Method for synthesizing intermediates of substituted tricyclic PRMT5 inhibitors

Abstract

The present invention belongs to the technical field of pharmaceutical chemical intermediate synthesis, and specifically relates to a method for synthesizing an intermediate of a substituted tricyclic PRMT5 inhibitor. 2-Chloro-5-fluoropyridine is selected as a raw material, and a carboxyl group, SN AR Substitution, methyl esterification, and reduction ring closure are a total of four steps to obtain 7'-chloro-2'-,3'-dihydro-1'-H-spiro[cyclopropane-1,4'-[2,6]naphthyridine]-1'-one product, which has a short route and obvious process advantages. AR The substitution reaction, a one-step reaction, solves the problem of high cost and low yield of the two-step reaction of palladium catalyst coupling and Corey-Chaykovsky reaction to prepare cyclopropyl in the previous process.

Description

Technical Field

[0001] The invention belongs to the technical field of pharmaceutical chemical intermediate synthesis, and specifically relates to a method for synthesizing an intermediate of a substituted tricyclic PRMT5 inhibitor. Background Art

[0002] Patent CN112645946A introduces a class of compounds or isomers with PRMT5 inhibitory activity, the general formula is as follows:

[0003] .

[0004] PRMT5 can specifically bind to methyltransferase complex protein 50 (MEP50) and has been shown to repress the expression of several tumor suppressor genes, such as tumor suppressor gene 7 (ST7), retinoblastoma (RB) tumor suppressor gene family, and receptor type O protein tyrosine phosphatase (PTPROt).

[0005] PRMT5 can also methylate p53 and alter its DNA binding activity, thereby initiating changes in the gene expression program controlled by p53. PRMT5 can also directly methylate transcription factors, modifying not only nuclear transcription factors but also methylating cytoplasmic proteins.

[0006] Numerous studies have demonstrated that PRMT5 is overexpressed in different types and aggressive forms of cancer, plays an important role in controlling cell growth and proliferation, and its overexpression promotes cell transformation.

[0007] Therefore, PRMT5 inhibitors have obvious therapeutic effects in the treatment of tumors and other related diseases, have great potential for drug development, and may become a new method for treating tumors. Therefore, in order to achieve large-scale production goals, it is of great significance to develop methods for synthesizing key intermediates of PRMT5 inhibitors.

[0008] Patent CN112645946A introduces the synthesis method of some intermediates, as shown below:

[0009] .

[0010] According to the synthesis method described in the patent, 5-bromo-2-chloroisonicotinic acid is used as the raw material, thionyl chloride is used to prepare the acid chloride, and then reacted with methanol to form a methyl ester, and then methylated under palladium catalysis, NBS brominates the methyl, and then TMSCN is used for substitution reaction, and 1,2-dibromoethane is reacted to form a three-membered ring, and the cyanide is reduced to form 7'-chloro-2'-,3'-dihydro-1'-H-spiro[cyclopropane-1,4'-[2,6]naphthyridine]-1'-one. This route uses expensive palladium catalysts, which greatly increases the production cost. TMSCN substitution reaction is used, and the reaction process has highly toxic cyanide anions. The production process requirements are very high. In addition, the price of the raw material 5-bromo-2-chloroisonicotinic acid is also relatively high, and there are many production steps, which does not have production advantages.

[0011] Patent CN116120320A introduces a synthesis method of 7'-chloro-2'-, 3'-dihydro-1'-H-spiro[cyclopropane-1,4'-[2,6]naphthyridine]-1'-one, as shown below:

[0012] .

[0013] The first step is the substitution reaction between potassium phthalimide and 2,3-dibromo-1-propylene. The second step is to synthesize the pinnacle ester under palladium catalysis, and then carry out Suzuki coupling reaction under palladium catalysis, and then deprotect under hydrazine hydrate conditions to form a bicyclic compound, and finally react with trimethyl sulfoxide iodide (sulfur ylide reagent) to produce a cyclopropyl compound. This method also requires a palladium catalyst for catalysis. Although the two steps of palladium catalysis are combined into one step, reducing the reuse of palladium catalysts, the yield is only 53%, and the cost is still high; the last step of sulfur ylide reagent reaction also has a yield of only 41%.

[0014] Therefore, it is of great significance to develop a low-cost process that can be mass-produced. Summary of the invention

[0015] In view of the deficiencies of the prior art, the object of the present invention is to provide a method for synthesizing an intermediate of a substituted tricyclic PRMT5 inhibitor, which has low cost, high yield and is suitable for large-scale production.

[0016] The method for synthesizing the intermediate of the substituted tricyclic PRMT5 inhibitor of the present invention comprises the following steps:

[0017] (1) Synthesis of 2-chloro-5-fluoronicotinic acid

[0018] 2-Methyltetrahydrofuran and diisopropylamine are added to a reaction container, 1.6M n-butyl lithium n-hexane solution is added dropwise, after the addition is complete, a 2-methyltetrahydrofuran solution of 2-chloro-5-fluoropyridine is added dropwise, after the addition is complete, the temperature is kept for reaction, and then carbon dioxide gas is introduced into the reaction container for reaction, and the content of 2-chloro-5-fluoropyridine is less than 1% under HPLC monitoring, then the temperature is raised, quenched, allowed to stand for separation, extraction, the aqueous phase is collected, the pH is adjusted to acidic, the temperature is kept for stirring, filtration is performed, the filter cake is rinsed, and the wet sample is dried to obtain 2-chloro-5-fluoronicotinic acid;

