Compounds inhibiting CDK2 / 4 / 6 activity

Abstract

The invention relates to the field of biological medicine, in particular to a compound for inhibiting CDK2 / 4 / 6 activity. The compound has a structure as shown in a formula (A), each group in the formula is defined in the specification, and the invention also relates to a pharmaceutically acceptable salt of the compound, a pharmaceutical composition of the compound and application of the compound. # imgabs0 #

Description

Technical Field

[0001] The present disclosure relates to the field of biomedicine, and specifically to a series of compounds having CDK2, CDK4 and CDK6 inhibitory activities at the same time, pharmaceutically acceptable salts of the above compounds, and pharmaceutical compositions of the above compounds and uses thereof. Background Art

[0002] The ubiquitin-proteasome pathway (UPP) is an important pathway for regulating proteins and degrading misfolded or abnormal proteins. The UPP is central to multiple cellular processes and, if defective or dysregulated, contributes to the pathogenesis of multiple diseases. The covalent attachment of ubiquitin to specific protein substrates is achieved through the action of E3 ubiquitin ligases. These ligases comprise more than 500 different proteins and are divided into multiple classes defined by the structural elements of their E3 functional activity. For example, cereblon (CRBN) interacts with damaged DNA binding protein 1, and forms an E3 ubiquitin ligase complex with retardin 4, in which proteins recognized by CRBN are ubiquitinated and degraded by the proteasome. Various immunomodulatory drugs (IMiDs), such as thalidomide and lenalidomide, bind to CRBN and modulate the role of CRBN in the ubiquitination and degradation of protein factors involved in maintaining normal cellular function.

[0003] Bifunctional compounds consisting of a target protein-binding portion and an E3 ubiquitin ligase-binding portion have been shown to induce proteasome-mediated degradation of selected proteins. These drug-like molecules offer the possibility of temporarily controlling protein expression and can be used as biochemical agents for the treatment of diseases.

[0004] Cyclin-dependent kinases (CDKs) are a group of serine / threonine protein kinases. CDKs drive the cell cycle by chemically acting on serine / threonine proteins. They work in concert with cyclins and are important factors in cell cycle regulation. CDK1, 2, 4, and 6 are important enzymes that drive cell cycle transitions. For example, CDK1 is a key determinant of mitotic progression, and CDK4 / 6 activates the expression of genes involved in cell cycle control through phosphorylation of Rb protein, driving the cell cycle from G0 or G1 to S phase. CDK2 is a key cell cycle regulator that is active from late G1 phase to the entire S phase. CDK2 participates in the DNA damage response (DDR) through the homologous recombination (HR) pathway. CDK2 also regulates various aspects of the apoptosis pathway. Cyclin E1 (CCNE1), cyclin E2 (CCNE2), cyclin A1 (CCNA1), and cyclin A2 (CCNA2) together with p21Cip1 / Waf1, p27Kip1, and p57Kip2 (cyclin-dependent kinase inhibitors of the cyclin-CDK2 complex) are master regulators of CDK2 activity. In cancer, dysregulated binding of cyclin E1, E2, A1, or A2 to CDK2 or dysregulated activity of cyclin-dependent kinase inhibitor proteins may occur. These findings indicate that CDK2 is a potential target for cancers in which CDK2 activity is dysregulated.

[0005] Existing literature has reported some CDK4 / 6 or CDK2 / 4 / 6 small molecule inhibitors for the treatment of cancer, but there are still a large number of patients who cannot obtain satisfactory clinical treatment effects. Therefore, there is still a need for better and more effective clinical treatments and solutions, especially compounds that can simultaneously target and degrade CDK2, CDK4 and CDK6. Summary of the invention

[0006] In view of this, the present disclosure provides a class of bifunctional compounds that simultaneously target and degrade CDK2, CDK4 and CDK6, wherein the simultaneous targeted degradation percentage of CDK2, CDK4 and CDK6 is greater than 80%.

[0007] In a first aspect of the present disclosure, there is provided a compound of formula (A) or a pharmaceutically acceptable salt thereof,

[0008]

[0009] In formula (A),

[0010] R A1 , R A2 Each independently is C 1-3 alkyl;

[0011] R B Halogen or C 1-3 Alkoxy;

[0012] R C is hydrogen, or R B , R C The carbon atoms connected thereto together form a 5-membered partially unsaturated heterocyclic ring; wherein, Selected from In some embodiments, the 5-membered partially unsaturated heterocyclic ring is In some embodiments, the compound of formula (A) is a compound of formula (A-1):

[0013]

[0014] In formula (A-1),

[0015] R A1 , R A2 Each independently is C 1-3 alkyl;

[0016] R D1 , R D2 are each independently an oxo group, and R D1 , R D2 There is only one oxo group.

[0017] In some embodiments, R C is hydrogen; R B Halogen or C 1-3 Alkoxy.

[0018] In some embodiments, R C is hydrogen; R B It is a halogen.

[0019] In some embodiments, R C is hydrogen; R B C 1-3 Alkoxy.

[0020] In some embodiments, R B is fluorine, chlorine or bromine.

[0021] In some embodiments, R B For fluorine.

[0022] In some embodiments, R B It is methoxy or ethoxy.

[0023] In some embodiments, R B It is a methoxy group.

[0024] In some embodiments, R Bis fluorine or methoxy.

[0025] In some embodiments, wherein Selected from:

[0026]

[0027] In some embodiments, R A1 , R A2 Each is independently methyl or ethyl.

[0028] In some embodiments, R A1 is methyl, R A2 It is methyl.

[0029] In some embodiments, the compound is selected from the following compounds:

[0030]

[0031]

[0032] In some embodiments, the compound is

[0033]

[0034] In some embodiments, the compounds are used to inhibit the activity of CDK2, CDK4, and CDK6.

[0035] In a second aspect of the present disclosure, a pharmaceutical composition is provided comprising the compound of formula (A) or a pharmaceutically acceptable salt thereof as described above, wherein the pharmaceutical composition optionally further comprises a pharmaceutically acceptable excipient.

[0036] The third aspect of the present disclosure provides use of the compound of formula (A) or a pharmaceutically acceptable salt thereof or the pharmaceutical composition described above in the preparation of a drug for treating breast cancer.

