers were separated and the organic phase was washed with brine It was washed with anhydrous Na ₂ SO ₄ , evaporated under reduced pressure, and purified by EtOAc EtOAc (EtOAc)

Step 4: 1-(((9H-Indol-9-yl)methoxy)carbonyl)amino)-3-(2-(tert-butoxy)-2-oxoethyl)cyclobutanecarboxylic acid preparation

The title compound was obtained according to the procedure of Step 6 in Example 1, except that the starting material benzyl 1-((((9H- -9) yl)) oxy)) Ethoxy-2-oxoethylidene)cyclobutanecarboxylate is replaced by the benzyl 1-(((9H-fluoren-9-yl)methoxy)carbonyl)amino)- 3-(2-(tert-Butoxy)-2-oxoethylidene)cyclobutanecarboxylate.

Step 5: (R,Z)-2-(3-(((9H-芴-9-yl)methoxy)carbonyl)amino)-3-(4-amino-5-(tert-butoxymethyl) Of tert-butyl 9-dimethyl-7-oxo-2,8-dioxa-3,6-diazacyclo-3-ene-1-yl)cyclobutyl)acetate

1-((((9H-芴-9-yl)methoxy)carbonyl)amino)-3-(2-(tert-butoxy)-2-oxoethyl)cyclobutanecarboxylic acid (1.51 g) , 3.34 mmol), dissolved in DMF (20 mL), EtOAc (EtOAc) (EtOAc (EtOAc) reaction at room temperature overnight, the reaction solution was slowly poured into ice water, the precipitated solid was filtered, washed with water, and the crude product was dissolved in ethyl acetate layers were separated and the organic phase was dried over anhydrous Na ₂ SO _4. Distillation under reduced pressure gave a white solid 1.6 g, yield 67.5%

Step 6: (R)-2-(3-((((9H-芴-9-yl))methoxy)carbonyl)amino)-3-(3-(2-(tert-butoxy)-1) Preparation of tert-butyl (-(tert-butoxycarbonyl)amino)ethyl)-1,2,4-oxadiazol-5-yl)cyclobutyl)acetate

(R,Z)-2-(3-(((9H-芴-9-yl)methoxy)carbonyl)amino)-3-(4-amino-5-(tert-butoxymethyl)) Tert-butyl 9-dimethyl-7-oxo-2,8-dioxa-3,6-diazacyclo-3-ene-1-yl)cyclobutyl)acetate (1.6 g, 2.27 mmol) was dissolved in a mixed solvent of ethanol (40 mL) and water (4 mL), and sodium acetate (280 mg, 3.4 mmol) was added and the mixture was refluxed for 10 h. Distilled under reduced pressure, extracted with ethyl acetate and water, washed with saturated brine, dried over anhydrous sodium sulfate, and evaporated. The yield was 52%.

Step 7: ((1-(3-((R)-1-Amino-2-hydroxyethyl)-1,2,4-oxadiazol-5-yl)-3-(carboxymethyl)cyclobutane Preparation of bis-carbamoyl)-L-pyrethine

The title compound was obtained according to the procedure of Steps 9, 11, 13 in Example 1, except that the starting material ethyl 2-(3-(((((((()))))))) -3(5-((1S,2S)-2-(tert-butoxy)-1-((tert-butoxycarbonyl)amino)propyl)-1,3,4-oxadiazole-2 -()-cyclobutyl)acetate is replaced by the above-mentioned step 6 (R)-2-(3-(((9H-芴-9-yl))methoxy)carbonyl)amino)-3-( Tert-butyl 3-(2-(tert-butoxy)-1-((tert-butoxycarbonyl)amino)ethyl)-1,2,4-oxadiazol-5-yl)cyclobutyl)acetate preparation. ¹ H NMR (400 MHz, D ₂ O) : δ 4.73 (dd, J = 8.5, 4.3 Hz, 1H), 4.38 - 4.29 (m, 1H), 4.17 (dd, J = 10.0, 2.3 Hz, 1H), 4.15 – 4.01 (m, 2H), 2.95 (dt, J = 16.5, 8.4 Hz, 1H), 2.81 (dt, J = 15.8, 8.0 Hz, 0.5H), 2.69 – 2.47 (m, 5H), 2.35 – 2.17 (m, 0.5H), 1.17 (t, J = 6.9 Hz, 3H). ESI-MS m/z: 402.2 [M+H] ⁺ .

Example 7: ((1-(3-((R)-1-Amino-2-hydroxyethyl)-1,2,4-oxadiazol-5-yl)-3-(2-amino-2) Of oxoethyl)cyclobutyl)carbamoyl)-L-pyrethine

Step 1: (R)-(1-(5-(1-(((9H-芴-9-yl))methoxy)carbonyl)amino)-3-(3-(2-amino-2-oxo) Preparation of tert-butyl ester of ethyl)cyclobutyl)-1,2,4-oxadiazol-3-yl)-2-(tert-butoxy)ethyl)carbamate

The title compound was obtained according to the procedure of Steps 5 and 6 in Example 6 except that the starting material was 1-((((9H-in-9-yl)methoxy)carbonyl)amino)-3-(2-) Replacement of (tert-butoxy)-2-oxoethyl)cyclobutanecarboxylic acid with 3-(2-amino-2-oxoethyl)-1-((tert-butoxycarbonyl)amino)cyclobutane Formic acid.

Step 2: ((1-(3-((R)-1-Amino-2-hydroxyethyl)-1,2,4-oxadiazol-5-yl)-3-(2-amino-2-) Preparation of oxoethyl)cyclobutyl)carbamoyl)-L-pyrethionine

The title compound was obtained by the procedure of Steps 9, 11, and 13 in Example 1. The difference is that the starting material is 2-(3-(((9H-芴-9-yl)methoxy)carbonyl)amino)-3-(5-((1S,2S)-2-(tert-butoxy) -1 -((tert-Butoxycarbonyl)amino)propyl)-1,3,4-oxadiazol-2-yl)cyclobutyl)acetate was replaced by (R)-(1-(5) -(1-(((9H-芴-9-yl)methoxy)carbonyl)amino)-3-(3-(2-amino-2-oxoethyl)cyclobutyl)-1,2,4 tert-Butyl oxazol-3-yl)-2-(tert-butoxy)ethyl)carbamate ¹ H NMR (400 MHz, D ₂ O): δ 4.41 - 4.32 (m, 1H), 4.22 (dt, J = 9.5, 3.3 Hz, 1H), 4.18 – 4.03 (m, 2H), 3.06 – 2.78 (m, 2H), 2.68 – 2.49 (m, 4H), 2.29 (ddd, J = 12.0, 8.5, 3.4 Hz, 1H), 1.21 (t, J = 6.6 Hz, 3H). ESI-MS m/z: 401.2 [M+H] ⁺ .

Example 8: (((1R,3S)-1-(3-((R)-1-Amino-2-hydroxyethyl)-1,2,4-oxadiazol-5-yl)-3- Preparation of (cyanomethyl)cyclobutyl)carbamoyl)-L-pyrethionine

Step 1: Preparation of (9H-fluoren-9-yl)methyl-((1R,3R)-3-(cyanomethyl)-1-(fluorocarbonyl)cyclobutyl)carbamate

1-((((9H-芴-9-yl)methoxy)carbonyl)amino)-3-(cyanomethyl)cyclobutanecarboxylic acid (200 mg, 0.53 mmol) was dissolved in DCM (5 mL) was added DAST (111 mg, 0.69 mmol) , stirred at rt for 1 h ,, the reaction was quenched with water, dichloromethane, water, dried the organic layer was washed with saturated brine, Na ₂ SO _4. The mixture was distilled under reduced pressure, and the resultant was directly poured into the next reaction.

Step 2: ((R)-1-(5-((1R,3R)-1-(((9H-芴-9-yl)methoxy)carbonyl)amino)-3-(cyanomethyl) Of tert-butyl)-1,2,4-oxadiazol-3-yl)2-(tert-butoxy)ethyl)carbamic acid tert-butyl ester

The title compound was obtained according to the procedure of Steps 5 and 6 in Example 6 except that the starting material was 1-((((9H-in-9-yl)methoxy)carbonyl)amino)-3-(2-) Replacement of (tert-butoxy)-2-oxoethyl)cyclobutanecarboxylic acid with (9H-fluoren-9-yl)methyl(3-(cyanomethyl)-1-(fluorocarbonyl)cyclobutane Carbamate.

Step 3: (((1R,3S)-1-(3-((R)-1-Amino-2-hydroxyethyl)-1,2,4-oxadiazol-5-yl)-3-( Preparation of cyanomethyl)cyclobutyl)carbamoyl)-L-pyrethine

The title compound was obtained by the procedure of Steps 9, 11, and 13 in Example 1. The difference is that the starting material is 2-(3-(((9H-芴-9-yl)methoxy)carbonyl)amino)-3-(5-((1S,2S)-2-(tert-butoxy) ) ethyl-1-((tert-butoxycarbonyl)amino)propyl)-1,3,4-oxadiazol-2-yl)cyclobutyl)acetate was replaced by ((R)-1-(5) -((1R,3R)-1-(((9H-芴-9-yl)methoxy)carbonyl)amino)-3-(cyanomethyl)cyclobutyl)-1,2,4- Tert-butyl ester of oxadiazol-3-yl)2-(tert-butoxy)ethyl)carbamate. ¹ H NMR (400 MHz, D ₂ O) : δ 4.65 – 4.56 (m, 1H), 4.21 (qd, J = 6.4, 2.7 Hz, 1H), 4.12 – 4.03 (m, 1H), 3.99 – 3.83 (m , 2H), 2.93 – 2.73 (m, 1H), 2.58 (t, J = 8.6 Hz, 2H), 2.50 (d, J = 8.7 Hz, 3H), 1.05 (d, J = 6.4 Hz, 3H).ESI -MS m/z: 383.2 [M+H] ⁺

Example 9: (((1S,3R)-1-(5-((S)-1-Amino-2-hydroxyethyl)-1,3,4-oxadiazol-2-yl)-3- Preparation of (cyanomethyl)cyclobutyl)carbamoyl)-L-pyrethionine

Tert-butyl (S)-(3-(tert-butoxy)-1-indol-1-ylpropan-2-yl)carbamate and 1-((((9H-芴-9-yl))) The title compound was obtained by the procedure of Steps 7, 8, 9, 11, and 13 of Example 1, using methoxy)carbonyl)amino)-3-(cyanomethyl)cyclobutanecarboxylic acid as the starting material.

Example 10: (((1R,3S)-1-(5-((S)-1-Amino-2-hydroxyethyl)-1,3,4-oxadiazol-2-yl)-3- Preparation of (cyanomethyl)cyclobutyl)carbamoyl)-L-pyrethionine

Another conformational isomer of 1-(((9H-fluoren-9-yl)methoxy)carbonyl)amino)-3-(cyanomethyl)cyclobutanecarboxylic acid was used as the starting material, as in Example 1. The title compound was obtained by the method of steps 7, 8, 9, 11, and 13.

Example 11 (((S)-4-Amino-1-(5-((2S,4R)-4-hydroxytetrahydropyrrole-2-yl)-1,3,4-oxadiazol-2-yl) )-4-oxobutyl)carbamoyl)-L-serine

Step 1 Preparation of (2S,4R)-N-(tert-Butoxycarbonyl)-4-((tert-butyldimethylmethyl)oxy)-2-pyrrolecarboxylic acid methyl ester

Dissolve (2S,4R)-N-(tert-butoxycarbonyl)-4-hydroxy-2-pyrrolecarboxylic acid methyl ester (5 g, 20.4 mmol, 1 eq) and imidazole (1.7 g, 24.5 mmol, 1.2 eq) To a solution of N,N-dimethylformamide (70 mL), tert-butyldimethylchloromethane (3.7 g, 24.5 mmol, 1.2 eq) was added to the solution at 0 ° C for about 24 h. After the reaction is completed, the saturated ammonium chloride solution and ethyl acetate are added to the mixed solution, and the organic phase is washed successively with saturated ammonium chloride solution, water and saturated sodium chloride solution, dried over anhydrous sodium sulfate, filtered, and concentrated. The product was obtained as a clear oil (6.0 g).

Step 2 Preparation of (2S,4R)-4-((tert-Butyldimethylmethyl)oxy)-2-(indolylcarbonyl)tetrahydropyrrole-1-carboxylic acid tert-butyl ester

Methyl (2S,4R)-N-(tert-butoxycarbonyl)-4-((tert-butyldimethylmethyl)oxy)-2-pyrrolecarboxylate (6 g, 16.7 mmol) obtained in Step 1 Dissolved in methanol (36 mL), and added hydrazine hydrate (15 mL) to the solution and stirred at room temperature for 24 h. After the reaction is completed, the methanol is evaporated to dryness. Water and ethyl acetate are added to the mixture, and the organic phase is washed with water, washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate, filtered and concentrated to give a white solid (5.5 g) The yield was 91.7%.