[0019] (2) Synthesis of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid

[0020] Add tetrahydrofuran, 2-chloro-5-fluoronicotinic acid, and cyclopropylnitrile to a reaction container, dropwise add a tetrahydrofuran solution of an alkaline salt, raise the temperature after the dropwise addition is completed, quench after the reaction is completed, dropwise add an acid for the first time to adjust the pH, remove the tetrahydrofuran by rotary evaporation, dropwise add a base to adjust the pH of the aqueous phase to alkaline, and under stirring, dropwise add an acid for the second time to adjust the pH to acidic; stir for 16 hours to allow the product to be fully precipitated and dispersed, filter press, wash the filter cake, filter press and air dry to obtain 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid;

[0021] (3) Synthesis of 2-chloro-5-(1-cyanocyclopropyl)nicotinate

[0022] Add 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid, 2-methyltetrahydrofuran, methanol, and 4-dimethylaminopyridine (DMAP) to a reaction container, cool down, and add EDCI; heat up to react. After the reaction is completed, add saturated brine to wash the organic phase, separate the liquids, retain the organic phase, and concentrate the solvent of the organic phase by rotary evaporation to obtain 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid methyl ester;

[0023] (4) Synthesis of 7'-chloro-2'-,3'-dihydro-1'-H-spiro[cyclopropane-1,4'-[2,6]naphthyridine]-1'-one

[0024] Methanol, 2-chloro-5-(1-cyanocyclopropyl)nicotinate methyl ester and cobalt chloride were added to the reaction vessel, and sodium borohydride was added under stirring. After the reaction was completed, acid was added dropwise to quench, the pH was adjusted, and a solvent was added for washing and extraction. The organic phase was taken, slurried, cooled to 0°C and maintained for 1 hour, and filtered to obtain a filter cake solid. The filter cake solid was washed and dried to obtain a solid powder, namely 7'-chloro-2'-, 3'-dihydro-1'-H-spiro[cyclopropane-1,4'-[2,6]naphthyridine]-1'-one;

[0025] The alkaline salt in step (2) is potassium hexamethyldisilazane, sodium hexamethyldisilazane, lithium hexamethyldisilazane or lithium diisopropylamide.

[0026] The temperature of the process of adding the n-butyl lithium n-hexane solution in step (1) and the process before that is controlled at -30~0°C, the temperature of the process of adding the 2-chloro-5-fluoropyridine 2-methyltetrahydrofuran solution and the process of keeping the temperature after the addition is controlled at -60~-70°C, the time of keeping the temperature is 2-5h, the temperature of the process of passing carbon dioxide gas is controlled at -50~-70°C, and the heating in step (1) is to heat to -10~10°C.

[0027] The pH adjustment in step (1) is to adjust the pH to 0.5-4, the temperature of the heat preservation and stirring in step (1) is 0-25°C, the stirring time is 15-30 minutes, and the temperature of the wet sample drying in step (1) is 45-50°C.

[0028] The molar ratio of diisopropylamine, n-butyl lithium and 2-chloro-5-fluoropyridine in step (1) is (1-2.5):(1-2.5):1.

[0029] The temperature of the tetrahydrofuran solution of the alkaline salt added dropwise in step (2) and the process before it is controlled at -45~-35°C, the heating in step (2) is heated to -20~30°C, the judgment standard for the end of the reaction in step (2) is that the raw material is less than 15wt.%, or the disubstituted product is greater than 15wt.%; the temperature of the quenching process in step (2) is controlled below 20°C; the first acid addition to adjust the pH in step (2) is to adjust the pH to 3~8, and the temperature of the first acid addition to adjust the pH in step (2) is controlled below 20°C; the alkali addition to adjust the pH of the aqueous phase in step (2) is to adjust the pH to 9.0~10.0; the second acid addition to adjust the pH in step (2) is to adjust the pH to 0.5~4.

[0030] The molar ratio of 2-chloro-5-fluoronicotinic acid, cyclopropyl nitrile and alkaline salt in step (2) is 1:(1-2):(2-3).

[0031] The cooling in step (3) is to a temperature between -10 and 10°C, and the temperature of the heating reaction in step (3) is between 15 and 50°C.

[0032] The molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid to 4-dimethylaminopyridine in step (3) is 1:(0.01-1); the molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid to carbodiimide in step (3) is 1:(1-3).

[0033] The molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinate, cobalt chloride and sodium borohydride in step (4) is 1:(1-5):(2-10).

[0034] The temperature of the process before adding sodium borohydride in step (4) is controlled at -5~5°C; the temperature of the quenching process in step (4) is controlled at -5~5°C; the pH adjustment in step (4) is to adjust the pH to 3~4; the solvent in step (4) is a mixture of dichloromethane and methanol in a volume ratio of (4~20):1; the beating temperature is 50-85°C, the beating time is 0.5-5h, and the solvent used for beating is acetonitrile. If the purity of the final product in step (4) is low, repeat the hot beating once.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1) Choose 2-chloro-5-fluoropyridine as the raw material, which is low in price, a bulk commodity, and has many suppliers. It only needs to be carboxylated with carbon dioxide, SN AR The target product can be obtained through four steps of reaction: substitution, methylation reaction and reduction ring closure. The route is short and the process advantages are obvious.