[0037] The fourth aspect of the present disclosure provides a method for inhibiting CDK2, CDK4 and / or CDK6 proteins in a biological sample, comprising contacting the biological sample with the compound of formula (A) or a pharmaceutically acceptable salt thereof as described above or the pharmaceutical composition as described above.

[0038] The fifth aspect of the present disclosure provides a method for treating breast cancer in a patient in need thereof, comprising administering to the patient the compound of formula (A) or a pharmaceutically acceptable salt thereof or the pharmaceutical composition described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The degradation activity of the compounds on CDK in MDA-MB-231 cells at different concentrations. DETAILED DESCRIPTION

[0040] I. Definitions

[0041] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0042] The compounds of the present disclosure may be asymmetric, for example, having one or more stereoisomers. Unless otherwise indicated, all stereoisomers are included, such as enantiomers and diastereomers. The compounds of the present disclosure containing asymmetric carbon atoms can be isolated in optically pure form or racemic form. Optically pure forms can be resolved from racemic mixtures or synthesized by using chiral raw materials or chiral reagents. Racemates, diastereomers, and enantiomers are all included within the scope of the present disclosure.

[0043] In this disclosure, It refers to the position where a substituent is bonded.

[0044] In this disclosure, numerical ranges refer to each integer in the given range. For example, "C 1-6 " means that the group may have 1 carbon atom, 2 carbon atoms, 3 carbon atoms, 4 carbon atoms, 5 carbon atoms or 6 carbon atoms; "C 1-3 ” means that the group can have 1 carbon atom, 2 carbon atoms, or 3 carbon atoms.

[0045] The term "optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes both occurring and not occurring of said event or circumstance.

[0046] The term "substituted" or "substitution" means that any one or more hydrogen atoms on a particular atom or group are replaced by a substituent as long as the valence state of the particular atom or group is normal and the substituted compound is stable.

[0047] When any variable (such as R n ) occurs more than once in a compound's composition or structure, its definition at each occurrence is independent. Thus, for example, if a group is substituted with one to three R, the group may be optionally substituted with up to three R, and each occurrence of R is an independent choice. In addition, combinations of substituents and / or variants thereof are permitted only if such combinations result in stable compounds.

[0048] The term "alkyl" refers to a saturated aliphatic hydrocarbon group, including straight-chain or branched saturated hydrocarbon groups, having the indicated number of carbon atoms. 1-3 "Alkyl" includes C1 alkyl, C2 alkyl, C3 alkyl, examples include, but are not limited to, methyl, ethyl, n-propyl, isopropyl.

[0049] The term "alkoxy" may be linear or branched. Specific examples thereof include methoxy, ethoxy, n-propoxy, isopropoxy, i-propyloxy, n-butoxy, isobutoxy, tert-butoxy, sec-butoxy, n-pentoxy, neopentoxy, isopentoxy, etc., but are not limited thereto.

[0050] In the present disclosure, examples of the halogen group may include fluorine, chlorine, bromine, or iodine.

[0051] The term "heterocycle" refers to a 5-8 membered partially unsaturated non-aromatic system having ring carbon atoms and 1 to 2 ring heteroatoms, wherein the heteroatoms are independently selected from nitrogen, sulfur or oxygen atoms. In heterocyclic groups containing one or more nitrogen atoms, the point of attachment can be a carbon or nitrogen atom as long as the valence permits.

[0052] Drug or drug composition

[0053] The term "pharmaceutically acceptable" refers to those compounds, materials, compositions, and / or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problem or complication commensurate with a reasonable benefit / risk ratio.

[0054] The term "pharmaceutically acceptable salt" refers to a salt that retains the biological effectiveness of the free acids and bases of a particular compound without adverse biological effects, such as acid (including organic acids and inorganic acids) addition salts or base addition salts (including organic bases and inorganic bases).

[0055] The term "treatment" includes suppressing, alleviating, preventing or eliminating one or more symptoms or side effects associated with the disease, illness or disorder treated. The term "effective amount" or "therapeutically effective amount" refers to a dosage that is enough to treat, suppress or alleviate one or more symptoms of the disease state treated or otherwise provide the desired pharmacological and / or physiological effects. The precise dosage will vary according to a variety of factors, such as the variable (e.g., age, immune system health, etc.) that the subject depends on, the disease or illness, and the treatment applied. The effect of the effective amount can be relative to a control. These controls are known in the art and discussed in this article, and can be, for example, the condition of the subject before or when the drug or drug combination is not applied, or in the case of a drug combination, the combined effect can be compared with the effect of only applying a drug.

[0056] The term "pharmaceutical composition" means a composition comprising the compound described in the present disclosure or a pharmaceutically acceptable salt thereof, and at least one pharmaceutically acceptable excipient selected from the following depending on the mode of administration and the nature of the dosage form, including but not limited to: carriers, diluents, adjuvants, excipients, preservatives, fillers, disintegrants, wetting agents, emulsifiers, suspending agents, sweeteners, flavoring agents, fragrances, antibacterial agents, antifungal agents, lubricants, dispersants, temperature-sensitive materials, temperature regulators, adhesives, stabilizers, suspending agents, etc.

[0057] II. Embodiment

[0058] The present disclosure is further explained below with reference to examples, and the description of specific exemplary embodiments of the present disclosure is for the purpose of illustration and illustration. These descriptions are not intended to limit the present disclosure to the precise form disclosed, and it is clear that many changes and variations can be made according to the teachings of the present application specification. The purpose of selecting and describing exemplary embodiments is to explain the specific principles of the present disclosure and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present disclosure and various different selections and changes.

[0059] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0060] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0061] Preparation Example 1: Synthesis of Intermediate 1

[0062]

[0063] Step 1: Synthesis of tert-butyl 4-(4-((7-cyclopentyl-6-(dimethylcarbamoyl)-7H-pyrrolo[2,3-d]pyrimidin-2-yl)amino)phenyl)piperazine-1-carboxylate

[0064] 2-Chloro-7-cyclopentyl-N, N-dimethyl-7H-pyrrolo[2,3-d]pyrimidine-6-carboxamide (10.0 g, 34.16 mmol) was dissolved in 1,4-dioxane (200 mL), tert-butyl 4-(4-aminophenyl)piperazine-1-carboxylate (11.37 g, 40.99 mmol,), XantPhos (1.0 g), cesium carbonate (22.22 g, 68.31 mmol) and palladium acetate (1.0 g) were added, and stirred at 110 ° C under nitrogen protection for 16 hours. LCMS showed that the reaction was complete. The reaction solution was poured into water and extracted with dichloromethane. The organic phase was dried over Na2SO4, filtered, and concentrated under reduced pressure. The residue was separated and purified by silica gel column (PE / EA, 2 / 1-1 / 1) to obtain 13.8 g of the target compound as a yellow solid with a yield of 75.5%.