Step 3 (2S,4R)-2-(2-(N ² -((9H-芴-9-yl)methoxy)carbonyl)-N ⁵ -trityl-L-glutamine oxime Preparation of tert-butyl ester of hydrazino-1-carbonyl)-4-((tert-butyldimethylmethyl)oxy)tetrahydropyrrole-1-carboxylate

(2S,4R)-4-((tert-Butyldimethylmethyl)oxy)-2-(indolylcarbonyl)tetrahydropyrrole-1-carboxylic acid tert-butyl ester (5.5 g, 15.3 mmol, 1 eq , N ² -(((9H-芴-9-yl)methoxy)carbonyl)-N ⁵ -trityl-L-glutamine (9.4 g, 15.3 mmol, 1 eq), 1- Ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (3.5 g, 18.4 mmol, 1.2 eq), 1-hydroxybenzotriazole (2.5 g, 18.4 mmol, 1.2 eq) N-methylmorpholine (3.9 g, 38.2 mmol, 2.5 eq) was slowly added dropwise to N,N-dimethylformamide (50 mL) at 0 ° C. After stirring, the reaction was stirred at room temperature for 12 h. . After the reaction is completed, the mixed solution is poured into ice water, stirred, solid precipitated, suction filtered, and the solid is dissolved with dichloromethane, the aqueous phase is removed, the organic phase is dried over anhydrous sodium sulfate, and dried, and then petroleum ether is added and washed. Filtration and solid drying gave a white solid (14.1 g).

Step 4 (2S,4R)-2-(5-((S)-1-(((9H-芴-9-yl)methoxy)carbonyl)amino)-4-oxo-4-(3) Benzylamino)butyl)-1,3,4-oxadiazol-2-yl)-4-((tert-butyldimethylmethyl)oxy)tetrahydropyrrole-1-carboxylic acid tert-butyl ester Preparation

(2S,4R)-2-(2-(N ² -((9H-芴-9-yl)methoxy)carbonyl)-N ⁵ -trityl-L-glutamine) tert-Butyl decyl-1-carbonyl)-4-((tert-butyldimethylmethyl)oxy)tetrahydropyrrole-1-carboxylate (14.1 g, 14.8 mmol, 1 eq) was dissolved in tetrahydrofuran (100) To a solution of triphenylphosphine (7.9 g, 30.1 mmol, 2 eq) and iodine (7.6 g, 30.1 mmol, 2 eq) at 0 ° C in EtOAc. . After the iodine was completely dissolved, triethylamine (5.9 g, 58.6 mmol, 4 eq) was added, and the mixture was stirred at room temperature for 5 h. After the reaction is completed, water and ethyl acetate are added to the mixed solution, and the organic phase is washed with a sodium thiosulfate solution and a saturated sodium chloride solution, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography. Ethyl acetate: petroleum ether = 1:3). A white solid (4.8 g) was obtained in a yield of 34.7%.

Step 5 (2S,4R)-2-(5-((S)-1-Amino-4-oxo-4-(tritylamino)butyl)-1,3,4-oxadiazole- Preparation of tert-butyl 2-yl)-4-((tert-butyldimethylmethyl)oxy)tetrahydropyrrole-1-carboxylate

(2S,4R)-2-(5-((S)-1-(((9H-芴-9-yl)methoxy)carbonyl)amino)-4-oxo-4-(triphenyl) Methylamino)butyl)-1,3,4-oxadiazol-2-yl)-4-((tert-butyldimethylmethyl)oxy)tetrahydropyrrole-1-carboxylic acid tert-butyl ester ( 3 g, 3.2 mmol) was dissolved in dichloromethane (15 mL). After the reaction was completed, the mixture was concentrated and purified by column chromatography (ethyl acetate: petroleum ether = 4:1). A white solid (1.7 g) was obtained in a yield of 74.2%.

Step 6 Preparation of O-(tert-butyl)-N-((4-nitrophenoxy)carbonyl)-L-serine tert-butyl ester

O-(tert-butyl)-L-serine tert-butyl ester (5 g, 23.01 mmol, 1 eq) was dissolved in dichloromethane (25 mL) and triethylamine (4.7 g, 46.02 mmol, 2 eq). 4-Nitrophenylchloroformate (5.1 g, 25.31 mmol, 1.1 eq) was slowly added dropwise to a solution of dichloromethane (25 mL) at 0 ° C. After the reaction was completed, citric acid and dichloromethane were added, and the organic phase was washed successively with citric acid saturated sodium carbonate solution and water, dried, concentrated, washed with petroleum ether, suction filtered, and the filtrate was dried to give a white solid (2.2 g). The yield was 25.0%.

Step 7 (2S,4R)-2-(5-((6S,10S)-10-(tert-butoxymethyl)-13,13-dimethyl-3,8,11-trioxo-1, 1,1-triphenyl-12-oxy-2,7,9-azatetradecane-6-yl)-1,3,4-oxadiazol-2-yl)-4-((uncle Preparation of tert-butyl butyl dimethyl decyl oxy) tetrahydropyrrole-1-carboxylate

(2S,4R)-2-(5-((S)-1-Amino-4-oxo-4-(tritylamino)butyl)-1,3,4-oxadiazole-2 -yl)-4-((tert-butyldimethylmethyl)oxy)tetrahydropyrrole-1-carboxylic acid tert-butyl ester (0.7 g, 0.98 mmol, 1 eq) and triethylamine (0.2 g, 1.97 mmol) , 2 eq) was dissolved in N,N-dimethylformamide (15 mL), and O-(tert-butyl)-N-((4-nitrophenoxy)carbonyl) was added dropwise at 0 °C. -L-Serine tert-butyl ester (0.41 g, 1.08 mmol, 1.1 eq). After stirring, the mixture was stirred at room temperature for 6 h. After the reaction is completed, dichloromethane and water are added, and the organic phase is washed with water, a saturated sodium chloride solution, dried over anhydrous sodium sulfate, filtered, filtered, and purified by column chromatography (ethyl acetate: petroleum ether = 2: 3) A white solid (0.8 g) was obtained in a yield of 85.2%.

Step 8 (((S)-4-Amino-1-(5-((2S,4R)-4-hydroxytetrahydropyrrole-2-yl)-1,3,4-oxadiazol-2-yl) Preparation of -4-oxobutyl)carbamoyl)-L-serine

(2S,4R)-2-(5-((6S,10S)-10-(tert-butoxymethyl)-13,13-dimethyl-3,8,11-trioxo-1,1 ,1-triphenyl-12-oxy-2,7,9-azatetradecane-6-yl)-1,3,4-oxadiazol-2-yl)-4-((tert-butyl) tert-Butyl dimethyl hydrazinyloxy)tetrahydropyrrole-1-carboxylate (800 mg, 0.84 mmol) dissolved in dichloromethane (16 mL), trifluoroacetic acid (16 mL) and triisopropyl Centane (0.8 mL) was stirred at room temperature for 6 h. After the reaction was completed, the mixture was evaporated to dryness, water and methylene chloride, and the aqueous phase was washed with methylene chloride and lyophilized to give a white solid (190 mg). ¹ H NMR (400 MHz, D ₂ O): δ 5.35-5.31 (t, 1H), 5.11-5.08 (t, 1H), 4.87-4.73 (m, 1H), 4.19 - 4.17 (t, 1H), 3.89 -3.83(d,2H), 3.70-3.66(t,1H),3.53-3.50(t,1H),2.69-2.60(m,2H),2.56-2.52(t,2H),2.44-2.37(m, 1H), 2.30-2.23 (m, 1H). ESI-MS m/z: 387.0 [M+H] ⁺ .

Example 12 (((S)-4-Amino-1-(5-((2S,3S)-3-hydroxytetrahydropyrrole-2-yl)-1,3,4-oxadiazol-2-yl) Preparation of 4-oxobutyl)carbamoyl)-L-serine

Step 1 Preparation of (2S,3S)-3-hydroxytetrahydropyrrole-2-carboxylic acid methyl ester

(2S,3S)-3-Hydroxytetrahydropyrrole-2-carboxylic acid (4 g, 30.5 mmol, 1 eq) was dissolved in methanol (40 mL). After the completion of the dropwise addition, the mixed solution was refluxed at 65-70 ° C for 3 h. After the reaction was completed, the mixture was evaporated to give the product (yield: 4.4 g).

Step 2 Preparation of (2S,3S)-N-(tert-Butoxycarbonyl)-3-hydroxy-2-pyrrolecarboxylic acid methyl ester

Methyl (2S,3S)-3-hydroxytetrahydropyrrole-2-carboxylate (4.4 g, 30.3 mmol, 1 eq) was dissolved in tetrahydrofuran (40 mL), and aqueous sodium hydrogencarbonate (8.9 g) was slowly added thereto. , 106.1 mmol, 3.5 eq, dissolved in 40 mL of water), di-tert-butyl dicarbonate (6.28 g, 28.8 mmol, 0.95 eq) was added dropwise at 0 ° C. After completion, the mixture was stirred at room temperature for 24 h. Water and ethyl acetate were added to the mixture, and the mixture was evaporated, evaporated, evaporated, evaporated

Step 3 (((S)-4-Amino-1-(5-((2S,3S)-3-hydroxytetrahydropyrrole-2-yl)-1,3,4-oxadiazol-2-yl) Preparation of -4-oxobutyl)carbamoyl)-L-serine

The preparation method is the same as the preparation method of Step 1 to Step 8 in Example 11, except that the starting material (2S, 4R)-N-(tert-butoxycarbonyl)-4-hydroxy-2-pyrrolecarboxylic acid A in Example 11 is prepared. The ester was replaced with the product of the above step 2 (2S,3S)-N-(tert-butoxycarbonyl)-3-hydroxy-2-pyrrolecarboxylic acid methyl ester. ¹ H NMR (400 MHz, D ₂ O): δ 5.12 - 5.10 (t, 1H), 5.09 - 5.06 (t, 1H), 4.95 - 4.94 (m, 1H), 4.20 - 4.19 (t, 1H), 3.87 -3.86(d,2H), 3.78-3.73(t,2H), 2.58-2.53(t,2H),2.53-2.48(m,1H), 2.47-2.37(m,1H), 2.29-2.22(m, 2H). ESI-MS m/z: 387.0 [M+H] ⁺ .

Example 13 (2S,4R)-1-(((S)-4-amino-1-(5-((1S,2R)-1-amino-2-hydroxypropyl)-1,3,4- Preparation of oxadiazol-2-yl)-4-oxobutyl)carbamoyl)-4-hydroxytetrahydropyrrole-2-carboxylic acid

Step 1 Preparation of N-(tert-Butoxycarbonyl)-O-(tert-butyl)-L-threonine methyl ester

N-(tert-Butoxycarbonyl)-O-(tert-butyl)-L-threonine (5 g, 18.2 mmol, 1 eq) was dissolved in N,N-dimethylformamide (35 mL). Methyl iodide (2.8 g, 20.0 mmol, 1.1 eq), potassium carbonate (7.9 g, 54.5 mmol, 3 eq) was added to the solution and stirred at room temperature for about 3 h. After the reaction was completed, water and ethyl acetate were added to the mixture, and the mixture was evaporated. 99.0%.

Step 2 Preparation of (2S,3R)-3-(tert-butoxy)-1-indolyl-1-oxobutan-2-yl)carbamic acid tert-butyl ester

N-(tert-Butoxycarbonyl)-O-(tert-butyl)-L-threonine methyl ester (5.2 g, 18.0 mmol) was dissolved in methanol, and hydrazine hydrate (15 mL) was added to the solution at room temperature. Stir under 24h. After the reaction was completed, MeOH was evaporated, EtOAcjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj The yield was 100.0%.

Step 3 ((5S,10S,11R)-1-(9H-芴-9-yl)-11,13,13-trimethyl-3,6,9-trioxo-5-(3-oxo Preparation of tert-butyl 3-(tritylmethylamino)propyl)-2,12-dioxa-4,7,8-triazatetradecane-10-yl)carbamate

tert-Butyl ((2S,3R)-3-(tert-butoxy)-1-indolyl-1-oxobutan-2-yl)carbamate (5.2 g, 18.0 mmol, 1 eq), N2- (((9H-芴-9-yl)methoxy)carbonyl)-N5-trityl-L-glutamine (11.0 g, 18.0 mmol, 1 eq), 1-ethyl-(3- Dimethylaminopropyl)carbodiimide hydrochloride (4.1 g, 21.6 mmol, 1.2 eq), 1-hydroxybenzotriazole (2.9 g, 21.6 mmol, 1.2 eq) dissolved in N,N- N-methylmorpholine (4.5 g, 44.9 mmol, 2.5 eq) was slowly added dropwise to methylformamide (40 mL) at 0 ° C, and the reaction was stirred at room temperature for 12 h. After the reaction was completed, the mixed solution was added to ice water and stirred, and the solid was precipitated and suction filtered. The solid was dissolved in dichloromethane, the aqueous phase was removed, the organic phase was dried, washed with petroleum ether, filtered, and dried to give a white solid (10.5 g).

Step 4 ((1S,2R)-1-(5-((S)-1-(((9H-芴-9-yl)methoxy)carbonyl)amino)-4-oxo-4-() Preparation of tert-butyl ester of tritylamino)butyl)-1,3,4-oxadiazol-2-yl)-2-(tert-butoxy)propyl)carbamate

((5S,10S,11R)-1-(9H-芴-9-yl)-11,13,13-trimethyl-3,6,9-trioxo-5-(3-oxo- tert-Butyl 3-(tritylamino)propyl)-2,12-dioxa-4,7,8-triazatetradecane-10-yl)carbamate (10.5 g, 11.9 mmol, 1 eq) was dissolved in tetrahydrofuran (75 mL) and N,N-dimethylformamide (30 mL). Triphenylphosphine (6.2 g, 23.8 mmol, 2 eq) and iodine (6.0 g, 23.8 mmol, 2 eq). After the iodine was completely dissolved, triethylamine (4.8 g, 47.6 mmol, 4 eq) was added, and the mixture was stirred at room temperature for 5 h. After the reaction is completed, water and ethyl acetate are added to the mixed solution, and the organic phase is washed with a saturated sodium thiosulfate solution and a saturated sodium chloride solution, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography. White solid (3.9 g), yield 38.0%.