[0037] 2) By using cyclopropyl nitrile to synthesize the SN of aromatic rings AR The substitution reaction is a one-step reaction that solves the problem of high cost and low yield of the two-step reaction of palladium catalyst coupling and Corey-Chaykovsky reaction to prepare cyclopropyl in the previous process, and has very obvious process advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of 2-chloro-5-fluoronicotinic acid prepared in Example 1;

[0039] Figure 2 is the hydrogen nuclear magnetic resonance spectrum of 2-chloro-5-(1-cyanocyclopropyl)nicotinate prepared in Example 1;

[0040] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of 7'-chloro-2'-,3'-dihydro-1'-H-spiro[cyclopropane-1,4'-[2,6]naphthyridine]-1'-one prepared in Example 1. DETAILED DESCRIPTION

[0041] The present invention will be further described below with reference to the embodiments.

[0042] Unless otherwise specified, all raw materials used in the examples are commercially available.

[0043] Lithium diisopropylamide 2M / tetrahydrofuran / ethylbenzene / heptane solution was purchased from MacLean.

[0044] Example 1

[0045] The method for synthesizing the intermediate of the substituted tricyclic PRMT5 inhibitor comprises the following steps:

[0046] (1-1) Preparation and Synthesis of 2-Chloro-5-fluoronicotinic Acid

[0047] ;

[0048] Take 2-methyltetrahydrofuran and diisopropylamine and add them to the reactor, replace with nitrogen, cool to -30°C, add 1.6M n-butyl lithium hexane solution, and control the temperature at -15±15°C. After the addition is complete, add 33.3% volume concentration of 2-chloro-5-fluoropyridine in 2-methyltetrahydrofuran solution. After the addition is complete, control the temperature at -65±5°C, keep the reaction for 3h, and then pass carbon dioxide gas into the reactor for reaction. The temperature is controlled at -60±10°C during the reaction process. HPLC monitors that the content of 2-chloro-5-fluoropyridine is less than 1%. Heat to 0±10°C, during which a large amount of gas is released. Pay attention to gas discharge, add purified water to quench, let stand for separation, temporarily store the organic phase, collect the aqueous phase, add ethyl acetate, stir for 15min, and let stand for separation. The organic phase was temporarily stored, and the aqueous phase was collected and transferred to another reactor. The pH was adjusted to 1.0 with 6M hydrochloric acid, and the temperature was controlled at 12.5±12.5℃. The mixture was stirred for 15 minutes and filtered. The filter cake was rinsed once with purified water. The wet sample was dried at 47.5±2.5℃ to obtain a white solid powder, namely 2-chloro-5-fluoronicotinic acid. The purity was 97.8% and the yield was 85%.

[0049] The molar ratio of diisopropylamine, n-butyllithium and 2-chloro-5-fluoropyridine is 1.3:1.2:1.

[0050] The amount of 2-methyltetrahydrofuran, purified water for quenching, purified water for elution, and ethyl acetate added per 1 kg of 2-chloro-5-fluoropyridine is 5 L, 6 L, 1 L, and 2 L, respectively. Figure 1 As shown, the data is as follows:

[0051] 1 H NMR (600 MHz, DMSO- d 6) δ 14.31 (s, 1H), 8.63 (d, J = 1.9 Hz, 1H),7.84 (d, J = 5.1 Hz, 1H).

[0052] (2-1) Synthesis of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid

[0053] ;

[0054] Prepare a reaction kettle, replace the nitrogen three times, add tetrahydrofuran, 2-chloro-5-fluoronicotinic acid, and cyclopropylnitrile to the reaction kettle, cool to -40°C, add 1M tetrahydrofuran solution of potassium hexamethyldisilazane, control the temperature at -40±5°C, raise the temperature to 15°C after the addition is complete, monitor once every 30 minutes by HPLC until the raw material is less than 15wt.%, add water to quench after the reaction is completed, control the temperature <20°C, add concentrated hydrochloric acid for the first time to adjust the pH to 5, control the temperature <20°C, remove tetrahydrofuran by rotary evaporation, add saturated sodium carbonate solution to adjust the pH of the aqueous phase to 9, stir, and add acid for the second time to adjust the pH to 1; stir for 16 hours to fully precipitate and disperse the product, filter press, wash the filter cake with water, filter press and blow dry to obtain 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid, and continue to the next step; the crude yield is 93% and the purity is 80%.

[0055] The molar ratio of 2-chloro-5-fluoronicotinic acid, cyclopropyl nitrile and potassium salt of hexamethyldisilazane is 1: 2: 2.2.

[0056] For every 1 kg of 2-chloro-5-fluoronicotinic acid, the volumes of tetrahydrofuran, quenching water, and washing water added are 10 L, 5 L, and 5 L, respectively.

[0057] (3-1) Synthesis of 2-chloro-5-(1-cyanocyclopropyl)nicotinate

[0058] ;

[0059] Prepare a reaction kettle, replace with nitrogen 3 times, add 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid, 2-methyltetrahydrofuran, methanol, 4-dimethylaminopyridine (DMAP), cool to -5°C, add dicarbodiimide (EDCI) under stirring; heat to 25°C for reaction, monitor by HPLC until there is no raw material, add saturated salt water to wash the organic phase, separate the liquids, keep the organic phase, wash the organic phase with saturated salt water, separate the liquids, keep the organic phase, and concentrate the solvent of the organic phase by rotary evaporation to obtain 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid methyl ester, without further purification, continue to the next step; the crude yield is 95% and the purity is 76%. The H NMR spectrum is as follows Figure 2 As shown, the data is as follows:

[0060] 1 H NMR (300 MHz, CHLOROFORM-d) δ 8.52 (s, 1H), 7.83 (s, 1H), 4.05 (d, J = 2.2 Hz, 3H), 1.81 (d, J = 6.8 Hz, 2H), 1.35 (d, J = 2.2 Hz, 2H).

[0061] The molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid to 4-dimethylaminopyridine is 1:0.1; the molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid to carbodiimide is 1:1.3.