[0065] LC-MS (ESI) m / z: 534.4 [M+H] + .

[0066] Step 2: Synthesis of 7-cyclopentyl-N,N-dimethyl-2-((4-(piperazin-1-yl)phenyl)amino)-7H-pyrrolo[2,3-d]pyrimidine-6-carboxamide hydrochloride

[0067] Tert-butyl 4-(4-((7-cyclopentyl-6-(dimethylcarbamoyl)-7H-pyrrolo[2,3-d]pyrimidin-2-yl)amino)phenyl)piperazine-1-carboxylate (13.8 g, 25.86 mmol, 1.0 eq) was dissolved in DCM (30 mL) and added to hydrogen chloride-1,4-dioxane (130 mL). The reaction solution was stirred at room temperature for 16 hours. LCMS showed that the reaction was complete. The reaction solution was concentrated under reduced pressure to obtain 10.44 g of the target compound as a light yellow solid with a yield of 98.0%.

[0068] LC-MS (ESI) m / z: 434.3 [M+H] + ,RT=0.680min.

[0069] 1 H NMR (400MHz, DMSO) δ: 10.68(s,1H),9.64(s,1H),9.00(s,1H),7.55-7.53(m,3H),7.13-7.11(m,2H),6.82(s,1H),4.68-4.59(m ,1H),3.60-3.56(m,6H),3.25(s,4H),3.05(s,4H),2.32-2.23(m,2H),2.00-1.98(m,2H),1.86-1.83(m,2H),1.61-1.56(m,2H).

[0070] Preparation Example 2: Synthesis of Intermediate 2

[0071]

[0072] Step 1: Synthesis of methyl 4-(4-(dimethoxymethyl)piperidin-1-yl)-2-fluorobenzoate

[0073] A mixture of 4-(dimethoxymethyl)piperidine (5.5 g, 34.9 mmol), methyl 2,4-difluorobenzoate (4 g, 23.3 mmol) and potassium carbonate (6.4 g, 46.6 mmol) in DMSO (40 mL) was replaced with nitrogen three times, heated to 80°C and stirred for 2 hours. The reaction solution was cooled to room temperature, water (300 mL) was added, and extracted twice with ethyl acetate (200 mL). The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and the residue obtained by vacuum rotary evaporation was separated and purified by flash silica gel column chromatography (petroleum ether-ethyl acetate, 95-90%) to obtain 3.5 g of the title compound as a white solid, with a yield of 49%.

[0074] LC-MS: Rt=2.551min, MS(ESI)m / z=312.0[M+H] + .

[0075] 1 H NMR(400MHz,DMSO-d6)δ7.86-7.76ppm(m,1H),6.63(dt,J=9.4,2.6Hz,1H),6.51(dt,J=14.8,2.6Hz,1H),4.20-4.01(m,1H),3 .93-3.84(m,5H),3.39(q,J=1.3Hz,6H),3.02-2.71(m,2H),1.86(dt,J=10.7,3.5Hz,3H),1.74-1.55(m,1H),1.52-1.23(m,2H)

[0076] Step 2: Synthesis of 4-(4-(dimethoxymethyl)piperidin-1-yl)-2-fluorobenzoic acid

[0077] The aqueous solution (60 mL) of lithium hydroxide monohydrate (7.9 g, 329.8 mmol) was slowly added to the methanol solution (60 mL) of methyl 4-(4-(dimethoxymethyl)piperidin-1-yl)-2-fluorobenzoate (25.4 g, 82.5 mmol), and the system was heated to 50°C and stirred for 1 hour. The reaction solution was evaporated under reduced pressure to remove methanol, and water (60 ml) was added to dilute it. Under stirring, a dilute aqueous hydrochloric acid solution (1 mol / L) was added dropwise until a large amount of precipitation was precipitated, and the pH was about 6. The mixture was filtered, and the filter cake was washed with water and dried to obtain 20 g of the title compound as a white solid with a yield of 87.0%.

[0078] LC-MS: Rt=2.391min, MS(ESI)m / z=298.0[M+H] + .

[0079] 1H NMR (400MHz, DMSO-d6) δ10.93ppm (s, 1H), 9.82 (d, J = 7.0Hz, 1H), 7.97-7.76 (m ,1H),7.29-7.08(m,1H),6.99(td,J=8.3,2.3Hz,1H),4.85-4.68(m,1H),4.50 (s,1H),3.16(s,2H),2.88-2.62(m,3H),2.24(d,J=12.6Hz,1H),2.12-1.91(m ,1H),1.77(d,J=11.5Hz,2H),1.45(d,J=12.3Hz,3H),1.27(d,J=17.1Hz,1H).

[0080] Step 3: Synthesis of 4-(4-(dimethoxymethyl)piperidin-1-yl)-N-(2,6-dicarbonylpiperidin-3-yl)-2-fluorobenzamide

[0081] 2-(7-Azobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (32.3 g, 85.5 mmol) was added to a dimethylformamide solution (1700 mL) of 4-(4-(dimethoxymethyl)piperidin-1-yl)-2-fluorobenzoic acid (17 g, 57 mmol), 3-aminopiperidine-2,6-dione hydrochloride (9.35 g, 57 mmol) and diisopropylethylamine (22.1 g, 171 mmol) at once, and the system was stirred at room temperature for 1 hour. Water (1000 mL) was added to the system, washed with ethyl acetate (200 mL), and the filter cake was filtered to obtain a relatively pure target compound. DCM:EA=1:10 was used for slurrying to obtain 17 g of the light yellow solid title compound with a yield of 73.0%.

[0082] LC-MS: Rt=1.12min, MS(ESI)m / z=408.3[M+H] + .