Step 5 ((1S,2R)-1-(5-((S)-1-Amino-4-oxo-4-(tritylamino)butyl)-1,3,4-oxadiazole Preparation of tert-butyl 2-yl)-2-(tert-butoxy)propyl)carbamate

((1S,2R)-1-(5-((S)-1-(((9H-芴-9-yl)methoxy)carbonyl)amino)-4-oxo-4-(3) Benzylamino)butyl)-1,3,4-oxadiazol-2-yl)-2-(tert-butoxy)propyl)carbamic acid tert-butyl ester (3.9 g, 4.5 mmol) dissolved in two Methyl chloride (20 mL) was added with diethylamine (20 mL). After completion of the reaction, the residue was purified by silica gel chromatography (ethyl acetate: petroleum ether = 4:1). A white solid (1.5 g) was obtained in a 51.7% yield.

Preparation of Step 6(2S,4R)-4-Hydroxytetrahydropyrrole-2-carboxylic Acid Methyl Ester

The preparation method is the same as the preparation method of the first step in the embodiment 12 except that (2S,3S)-3-hydroxytetrahydropyrrole-2-carboxylic acid is replaced by (2S,4R)-4-hydroxytetrahydropyrrole-2. - Formic acid.

Step 7 Preparation of (2S,4R)-4-((tert-Butyldimethylmethyl)oxy)tetrahydropyrrole-2-carboxylic acid methyl ester

The preparation method is the same as the preparation method of the first step in the embodiment 11, except that the methyl (2S,4R)-N-(tert-butoxycarbonyl)-4-hydroxy-2-pyrrolecarboxylate is replaced with (2S, 4R). Methyl 4-hydroxytetrahydropyrrole-2-carboxylate.

Preparation of methyl (2S,4R)-4-((tert-butyldimethylmethyl)oxy)-1-(chloromethylindenyl)tetrahydropyrrole-2-carboxylate

Methyl (2S,4R)-4-((tert-butyldimethylmethyl)oxy)tetrahydropyrrole-2-carboxylate (1 g, 3.9 mmol, 1 eq) was dissolved in dichloromethane (100 mL Add pyridine (0.4 g, 5.0 mmol, 1.3 eq), and add a solution of triphosgene in dichloromethane (0.5 g, 1.7 mmol, 0.44 eq, dissolved in 15 mL of DCM). After stirring for 1 h in the bath, the mixture was stirred at room temperature and stirred for 18 h. The mixture was extracted with citric acid and dichloromethane. EtOAc (EtOAc m.

Step 9 (1R,4S)-2-(((S)-1-(5-((1S,2R)-2-tert-butoxy-1-(tert-butoxycarbonyl)amino)propyl)-1 ,3,4-oxadiazol-2-yl)-4-oxy-4-(tritylamino)butyl)carbamoyl)-4-((tert-butyldimethylmethyl) Preparation of oxy)tetrahydropyrrole-1-carboxylic acid methyl ester

((1S,2R)-1-(5-((S)-1-Amino-4-oxo-4-(tritylamino)butyl)-1,3,4-oxadiazole- Tert-butyl 2-yl)-2-(tert-butoxy)propyl)carbamate (700 mg, 1.1 mmol, 1 eq) was dissolved in dioxane (10 mL). (331 mg, 3.3 mmol, 3 eq) and (2S,4R)-4-((tert-butyldimethylmethyl)oxy)-1-(chloromethylindenyl)tetrahydropyrrole-2-carboxylic acid The ester (422 mg, 1.3 mmol, 1.2 eq) was warmed to reflux and stirred for 12 h. To the mixed solution, citric acid and ethyl acetate were added, and the organic phase was washed with saturated sodium bicarbonate solution, water and saturated sodium chloride solution, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography. PE=3:2). A white solid (300 mg) was obtained in a yield of 29.7%.

Step 10 (1R,4S)-2-(((S)-1-(5-((1S,2R)-2-tert-butoxy-1-(tert-butoxycarbonyl)amino)propyl)-1 ,3,4-oxadiazol-2-yl)-4-oxy-4-(tritylamino)butyl)carbamoyl)-4-((tert-butyldimethylmethyl) Preparation of oxy)tetrahydropyrrole-1-carboxylic acid

(1R,4S)-2-(((S)-1-(5-((1S,2R)-2-tert-butoxy-1-(tert-butoxycarbonyl)amino)propyl)-1, 3,4-oxadiazol-2-yl)-4-oxo-4-(tritylamino)butyl)carbamoyl)-4-((tert-butyldimethylmethyl)oxyl Methyl tetrahydropyrrole-1-carboxylate (300 mg, 0.32 mmol, 1 eq) was dissolved in tetrahydrofuran (2 mL). 2M lithium hydroxide solution (4.5 mg, 0.64 mmol, 2 eq dissolved in 0.05 mL water) Heat to reflux (70 ° C) for 3 h. It was extracted with citric acid and dichloromethane, and the organic phase was washed with EtOAc, EtOAc, EtOAc (EtOAc)

Step 11 (2S,4R)-1-(((S)-4-Amino-1-(5-((1S,2R)-1-amino-2-hydroxypropyl)-1,3,4- oxox Preparation of oxazol-2-yl)-4-oxobutyl)carbamoyl)-4-hydroxytetrahydropyrrole-2-carboxylic acid

The preparation method is the same as the preparation method of the step 8 in the embodiment 11, except that (2S,4R)-2-(5-((6S,10S)-10-(tert-butoxymethyl)-13,13-di Methyl-3,8,11-trioxo-1,1,1-triphenyl-12-oxy-2,7,9-azatetradecane-6-yl)-1,3,4 - Oxadiazol-2-yl)-4-((tert-butyldimethylmethyl)oxy)tetrahydropyrrole-1-carboxylic acid tert-butyl ester was replaced by (1R, 4S)-2-((( S)-1-(5-((1S,2R)-2-tert-butoxy-1-(tert-butoxycarbonyl)amino)propyl)-1,3,4-oxadiazol-2-yl) -4-Oxo-4-(tritylamino)butyl)carbamoyl)-4-((tert-butyldimethylmethyl)oxy)tetrahydropyrrole-1-carboxylic acid, can be made The target compound is obtained. ¹ H NMR (400 MHz, D ₂ O: δ 4.67 - 4.65 (d, 1H), 4.39 - 4.35 (m, 1H), 4.3-4.19 (m, 1H), 4.15 - 4.13 (t, 1H), 3.05- 3.02 (m, 2H), 2.90-2.89 (d, 2H), 2.52-2.48 (t, 2H), 2.46-2.43 (m, 1H), 2.34-2.29 (m, 1H), 2.12-2.10 (t, 1H) ), 1.35-1.33 (d, 3H). ESI-MS m/z: 401.2 [M+H] ⁺ .

Example 14 (2S,3S)-1-(((S)-4-amino-1-(5-((1S,2R)-1-amino-2-hydroxypropyl)-1,3,4- Preparation of Oxadiazol-2-yl)-4-oxobutyl)carbamoyl)-3-hydroxytetrahydropyrrole-2-carboxylic acid

The preparation method is the same as the production method of Example 13, except that the 4-hydroxyproline in Step 7 is replaced with 3-hydroxyproline to prepare the target compound. ¹ H NMR (400 MHz, D ₂ O): δ 4.67-4.65 (d, 1H), 4.43-4.42 (d, 1H), 4.39-4.35 (m, 1H), 4.23-4.19 (m, 1H), 4.15 -4.13(t,1H),3.57-3.45(t,2H),3.05-3.02(m,2H),2.90-2.89(d,2H),2.46-2.43(m,1H),2.34-2.29(m, 1H), 1.35-1.33 (d, 3H). ESI-MS m/z: 401.3 [M+H] ⁺ .

Example 15 (2S,3R)-2-(3-((S)-4-Amino-1-(5-(1-amino-3-(hydroxymethyl)cyclobutyl)-1,3,4 -Oxadiazol-2-yl)-4-oxobutyl)ureido)-3-hydroxybutyric acid

The preparation method was the same as the preparation method of Example 12 except that the (2S,3S)-3-hydroxytetrahydropyrrole-2-carboxylic acid in the step 1 of Example 12 was replaced with 1-amino-3-(hydroxymethyl group). The target compound can be obtained by replacing cyclobutane-1-carboxylic acid with O-(tert-butyl)-L-serine tert-butyl ester with O-(tert-butyl)-L-threonine tert-butyl ester. ¹ H NMR (400 MHz, D ₂ O): δ 5.00-4.98 (d, 2H), 4.17-4.15 (d, 1H), 3.60-3.58 (d, 2H), 2.76-2.73 (d, 1H), 2.60 -2.44 (m, 6H), 2.24-2.22 (d, 1H), 2.10-2.08 (d, 1H), 1.10-1.08 (d, 3H) ESI-MS m / z:. 415.3 [m + H] +.

Example 16 2-(3-((S)-4-Amino-1-(5-(1-aminocyclopropyl)-1,3,4-oxadiazol-2-yl)-4-oxo Preparation of butyl)ureido)-3-hydroxypropionic acid

The preparation method was the same as that of the production method of Example 12 except that (2S,3S)-3-hydroxytetrahydropyrrole-2-carboxylic acid was replaced with 1-aminocyclopropane-1-carboxylic acid to obtain the target compound. ¹ H NMR (400 MHz, D ₂ O): δ 5.11-5.08 (t, 1H), 4.19-4.17 (t, 1H), 3.89-3.83 (d, 2H), 2.56-2.52 (t, 2H), 2.44-2.37(m,1H), 2.30-2.23(m,1H),1.63-1.59(t,2H),1.59-1.54(t,2H).ESI-MS m/z:357.2[M+H] ⁺ .

Example 17 (S)-2-(3-((S)-4-Amino-1-(5-(1-amino-3-(hydroxy)cyclobutyl)-1,3,4-oxadiazole) Preparation of -2-yl)-4-oxobutyl)ureido)-3-hydroxypropionic acid

The preparation method was the same as the preparation method of Example 12 except that (2S,3S)-3-hydroxytetrahydropyrrole-2-carboxylic acid was replaced by 1-amino-3-(hydroxymethyl)cyclobutane-1- Formic acid can be used to prepare the target compound. ¹ H NMR (400 MHz, D ₂ O): δ 4.17 - 4.15 (d, 2H), 3.89-3.83 (d, 2H), 3.60-3.58 (d, 2H), 2.76-2.73 (d, 1H), 2.60 - 2.44 (m, 6H), 2.24 - 2.22 (m, 1H), 2.10 - 2.08 (m, 1H). ESI-MS m/z: 415.3 [M+H] ⁺ .

Example 18 1-(3-((S)-4-Amino-1-(5-((1S,2R)-1-amino-2-hydroxypropyl)-1,3,4-oxadiazole- Preparation of methyl 2-yl)-4-oxobutyl)ureido)cyclopropylcarboxylate

The preparation method of the steps 1 to 5 is the same as the preparation method of the steps 1 to 5 in the embodiment 13, and the preparation methods of the steps 6 to 8 are the same as the preparation methods of the steps 6 to 8 in the embodiment 11, except that the O-(tert-butyl group) is used. The L-serine tert-butyl ester is replaced with methyl 1-aminocyclopropane-1-carboxylate to obtain the target compound. ¹ H NMR (400 MHz, D ₂ O): δ 5.01-4.98 (m, 1H), 4.61-4.59 (d, 1H), 4.28-4.25 (t, 1H), 3.59 (s, 3H), 2.40-2.37 (t, 2H), 2.30-2.27 (m, 1H), 2.25-2.23 (m, 1H), 1.47 (t, 2H), 1.24-1.23 (d, 3H), 1.13 (t, 2H). ESI-MS m/z: 385.2 [M+H] ⁺ .

Example 19 (((S)-4-Amino-1-(5-(1-amino-3-hydroxycyclobutyl)-1,3,4-oxadiazol-2-yl)-4-oxo Preparation of butyl)carbamoyl)-L-serine

The preparation method is the same as the preparation method of Example 12, except that (2S,3S)-3-hydroxytetrahydropyrrole-2-carboxylic acid is replaced by 1-amino-3-hydroxycyclobutane-1-carboxylic acid. The target compound is obtained. ¹ H NMR (400 MHz, D ₂ O): δ 5.11-5.08 (t, 1H), 4.59-4.52 (m, 1H), 4.28-4.25 (t, 1H), 3.89-3.83 (d, 2H), 2.63 - 2.60 (d, 2H), 2.40-2.37 (t, 2H), 2.37-2.34 (d, 2H), 2.30-2.27 (m, 1H), 2.25-2.23 (m, 1H). ESI-MS m/z : 387.2 [M+H] ⁺ .

Example 20 (S)-4-(5-(1-Amino-3-(hydroxymethyl)cyclobutyl)-1,3,4-oxadiazol-2-yl)-4-(3-( Preparation of (1S,2R)-1-carboxy-2-hydroxypropyl)ureido)butyric acid

The preparation method is the same as the preparation method of Example 15, except that N ² -(((9H-fluoren-9-yl)methoxy)carbonyl)-N ⁵ -trityl-L-glutamine is replaced (S)-2-(((9H-fluoren-9-yl)methoxy)carbonyl)amino)-5-(tert-butoxy)-5-oxopentanoic acid can be obtained to obtain the target compound . ¹ H NMR (400 MHz, D ₂ O): δ 5.00-4.98 (d, 2H), 4.17-4.15 (d, 1H), 3.60-3.58 (d, 2H), 2.76-2.73 (d, 1H), 2.60 -2.44 (m, 6H), 2.24-2.22 (d, 1H), 2.10-2.08 (d, 1H), 1.10-1.08 (d, 3H) .ESI-MS m / z: 416.2 [m + H] +.