[0062] The volumes of 2-methyltetrahydrofuran, methanol and saturated brine added per 1 kg of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid are 10 L, 2.7 L and 10 L respectively.

[0063] (4-1) Synthesis of 7'-chloro-2'-,3'-dihydro-1'-H-spiro[cyclopropane-1,4'-[2,6]naphthyridine]-1'-one

[0064] ;

[0065] Prepare a reaction kettle, replace with nitrogen 3 times, add methanol and 2-chloro-5-(1-cyanocyclopropyl)nicotinate, cool to 0°C, add cobalt chloride, add sodium borohydride under stirring, control the temperature at 0±5°C, monitor by HPLC until there is no raw material, add concentrated hydrochloric acid dropwise to quench, adjust pH=3, control the temperature at 0±5°C, add solvent (a mixture of dichloromethane and methanol in a volume ratio of 5:1) and water to wash, extract the separated aqueous phase with solvent (a mixture of dichloromethane and methanol in a volume ratio of 5:1), combine the two organic phases, spin dry to obtain a solid, heat slurry with acetonitrile at 80°C for 1h, cool to 0°C and keep for 1h, filter to obtain a filter cake solid, wash the filter cake solid with acetonitrile, and dry to obtain a light yellow solid powder, which is 7'-chloro-2'-, 3'-dihydro-1'-H-spiro[cyclopropane-1,4'-[2,6]naphthyridine]-1'-one. Purity 98%, yield 67%.

[0066] The molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinate, cobalt chloride and sodium borohydride is 1:2:5.

[0067] The volumes of methanol, washing solvent, extraction solvent, hot pulping acetonitrile, and washing acetonitrile are 10L, 10L, 5L, 5L, and 1L for every 1kg of 2-chloro-5-(1-cyanocyclopropyl)nicotinate methyl ester. Figure 3 As shown, the data is as follows:

[0068] 1 H NMR (600 MHz, DMSO-d6) δ 8.53 (d, J = 2.8 Hz, 1H), 8.22 (d, J =0.7 Hz, 1H), 7.71 (s, 1H), 3.28 (d, J = 2.9 Hz, 2H), 1.23 - 1.22 (m, 2H), 1.06- 1.04 (m, 2H).

[0069] Example 2

[0070] The method for synthesizing the intermediate of the substituted tricyclic PRMT5 inhibitor comprises the following steps:

[0071] (1-2) Preparation and Synthesis of 2-Chloro-5-fluoronicotinic Acid

[0072] ;

[0073] Take 2-methyltetrahydrofuran and diisopropylamine and add them to the reactor, replace with nitrogen, cool to -30°C, add 1.6M n-butyl lithium hexane solution, and control the temperature at -15±15°C. After the addition is complete, add 33.3% volume concentration of 2-chloro-5-fluoropyridine in 2-methyltetrahydrofuran solution. After the addition is complete, control the temperature at -65±5°C, keep the reaction for 5 hours, and then pass carbon dioxide gas into the reactor for reaction. The temperature during the reaction is controlled at -60±10°C. HPLC monitors that the content of 2-chloro-5-fluoropyridine is less than 1%. Heat to 0±10°C, during which a large amount of gas is released. Pay attention to gas discharge, add purified water to quench, let stand for separation, temporarily store the organic phase, collect the aqueous phase, add ethyl acetate, stir for 17 minutes, and let stand for separation. The organic phase was temporarily stored, and the aqueous phase was collected and transferred to another reactor. The pH was adjusted to 0.5 with 6M hydrochloric acid, and the temperature was controlled at 12.5±12.5℃. The mixture was stirred for 20 minutes and filtered. The filter cake was rinsed once with purified water. The wet sample was dried at 47.5±2.5℃ to obtain a white solid powder, namely 2-chloro-5-fluoronicotinic acid. The purity was 95.8% and the yield was 82%.

[0074] The molar ratio of diisopropylamine, n-butyllithium and 2-chloro-5-fluoropyridine is 1:1:1.

[0075] For every 1 kg of 2-chloro-5-fluoropyridine, the amount of 2-methyltetrahydrofuran, purified water for quenching, purified water for rinsing, and ethyl acetate added were 5 L, 6 L, 1 L, and 2 L, respectively.

[0076] (2-2) Synthesis of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid

[0077] ;

[0078] Prepare a reaction kettle, replace the nitrogen three times, add tetrahydrofuran, 2-chloro-5-fluoronicotinic acid, and cyclopropylnitrile to the reaction kettle, cool to -40°C, add 1M tetrahydrofuran solution of hexamethyldisilazane lithium salt, control the temperature at -40±5°C, raise the temperature to -20°C after the addition is complete, monitor once every 30 minutes by HPLC until the raw material is less than 15wt.%, add water to quench after the reaction is completed, control the temperature <20°C, add concentrated hydrochloric acid for the first time to adjust the pH to 3, control the temperature <20°C, remove tetrahydrofuran by rotary evaporation, add saturated sodium carbonate solution to adjust the aqueous phase pH to 9.4, stir, and add acid for the second time to adjust the pH to 2.5; stir for 16 hours to fully precipitate and disperse the product, filter press, wash the filter cake with water, filter press and blow dry to obtain 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid, and continue to the next step; the crude yield is 90% and the purity is 86%.

[0079] The molar ratio of 2-chloro-5-fluoronicotinic acid, cyclopropyl nitrile and lithium hexamethyldisilazane is 1:1.2:2.