[0083] 1 H NMR (400MHz, DMSO-d6) δ10.85(s,1H),8.01(t,J=7.3Hz,1H),7.62(t,J=9.1Hz,1H), 6.95-6.67(m,2H),4.83-4.67(m,1H),4.07(d,J=6.9Hz,1H),3.90(dd,J=13.2,3.4Hz ,2H),3.27(s,6H),2.78(tdd,J=13.5,9.6,4.1Hz,3H),2.19-1.93(m,2H),1.83(dtt, J=11.4,7.3,3.6Hz,1H),1.68(dd,J=13.4,3.7Hz,2H),1.26(qd,J=12.4,4.1Hz,2H).

[0084] Step 4: Synthesis of N-(2,6-dioxopiperidin-3-yl)-2-fluoro-4-(4-formylpiperidin-1-yl)benzamide 2,2,2-trifluoroacetate

[0085] Trifluoroacetic acid (17 mL) was added dropwise to a dichloromethane solution (170 mL) of 4-(4-(dimethoxymethyl)piperidin-1-yl)-N-(2,6-dicarbonylpiperidin-3-yl)-2-fluorobenzamide (17 g, 2.9 mmol), and the system was stirred at room temperature for 4 hours. The reaction solution was evaporated under reduced pressure to obtain a residue, and the pH was adjusted to weak alkalinity with saturated sodium bicarbonate solution, and DCM1.5 L was added for extraction once, and the organic phase was washed with water 3 times and dried to obtain 12 g of the title compound as an off-white solid, with a yield of 79%.

[0086] LC-MS: Rt=0.967min, MS(ESI)m / z=362.0[M+H] + .

[0087] 1H NMR (400MHz, DMSO-d6) δ = 10.85ppm (s, 1H), 1H NMR (400MHz, DMSO-d6) δ10.85(s,1H),9.62(s,1H),8.03(t,J=7.2Hz,1H),7.63(t,J=9. 1Hz,1H),6.97-6.64(m,2H),4.73(ddd,J=12.7,7.7,5.4Hz,1H),3.02(ddd,J=13.5,10.9 ,3.0Hz,2H),2.78(ddd,J=17.2,13.3,5.6Hz,1H),2.59(dtd,J=12.2,8.2,7.3,4.0Hz,1H ),2.19-1.97(m,2H),1.90(dt,J=12.4,3.8Hz,2H),1.54(dtd,J=14.4,10.8,3.9Hz,2H).

[0088] Preparation Example 3: Synthesis of Intermediate 3

[0089]

[0090] Step 1: Preparation of methyl 4-(4-(dimethoxymethyl)piperidin-1-yl)-2-methoxybenzoate

[0091] Palladium acetate (640 mg, 2.86 mmol), 1,1'-binaphthyl-2,2'-bisdiphenylphosphine (3810 mg, 6.12 mmol), cesium carbonate (26.59 g, 81.61 mmol) were added to a mixed solution of methyl 4-bromo-2-methoxybenzoate (10.00 g, 40.81 mmol) and 4-(dimethoxymethyl)piperidine (7.15 g, 44.89 mmol) in 1,4-dioxane (150 mL), argon was replaced 3 times, and the mixture was stirred at 100°C for 8 hours under argon protection. After the reaction was completed, diatomaceous earth was used for suction filtration and washed with ethyl acetate. The filtrate was dried and the obtained crude product was separated by a normal silica gel column (ethyl acetate / petroleum ether = 1 / 10 to 3 / 1) to obtain 8.0 g of the crude product of the light yellow solid title compound, with a yield of 60.63%.

[0092] LC-MS: MS (ESI) m / z = 324.2 [M + H] + .

[0093] Step 2: Preparation of 4-(4-(dimethoxymethyl)piperidin-1-yl)-2-methoxybenzoic acid

[0094] Dissolve 4-(4-(dimethoxymethyl)piperidin-1-yl)-2-methoxybenzoic acid methyl ester (8.0g, 24.74mmol) in 40mL tetrahydrofuran and 40mL methanol, add 40mL of prepared lithium hydroxide (4.15g, 98.95mmol) aqueous solution, and stir at room temperature for 16 hours. After the reaction is completed, spin dry, add 100mL of water again, extract twice with ethyl acetate (60mL*2), adjust the pH of the aqueous phase to 4-5 with 1N hydrochloric acid, a large amount of solid precipitates, and filter to obtain 6.0g of light yellow solid title compound with a yield of 78.40%.

[0095] LC-MS: MS (ESI) m / z = 310.2 [M+H] + .

[0096] Step 3: Preparation of (S)-4-(4-(dimethoxymethyl)piperidin-1-yl)-N-(2,6-dicarbonylpiperidin-3-yl)-2-methoxybenzamide

[0097] Under ice bath, (S)-3-aminopiperidine-2,6-dione hydrochloric acid (3.35 g, 20.37 mmol) and diisopropylethylamine (7.52 g, 58.19 mmol) were added to a mixed solution of 4-(4-(dimethoxymethyl)piperidin-1-yl)-2-methoxybenzoic acid (6.0 g, 19.40 mmol) and O-(7-azabenzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate (8.85 g, 23.27 mmol) in N,N-dimethylformamide (30 mL) and dichloromethane (120 mL), and the system was stirred at 25 ° C for 16 hours. The dichloromethane and diisopropylethylamine were removed by rotary evaporation under reduced pressure, and the reaction solution was added dropwise into 200 mL of water with stirring. After stirring for 1 hour, the mixture was filtered and the filter cake was washed with water. After the filter cake was dried, it was rotary evaporated under reduced pressure to obtain 7.8 g of the title compound as a white solid with a yield of 95.87%.

[0098] LC-MS: MS (ESI) m / z = 420.2 [M + H] + .

[0099] Step 4: Preparation of (S)-N-(2,6-dicarbonylpiperidin-3-yl)-4-(4-formylpiperidin-1-yl)-2-methoxybenzamide trifluoroacetate

[0100] (S)-4-(4-(dimethoxymethyl)piperidin-1-yl)-N-(2,6-dicarbonylpiperidin-3-yl)-2-methoxybenzamide (7.80 g, 18.59 mmol) was dissolved in 30 mL of dichloromethane, and 30 mL of trifluoroacetic acid was added, and stirred at room temperature for 3 hours. After the reaction was completed, the reaction solution was spin-dried, and the obtained crude product was separated by a normal silica gel column (methanol / dichloromethane = 1 / 20 to 10 / 1) to obtain 3.90 g of the light yellow solid title compound, with a yield of 46.01%.