Example 21 (S)-4-(5-(1-Amino-3-(hydroxymethyl)cyclobutyl)-1,3,4-oxadiazol-2-yl)-4-(3-( Preparation of (S)-1-carboxy-2-hydroxyethyl)ureido)butyric acid

The preparation method is the same as the preparation method of Example 17, except that N ² -(((9H-fluoren-9-yl)methoxy)carbonyl)-N ⁵ -trityl-L-glutamine is replaced (S)-2-(((9H-fluoren-9-yl)methoxy)carbonyl)amino)-5-(tert-butoxy)-5-oxopentanoic acid can be obtained to obtain the target compound . ¹ H NMR (400 MHz, D ₂ O): δ 4.17 - 4.15 (d, 2H), 3.89-3.83 (d, 2H), 3.60-3.58 (d, 2H), 2.76-2.73 (d, 1H), 2.60 - 2.44 (m, 6H), 2.24 - 2.22 (m, 1H), 2.10 - 2.08 (m, 1H). ESI-MS m/z: 402.2 [M+H] ⁺ .

Example 22 ((1-(5-((1S,2R)-1-amino-2-hydroxypropyl)-1,3,4-oxadiazol-2-yl)cyclopropyl)carbamoyl) -L-serine preparation

The preparation method of the steps 1 to 5 is the same as the preparation method of the steps 1 to 5 in the embodiment 13, except that N ² -(((9H-fluoren-9-yl)methoxy)carbonyl)-N ⁵ -3 Benzyl-L-glutamine is replaced by 1-(((9H-芴-9-yl)methoxy)carbonyl)amino)cyclopropane-1-carboxylic acid, the preparation method of steps 6-8 is the same In the preparation method of 6 to 8 in Example 11, the target compound can be obtained. ¹ H NMR (400 MHz, D ₂ O): δ 5.11-5.08 (t, 1H), 5.01-4.98 (m, 1H), 4.61-4.59 (d, 1H), 3.89-3.83 (d, 2H), 1.47 (t, 2H), 1.24-1.23 (d, 3H), 1.13 (t, 2H). ESI-MS m/z: 330.2 [M+H] ⁺ .

Example 23 (2S,3S)-2-(3-((S)-4-Amino-1-(5-(4-aminotetrahydro-2H-pyran-4-yl)-1,3,4 -Oxadiazol-2-yl)-4-oxobutyl)ureido)-3-hydroxybutyric acid

Step 1 Preparation of 4-aminotetrahydro-2H-pyran-4-carboxylic acid methyl ester

4-Aminotetrahydro-2H-pyran-4-carboxylic acid (5.00 g, 34.48 mmol) was dissolved in 50 mL of methanol, stirred and cooled to -10 ° C, and dichloromethane (13.96 g, 103.38 mmol) was slowly added dropwise. After the addition, the temperature was refluxed for 3 hours. The reaction solution was concentrated to remove methanol and dichloromethane, and 6.5 g of crude product was obtained.

Step 2 Preparation of methyl 4-(tert-butoxycarbonyl)aminotetrahydro-2H-pyran-4-carboxylate

Methyl 4-aminotetrahydro-2H-pyran-4-carboxylate (6.50 g, 0.04 mol) was dissolved in 65 mL of tetrahydrofuran and 65 mL of water, sodium bicarbonate (12.10 g, 0.14 mol) was added, At 0 ° C, di-tert-butyl dicarbonate (8.50 g, 0.038 mol) was added, and the reaction was allowed to warm up to room temperature for about 24 h. The residue was concentrated with EtOAc (EtOAc m.

Step 3 Preparation of 4-(tert-butoxycarbonyl)aminotetrahydro-2H-pyran-4-carboxylic acid

Methyl 4-(tert-butoxycarbonyl)aminotetrahydro-2H-pyran-4-carboxylate (5.30 g, 0.02 mmol) was dissolved in 53 mL of methanol, then hydrazine hydrate (13 mL, 0.2 mmol). The reaction mixture was warmed to EtOAc (EtOAc).

Step 4 (4-(2-(N ² -((9H-fluoren-9-yl)methoxy)carbonyl)-N ⁵ -trityl-L-glutamyl) fluoren-1-ylcarbonyl Preparation of tert-butyl tetrahydro-2H-pyran-4-yl)carbamate

4-(tert-Butoxycarbonyl)aminotetrahydro-2H-pyran-4-indole (1.40 g, 5.40 mmol) was dissolved in 14 mL of DMF and N ² -((((9H-芴-) 9-yl)methoxy)carbonyl)-N ⁵ -trityl-L-glutamine (3.30 g, 5.40 mmol), to be dissolved, then NMM (1.36 g, 13.50 mmol) and HATU ( 2.05 g, 5.40 mmol), after adding room temperature for 3 h, the reaction mixture was added to 60 mL of ice water to precipitate a solid, which was filtered, washed with water and dried to give the product 4.5 g, yield 97.8%.

Step 5 (S)-(4-(5-(1-(((9H-芴-9-yl))methoxy)carbonyl)amino)-4-carbonyl-4-(trimethylamino)butane Of tert-butyl-1,3,4-oxadiazol-2-yl)tetrahydro-2H-pyran-4-yl)carbamate

(4-(2-(N ² -((9-Dithio)methoxy)carbonyl)-N ⁵ -trityl-L-glutamyl) fluoren-1-yl)-tetra Hydrogen-2H pyran-4)carbamic acid tert-butyl ester (4.00 g, 4.59 mmol) was dissolved in 40 mL dichloromethane, and triphenylphosphine TPP (3.40 g, 9.18 mmol) was added at room temperature until dissolved. The reaction solution was cooled to -10 ° C, and iodine (2.32 g, 9.18 mmol) was slowly added to the reaction mixture. After the iodine was completely dissolved, triethylamine (3.72 g, 36.72 mmol) was added, and the reaction was allowed to rise to room temperature for 2 h. . After the reaction was completed, the reaction mixture was concentrated and evaporated with ethyl~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ %.

Step 6 (S)-(4-(5-(1-Amino-4-carbonyl-4-tritylamino)butyl)-1,3,4-oxadiazol-2-yl)tetrahydro- Preparation of tert-butyl 2H-pyran-4-yl)carbamate

(S)-(4-(5-(1-(((9H-芴-9-yl))methoxy)carbonyl)amino)-4-carbonyl-4-(trimethylamino)butyl -1,3,4-oxadiazol-2-yl)tetrahydro-2H-pyran-4-yl)carbamic acid tert-butyl ester (2.0 g, 2.11 mmol), dissolved in 20 mL dichloromethane After adding 20 mL of ethylenediamine, the reaction was carried out for 6 h at room temperature, and the reaction was completed by TLC. The reaction mixture was concentrated, and then purified by column chromatography to obtain a product yellow solid 1.0 g (yield: 83.3%).

Step 7 N-(((S)-1-(5-(4-(di-tert-Butyl)-)-tetrahydro-2H-pyran-4-yl)-1,3,4-Ethyl Preparation of oxazol-2-yl)-4-carbonyl-4-(tritylamino)butyl)carbamyl)-O-(tert-butyl)-L-threonine tert-butyl ester

(S)-(4-(5-(1-Amino-4-carbonyl-4-tritylamino)butyl)-1,3,4-oxadiazol-2-yl)tetrahydro-2H tert-Butyl pyran-4-yl)carbamate (300 mg, 0.49 mmol), dissolved in 3 mL DMF, then added triethylamine (100 mg, 0.98 mmol), and then cooled to 0 ° C, then added O-(tert-butyl)-N-((4-nitrophenyl)carbamoyl)-L-isoleucine tert-butyl ester (387 mg, 0.53 mmol), added to room temperature for 10 h The reaction mixture was poured into water (20 mL), EtOAc (EtOAc)EtOAc. 340 mg, yield 81.0%.

Step 8 (2S,3S)-2-(3-((S)-4-Amino-1-(5-(4-aminotetrahydro-2H-pyran-4-yl)-1,3,4- Preparation of oxadiazol-2-yl)-4-oxobutyl)ureido)-3-hydroxybutyric acid

N-(((S)-1-(5-(4-((di-tert-Butyl)))-tetrahydro-2H-pyran-4-yl)-1,3,4-oxan Zin-2-yl)-4-carbonyl-4-(tritylamino)butyl)carbamyl)-O-(tert-butyl)-L-threonine tert-butyl ester (300 mg, 0.345 Methyl) was dissolved in 5 mL of dichloromethane, 5 mL of trifluoroacetic acid was added at room temperature, and two drops of triisopropylethylamine were added dropwise, and reacted at room temperature for 5 h. The reaction solution was concentrated, and 15 mL of water was added to the residue, which was extracted with dichloromethane, and the aqueous layer was lyophilized and passed through a reversed phase column to give product. ¹ H NMR (400 MHz, D ₂ O) δ 4.97 (dd, J = 9.5, 4.9 Hz, 1H), 4.25 (dd, J = 12.2, 9.7 Hz, 1H), 4.18 (d, J = 13.8 Hz, 1H ), 3.93 (d, J = 12.0 Hz, 2H), 3.49 (td, J = 11.6, 5.9 Hz, 2H), 2.56 – 2.02 (m, 8H), 1.09 (d, J = 6.3 Hz, 3H). ESI - MS m/z: 511.2 [M+H] ⁺ .

Example 24 (S)-2-(3-((S)-4-Amino-1-(5-(4-aminotetrahydro-2H-pyran-4-yl)-1,3,4-oxa) Preparation of oxazol-2-yl)-4-oxobutyl)ureido)-3-hydroxypropionic acid

By the synthesis route of Example 23, (((S)-4-amino-1-(5-(4-amino-2H-pyran-4-yl)-1,3,4-oxadiazole) can be synthesized. -2-yl)-4-butylcarbonyl)carzamide)-L-serine. ¹ H NMR (400 MHz, D ₂ O) δ 4.96 (dd, J = 9.7, 4.9 Hz, 1H), 4.24 (t, J = 4.2 Hz, 1H), 3.92 (d, J = 12.3 Hz, 2H), 3.83 (dd, J = 11.7, 4.8 Hz, 1H), 3.73 (dd, J = 11.6, 3.8 Hz, 1H), 3.48 (td, J = 11.1, 5.8 Hz, 2H), 2.49 – 2.34 (m, 4H) , 2.26 (dt, J = 13.0, 7.0 Hz, 1H), 2.18 - 2.04 (m, 3H). ESI-MS m/z: 401.2 [M+H] ⁺ .

Example 25 (S)-4-(5-(4-Aminotetrahydro-2H-pyran-4-yl)-1,3,4-oxadiazol-2-yl)-4-(3-( Preparation of (1S,2S)-1-carboxy-2-hydroxypropyl)ureido)butyric acid

By the synthesis route of Example 23, (S)-4-(5-(4-aminotetrahydro-2H-pyran-4-yl)-1,3,4-oxadiazol-2-yl can be synthesized. -4-(3-((1S,2S)-1-carboxy-2-hydroxypropyl)ureido)butyric acid. ¹ H NMR (400 MHz, D ₂ O) δ 4.94 (d, J = 7.0 Hz, 1H), 4.19 (d, J = 5.7 Hz, 1H), 4.07 (s, 1H), 3.88 (d, J = 12.5 Hz, 2H), 3.44 (t, J = 12.0 Hz, 2H), 2.41 (dd, J = 19.7, 10.2 Hz, 3H), 2.29 – 2.15 (m, 1H), 2.08 (t, J = 10.8 Hz, 3H ), 1.03 (d, J = 6.2 Hz, 3H). ESI-MS m/z: 416.2 [M+H] ⁺ .

Example 26 (S)-4-(5-(4-Aminotetrahydro-2H-pyran-4-yl)-1,3,4-oxadiazol-2-yl)-4-(3-( Preparation of (S)-1-carboxy-2-hydroxyethyl)ureido)butyric acid

By the synthesis route of Example 23, (S)-4-(5-(4-aminotetrahydro-2H-pyran-4-yl)-1,3,4-oxadiazol-2-yl can be synthesized. -4-(3-((1S,2S)-1-carboxy-2-hydroxyethyl)ureido)butyric acid. ¹ H NMR (400 MHz, D ₂ O) δ 5.03 – 4.93 (m, 1H), 4.21 (d, J = 4.0 Hz, 1H), 3.91 (s, 2H), 3.79 (dd, J = 11.4, 4.7 Hz , 1H), 3.76 – 3.66 (m, 1H), 3.46 (d, J = 9.3 Hz, 2H), 2.53 – 2.33 (m, 4H), 2.23 (d, J = 5.1 Hz, 1H), 2.10 (s, 3H). ESI-MS m/z: 402.2 [M+H] ⁺ .

Example 27 (S)-4-(3-(4-Aminotetrahydro-2H-pyran-4-yl)-1,2,4-oxadiazol-5-yl)-4-(3-( Preparation of (S)-1-carboxy-2-hydroxyethyl)ureido)butyric acid

Step 1 Preparation of 4-aminotetrahydro-2H-pyran-4-carboxylic acid methyl ester

4-Aminotetrahydro-2H-pyran-4-carboxylic acid (5.00 g, 34.48 mmol) was dissolved in 50 mL of MeOH, stirred and cooled to -10 ° C, and dichloromethane (13.96 g, 103.38 mmolq) was slowly added dropwise. The temperature was refluxed for 3 h. The reaction solution was concentrated to remove methanol and dichloromethane, and 6.5 g of crude product was obtained.