[0080] For every 1 kg of 2-chloro-5-fluoronicotinic acid, the volumes of tetrahydrofuran, quenching water, and washing water added are 10 L, 5 L, and 5 L, respectively.

[0081] (3-2) Synthesis of 2-chloro-5-(1-cyanocyclopropyl)nicotinate

[0082] ;

[0083] Prepare a reaction kettle, replace the atmosphere with nitrogen three times, add 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid, 2-methyltetrahydrofuran, methanol, and 4-dimethylaminopyridine (DMAP), cool to -10°C, add dicarbodiimide (EDCI) under stirring; heat to 15°C for reaction, monitor by HPLC until there is no raw material, add saturated brine to wash the organic phase, separate the liquids, retain the organic phase, wash the organic phase with saturated brine, separate the liquids, retain the organic phase, and concentrate the solvent from the organic phase by rotary evaporation to obtain 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid methyl ester, which is not further purified and is continuously subjected to the next step; the crude product yield is 99% and the purity is 74%.

[0084] The molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid to 4-dimethylaminopyridine is 1:0.01; the molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid to carbodiimide is 1:2.8.

[0085] The volumes of 2-methyltetrahydrofuran, methanol and saturated brine added per 1 kg of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid are 10 L, 2.7 L and 10 L respectively.

[0086] (4-2) Synthesis of 7'-chloro-2'-,3'-dihydro-1'-H-spiro[cyclopropane-1,4'-[2,6]naphthyridine]-1'-one

[0087] ;

[0088] Prepare a reaction kettle, replace with nitrogen three times, add methanol and 2-chloro-5-(1-cyanocyclopropyl)nicotinate, cool to 0°C, add cobalt chloride, add sodium borohydride with stirring, control the temperature at 0±5°C, monitor by HPLC until there is no raw material, quench with concentrated hydrochloric acid, adjust pH=3.3, control the temperature at 0±5°C, add solvent (a mixture of dichloromethane and methanol in a volume ratio of 10:1) and water to wash, extract the separated aqueous phase with solvent (a mixture of dichloromethane and methanol in a volume ratio of 10:1), combine the two organic phases, spin dry to obtain a solid, heat slurry with acetonitrile at 85°C for 0.5h, cool to 0°C and keep for 1h, filter to obtain a filter cake solid, wash the filter cake solid with acetonitrile, and dry to obtain a light yellow solid powder, which is 7'-chloro-2'-, 3'-dihydro-1'-H-spiro[cyclopropane-1,4'-[2,6]naphthyridine]-1'-one. Purity 98%, yield 60%.

[0089] The molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinate, cobalt chloride and sodium borohydride is 1:5:9.5.

[0090] The volumes of methanol, washing solvent, extraction solvent, hot slurrying acetonitrile, and washing acetonitrile added per 1 kg of 2-chloro-5-(1-cyanocyclopropyl)nicotinate were 10 L, 10 L, 5 L, 5 L, and 1 L, respectively.

[0091] Example 3

[0092] The method for synthesizing the intermediate of the substituted tricyclic PRMT5 inhibitor comprises the following steps:

[0093] (1-3) Preparation and Synthesis of 2-Chloro-5-fluoronicotinic Acid

[0094] ;

[0095] Take 2-methyltetrahydrofuran and diisopropylamine and add them to the reaction kettle, replace with nitrogen, cool to -30°C, add 1.6M n-butyl lithium n-hexane solution dropwise, and control the temperature at -15±15°C. After the addition is complete, add 33.3% volume concentration of 2-chloro-5-fluoropyridine in 2-methyltetrahydrofuran solution dropwise. After the addition is complete, control the temperature at -65±5°C, keep the reaction for 2h, then pass carbon dioxide gas into the reaction kettle for reaction, control the temperature at -60±10°C during the reaction process, and monitor the 2-chloro-5-fluoropyridine content to be less than 1% by HPLC. Heat to 0±10°C, during which a large amount of gas is released, pay attention to gas discharge, add purified water to quench, let stand for separation, temporarily store the organic phase, collect the aqueous phase, add ethyl acetate, stir for 20min, and let stand for separation. The organic phase was temporarily stored, and the aqueous phase was collected and transferred to another reactor. The pH was adjusted to 4 with 6M hydrochloric acid, and the temperature was controlled at 12.5±12.5℃. The mixture was stirred for 30 minutes and filtered. The filter cake was rinsed once with purified water. The wet sample was dried at 47.5±2.5℃ to obtain a white solid powder, namely 2-chloro-5-fluoronicotinic acid. The purity was 96.9% and the yield was 84%.

[0096] The molar ratio of diisopropylamine, n-butyllithium and 2-chloro-5-fluoropyridine is 2.5:2.3:1.

[0097] For every 1 kg of 2-chloro-5-fluoropyridine, the amount of 2-methyltetrahydrofuran, purified water for quenching, purified water for rinsing, and ethyl acetate added were 5 L, 6 L, 1 L, and 2 L, respectively.

[0098] (2-3) Synthesis of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid

[0099] ;

[0100] Prepare a reaction kettle, replace the nitrogen three times, add tetrahydrofuran, 2-chloro-5-fluoronicotinic acid, and cyclopropylnitrile to the reaction kettle, cool to -40°C, add diisopropylamine lithium 2M / tetrahydrofuran / ethylbenzene / heptane solution, control the temperature at -40±5°C, raise the temperature to 30°C after the addition is complete, monitor once every 30 minutes by HPLC until the raw material is less than 15wt.%, add water to quench after the reaction is completed, control the temperature <20°C, add concentrated hydrochloric acid for the first time to adjust the pH to 8, control the temperature <20°C, remove tetrahydrofuran by rotary evaporation, add saturated sodium carbonate solution to adjust the aqueous phase pH to 10, stir, and add acid for the second time to adjust the pH to 4; stir for 16 hours to fully precipitate and disperse the product, filter press, wash the filter cake with water, filter press and blow dry to obtain 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid, and continue to the next step; the crude yield is 95% and the purity is 77%.