[0101] LC-MS: MS (ESI) m / z = 374.2 [M + H] + .

[0102] Preparation Example 4: Synthesis of Intermediate 4

[0103]

[0104] Step 1: Preparation of 3-(6-bromo-1-oxoisoindolin-2-yl)piperidine-2,6-dione

[0105] Sodium acetate (5.4 g, 65.8 mmol) was added to a methanol solution (160 mL) of 3-amino-2,6-piperidindione hydrochloride (5.69 g, 36.2 mmol), and the resulting turbid solution was stirred at 15°C for 10 minutes, glacial acetic acid (19.76 g, 0.33 mol) was added dropwise, and then methyl 5-bromo-2-formylbenzoate (8 g, 33 mmol) was added, and the system was stirred at 15°C for 20 minutes, sodium cyanoborohydride (4.13 g, 65.8 mmol) was added in batches, and the system was heated to 35°C and stirred for 16 hours. Water (20 mL) was added dropwise to the reaction solution, and then the methanol was removed by rotary drying under reduced pressure, and water (500 mL) was added, filtered, and the filter cake was dried to obtain 8.3 g of the title compound as a white solid, with a yield of 78.12%.

[0106] LC-MS: Rt=1.07min, MS(ESI)m / z=323.0 / 325.0[M+H] + .

[0107] Step 2: Preparation of 3-(6-(4-(dimethoxymethyl)piperidin-1-yl)-1-oxoisoindolin-2-yl)piperidine-2,6-dione

[0108] (SP-4-1)-[1,3-bis[2,6-bis(1-propylbutyl)phenyl]-4,5-dichloro-1,3-dihydro-2H-imidazol-2-ylidene]dichloro(3-chloropyridine-κN)-palladium (0.3 g, 0.3 mmol) was added to a mixture of 3-(6-bromo-1-oxoisoindolin-2-yl)piperidine-2,6-dione (2 g, 6.2 mmol), 4-(dimethoxymethyl)piperidine (1.28 g, 8.1 mmol) and cesium carbonate (6.06 g, 18.6 mmol) in dioxane (40 mL), the nitrogen was replaced three times, the system was heated to 100°C and stirred for 3 hours. The reaction solution was cooled to room temperature, diluted with ethyl acetate and filtered. The filtrate was dried under reduced pressure and separated and purified by silica gel column chromatography (methanol / dichloromethane, 0-10%) to obtain 0.9 g of the title compound as a yellow solid. The yield was 35.48%.

[0109] LC-MS: Rt=0.98min, MS(ESI)m / z=402.0[M+H] + .

[0110] Step 3: Preparation of 1-(2-(2,6-dioxopiperidin-3-yl)-3-oxoisoindolin-5-yl)piperidine-4-carboxaldehyde trifluoroacetate Trifluoroacetic acid (6 mL) was added dropwise to a dichloromethane solution (20 mL) of 3-(6-(4-(dimethoxymethyl)piperidin-1-yl)-1-oxoisoindolin-2-yl)piperidine-2,6-dione (0.9 g, 2.2 mmol), and the system was stirred at room temperature for 2 hours. The reaction solution was decompressed and dried to remove the solvent, ether (30 mL) was added, ultrasonically shaken for 10 minutes, filtered, and the filter cake was dried to obtain 0.83 g of the title compound as a gray solid, with a yield of 72.73%.

[0111] LC-MS: Rt=0.88min, MS(ESI)m / z=356.2[M+H] + .

[0112] 1H NMR(400MHz,DMSO)δppm 10.98(s,1H),9.64(s,1H),7.43(d,J=8.4Hz,1H),7.27(m,2H),5.10(dd,J=13.3,5.1Hz,1H),4.34(d,J=16.7Hz,1H),4.20(d ,J=16.8Hz,1H),3.67(d,J=12.6Hz,2H),2.91(m,3H),2.56(m,2H),2.37(m,1H),1.97(dd,J=12.9,10.7Hz,3H),1.61(m,2H).

[0113] Preparation Example 5: Synthesis of Intermediate 5

[0114]

[0115] Step 1: Preparation of 3-(5-bromo-1-oxoisoindolin-2-yl)piperidine-2,6-dione

[0116] Sodium acetate (670 mg, 8.2 mmol) was added to a methanol solution (20 mL) of 3-amino-2,6-piperidindione hydrochloride (0.74 g, 4.5 mmol), and the resulting turbid solution was stirred at 15°C for 10 minutes, glacial acetic acid (2.46 g, 41 mmol) was added dropwise, and then methyl 4-bromo-2-formylbenzoate (1 g, 4.1 mmol) was added, and the system was stirred at 15°C for 20 minutes, sodium cyanoborohydride (0.52 g, 8.2 mmol) was added in batches, and the system was heated to 35°C and stirred for 16 hours. Water (5 mL) was added dropwise to the reaction solution, and then the methanol was removed by rotary drying under reduced pressure, and water (50 mL) was added, filtered, and the filter cake was dried to obtain 1.2 g of the title compound as a white solid, with a yield of 81.11%.

[0117] LC-MS: Rt=1.03min, MS(ESI)m / z=322.9 / 324.9[M+H] + .

[0118] Step 2: Preparation of 3-(5-(4-(dimethoxymethyl)piperidin-1-yl)-1-oxoisoindolin-2-yl)piperidine-2,6-dione

[0119] (SP-4-1)-[1,3-bis[2,6-bis(1-propylbutyl)phenyl]-4,5-dichloro-1,3-dihydro-2H-imidazol-2-ylidene]dichloro(3-chloropyridine-κN)-palladium (0.3 g, 0.3 mmol) was added to a mixture of 3-(5-bromo-1-oxoisoindolin-2-yl)piperidine-2,6-dione (2 g, 6.2 mmol), 4-(dimethoxymethyl)piperidine (1.28 g, 8.1 mmol) and cesium carbonate (6.06 g, 18.6 mmol) in dioxane (40 mL), the nitrogen was replaced three times, the system was heated to 100°C and stirred for 3 hours. The reaction solution was cooled to room temperature, diluted with ethyl acetate and filtered. The filtrate was dried under reduced pressure and separated and purified by silica gel column chromatography (methanol / dichloromethane, 0-10%) to obtain 1.5 g of the title compound as a yellow solid in a yield of 59.68%.

[0120] LC-MS: Rt=1.17min, MS(ESI)m / z=402.0[M+H] + .