Step 2 Preparation of methyl 4-(tert-butoxycarbonyl)aminotetrahydro-2H-pyran-4-carboxylate

Methyl 4-aminotetrahydro-2H-pyran-4-carboxylate (6.50 g, 0.04 mol) was dissolved in 65 mL of tetrahydrofuran and 65 mL of water, sodium bicarbonate (12.10 g, 0.14 mol) was added, At 0 ° C, di-tert-butyl dicarbonate (8.50 g, 0.038 mol) was added and the reaction was allowed to warm to room temperature for about 24 h. The reaction mixture was concentrated, the~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Step 3 Preparation of 4-(tert-butoxycarbonyl)aminotetrahydro-2H-pyran-4-carboxylic acid

Methyl 4-(tert-butoxycarbonyl)aminotetrahydro-2H-pyran-4-carboxylate (7.00 g, 27.02 mmol) was dissolved in 70 mL of methanol, then 40 mL water was added, then (1.63 g, 40.53 mmol) After reacting for 4 h at room temperature, the reaction mixture was adjusted to pH 4-5 with 1 N hydrochloric acid, and then extracted with ethyl acetate.

Step 4 Preparation of 4-(tert-butoxycarbonyl)aminotetrahydro-2H-pyran-4-carbamide

4-(tert-Butoxycarbonyl)aminotetrahydro-2H-pyran-4-carboxylic acid (5.00 g, 20 mmol) was dissolved in 50 mL THF and NMM (2.50 g, 24 mmol) The temperature of the solution was lowered to -10 ° C, and ethyl chloroformate (2.70 g, 24 mmol) was slowly added dropwise. The reaction was carried out for 2 h at low temperature. Ammonia water (13 mL, 160 mmol) was slowly added dropwise at low temperature, and the reaction was continued for 3 h. The reaction mixture was concentrated. EtOAc m.

Step 5 Preparation of (4-cyanotetrahydro-2H-pyran-4-yl)carbamic acid tert-butyl ester

4-(tert-Butoxycarbonyl)aminotetrahydro-2H-pyran-4-carbamide (3.70 g, 15.14 mmol) was dissolved in pyridine (12.0 g, 151.4 mmol) and trifluoroacetic anhydride was added dropwise at low temperature. (4.80 g, 22.71 mmol) was added to room temperature for 4 h. The reaction mixture was poured into saturated sodium hydrogen sulfate solution and extracted with ethyl acetate. The organic layer was washed with 1M EtOAc. Drying and concentrating to give a crude product which was washed with petroleum ether to give 2.9 g of product.

Step 6 Preparation of E-(4-(N'-hydroxymethylindenyl)tetrahydro-2H-pyran-4-yl)carbamic acid tert-butyl ester

(4-Cyanotetrahydro-2H-pyran-4-yl)carbamic acid tert-butyl ester (2.50 g, 0.01 mol), dissolved in 25 mL of ethanol, and then added 5 mL of water, hydroxylamine hydrochloride (1.20 g, 0.015 mol), potassium carbonate (2.30 g, 0.015 mol), after heating and reflux reaction. The reaction mixture was concentrated. EtOAc EtOAc m.

Step 7 Tert-Butyl (S,Z)-4-(((9H-fluoren-9-yl)methoxy)carbonyl)amino)-5-((((((((((((((((((( Preparation of ethyl tetrahydro-2H-pyran-4-yl)methylene)amino)oxy)-5-oxopentanoate

E-(4-(N'-hydroxycarbamimido)tetrahydro-2H-pyran-4-yl)carbamic acid tert-butyl ester (2.00 g, 7.72 mmol), dissolved in 20 mL DCM, then NMM (1.6 g, 15.44 mmol), (S)-2-((((9H-芴-9-yl)methoxy)carbonyl)amino)-5-(tert-butoxy)-5-oxopentane The acid (3.6 g, 8.49 mmol) was added to room temperature, and the reaction was completed by TLC. The reaction mixture was concentrated, and the residue was purified by column chromatography.

Step 8 Tert-Butyl (S)-4-(((9H-fluoren-9-yl)methoxy)carbonyl)amino)-4-(3-(4-((tert-butoxycarbonyl)amino) Preparation of ethyl tetrahydro-2H-pyrano-pyridin-4-yl)-1,2,4-oxadiazol-5-yl)butanoate

tert-Butyl (S,Z)-4-((((9H-芴-9-yl)methoxy)carbonyl)amino)-5-(((((((((((((((((((((((((((((((( Tetrahydro-2H-pyran-4-yl)methylene)amino)oxy)-5-oxopentanoate (2.20 g, 3.29 mmol) was dissolved in 22 mL of ethanol and 3 mL of water, then acetic acid was added. The reaction was carried out with aq. EtOAc (EtOAc).

Step 9 tert-Butyl (S)-4-amino-4-(3-(4-((tert-butoxycarbonyl)amino)tetrahydro-2H-pyran-4-yl)-1,2,4- Preparation of Oxadiazole-5-yl) Butyrate

tert-Butyl (S)-4-(((9H-fluoren-9-yl)methoxy)carbonyl)amino)-4-(3-(4-((tert-butoxycarbonyl))amino) Hydrogen-2H-pyrano-pyridin-4-yl)-1,2,4-oxadiazol-5-yl)butyrate ethyl ester (1.80 g, 2.77 mmol), dissolved in 18 mL of dichloromethane, then added 18 mL of diethylamine was added to the room temperature for 6 h, and the reaction was completed by TLC. The reaction solution was concentrated and purified by column chromatography to yield white crystals (yel.

Step 10 tert-Butyl (S)-4-(3-(4-((tert-butoxycarbonyl)amino)tetrahydro-2H-pyran-4-yl)-1,2,4-oxadiazole- Preparation of 5-ethyl)-4-(3-((S)-1,3-di-tert-butoxy-1-oxopropan-2-yl)ureido)butyric acid ethyl ester

tert-Butyl (S)-4-amino-4-(3-(4-((tert-butoxycarbonyl)amino)tetrahydro-2H-pyran-4-yl)-1,2,4-oxo Diazol-5-yl)butyrate (300 mg, 0.70 mmol), dissolved in 3 mL of DMF, added with triethylamine (142 mg, 1.40 mmol), cooled to 0 ° C, then added O- ( tert-Butyl)-N-((4-nitrophenyl)carbamoyl)-L-serine tert-butyl ester (352 mg, 0.77 mmol), added to room temperature for 10 h, poured into the reaction solution The mixture was extracted with EtOAc EtOAc (EtOAc)EtOAc. %.

Step 11 (S)-4-(3-(4-Aminotetrahydro-2H-pyran-4-yl)-1,2,4-oxadiazol-5-yl)-4-(3-(( S)-1-carboxy-2-hydroxyethyl)ureido)butyric acid

tert-Butyl (S)-4-(3-(4-((tert-butoxycarbonyl)amino)tetrahydro-2H-pyran-4-yl)-1,2,4-oxadiazole-5 Ethyl 4-(3-((S)-1,3-di-tert-butoxy-1-oxopropan-2-yl)ureido)butyrate (150 mg, 0.219 mmol) was dissolved in 5 mL of dichloromethane, 5 mL of trifluoroacetic acid was added at room temperature, two drops of triisopropylethylamine were added dropwise, and reacted at room temperature for 5 h. The reaction solution was concentrated, and 15 mL of water was added to the residue to dichloride. Methane is extracted and the aqueous layer is lyophilized to give the product. ¹ H NMR (400 MHz, D ₂ O) δ 4.94 (dt, J = 17.8, 8.9 Hz, 1H), 4.16 (t, J = 3.5 Hz, 1H), 3.86 - 3.71 (m, 3H), 3.65 (dd , J = 11.6, 3.5 Hz, 1H), 3.46 (t, J = 11.4 Hz, 2H), 2.40 (t, J = 6.9 Hz, 2H), 2.31 (d, J = 13.6 Hz, 2H), 2.18 (td , J = 13.3, 6.6 Hz, 1H), 2.11 - 1.92 (m, 3H). ESI-MS m/z: 402.2 [M+H] ⁺ .

Example 28 (S)-3-Amino-3-(3-((2S,4R)-4-hydroxytetrahydropyrrole-2-yl)-1,2,4-oxadiazol-5-yl)propane Preparation of guanamine

Step 1: Preparation of (2S,4R)-1-tert-butoxycarbonyl-2-cyano-4-(tert-butyldimethylmethyl)oxytetrahydropyrrole

Compound 1a (30 g, 141.34 mmol) was dissolved in DMF (300 mL), EtOAc (11.55 g, 169.61 mmol) was added, and then cooled to -5 ° C. TBDMSCl (25.56 g, 169.61 mmol) in DMF (120 mL) The solution was stirred for 2 h, and the mixture was warmed to room temperature for 13 h. The reaction solution was poured into a saturated aqueous solution of ammonium chloride and then quenched, extracted with ethyl acetate, and the mixture was evaporated. Drying, distillation under reduced pressure to give a yellow oily liquid, which was white solid after standing to cool, and the crude compound was purified by column chromatography (purification: 0-5% ethyl acetate in petroleum ether). The mixture was dried in vacuo and cooled to give 44.61 g of white solid compound 1b (yield: 91.7%).

Step 2: (2S,4R)-1-tert-Butoxycarbonyl-2-((Z)-N'-hydroxymethylindenyl)-4-(tert-butyldimethylmethyl)oxytetrahydropyrrole preparation

Compound 1b (20 g, 61.25 mmol) was dissolved in ethanol (200 mL), and then potassium carbonate (12.70 g, 91.88 mmol) and hydroxylamine hydrochloride (6.38 g, 91.88 mmol) were added, and the mixture was refluxed for 5 h. The reaction was filtered, the filtrate by rotary evaporation, dissolved with ethyl acetate and water, layers were separated and the organic phase was washed with saturated saline solution and water several times, dried over anhydrous Na ₂ SO _4, evaporated under reduced pressure, ethyl acetate was added to the obtained solid Ultrasonic treatment, filtration, filter cake is dissolved in a small amount of tetrahydrofuran, a large amount of petroleum ether is added, and the filter cake is pure white solid. The filtrate is distilled under reduced pressure and purified by gel column chromatography (purification agent: petroleum ether) 0-30% ethyl acetate). The obtained solid was combined with a filter cake to give 9.6 g (yield: 43.6%).

Step 3: (2S,4R)-1-tert-Butoxycarbonyl-2-(5-((S)-1-(((9H-fluoren-9-yl))methoxy)carbonyl)amino)-3 -keto-3-(tritylamino)propyl)-1,2,4-oxadiazol-3-yl)-4-((tert-butyldimethylmethyl)oxy)tetrahydrol Preparation of pyrrole

The compound Fmoc-Asn(Trt)-OH (20.71 g, 34.71 mmol) was dissolved in dichloromethane (200 mL), cooled in an ice bath, and BAST (8.45 g, 38.18 mmol) was added at -7 ° C. 8h. The reaction solution was evaporated under reduced pressure, and aq. hexane (hexane) was added, and the mixture was shaken and filtered, and the mixture was repeated several times. The filter cake was dried and dissolved in tetrahydrofuran (200 mL), and compound 1c (9.6 g, 26.70 mmol), nitrogen methyl morpholine ( 5.40 g, 53.40 mmol), stirred at room temperature for 13 h. The tetrahydrofuran was distilled off under reduced pressure, and ethanol (200 mL) and sodium acetate (3.29 g, 40.05 mmol) were directly added thereto, and the mixture was stirred and refluxed for 2.5 hours. The reaction mixture was evaporated under reduced pressure. EtOAc was evaporated. Toluene: 0-25% ethyl acetate in petroleum ether gave 7.18 g of pale yellow solid 1d (yield: 29.2%).

Step 4: (2S,4R)-1-tert-Butoxycarbonyl-2-(5-((S)-1-amino-3-keto-3-(tritylamino)propyl)-1, Preparation of 2,4-oxadiazol-3-yl)-4-((tert-butyldimethylmethyl)oxy)tetrahydropyrrole

Compound 1d (6.0 g, 6.52 mmol) was added to dichloromethane (60 mL), diethylamine (30 mL) was added dropwise, and the mixture was stirred at room temperature for about 1.5 h, and the solvent was evaporated under reduced pressure. Purification (purification: 0-45% ethyl acetate in petroleum ether) gave 2.8 g (yield: 61.5%).

Step 5: (S)-3-Amino-3-(3-((2S,4R)-4-hydroxytetrahydropyrrol-2-yl)-1,2,4-oxadiazol-5-yl)-propyl Preparation of guanamine

Compound 1e (600 mg, 0.86 mmol) was dissolved in dichloromethane (18 mL), trifluoroacetic acid (18 mL) was added at room temperature, and a catalytic amount of triisopropyl decane was stirred at room temperature for 4.5 h. The solvent was distilled off, and the liquid phase was purified to give Compound 1. ¹ H NMR (300 MHz, D ₂ O) δ 5.05 (dd, J = 10.1, 7.3 Hz, 1H), 4.72 (s, 1H), 4.62 (d, J = 6.4 Hz, 1H), 3.51 (dd, J = 12.6, 4.2 Hz, 1H), 3.33 (d, J = 12.7 Hz, 1H), 2.99 – 2.84 (m, 2H), 2.54 – 2.31 (m, 2H). ESI-MS m/z: 242.0 [M+ H] ⁺ .