[0101] The molar ratio of 2-chloro-5-fluoronicotinic acid, cyclopropyl nitrile and lithium diisopropylamide is 1:1.5:3.

[0102] For every 1 kg of 2-chloro-5-fluoronicotinic acid, the volumes of tetrahydrofuran, quenching water, and washing water added are 10 L, 5 L, and 5 L, respectively.

[0103] (3-3) Synthesis of 2-chloro-5-(1-cyanocyclopropyl)nicotinate

[0104] ;

[0105] Prepare a reaction kettle, replace with nitrogen 3 times, add 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid, 2-methyltetrahydrofuran, methanol, 4-dimethylaminopyridine (DMAP), cool to 10°C, add dicarbodiimide (EDCI) under stirring; heat to 50°C for reaction, monitor by HPLC until there is no raw material, add saturated brine to wash the organic phase, separate the liquids, keep the organic phase, wash the organic phase with saturated brine, separate the liquids, keep the organic phase, and concentrate the solvent of the organic phase by rotary evaporation to obtain 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid methyl ester, without further purification, and continue to the next step; the crude product yield is 92% and the purity is 77%.

[0106] The molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid to 4-dimethylaminopyridine is 1:1; the molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid to carbodiimide is 1:1.

[0107] The volumes of 2-methyltetrahydrofuran, methanol and saturated brine added per 1 kg of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid are 10 L, 2.7 L and 10 L respectively.

[0108] (4-3) Synthesis of 7'-chloro-2'-,3'-dihydro-1'-H-spiro[cyclopropane-1,4'-[2,6]naphthyridine]-1'-one

[0109] ;

[0110] Prepare a reaction kettle, replace with nitrogen 3 times, add methanol and 2-chloro-5-(1-cyanocyclopropyl)nicotinate, cool to 0°C, add cobalt chloride, add sodium borohydride under stirring, control the temperature at 0±5°C, monitor by HPLC until there is no raw material, add concentrated hydrochloric acid dropwise to quench, adjust pH=4, control the temperature at 0±5°C, add solvent (mixture of dichloromethane and methanol in a volume ratio of 20:1) and water to wash, extract the separated aqueous phase with solvent (mixture of dichloromethane and methanol in a volume ratio of 20:1), combine the two organic phases, spin dry to obtain a solid, heat slurry with acetonitrile at 50°C for 5h, cool to 0°C and keep for 1h, filter to obtain a filter cake solid, wash the filter cake solid with acetonitrile, and dry to obtain a light yellow solid powder, which is 7'-chloro-2'-, 3'-dihydro-1'-H-spiro[cyclopropane-1,4'-[2,6]naphthyridine]-1'-one. Purity 98%, yield 70%.

[0111] The molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinate, cobalt chloride and sodium borohydride is 1:1:3.5.

[0112] The volumes of methanol, washing solvent, extraction solvent, hot slurrying acetonitrile, and washing acetonitrile added per 1 kg of 2-chloro-5-(1-cyanocyclopropyl)nicotinate were 10 L, 10 L, 5 L, 5 L, and 1 L, respectively.

[0113] Example 4

[0114] The following experiment was conducted for the reaction temperature of step (1):

[0115] (1) Preparation and Synthesis of 2-Chloro-5-fluoronicotinic Acid

[0116] ;

[0117] Take 2-methyltetrahydrofuran and diisopropylamine and add them to the reaction kettle, replace with nitrogen, cool to -30°C, add 1.6M n-butyl lithium hexane solution, and control the temperature at -15±15°C. After the addition is complete, add 33.3% volume concentration of 2-chloro-5-fluoropyridine in 2-methyltetrahydrofuran solution. After the addition is complete, control the temperature at -30±5°C, keep the reaction for 3h, then pass carbon dioxide gas into the reactor for reaction, control the temperature at -30±10°C during the reaction process, and monitor the 2-chloro-5-fluoropyridine content to be less than 1% by HPLC. Heat to 0±10°C, during which a large amount of gas is released, pay attention to gas discharge, add purified water to quench, let stand and separate, temporarily store the organic phase, collect the aqueous phase, add ethyl acetate, stir for 15min, and let stand and separate. The organic phase was temporarily stored, and the aqueous phase was collected and transferred to another reactor. The pH was adjusted to 1.0 with 6M hydrochloric acid, and the temperature was controlled at 12.5±12.5℃. The mixture was stirred for 15 minutes and filtered. The filter cake was rinsed once with purified water. The wet sample was dried at 47.5±2.5℃ to obtain a white solid powder, namely 2-chloro-5-fluoronicotinic acid. The purity was 85.9% and the yield was 56%.

[0118] The molar ratio of diisopropylamine, n-butyllithium and 2-chloro-5-fluoropyridine is 1.3:1.2:1.

[0119] For every 1 kg of 2-chloro-5-fluoropyridine, the amount of 2-methyltetrahydrofuran, purified water for quenching, purified water for rinsing, and ethyl acetate added were 5 L, 6 L, 1 L, and 2 L, respectively.

[0120] Experiments show that the dropwise addition temperature of the 2-methyltetrahydrofuran solution of 2-chloro-5-fluoropyridine of the present invention is preferably -60 to -70°C, and the reaction temperature of the carbon dioxide gas is preferably -50 to -70°C. The reaction can proceed at an increased temperature, but the yield will decrease.