[0121] Step 3: Preparation of 1-(2-(2,6-dioxopiperidin-3-yl)-1-oxoisoindolin-5-yl)piperidine-4-carboxaldehyde trifluoroacetate

[0122] Trifluoroacetic acid (10 mL) was added dropwise to a dichloromethane solution (30 mL) of 3-(5-(4-(dimethoxymethyl)piperidin-1-yl)-1-oxoisoindolin-2-yl)piperidine-2,6-dione (1.5 g, 3.7 mmol), and the system was stirred at room temperature for 2 hours. The reaction solution was decompressed and dried to remove the solvent, and ether (50 mL) was added. Ultrasonic vibration was performed for 10 minutes, and the mixture was filtered and the filter cake was dried to obtain 1.35 g of the title compound as a green solid with a yield of 70.27%.

[0123] 1 H NMR(400MHz,DMSO)δppm 10.95(s,1H),9.62(s,1H),7.51(d,J=8.4Hz,1H),7.07(d,J=10.4Hz,2H),5.05(dd,J=13.3,5.1Hz,1H),4.26(dd,J=49.5,16.8Hz,2H),3.7 8(m,2H),3.02(m,2H),2.90(m,1H),2.58(dd,J=11.0,4.0Hz,2H),2.36(dt,J=13.3,8.9Hz,1H),1.94(m,3H),1.57(qd,J=11.0,3.7Hz,2H).

[0124] LC-MS: Rt=0.97min, MS(ESI)m / z=356.1[M+H] +

[0125] Example 1: Preparation of 7-cyclopentyl-2-((4-(4-((1-(4-((2,6-dioxopiperidin-3-yl)carbamoyl)-3-fluorophenyl)piperidin-4-yl)methyl)piperazin-1-yl)phenyl)amino)-N,N-dimethyl-7H-pyrrolo[2,3-d]pyrimidine-6-carboxamide

[0126]

[0127] The aldehyde E3 compound intermediate 2 (0.1 mmol) was added to a solution (3-4 mL) of the amine compound intermediate 1 (0.1 mmol) in N,N-dimethylformamide, and stirred at room temperature for 5 minutes. Triethylamine (0.2 mmol) was added dropwise, and stirred at room temperature for 2 hours. Then sodium triacetoxyborohydride (0.2 mmol) was added in two batches, and the system was stirred at room temperature for 1 hour. The reaction was completed under TLC monitoring. 15 ml of water was added to the system, and then extracted with ethyl acetate and n-butanol in sequence. The organic phases were combined, dried over Na2SO4 and filtered. The filtrate was concentrated under reduced pressure and further purified by preparative TLC (DCM:MeOH=10:1) to obtain 70 mg of the target compound in a yield of 90%.

[0128] LC-MS: [M+H] + :779.4

[0129] 1 H NMR(400MHz,Chloroform-d)δ8.59(s,1H),7.93(t,J=9.2Hz,1H),7.65(d,J=8.9Hz,2H),6.96(d,J =8.7Hz,2H),6.72(dd,J=9.1,2.4Hz,1H),6.52(dd,J=16.5,2.4Hz,1H),6.42(s,1H),4.81-4.71(m, 2H),3.85(d,J=12.8Hz,2H),3.23-3.17(m,4H),3.15(s,6H),2.94-2.85(m,2H),2.85-2.78(m,2H), 2.62-2.49(m,8H),2.33(d,J=6.9Hz,2H),2.05-1.79(m,7H),1.73-1.63(m,2H),1.37-1.27(m,2H).

[0130] Example 2: Preparation of (S)-7-cyclopentyl-2-((4-(4-((1-(4-((2,6-dioxopiperidin-3-yl)carbamoyl)-3-methoxyphenyl)piperidin-4-yl)methyl)piperazin-1-yl)phenyl)amino)-N,N-dimethyl-7H-pyrrolo[2,3-d]pyrimidine-6-carboxamide

[0131]

[0132] Referring to the synthesis method of compound Example 1, the aldehyde E3 compound intermediate 3 was added to the amine compound intermediate 1 to prepare the compound of Example 2 (70 mg, 89%). LC-MS: [M+H] + :791.4

[0133] 1 H NMR(400MHz,Chloroform-d)δ9.05(s,1H),8.69(d,J=5.5Hz,1H),8.56(s,1H),8.33(s,1H),8.04( d,J=8.8Hz,1H),7.66(d,J=8.4Hz,2H),6.95(d,J=8.5Hz,2H),6.59(d,J=8.9Hz,1H),6.41(d,J=6.4 Hz,2H),4.83-4.71(m,2H),4.00(s,3H),3.86(d,J=12.7Hz,2H),3.27-3.19(m,4H),3.15(s,6H),2 .91-2.64(m,11H),2.37(d,J=6.9Hz,2H),2.07-1.78(m,8H),1.73-1.63(m,2H),1.37-1.30(m,2H).

[0134] Example 3: Preparation of 7-cyclopentyl-2-((4-(4-((1-(2-(2,6-dioxopiperidin-3-yl)-3-oxoisoindolin-5-yl)piperidin-4-yl)methyl)piperazin-1-yl)phenyl)amino)-N,N-dimethyl-7H-pyrrolo[2,3-d]pyrimidine-6-carboxamide

[0135]

[0136] Referring to the synthesis method of compound Example 1, the aldehyde E3 compound intermediate 4 was added to the amine compound intermediate 1 to prepare the compound of Example 3 (62.5 mg, 81%).

[0137] LC-MS: [M+H] + :773.4

[0138] 1H NMR(400MHz,Chloroform-d)δ8.90(s,1H),8.56(s,1H),8.29(s,1H),7.65(d,J=8.6Hz,2H),7.39(d,J=2.3Hz,1H),7.32(d, J=8.4Hz,1H),7.19(dd,J=8.5,2.3Hz,1H),6.94(d,J=8.7Hz,2H),6.41(s,1H),5.23(dd,J=13.3,5.1Hz,1H),4.75(p,J=8.7 Hz,1H),4.41(d,J=15.5Hz,1H),4.27(d,J=15.6Hz,1H),3.76(d,J=12.2Hz,2H),3.33-3.22(m,4H),3.15(s,6H),2.98-2.73 (m,8H),2.63-2.45(m,4H),2.41-2.31(m,1H),2.26-2.19(m,1H),2.06-1.80(m,7H),1.73-1.62(m,2H),1.50-1.39(m,2H).