Example 29 (2S,3R)-2-(3-((S)-3-Amino-1-(3-((2S,4R)-4-hydroxytetrahydropyrrol-2-yl)-1,2 Of 4-oxaoxazol-5-yl)-3-oxopropyl)ureido)-3-hydroxybutyric acid

Step 1: (2S,4R)-1-tert-Butoxycarbonyl-2-(5-((5S,9S)-9-((R)-1-(tert-butyl)ethyl)-12,12- Dimethyl-3,7,10-trione-1,1,1-triphenyl-11-oxa-2,6,8-triaza-5-yl)-1,2,4- Preparation of Oxadiazol-3-yl)-4-((tert-butyldimethylmethyl)oxy)tetrahydropyrrole

Compound 1e (1.0 g, 1.43 mmol) was dissolved in tetrahydrofuran (10 mL). Compound 2b (0.68 g, 1.72 mmol) and triethylamine (0.29 g, 2.86 mmol). After stirring at room temperature for 24 hours, the solvent was evaporated under reduced pressure, and ethyl acetate and water were evaporated and evaporated, and the organic phase was washed with brine, dried over anhydrous sodium sulfate, and evaporated under reduced pressure. Extract: 0-25% ethyl acetate in petroleum ether, yielding 700 mg of pale yellow crystal 2a (yield: 51.3%).

Step 2: (2S,3R)-2-(3-((S)-3-Amino-1-(3-((2S,4R)-4-hydroxytetrahydropyrrole-2-yl)-1,2 Of 4-oxaoxazol-5-yl)-3-oxopropyl)ureido)-3-hydroxybutyric acid

Compound 2a (550 mg, 0.576 mmol) was dissolved in dichloromethane (11.5 mL), trifluoroacetic acid (11.5 mL) was added at room temperature, and the catalytic amount of triisopropyl decane was stirred at room temperature for 5 h. The reaction solvent is removed, dissolved in dichloromethane and water, and the organic phase is extracted several times with water, and the aqueous phase is combined, washed with dichloromethane several times, lyophilized, and purified in liquid phase to obtain compound 2. ¹ H NMR (500 MHz, D ₂ O) δ 5.46 (t, J = 6.4 Hz, 1H), 5.25 – 5.19 (m, 1H), 4.85 (s, 1H), 4.26 (dt, J = 17.5, 8.7 Hz , 1H), 4.02 (d, J = 17.0 Hz, 1H), 3.67 (dt, J = 13.3, 6.7 Hz, 1H), 3.55 – 3.47 (m, 1H), 3.20 – 3.11 (m, 2H), 2.62 ( Dd, J = 14.1, 7.1 Hz, 1H), 2.50 (tt, J = 9.4, 4.7 Hz, 1H), 1.22 (d, J = 6.4 Hz, 3H). ESI-MS m/z: 386.9 [M+H ] ⁺ .

Step 3: Preparation of O-(tert-butyl)-N-((4-nitrophenoxy)carbonyl)-L-threonine tert-butyl ester

H-Thr(OtBu)-OtBu (15 g, 64.84 mmol) was dissolved in dichloromethane (150 mL), cooled in an ice bath, and triethylamine (9.84 g, 97.26 mmol) and chlorine were added dropwise at -5 °C. A solution of formic acid 4-nitrophenyl ester (14.38 g, 71.33 mmol) in dichloromethane (60 mL) was evaporated. Filtration, distillation of the filtrate to remove some solvent under reduced pressure, addition of a 1:1 mixed solvent of ethyl acetate and petroleum ether, solid precipitation, filtration, distillation under reduced pressure, further purification by gel column chromatography (extraction: petroleum 0-5% ethyl acetate in ether gave 13.86 g of a yellow oily liquid 2b (yield: 53.9%).

Example 30 (S)-2-(3-((S)-3-Amino-1-(3-((2S,4R)-4-hydroxytetrahydropyrrole-2-yl)-1,2,4 -Oxadiazole-5-yl)-3-oxopropyl)ureido)-3-hydroxypropionic acid

The title compound was synthesized in a similar manner to the preparation of Example 29, in which H-Thr(OtBu)-OtBu in Example 29 was replaced with H-Ser(OtBu)-OtBu. ¹ H NMR (300 MHz, D ₂ O) δ 5.36 (t, J = 6.1 Hz, 1H), 5.19 – 5.09 (m, 1H), 4.75 (s, 1H), 4.06 (d, J = 4.3 Hz, 1H ), 3.75 (d, J = 6.1 Hz, 2H), 3.59 (dd, J = 12.6, 3.9 Hz, 1H), 3.41 (d, J = 12.8 Hz, 1H), 3.03 (t, J = 6.6 Hz, 2H ), 2.58 - 2.35 (m, 2H). ESI-MS m/z: 372.9 [M+H] ⁺ .

Example 31 (S)-3-(3-((R)-1-Amino-2-hydroxyethyl)-1,2,4-oxadiazol-5-yl)-3-(3-(( Preparation of S)-2-ketotetrahydrofuran-3-yl)ureido)propanamide

Step 1: Preparation of (S)-2-(tert-butoxycarbonyl)amino-3-tert-butoxy-1-propanamide

L-Boc-Ser(tBu)-OH (50 g, 191.45 mmol) was dissolved in tetrahydrofuran (500 mL), N-methylmorpholine (23.2 g, 229.74 mmol) was added, and the temperature was gradually lowered to -15 ° C. Ethyl chloroformate (24.8 g, 229.74 mmol), stirred at -15 ° C for 1.5 h; slowly add ammonia water (48 mL, 693.48 mmol) to the reaction solution, warm to -5 ° C for 2.5 h, and distill off the tetrahydrofuran under reduced pressure. The remaining liquid was dissolved in ethyl acetate and water, and the organic layer was washed with 1M citric acid, saturated sodium hydrogen carbonate and brine, dried over anhydrous sodium sulfate The petroleum ether was recrystallized to give 39.3 g of a white solid 4a (yield: 78.9%).

Step 2: Preparation of (R)-(2-(tert-butoxy)-1-cyanoethyl)carbamic acid tert-butyl ester

Compound 4a (39 g, 149.81 mmol) was dissolved in pyridine (118.5 g, 1498.1 mmol), cooled in an ice bath, and trifluoroacetic anhydride (47.2 g, 224.72 mmol) was added dropwise at -5 ° C for 40 min. The mixture was stirred at room temperature for 3.5 h. The reaction mixture was poured into EtOAc EtOAc (EtOAc m. 4b (yield: 102.9%).

Step 3: Preparation of (R,Z)-(1-amino-3-(tert-butoxy)-1-(indolyl)propan-2-yl)carbamic acid tert-butyl ester

Compound 4b (23 g, 184.88 mmol) was dissolved in ethanol (450 mL), followed by potassium carbonate (38.34 g, 277.33 mmol), hydroxylamine hydrochloride (19.28 g, 277.33 mmol), stirred, refluxed for 1.5 h, decompressed The solvent was evaporated, and the mixture was combined with ethyl acetate and water, and then evaporated and evaporated, evaporated, evaporated, evaporated, evaporated. PE was beaten, filtered, and the cake was dried to give 38.67 g of a white solid 4c (yield: 76.0%).

Step 4: tert-Butyl-((5S,Z)-9-amino-13,13-dimethyl-3,6-dione-1,1,1-triphenyl-7,12-dioxo Preparation of (hetero-2,8-aza-8-ene-5,10-diyl)dicarbamic acid (9H-fluoren-9-yl)methyl ester

Fmoc-Asn(Trt)-OH (10 g, 36.32 mmol) and compound 4c were dissolved in DMF (200 mL), cooled in an ice bath, and added to the mixture of HOBt (5.90 g, 43.58 mmol) and EDC (8.35) at -5 °C g, 43.58 mmol), stirring in an ice bath for 20 min, heating, room temperature reaction for 4 h, the reaction solution was poured into water, a large amount of solids were precipitated, filtered, and the filter cake was washed several times with water, and dried to obtain 33.8 g of white solid 4d ( Yield: 108.98%).

Step 5: ((R)-1-(5-((S)-1-(((9H-芴-9-yl)methoxy)carbonyl)))))))) Preparation of tert-butyl ester of benzylamino)propyl)-1,2,4-oxadiazol-3-yl)-2-(tert-butoxy)ethyl)carbamate

The compound 4d (28.0 g, 32.79 mmol) was dissolved in ethanol (420 mL), and a solution of sodium acetate (4.04 g, 49.19 mmol) in water (60 mL) was added, and the mixture was stirred and refluxed for 2 hr. The ethyl ester was dissolved, washed several times with saturated brine, distilled under reduced pressure, and purified by silica gel column chromatography (purification: 0-30% ethyl acetate in petroleum ether). 6.6 g of milky white solid 4e (yield: 24.1%).

Step 6: ((R)-1-(5-((S)-1-Amino-3-keto-3-(tritylamino)propyl)-1,2,4-oxadiazole- Preparation of tert-butyl 3-yl)-2-(tert-butoxy)ethyl)carbamate

Compound 4e (6.6 g, 7.89 mmol) was added to dichloromethane (66 mL). The solvent was evaporated under reduced pressure and purified by silica gel column chromatography (EtOAc: EtOAc:EtOAc:EtOAc

Step 7: Preparation of (S)-(2-ketotetrahydrofuran-3-yl)carbamic acid 4-nitrophenyl ester

The title compound was synthesized in a similar manner to the preparation of the compound 2b in Example 29, in which the H-Thr(OtBu)-OtBu in Example 29 was replaced with (S)-2-keto-3-aminotetrahydrofuran.

Step 8: ((R)-2-(tert-Butoxy)-1-(5-((S)-3-keto-1-(3-((S)-2-ketotetrahydrofuran-3- Preparation of tert-butyl ester of ureido)-3-(tritylamino)propyl)-1,2,4-oxadiazol-3-yl)ethyl)carbamate

Compound 4f (500 mg, 0.815 mmol) and 4 g were dissolved in tetrahydrofuran (5 mL), triethylamine (9.84 g, 97.26 mmol). The solvent was distilled off under reduced pressure, and the mixture was evaporated, evaporated, evaporated, evaporated, evaporated, evaporated, evaporated, evaporated Ethyl ester) gave 400 mg of white foamy solid 4h (yield: 66.2%).

Step 9: (S)-3-(3-((R)-1-Amino-2-hydroxyethyl)-1,2,4-oxadiazol-5-yl)-3-(3-(( Preparation of S)-2-ketotetrahydrofuran-3-yl)ureido)propanamide

The compound 4h (280 mg, 0.378 mmol) was dissolved in dichloromethane (7 mL), trifluoroacetic acid (3.88 g, 34.04 mmol), and a catalytic amount of triisopropyl decane were added at room temperature, and the reaction was stirred at room temperature for 2.5 h. The solvent is distilled off under reduced pressure, dissolved in dichloromethane and water, and the organic phase is extracted several times with water, the aqueous phase is combined, and then washed several times with dichloromethane, and the aqueous phase is lyophilized to obtain a compound 4 . ¹ H NMR (500 MHz, D ₂ O) δ 6.00 – 5.94 (m, 1H), 4.13 – 4.03 (m, 2H), 3.75 (tt, J = 11.1, 5.4 Hz, 2H), 3.48 (ddd, J = 15.8, 6.3, 3.4 Hz, 1H), 3.34 (ddd, J = 15.1, 10.1, 5.7 Hz, 1H), 2.19 – 2.02 (m, 2H), 1.96 (s, 2H). ESI-MS m/z: 343.3 [M+H] ⁺ .

Example 32 1-(3-((S))-1-amino-1-(3-((R)-1-amino-2-hydroxyethyl)-1,2,4-oxadiazole-5- Preparation of benzyl-3-propyloxy)ureido)cyclopropane-1-carboxylic acid

Step 5a 1-(3-((S)-1-(3-((R))-2-(tert-butoxy)-1-((tert-butoxycarbonyl)amino)ethyl)-1,2, Preparation of methyl 4-oxadiazol-5-yl)-3-keto-3-(tritylamino)propyl)ureido)cyclopropane-1-carboxylate .

The title compound was synthesized in a similar manner to the preparation of compound 4 in Example 31, which was replaced with 1-aminocyclopropane-1-carboxylic acid methyl ester hydrochloride to replace the (S)-2-keto group in the step 4i of Example 31. 3-aminotetrahydrofuran.

Step 5b: 1-(3-((S)-1-(3-((R))-2-(tert-butoxy)-1-((tert-butoxycarbonyl)amino)ethyl)-1,2 Of 4-oxaoxazol-5-yl)-3-keto-3-(tritylamino)propyl)ureido)cyclopropane-1-carboxylic acid

Compound 5a (770 mg, 1.02 mmol) was dissolved in tetrahydrofuran (6 mL), and a solution of lithium hydroxide monohydrate (85 mg, 2.04 mmol) in water (1.1 mL) was added at room temperature, and refluxed for 3 h. The tetrahydrofuran was distilled off under reduced pressure, and ethyl acetate and water were added and dissolved, and the layers were separated. The ethyl acetate layer was washed successively with 1 M citric acid and brine, dried over anhydrous sodium sulfate, and evaporated under reduced pressure. Purification (extraction: 0-50% ethyl acetate in petroleum ether, 0-10% methanol in dichloromethane) afforded 180 mg of white solid 5b (yield: 23.8%).

Step 5c: 1-(3-((S)-3-Amino-1-(3-((R)-1-amino-2-hydroxyethyl)-1,2,4-oxadiazole-5- Preparation of benzyl-3-propyloxy)ureido)cyclopropane-1-carboxylic acid

Compound 5b (180 mg, 0.243 mmol) was dissolved in dichloromethane (3 mL), and then trifluoroacetic acid (1.66 g, 14.58 mmol) and a catalytic amount of triisopropyl decane were added at room temperature, and the reaction was stirred for 4 h. The liquid was distilled under reduced pressure, dissolved in dichloromethane and water, and the organic phase was extracted several times with water. The aqueous phase was combined and washed several times with dichloromethane, and the aqueous phase was lyophilized to obtain a compound 32. ¹ H NMR (500 MHz, D ₂ O) δ 5.51 – 5.43 (m, 1H), 4.17 – 4.08 (m, 2H), 3.12 (d, J = 6.4 Hz, 2H), 1.39 (s, 2H), 1.07 (s, 2H). ESI-MS m/z: 343.2 [M+H] ⁺ .