[0121] Comparative Example 1

[0122] A replacement experiment was conducted for the alkaline salt type in step (2):

[0123] (2) Synthesis of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid

[0124] ;

[0125] Prepare the reaction kettle, replace it with nitrogen three times, add tetrahydrofuran, 2-chloro-5-fluoronicotinic acid and cyclopropylnitrile into the reactor, cool to -40℃, add solid potassium carbonate, control the temperature at -40±5℃, raise the temperature to 25℃ after the addition is complete, monitor by HPLC every 30 minutes until the raw material is less than 15wt.%, and add water to quench the reaction; the central control shows that the remaining raw material exceeds 90%, and potassium carbonate cannot make the reaction proceed smoothly.

[0126] The molar ratio of 2-chloro-5-fluoronicotinic acid, cyclopropylnitrile and potassium carbonate is 1:2:3.

[0127] For every 1 kg of 2-chloro-5-fluoronicotinic acid, the volumes of tetrahydrofuran and quenching water added were 10 L and 5 L respectively.

[0128] Example 5

[0129] Experiments were conducted on the molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid and carbodiimide in step (3):

[0130] (3) Synthesis of 2-chloro-5-(1-cyanocyclopropyl)nicotinate

[0131] ;

[0132] Prepare a reaction kettle, replace with nitrogen 3 times, add 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid, 2-methyltetrahydrofuran, methanol, 4-dimethylaminopyridine (DMAP), cool to -5°C, add dicarbodiimide (EDCI) under stirring; heat to 25°C for reaction, monitor by HPLC until there is no raw material, add saturated brine to wash the organic phase, separate the liquids, keep the organic phase, wash the organic phase with saturated brine, separate the liquids, keep the organic phase, and concentrate the solvent of the organic phase by rotary evaporation to obtain 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid methyl ester, without further purification, and continue to the next step; the crude product yield is 75% and the purity is 69%.

[0133] The molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid to 4-dimethylaminopyridine is 1:0.1; the molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid to carbodiimide is 1:0.8.

[0134] The volumes of 2-methyltetrahydrofuran, methanol and saturated brine added per 1 kg of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid are 10 L, 2.7 L and 10 L respectively.

[0135] Experiments have shown that the molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid to carbodiimide is preferably 1:(1-3). A lower molar ratio can result in a normal reaction, but will lead to a decrease in yield.

[0136] Example 6

[0137] The temperature of adding sodium borohydride in step (4) was adjusted:

[0138] (4) Synthesis of 7'-chloro-2'-,3'-dihydro-1'-H-spiro[cyclopropane-1,4'-[2,6]naphthyridine]-1'-one

[0139] ;

[0140] Prepare a reaction kettle, replace with nitrogen 3 times, add methanol and 2-chloro-5-(1-cyanocyclopropyl)nicotinate, cool to 0°C, add cobalt chloride, add sodium borohydride under stirring, control the temperature at 20±5°C, monitor by HPLC until there is no raw material, add concentrated hydrochloric acid dropwise to quench, adjust pH=3, control the temperature at 0±5°C, add solvent (a mixture of dichloromethane and methanol in a volume ratio of 5:1) and water to wash, extract the separated aqueous phase with solvent (a mixture of dichloromethane and methanol in a volume ratio of 5:1), combine the two organic phases, spin dry to obtain a solid, heat slurry with acetonitrile at 80°C for 1h, cool to 0°C and keep for 1h, filter to obtain a filter cake solid, wash the filter cake solid with acetonitrile, and dry to obtain a light yellow solid powder, which is 7'-chloro-2'-, 3'-dihydro-1'-H-spiro[cyclopropane-1,4'-[2,6]naphthyridine]-1'-one. Purity 87%, yield 60%.

[0141] The molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinate, cobalt chloride and sodium borohydride is 1:2:5.

[0142] The volumes of methanol, washing solvent, extraction solvent, hot slurrying acetonitrile, and washing acetonitrile added per 1 kg of 2-chloro-5-(1-cyanocyclopropyl)nicotinate were 10 L, 10 L, 5 L, 5 L, and 1 L, respectively.

[0143] Experiments have shown that the temperature for adding sodium borohydride is preferably -5~5°C. The reaction can proceed normally when the temperature is raised to 20±5°C, but the impurity content increases as the temperature rises, and the yield decreases.