[0139] Example 4: Preparation of 7-cyclopentyl-2-((4-(4-((1-(2-(2,6-dioxopiperidin-3-yl)-1-oxoisoindolin-5-yl)piperidin-4-yl)methyl)piperazin-1-yl)phenyl)amino)-N,N-dimethyl-7H-pyrrolo[2,3-d]pyrimidine-6-carboxamide

[0140]

[0141] Referring to the synthesis method of Example 1, the aldehyde E3 compound intermediate 4 was added to the amine compound intermediate 1 to prepare Example 4 compound (60 mg, 69%).

[0142] LC-MS: [M+H] + :773.4

[0143] 1H NMR(400MHz,Chloroform-d)δ8.58(s,1H),7.72(d,J=8.6Hz,1H),7.67-7.60(m,2H),7.00(dd,J=8.7,2.1Hz,1H),6.95(d ,J=8.8Hz,2H),6.89(d,J=2.1Hz,1H),6.41(s,1H),5.19(dd,J=13.2,5.1Hz,1H),4.74(p,J=8.9Hz,1H),4.41(d,J=15.7Hz ,1H),4.26(d,J=15.8Hz,1H),3.85(d,J=12.5Hz,2H),3.26-3.18(m,4H),3.15(s,6H),2.95-2.80(m,6H),2.73-2.66(m,4 H),2.62-2.54(m,2H),2.36(d,J=6.9Hz,2H),2.23-2.17(m,1H),2.03-1.79(m,6H),1.71-1.63(m,2H),1.33-1.24(m,2H).

[0144] Comparative Example 1: Synthesis of Control Compound 2

[0145] Reference Eur. J. Med. Chem., 2021, 209, 112903 was used to prepare control compound 2, and the reference synthesis route is shown below. 1 H-NMR(400MHz,Chloroform-d)δ11.19(s,1H),8.68(d,J=3.0Hz,1H),8.52(s,1H),7.82-7.65(m,4H),7.4 7-7.36(m,1H),7.08-6.97(m,1H),6.80(d,J=8.6Hz,1H),6.58(d,J=5.7Hz,1H),6.37(d,J=3.0Hz,1H),6.1 7(q,J=4.8Hz,1H),4.91(q,J=5.7,5.2Hz,1H),4.72(t,J=9.3Hz,1H),3.46-3.31(m,2H),3.13(d,J=26.6H z,8H),2.88-2.69(m,3H),2.54(d,J=10.4Hz,2H),2.05(d,J=30.2Hz,5H),1.70-1.53(m,6H),1.37(s,4H).

[0146]

[0147] Effect Example 1: Antiproliferation activity of compounds on tumor cells

[0148] MDA-MB-231 cells in the logarithmic growth phase (purchased from the Cell Bank of the Chinese Academy of Sciences) were inoculated in a 96-well plate (NEST, 701001), with 80 μL per well (2 × 10 cells per well). 3 ), place the culture plate in a 37°C incubator containing 5% carbon dioxide and incubate for 4 hours. The test compound was prepared into a 10mM stock solution using dimethyl sulfoxide (DMSO) (Aladdin, D103277). After gradient dilution, a series of working solutions of different concentrations were prepared using complete culture medium. Add 20uL of the working solution to the corresponding wells of the well plate, place the well plate in a 5% carbon dioxide incubator, and take it out after incubation at 37°C for 72h. Add 10μL Cellcounting kit-8 reagent (Mei5bio, MF128-Pro-02) to each well, incubate at room temperature for 90min, and measure the absorbance at 450nm using an enzyme reader. Calculate the cell proliferation inhibition rate, cell proliferation inhibition rate = [1-(A 样品孔 -A 空白孔 ) / (A 对照孔 -A 空白 )] × 100%. The inhibition curve was drawn using the four-parameter equation in GraphPad 8.0 software, and the IC 50 The results of the inhibitory activity of each compound in the examples of the present invention on MDA-MB-231 cell proliferation are shown in Table 1. The control compound 1 is Palbociclib.

[0149] ++++ indicates IC 50 <10nM; +++ means 10nM <IC 50 <100nM; ++ means 100nM <IC 50 <500nM.

[0150] Table 1: Proliferation inhibition activity of compounds on breast cancer cells

[0151] Compound <![CDATA[IC 50 (nM)]]> Example 1 Compound +++ Example 2 Compound +++ Example 3 Compound ++++ Control compound 1 ++

[0152] Effect Example 2: Degradation activity of compounds on CDK2 / CDK4 and CDK6 proteins

[0153] Experimental steps:

[0154] 1) After subculturing MDA-MB-231 cells with cell culture medium, cells with good growth status were inoculated into 12-well plates (NEST, 712001), with 1 mL of culture medium per well and 2*10 cells per well. 5 , and cultured overnight in a 37°C, 5% CO2 cell incubator.

[0155] 2) Prepare the test compound with dimethyl sulfoxide (DMSO) into a 10mM stock solution. Dilute with DMSO again before use, add 1μl of the diluted compound to the cell culture well, and gently shake to mix. Also set up a negative control well (add an equal amount of DMSO) and a positive control well.

[0156] 3) After 16 hours of culture, cells were lysed with RIPA cell lysis buffer (Biyuntian, P0013) (containing 1% Cocktail), protein was extracted, and protein concentration was measured with BCA kit (Thermo, 23227). 5 times concentrated protein loading buffer was added, heated at 100°C for 5 minutes, and then the samples were stored at -20°C.

[0157] 4) SDS-PAGE gel electrophoresis experiment: ①. Gel preparation: All 7.5%-15% polyacrylamide gels of the present invention are used to separate proteins; ②. Sample loading: After the device is assembled, add Running buffer, add protein markers and samples to the sample loading wells, the sample loading volume of each well is 5-15μL, and the amount of sampled protein is 20-30μg; ③. Electrophoresis: Connect the power supply, run the sample at a constant voltage of 80V until the pre-stained protein marker is completely separated, then stop the voltage, discard the electrophoresis well, and rinse the sample tank with water; ④. Transfer to membrane: Remove the gel in the glass plate, cut off the required part and place it in Trans buffer, assemble the transfer to membrane device in the order of sponge-filter paper-gel-activated PVDF membrane-filter paper-sponge, then place the electrophoresis tank in an ice water bath, turn on the power supply, and transfer the membrane at 300V for 1h. After the transfer to membrane, quickly place the PVDF membrane in TBS buffer.