Example 33 1-(3-((R)-3-Amino-1-(3-((S)-1-amino-2-hydroxyethyl)-1,2,4-oxadiazol-5-) Preparation of benzyl-3-propyloxy)ureido)cyclopropane-1-carboxylic acid

The title compound was synthesized in a similar manner to the preparation of compound 5 in Example 32, in which Boc-L-Ser(tBu)-OH in Example 32 was replaced with Boc-D-Ser(tBu)-OH, using Fmoc-D -Asn(Trt)-OH Replaces Fmoc-L-Asn(Trt)-OH in Example 5. The crude product was purified by preparative liquid to give the title compound. ¹ H NMR (400 MHz, D ₂ O): δ 5.30 (t, J = 6.1 Hz, 1H), 4.59 (s, 1H), 3.94 (d, J = 4.7 Hz, 2H), 2.95 (d, J = 6.3 Hz, 2H), 1.22 (s, 2H), 0.90 (s, 2H). ESI-MS m/z: 343.1 [M+H] ⁺ .

Example 34 1-(3-((S)-1-(3-((R))-1-amino-2-hydroxyethyl)-1,2,4-oxadiazol-5-yl)-3 -Carboxypropyl)ureido)cyclopropane-1-carboxylic acid preparation

The title compound was synthesized in a similar manner to the preparation of Compound 5 in Example 32, in which Fmoc-L-Asn(Trt)-OH in Example 32 was replaced with Fmoc-L-Glu(OtBu)-OH. The crude product was purified by preparative liquid to give the title compound. ¹ H NMR (300 MHz, D ₂ O): δ 5.02 (s, 1H), 4.05 (s, 2H), 2.30 (d, J = 7.5 Hz, 2H), 2.19 (dd, J = 19.8, 6.4 Hz, 2H), 1.32 (s, 2H), 0.99 (s, 2H). ESI-MS m/z: 343.1 [M+H] ⁺ .

Example 35 (2S,3R)-2-(3-((S)-3-Amino-1-(3-(1-amino-3-(hydroxymethyl)cyclobutyl)-1,2,4 -Oxadiazole-5-yl)-3-oxopropyl)ureido)-3-hydroxybutyric acid

Step 1 (S)-(1-Fluoro-1,4-dione-4-(tritylamino)butan-2-yl)carbamic acid ((9H-fluoren-9-yl)methyl)ester Preparation

Fmoc-Asn(Trt)-OH (5.0 g, 8.380 mmol) was dissolved in dichloromethane (84 mL), DAST (1.62 g, 10.056 mmol) was slowly added at room temperature, and the reaction was stirred at room temperature for 15 min. It is quenched in ice water, layered, and the methylene chloride layer is washed with water several times, dried over anhydrous sodium sulfate, and evaporated under reduced pressure to give a pale yellow oily liquid, which is dissolved in a small amount of dichloromethane, and then recrystallized, filtered and filtered. The cake was washed with a small amount of n-hexane and distilled under reduced pressure to yield 4.5 g of white solid (yield: 89.8%).

Step 2: Preparation of methyl 1-amino-3-(hydroxymethyl)cyclobutane-1-carboxylate

Compound 8a (4 g, 27.56 mmol) was dissolved in methanol (40 mL), cooled in an ice-bath, and then dichloro-hydrazide (6.5 g, 55.13 mmol) was slowly added dropwise at 0 ° C. After the addition was completed, the mixture was heated to reflux. 4 h. The solvent was distilled off under reduced pressure to give a pale yellow oily liquid, which was taken directly to the next step.

Step 3: Preparation of methyl 1-((tert-butoxycarbonyl)amino)-3-(hydroxymethyl)cyclobutane-1-carboxylate

Compound 8b (4 g, 25.14 mmol) was dissolved in tetrahydrofuran (20 mL). A solution of sodium bicarbonate (8.3 g, 88.00 mmol) in water (40 mL). A solution of di-tert-butyl dicarbonate (5.7 g, 23.88 mmol) in tetrahydrofuran (20 mL) was stirred at room temperature overnight. The solvent was evaporated, evaporated, evaporated, evaporated The mixture was washed several times with saturated brine, and evaporated under reduced pressure and purified by silica gel column chromatography to yield 3.7 g of white solid 8c (yield: 56.9%).

Step 4: Preparation of methyl 1-((tert-butoxycarbonyl)amino)-3-(tert-butyldimethylammoniomethyl)cyclobutane-1-carboxylate

Compound 8c (700 mg, 2.70 mmol) was dissolved in DMF (7 mL). EtOAc (EtOAc) 4.05 mmol) of DMF (3.5 mL) solution. The reaction mixture was stirred at room temperature for 4 h, and the mixture was diluted with EtOAc EtOAc EtOAc EtOAc EtOAc. The extracting agent: 0-50% ethyl acetate in petroleum ether) gave 900 mg of a colorless oily liquid 8d (yield: 89.3%).

Step 5: Preparation of 1-((tert-Butoxycarbonyl)amino)-3-(tert-butyldimethylammoniomethyl)cyclobutane-1-carboxylic acid

The compound 8d (1.6 g, 4.283 mmol) was dissolved in methanol (16 mL), and a solution of lithium hydroxide (270 mg, 6.425 mmol) in water (3.2 mL) was added, and the mixture was stirred at room temperature for 3 h, and evaporated under reduced pressure. The reaction solvent, ethyl acetate and water were dissolved, and the organic phase was extracted with water, the aqueous phase was combined, the aqueous phase was combined, and the organic phase was extracted with ethyl acetate. The organic phase was combined and dried over anhydrous Na ₂ SO ₄ . Distillation under reduced pressure gave 1.42 g of colorless oily liquid 8e (yield: 92.2%).

Step 6: Preparation of 1-((tert-Butoxycarbonyl)amino)-3-(tert-butyldimethyloxyloxymethyl)cyclobutane-1-carboxamide

Compound 8e (2.6 g, 7.231 mmol) was dissolved in tetrahydrofuran (26 mL), N-methylmorpholine (880 mg, 8.677 mmol) was added to form a flocculent solid; ice bath was cooled, and chlorine was added at -5 °C. Ethyl formate (940 mg, 8.677 mmol), a large amount of solid precipitated, stirred for 0.5 h in an ice bath; slowly added 3.9 mL of 25% aqueous ammonia solution, stirred for 3 h in an ice bath, and the solvent was evaporated under reduced pressure. The ester and water are dissolved and layered. The organic phase was washed successively with 1 M citric acid, saturated sodium hydrogen sulfate and water, dried over anhydrous sodium sulfate, and evaporated under reduced pressure to give 1.5 g of white solid (yield: 57.9%).

Step 7: Preparation of tert-butyl (3-tert-butyldimethylammoniomethyl-1-cyanocyclobutyl)carbamate

The compound 8f (1.58 g, 4.407 mmol) was dissolved in pyridine (16 mL), cooled in ice-cooled, trifluoroacetic anhydride (1.39 g, 6.611 mmol) was slowly added at -5 ° C, and the reaction was stirred for 3 h in an ice bath. The solution was poured into an excess of saturated sodium bicarbonate solution, and extracted with ethyl acetate. The organic phase was washed successively with 1 M citric acid and brine, dried over anhydrous sodium sulfate, and evaporated under reduced pressure. Purification (extraction: 0-15% ethyl acetate in petroleum ether) gave 1.36 g of a colorless oily liquid (yield: 90.7%).

Step 8: Preparation of (Z)-(3-tert-butyldimethylammoniomethyl-1-(N'-hydroxymethylindenyl)cyclobutyl)carbamic acid tert-butyl ester

The compound 8 g (1.3 g, 3.817 mmol) was dissolved in ethanol (13 mL), and a solution of potassium carbonate (791 mg, 5.726 mmol) in water (2.6 mL), hydroxyamine (398 mg, 5.726 mmol) The mixture was stirred and refluxed for 2 h. The solvent was evaporated and evaporated, evaporated, evaporated, evaporated, evaporated, evaporated. The extracting agent: 0-20% ethyl acetate in petroleum ether) gave 700 mg of white solid 8h (yield: 49.3%).

Step 9: (Z)-(1-(N'-((N ² -((9H-芴-9-yl)methoxy)carbonyl)-N ⁴ -trityl-L-aspartate Preparation of tert-butyl ester of amino)oxy)hydroxymethylindenyl)-3-(tert-butyldimethylammoniomethyl)cyclobutyl)carbamate

Compound 8h (300 mg, 0.803 mmol) was dissolved in tetrahydrofuran (3 mL). A solution of N-methylmorpholine (240 mg, 2.409 mmol) and compound 8i (960 mg, 1.606 mmol) in tetrahydrofuran (10 mL) was added, and the mixture was stirred at room temperature overnight, and the reaction mixture was evaporated to remove tetrahydrofuran under reduced pressure. Add ethyl acetate to dissolve, wash several times with saturated brine, dry over anhydrous sodium sulfate, distill under reduced pressure, and purify by column chromatography (purification: 0-15% ethyl acetate in petroleum ether) 350 mg Colorless oil 8j (yield: 55.8%).

Step 10: (S)-(1-(5-(1-(((9H-芴-9-yl))methoxy)carbonyl)amino)-3-yl-3-yl-3-phenylphenylamino Of propyl)-1,2,4-oxadiazol-3-yl)-3-(((tert-butyldimethylmethyl)oxy)methyl)cyclobutyl)carbamic acid tert-butyl ester preparation

Compound 8j (1 g, 1.050 mmol) was dissolved in EtOAc (20 mL). Sodium acetate (129 mg, 1.575 mmol) was added at room temperature, and the mixture was stirred and refluxed for 3 h. The solvent was evaporated and evaporated, evaporated, evaporated, evaporated. Purification by hydrazine column chromatography (purification: 0-20% ethyl acetate in petroleum ether) afforded 520 mg (yield: 53%) as colorless oil.

Step 11: (S)-(1-(5-(1-Amino-3-keto-3-(tritylamino)propyl)-1,2,4-oxadiazol-3-yl) Preparation of tert-butyl 3-(((tert-butyldimethylmethyl)oxy)methyl)cyclobutyl)carbamate

Compound 8k (500 mg, 0.535 mmol) was dissolved in dichloromethane (5 mL), diethylamine (783 mg, 10.7 mmol). The completion of the reaction was confirmed by TLC analysis. The solvent was evaporated under reduced pressure and purified by silica gel column chromatography (yield: 0-40% ethyl acetate in petroleum ether) to afford 330 mg (yield: 86.6%).

Step 12: N-(((S)-1-(3-(1-((tert-Butyloxycarbonyl))amino)-3-(((tert-butyldimethylmethyl)oxy)methyl)) Butyl)-1,2,4-oxadiazol-5-yl)-3-keto-3-(tritylamino)propyl)carbamyl)-O-(tert-butyl)- Preparation of L-threonine tert-butyl ester

Compound 8l (270 mg, 0.379 mmol) was dissolved in tetrahydrofuran (5 mL). Compound 2b (180 mg, 0.455 mmol), triethylamine (77 mg, 0.758 mmol) The solvent was evaporated under reduced pressure, and the mixture was evaporated, evaporated, evaporated, evaporated, evaporated, evaporated, evaporated 0-15% ethyl acetate) gave 400 mg of white solid (yield: 95.1%).

Step 13: (2S,3R)-2-(3-((S)-3-Amino-1-(3-(1-amino-3-(hydroxymethyl)cyclobutyl)-1,2,4 -Oxadiazole-5-yl)-3-oxopropyl)ureido)-3-hydroxybutyric acid

Compound 8n (350 mg, 0.361 mmol) was dissolved in dichloromethane (7 mL), trifluoroacetic acid (2.06 g, 18.05 mmol), and a catalytic amount of triisopropyl decane were added at room temperature and stirred at room temperature for 5 h. The reaction solution is distilled off under reduced pressure to remove the solvent, dissolved in dichloromethane and water, and the organic phase is extracted with water several times, the aqueous phase is combined, and then washed several times with dichloromethane, the aqueous phase is lyophilized, and the liquid phase is purified. 70 mg of a white solid 8 (yield: 37.8%). ¹ H NMR (400 MHz, D ₂ O) δ 5.31 (dd, J = 8.2, 4.7 Hz, 1H), 4.16 – 4.10 (m, 1H), 3.89 (d, J = 3.0 Hz, 1H), 3.61 (d , J = 6.8 Hz, 2H), 2.99 (d, J = 6.4 Hz, 2H), 2.77 (dt, J = 16.0, 7.9 Hz, 1H), 2.59 – 2.47 (m, 4H), 1.08 (d, J = 6.4 Hz, 3H). ESI-MS m/z: 401.2 [M+H] ⁺ .