Claims

1. A method for synthesizing an intermediate of a substituted tricyclic PRMT5 inhibitor, characterized in that: The following steps are involved: (1) Synthesis of 2-chloro-5-fluoronicotinic acid 2-Methyltetrahydrofuran and diisopropylamine are added to a reaction container, and a n-hexane solution of n-butyl lithium is added dropwise. After the addition is completed, a 2-methyltetrahydrofuran solution of 2-chloro-5-fluoropyridine is added dropwise. After the addition is completed, the temperature is kept for reaction, and then carbon dioxide gas is introduced into the reaction container for reaction, followed by heating, quenching, standing for separation, extraction, collecting the aqueous phase, adjusting the pH to acidic, keeping the temperature and stirring, filtering, eluting the filter cake, and drying the wet sample to obtain 2-chloro-5-fluoronicotinic acid; (2) Synthesis of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid Add tetrahydrofuran, 2-chloro-5-fluoronicotinic acid, and cyclopropylnitrile to a reaction container, dropwise add a tetrahydrofuran solution of an alkaline salt, raise the temperature after the dropwise addition is completed, quench after the reaction is completed, dropwise add an acid for the first time to adjust the pH, remove the tetrahydrofuran by rotary evaporation, dropwise add a base to adjust the pH of the aqueous phase to alkaline, and under stirring, dropwise add an acid for the second time to adjust the pH to acidic; stir to precipitate and break up the product, filter press, wash the filter cake, filter press, and blow dry to obtain 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid; (3) Synthesis of 2-chloro-5-(1-cyanocyclopropyl)nicotinate Add 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid, 2-methyltetrahydrofuran, methanol, and 4-dimethylaminopyridine to a reaction container, cool down, and add carbodiimide; heat up to react. After the reaction is complete, add saturated brine to wash the organic phase, separate the liquids, retain the organic phase, and rotary evaporate the organic phase to concentrate the solvent to obtain 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid methyl ester; (4) Synthesis of 7'-chloro-2'-,3'-dihydro-1'-H-spiro[cyclopropane-1,4'-[2,6]naphthyridine]-1'-one Methanol, 2-chloro-5-(1-cyanocyclopropyl)nicotinate methyl ester and cobalt chloride are added to a reaction vessel, and sodium borohydride is added under stirring. After the reaction is completed, an acid is added dropwise to quench the reaction, the pH is adjusted, a solvent is added for washing and extraction, and an organic phase is taken, pulped, cooled, and filtered to obtain a filter cake solid. The filter cake solid is washed and dried to obtain a solid powder, namely 7'-chloro-2'-, 3'-dihydro-1'-H-spiro[cyclopropane-1,4'-[2,6]naphthyridine]-1'-one; The alkaline salt in step (2) is potassium hexamethyldisilazane, sodium hexamethyldisilazane, lithium hexamethyldisilazane or lithium diisopropylamide; The temperature of the tetrahydrofuran solution of the alkaline salt added dropwise in step (2) and the process before that is controlled at -45 to -35°C, the heating in step (2) is heated to -20 to 30°C, and the temperature of the quenching process in step (2) is controlled below 20°C; the first acid addition to adjust the pH in step (2) is to adjust the pH to 3 to 8, and the temperature of the first acid addition to adjust the pH in step (2) is controlled below 20°C; the alkali addition to adjust the pH of the aqueous phase in step (2) is to adjust the pH to 9.0 to 10.0; the second acid addition to adjust the pH in step (2) is to adjust the pH to 0.5 to 4; The temperature of the quenching process described in step (4) is controlled at -5~5°C, and the pH adjustment described in step (4) is to adjust the pH to 3~4; the temperature of the pulping described in step (4) is 50-85°C, and the pulping time is 0.5-5h.

2. The method for synthesizing an intermediate of a substituted tricyclic PRMT5 inhibitor according to claim 1, characterized in that: The temperature of the process of adding the n-butyl lithium n-hexane solution in step (1) and the process before that is controlled at -30~0°C, the temperature of the process of adding the 2-chloro-5-fluoropyridine 2-methyltetrahydrofuran solution and the process of keeping the temperature after the addition is controlled at -60~-70°C, the time of keeping the temperature is 2-5h, the temperature of the process of passing carbon dioxide gas is controlled at -50~-70°C, and the heating in step (1) is to heat to -10~10°C.

3. The method for synthesizing an intermediate of a substituted tricyclic PRMT5 inhibitor according to claim 1, characterized in that: The pH adjustment in step (1) is to adjust the pH to 0.5-4, the temperature of the heat preservation and stirring in step (1) is 0-25°C, the stirring time is 15-30 minutes, and the temperature of the wet sample drying in step (1) is 45-50°C.

4. The method for synthesizing an intermediate of a substituted tricyclic PRMT5 inhibitor according to claim 1, characterized in that: The molar ratio of diisopropylamine, n-butyl lithium and 2-chloro-5-fluoropyridine in step (1) is (1-2.5):(1-2.5):

1.

5. The method for synthesizing an intermediate of a substituted tricyclic PRMT5 inhibitor according to claim 1, characterized in that: The criterion for judging the end of the reaction in step (2) is that the raw material is less than 15 wt.%, or the disubstituted product is greater than 15 wt.%.

6. The method for synthesizing an intermediate of a substituted tricyclic PRMT5 inhibitor according to claim 1, characterized in that: The molar ratio of 2-chloro-5-fluoronicotinic acid, cyclopropyl nitrile and alkaline salt in step (2) is 1:(1-2):(2-3).

7. The method for synthesizing an intermediate of a substituted tricyclic PRMT5 inhibitor according to claim 1, characterized in that: The cooling in step (3) is to a temperature between -10 and 10°C, and the temperature of the heating reaction in step (3) is between 15 and 50°C.

8. The method for synthesizing an intermediate of a substituted tricyclic PRMT5 inhibitor according to claim 1, characterized in that: The molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid to 4-dimethylaminopyridine in step (3) is 1:(0.01-1); the molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinic acid to carbodiimide in step (3) is 1:(1-3).

9. The method for synthesizing an intermediate of a substituted tricyclic PRMT5 inhibitor according to claim 1, characterized in that: The molar ratio of 2-chloro-5-(1-cyanocyclopropyl)nicotinate, cobalt chloride and sodium borohydride in step (4) is 1:(1-5):(2-10).

10. The method for synthesizing an intermediate of a substituted tricyclic PRMT5 inhibitor according to claim 1, characterized in that: The temperature of the process before adding sodium borohydride in step (4) is controlled at -5~5°C; the solvent in step (4) is a mixture of dichloromethane and methanol in a volume ratio of (4~20):1; the solvent used for pulping is acetonitrile.

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