[0158] 5) Immunoblotting and color development: ①. Wash the PVDF membrane with 50 mL 1×TBS for 5 min, then add 50 mL 5% skim milk blocking buffer and shake at room temperature for 1 h; ②. Wash the PVDF membrane with 50 mL 1×TBS / T for 3 times, 10 min each time; ③. Add primary antibodies of appropriate dilution, CDK2 (Beyotime, AF1063), CDK4 (Beyotime, AF2515), CDK6 (Beyotime, AF0114), α-Actin (abclonal, A2319), and incubate overnight at 4°C; ④. Wash the PVDF membrane with 50 mL 1×TBS / T buffer for 3 times, 10 min each time; ⑤. Add secondary antibodies of appropriate dilution, Peroxidase Affinipure (HRP) Goat Anti-Rabbit IgG (Bio-Ray, Cat. BN20601), incubate at room temperature for 2 hours; ⑥. Wash the membrane three times with 50 mL 1×TBS / T buffer, 10 minutes each time; ⑦. Develop and expose, using α-actin as an internal reference.

[0159] 6) Result detection: Finally, ECL color developing solution (Biyuntian, Cat. No. P0018S) was added for color development, and photos were taken with an automatic chemiluminescence instrument. The images were collected for analysis and the degradation rate was calculated.

[0160] Experimental results: The degradation activities of the disclosed compounds on CDK2, CDK4, and CDK6 at the concentrations shown in Table 2 and Figure 1 Among them, A represents that the degradation percentage of the target protein is greater than 80%; B represents that the degradation percentage of the target protein is between 50% and 80%; C represents that the degradation percentage of the target protein is less than 50%;

[0161] Table 2: Degradation activity of compounds at different concentrations on CDK2, CDK4, and CDK6 in MDA-MB-231 cells

[0162]

[0163] It is not difficult to see from the results in Table 1 and Table 2 that the compounds of the embodiments of the present disclosure have significant breast cancer cell proliferation inhibition activity, and their inhibitory activity IC 50 The value is less than 100 nM, even less than 10 nM, which is obviously better than the control compound 2.

[0164] Effect Example 3: PK data of the compounds disclosed in the present invention in mice

[0165] (1) Experimental purpose:

[0166] This experiment aims to study the pharmacokinetics of the test compound in the plasma of ICR male mice after intravenous and oral administration.

[0167] (2) Experimental operation:

[0168] Intravenous injection group: Weigh an appropriate amount of the test compound and dissolve it in 5% DMSO / 10% Solutol / 85% H2O and adjust the pH to 3-4 with 6M hydrochloric acid. Vortex to prepare a 1.0 mg / mL clear solution, filter it with a 0.22μM microporous filter membrane and set aside. Select 6 to 10-week-old ICR male mice and intravenously inject the test compound solution at a dose of 2 mg / kg. Sample collection time: 0.083, 0.25, 0.5, 1, 2, 4, 6, 8, 24 hours.

[0169] Oral administration group: Weigh an appropriate amount of the test compound and dissolve it in 5% DMSO / 20% PEG400 / 75% (20% Captisolin water) and adjust the pH to 3-4 with 6M hydrochloric acid, vortex to prepare a 2.0 mg / mL clear solution, filter it with a 0.22μM microporous filter membrane and set aside. Select 6 to 10 week old ICR male mice and orally administer the test compound solution at a dose of 5 mg / kg. Sample collection time: 0.25, 0.5, 1, 2, 4, 6, 8, 24 hours.

[0170] Approximately 50 μL of whole blood was collected from the jugular vein at each time point to prepare plasma for concentration determination by high performance liquid chromatography-tandem mass spectrometry (LC-MS / MS). All animals were euthanized by CO2 anesthesia after the last PK sample was collected. WinNonlin TM Plasma concentrations were treated with a noncompartmental model using the pharmacokinetic software Version 6.3 (Pharsight, Mountain View, CA), and pharmacokinetic parameters were calculated using the linear-log trapezoidal method.

[0171] The pharmacokinetic study of the disclosed compounds in ICR mice showed good bioavailability.

[0172] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A compound of formula (A) or a pharmaceutically acceptable salt thereof, In formula (A), R A1 , R A2 Each independently is C 1-3 alkyl; R B Halogen or C 1-3 Alkoxy; R C is hydrogen, or R B , R C The carbon atom to which it is connected forms a 5-membered partially unsaturated heterocyclic ring, wherein the 5-membered partially unsaturated heterocyclic ring is substituted by an oxo group; in, Selected from 2. The compound of formula (A) or a pharmaceutically acceptable salt thereof according to claim 1, wherein The compound of formula (A) is a compound of formula (A-1): In formula (A-1), R A1 , R A2 Each independently is C 1-3 alkyl; R D1 , R D2 are each independently an oxo group, and R D1 , R D2 There is only one oxo group.

3. The compound of formula (A) or a pharmaceutically acceptable salt thereof according to claim 1, wherein R C is hydrogen; R B Halogen or C 1-3 Alkoxy.

4. The compound of formula (A) or a pharmaceutically acceptable salt thereof according to claim 3, wherein: R B is fluorine or methoxy.

5. The compound of formula (A) or a pharmaceutically acceptable salt thereof according to claim 1, wherein Selected from:

6. A compound of formula (A) or a pharmaceutically acceptable salt thereof according to any one of claims 1 to 5, wherein: R A1 is methyl, R A2 It is methyl.

7. The compound of formula (A) or a pharmaceutically acceptable salt thereof according to claim 1, wherein the compound is selected from the following compounds:

8. The compound of formula (A) or a pharmaceutically acceptable salt thereof according to claim 7, wherein: The compounds are used to inhibit the activities of CDK2, CDK4 and CDK6.

9. A pharmaceutical composition comprising the compound of formula (A) or a pharmaceutically acceptable salt thereof according to any one of claims 1 to 8, wherein the pharmaceutical composition optionally further comprises a pharmaceutically acceptable excipient.

10. Use of the compound according to any one of claims 1 to 8 or the pharmaceutical composition according to claim 9 in the preparation of a medicament for treating breast cancer.

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