Example 36: (S)-4-(3-(1-Amino-3-(hydroxymethyl)cyclobutyl)-1,2,4-oxadiazol-5-yl)-4-(3- Preparation of ((1S,2R)-1-carboxy-2-hydroxypropyl)ureido)butyric acid

The title compound was synthesized in a similar manner to the preparation of the compound in Example 35. Wherein Fmoc-Asn(Trt)-OH was replaced with Fmoc-Glu(OtBu)-OH. ¹ H NMR (400 MHz, D ₂ O) δ 5.02 – 4.97 (m, 1H), 4.25 (dd, J = 6.3, 2.8 Hz, 1H), 4.15 (d, J = 2.6 Hz, 1H), 3.60 (d , J = 6.7 Hz, 2H), 2.76 (dd, J = 15.4, 8.3 Hz, 1H), 2.60 – 2.44 (m, 6H), 2.24 (dd, J = 13.5, 6.4 Hz, 1H), 2.10 (dd, J </ RTI>^< / RTI>^<RTIgt;

Example 37: (S)-3-(3-(1-Amino-3-(hydroxymethyl)cyclobutyl)-1,2,4-oxadiazol-5-yl)-3-(3- Preparation of ((S)-1-carboxy-2-hydroxyethyl)ureido)propionic acid

The title compound was synthesized in a similar manner to the preparation of the compound in Example 35. Wherein Fmoc-Asn(Trt)-OH in Example 8 was replaced with Fmoc-Asp(OtBu)-OH, and H-Thr(OtBu)-OtBu in Example 35 was replaced with H-Ser(OtBu)-OtBu. ¹ H NMR (400 MHz, D ₂ O) δ 5.35 (t, J = 6.0 Hz, 1H), 4.28 (t, J = 4.0 Hz, 1H), 3.86 (dd, J = 11.7, 4.6 Hz, 1H), 3.76 (dd, J = 11.7, 3.6 Hz, 1H), 3.61 (d, J = 6.7 Hz, 2H), 3.13 – 3.08 (m, 2H), 2.78 (dt, J = 15.8, 8.0 Hz, 1H), 2.56 (p, J = 13.8 Hz, 4H). ESI-MS m/z: 388.1 [M+H] ⁺ .

Example 38 (2S,3S)-2-(3-((S)-4-Amino-1-(5-(1-aminocyclopropyl)-1,3,4-oxadiazol-2-yl) Preparation of 4-oxobutyl)ureido)-3-hydroxybutyric acid

Preparation method The same as the preparation method of Example 12, the (2S,3S)-3-hydroxytetrahydropyrrole-2-carboxylic acid in the step 1 of Example 12 was replaced with 1-aminocyclopropane-1-carboxylic acid, and O was The (t-butyl)-L-serine tert-butyl ester is replaced with O-(tert-butyl)-L-threonine tert-butyl ester to obtain the target compound.

Comparative example 1

The compound represented by the following formula (Compound A) was prepared according to the method disclosed in Example 2 of WO2015/033301 (PCT/IB2014/064281), and identified by hydrogen spectrum and mass spectrometry, (Compound A).

The pharmacokinetic characteristics of Compound A and the antitumor effect on colon cancer CT26 subcutaneous xenograft model were tested using the following Experimental Examples 1 and 2, and the results showed that the bioavailability (F) and tumor inhibition of Compound A were observed. The rate is weaker than some of the compounds of the invention.

In addition, the inventors of the present invention also synthesized and tested Compound No. 12 in Table 3 of WO2015/033301 according to the method disclosed in WO2015/033301, and the results show that the bioavailability and tumor inhibition rate of Compound No. 12 are significantly weaker than the present invention. Compound and Compound A.

Experimental Example 1 Drug Metabolism Experiment

1 experimental material

1.1 compound

The experiment was carried out using the compound of the present invention prepared in the above examples and the compound of Example 2 ("Compound A") in WO2015/033301. The oral drug was dissolved in physiological saline to prepare a clear solution of 0.5 mg/mL, and the intravenous drug was dissolved in physiological saline to prepare a 0.1 mg/mL clear solution.

1.2 Animals

Male BALB/c mice, 3 in each group, weighing 18-22 g, were provided by Shanghai Xipuer-Beikai Experimental Animal Co., Ltd.

The mice were given an environmental adaptation period of 2 to 4 days before the experiment, and fasted for 8-12 h before administration, and given water for 2 hours after administration, and fed for 4 hours.

1.3 reagent

Methanol (chromatographic purity): produced by Spectrum;

Acetonitrile (chromatographic purity): produced by Spectrum;

The remaining reagents are of commercially available analytical grade purity.

1.4 Instrument

American AB company API 4500 triple quadrupole liquid chromatography instrument with electrospray ion source (ESI), LC-30AD double pump; SIL-30AC autosampler; CTO-30AC column thermostat; DGU-20A3R off Gas machine; Analyst QS A01.01 chromatography workstation; Milli-Q ultrapure water (Millipore Inc); Qilinbeier Vortex-5 oscillator; HITACHI CF16RXII desktop high speed refrigerated centrifuge.

2 experimental methods

1) The mice were fasted but allowed to drink water for 12 hours, and the blank plasma was taken at 0 o'clock;

2) taking the mouse in step 1), administering intragastric administration (IG) to the test compound 10 mg/kg; intravenous (IV) administering the test compound 1 mg/kg;

3) 5 min, 15 min, 30 min, 1 h, 2 h, 4 h, 8 h, 10 h, 24 h after intragastric administration, continuous blood was taken from the fundus venous plexus in an EP tube with heparin distributed, and centrifuged at 8000 rpm/min for 5 min. Upper layer plasma, frozen at -20 ° C, to be analyzed by LC-MS/MS;

4) according to the plasma concentration-time data obtained in step 3), using WinNonlin software to calculate the pharmacokinetic parameters;

3 experimental results:

The pharmacokinetic experimental data are shown in Table 1. The results indicate that after oral administration of the compound of the above examples to mice, there is a certain amount of exposure and a suitable half-life in the plasma of the animal, especially Example 4, Example 5, The compounds of Example 8, Example 6 and Example 22 have very good half-life, area under the curve and bioavailability, and have good drug-forming properties, and have good clinical application prospects.

Table 1 Pharmacokinetic data of the compounds of the examples of the invention

Experimental Example 2 In vivo pharmacodynamic experiment

1. Experimental materials

1.1 compound

This experiment was carried out using the compounds prepared according to the examples of the present invention. The negative control group was given physiological saline. Orally administered, the test compound was dissolved in physiological saline to prepare a 2 mg/mL clear solution.

1.2 animals

Female BALB/c mice, 3 in each group, weighing 18-22 g, were provided by Shanghai Xipuer-Beikai Experimental Animal Co., Ltd. The mice were given an environmental adaptation period of 2 to 4 days before the experiment, and fasted for 8-12 h before administration, and given water for 2 hours after administration, and fed for 4 hours.

1.3 positive control

Compound A was prepared according to the method disclosed in Example 2 of WO 2015/033301.

2, experimental methods

After the cells were inoculated and the tumors were grown to an average volume of 40 mm ³ (first round of experiments) or 50 mm ³ (second round of experiments), the animals were randomized into groups of 6 each, and each test group was orally administered with 20 mg/kg. Once a day, continuous administration for 14 days. Changes in body weight of the experimental animals and whether tumor growth were inhibited or delayed were observed. Tumor diameters were measured with vernier calipers three times a week.

The tumor volume is calculated as: V = 0.5 a × b ² , a and b represent the long and short diameters of the tumor, respectively.

The relative tumor growth rate T/C (%) was calculated as: T/C = T _RTV / C _RTV X 100% (T _RTV : treatment group RTV; C _RTV : solvent control group RTV). The measurement result is calculated relative tumor volume (relative tumor volume, RTV), RTV = V t / V 0, wherein V ₀ is the tumor volume when the tumor volume at the start of the experiment, V _t for every measurement.

The tumor growth inhibition rate TGI (%) was calculated as: TGI = [1 - (the average tumor volume at the end of a treatment group - the average tumor volume at the start of administration of the treatment group) / (the average of the solvent control group at the end of treatment) Tumor volume - mean tumor volume at the start of treatment in the solvent control group)] X 100%.

3. Experimental conclusion

3.1 Weight changes

The compound of the present invention has no effect on the body weight of mouse colon cancer CT26 cell subcutaneous homologous tumor in the BALB/C mouse model, and Table 2 shows the weight of Example 4, Example 5, Example 35 and Compound A after administration. The effect indicates that the body weight of the control group and each of the administered groups gradually increased during the administration period, and was well tolerated.

Table 2 Effect of the compound of the present invention on the body weight of mice after administration

3.2 Anti-tumor efficacy evaluation indicators

The efficacy evaluation indicators are shown in Table 3. On the 15th day after the first round of experiment started, the average tumor volume of the tumor-bearing mice in the solvent control group reached 3672 mm ³ , and the tumor volume of the tumor-bearing mice in the other groups was average. All of them were smaller than the average tumor volume of the control group, wherein the compound of Example 4 had a T/C value of 41.5% on the 15th day and a TGI value of 52.4%, indicating that it had a significant inhibitory effect on CT26 colon cancer xenografts. The effect is significantly better than Compound A. On the 14th day after the start of the second round of experiment, the average tumor volume of the tumor-bearing mice in the solvent control group reached 1524 mm ³ , and the average tumor volume of the tumor-bearing mice in the other administration groups was smaller than the average tumor volume of the control group. The compound of Example 5 had a T/C value of 39.0% at day 14 and a TGI value of 63.7%, indicating that it had a significant inhibitory effect on CT26 colon cancer xenografts.

Table 3 Anti-tumor efficacy evaluation indicators

While the invention has been described hereinabove in detail, it will be understood by those skilled in the art that various modifications and changes of the invention may be made without departing from the spirit and scope of the invention. The scope of the invention is not limited to the detailed description set forth above, but is intended to be within the scope of the claims.

Claims (10)

a compound of the formula A or a stereoisomer thereof, a pharmaceutically acceptable salt, a solvate, a crystal or a prodrug, (A) wherein: X and Y are each independently selected from N, O and S, and when X is N, Y is selected from O and S; when X is O or S, Y is N; when Y is N, X is selected From O and S; when Y is O or S, X is N; when X is N, Y is selected from O and S or Y is O or S, and X is N, the group for When X is O or S, Y is N or Y is N, and X is selected from O and S, the group for R _{1 is} selected from the side chain of the amino acids Ser and Thr; R _{2 is} selected from the amino acid Ser and Thr residues; R _{3 is} selected from H, -(CH ₂ ) _m C(O)OR ₄ , -(CH ₂ ) _m C (O)N(R ₅ )(R ₆ ) and —(CH ₂ ) _m CN, wherein R ₄ , R ₅ , R ₆ are each independently selected from H and alkyl, and m is 0, 1, 2, 3 or 4; and n is 1, 2, 3 or 4. A compound of the formula A, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, according to claim 1 of the patent application, wherein the formula A has the following formula II Structure, (II), wherein: Q is selected from O and S; and R ₁ , R ₂ , and R ₃ are as defined in Patent Application No. 1. A compound of the formula A, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, according to claim 1, wherein the formula A has the following formula I Structure, (I), wherein: Q is selected from O and S; and R ₁ , R ₂ , and R ₃ are as defined in Patent Application No. 1. A compound of the formula A, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, according to any one of claims 1 to 3, wherein: R ₁ selected from with ; R _{2 is} selected from with ; R _{3 is} selected from the group consisting of H, -(CH ₂ ) _m C(O)OR ₄ , -(CH ₂ ) _m C(O)N(R ₅ )(R ₆ ) and -(CH ₂ ) _m CN, wherein R ₄ , R ₅ and R ₆ are each independently selected from H and C _1-6 alkyl, m is 1, 2, 3 or 4; and n is 1, 2, 3 or 4. A compound of the formula A, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, according to any one of claims 1 to 3, wherein: R ₁ selected from with ; R _{2 is} selected from with ; R _{3 is} selected from H, , , , , , with ; and n is 1, 2, 3 or 4. A compound of the formula A, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, according to the invention of claim 1, wherein the compound represented by the formula A is A compound selected from the group consisting of: , , , , , , , , , , , , with . A process for the preparation of a compound of the formula A, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, according to claim 2 of the patent application, comprising the steps of: (1) a compound of the formula ia is reacted with a compound of the formula iib to form a compound of the formula iic; (2) a compound of the formula iic is cyclized to give a compound of the formula iid; (3) a compound of the formula iid is reacted with an amine compound to give a compound of the formula iie; a compound of the formula iie and a compound of the formula if subjected to nucleophilic substitution to give a compound of the formula iig; and (5) a hydrolysis reaction of the compound of the formula iig under acidic conditions to give a compound of the formula II; wherein: Pg ₁ represents a protecting group for R ₁ ; Pg ₂ represents a protecting group of R ₂ ; Pg ₃ represents a protecting group of R ₃ or is absent; and Pg ₄ and Pg ₅ represent an amino protecting group. A process for the preparation of a compound of the formula A, or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, according to claim 3 of the patent application, comprising the steps of: (1) a compound of the formula ia is reacted with a compound of the formula ib to form a compound of the formula ic; (2) a compound of the formula ic is cyclized to give a compound of the formula id; (3) a compound of the formula id is reacted with an amine compound to give a compound of the formula IE; a compound of the formula IE is subjected to a nucleophilic substitution reaction with a compound of the formula i to give a compound of the formula ig; and (5) a compound of the formula ig is hydrolyzed under acidic conditions to give a compound of the formula I; wherein: Pg ₁ represents a protecting group for R ₁ ; Pg ₂ represents a protecting group of R ₂ ; Pg ₃ represents a protecting group of R ₃ or is absent; and Pg ₄ and Pg ₅ represent an amino protecting group. A pharmaceutical composition comprising a compound according to any one of claims 1 to 6 or a stereoisomer thereof, a pharmaceutically acceptable salt, a solvate, a crystal or a prodrug thereof, and a pharmaceutically acceptable Accepted carrier. A compound according to any one of claims 1 to 6 or a stereoisomer, pharmaceutically acceptable salt, solvate, crystal or prodrug thereof, or as described in claim 9 Use of the pharmaceutical composition for the preparation of a medicament for the treatment of cancer or an infectious disease.