WO-2018001353, APREMILAST, NEW PATENT, ZHEJIANG HUAHAI PHARMACEUTICAL CO., LTD

Apremilast is a PDE4 inhibitor developed by Celgene. Currently, there are clinical indications such as rheumatoid arthritis, psoriatic arthritis, Behcet’s disease and ulcerative colitis. March 21, 2014 FDA approves first indication – adult active psoriatic arthritis (PsA). Name of Product: (FDA, as a post-marketing requirement, will evaluate the effect of this drug on pregnant women through a pregnancy registry study.) Three clinical trials evaluated the safety and efficacy of Asprate in the treatment of PsA, The response rates to ACR20 in the prest and placebo groups were 32-41% and 18-19%, respectively.

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The original patent CN 101683334A reports the synthesis of (S) -1- (3-ethoxy-4-methoxyphenyl) -2- (methylsulfonyl) ethylamine N-acetyl- ) And 3-acetylaminophthalic anhydride (3) Prepared with acetic acid as solvent (1), and the synthetic route is as follows:

The method has low yield, needs lower than 50 DEG C to distill the high-boiling acetic acid, and produces one deacetyl impurity (4) during the reflux reaction and the acetic acid distillation, which affects the product purity. Acetic acid will corrode the equipment at high temperatures. Distillation of high-boiling acetic acid will also increase plant production time. Acetic acid, which is not distilled away, consumes a large amount of lye to neutralize and increases the amount of wastes and production costs, which is not conducive to industrialized production.

Example one

10.0 g (0.0224 mol) of (S) -1- (3-ethoxy-4-methoxyphenyl) -2- (methylsulfonyl) ethylamine N-acetyl- 4.6g (0.0224mol) 3-acetamidophthalic anhydride into a 250mL three-necked flask, then add 50mL of acetonitrile, heating 75 ~ 80 ℃, the reaction incubated for 18 hours and cooled to room temperature. After the reaction mixture was evaporated to dryness, 60 mL of methylene chloride was added, 25 g of 10% sodium carbonate solution was added thereto and the mixture was stirred for 10 to 30 minutes. The mixture was allowed to stand for further delamination and then 25 mL of water was added to the organic layer and stirred for 10-30 minutes. The layers were evaporated to dryness to give a light yellow solid, then add 30mL absolute ethanol, evaporated again. The mixture was hot beaten with ethanol, cooled to 0-5 ° C, stirred for 1-2 hours, filtered and drained. The filter cake was vacuum dried to give 9.4 g of a white powder in 91.2% yield. HPLC: 99.9% ) Has an HPLC area of 0.03%.

Example two

10.0 g (0.0224 mol) of (S) -1- (3-ethoxy-4-methoxyphenyl) -2- (methylsulfonyl) ethylamine N-acetyl- A solution of 4.6 g (0.0224 mol) of 3-acetylaminophthalic anhydride in a 250 mL three-necked flask was charged with 80 mL of toluene and 10 mL of N, N-dimethylformamide. The mixture was heated to 100 ° C and the reaction was incubated for 12 hours and then cooled to room temperature. After the reaction solution was evaporated to dryness, 80 mL of methylene chloride was added, 25 g of 10% sodium carbonate solution was added thereto and the mixture was stirred for 10 to 30 minutes. The mixture was allowed to stand for further delamination and then 50 mL of water was added to the organic layer and stirred for 10 to 30 minutes. Evaporated to a pale yellow solid, then add 30mL of absolute ethanol, evaporated again. Cooled to 0 ~ 5 ℃ and stirred for 1 ~ 2 hours, filtered and drained, the filter cake was dried in vacuo to give 9.2g white powder, yield 89.2%, HPLC: 99.9%, wherein the deacetyl impurities (4 ) Has an HPLC area of 0.03%.

Example three:

10.0 g (0.0224 mol) of (S) -1- (3-ethoxy-4-methoxyphenyl) -2- (methylsulfonyl) ethylamine N-acetyl- To a 250 mL three-necked flask was added 4.6 g (0.0224 mol) of 3-acetamidophthalic anhydride followed by 50 mL of ethyl acetate and 1.81 g (0.8 eq) of triethylamine. The mixture was heated at 75-80 ° C and incubated for 18 hours. The reaction was stopped, 100 mL of ethyl acetate was further added and the mixture was cooled to 20-30 ° C. The reaction solution was added 30g of 8% sodium carbonate solution, stirred for 10 to 30 minutes, allowed to stand layered, the organic layer was added 30mL of water, stirred for 10 to 30 minutes, allowed to stand layered, the organic layer was added 30mL of water, stirred 10 ~ 30 minutes, standing stratification, the organic layer was evaporated to dryness to a pale yellow solid, then add 30mL of absolute ethanol, evaporated again. The mixture was heated to 0-5 ° C for 1 to 2 hours, filtered and drained. The filter cake was vacuum dried to give 9.8 g of a white powder in 95.1% yield. HPLC: 99.9% ) Had an HPLC area of 0.04%.

Example 4:

10.0 g (0.0224 mol) of (S) -1- (3-ethoxy-4-methoxyphenyl) -2- (methylsulfonyl) ethylamine N-acetyl- (0.0224mol) 3-acetamidophthalic anhydride into a 250mL three-necked flask, followed by the addition of 120mL of isopropyl acetate and 30mL of acetonitrile and 1.81g (0.8eq) of triethylamine, heating 75 ~ 80 ℃, incubated reaction 16 hours. Stop the reaction, cooled to 20 ~ 30 ℃. The reaction solution was added 30g of 8% sodium carbonate solution, stirred for 10 to 30 minutes, allowed to stand layered, the organic layer was added 30mL of water, stirred for 10 to 30 minutes, allowed to stand layered, the organic layer was added 30mL of water, stirred 10 ~ 30 minutes, standing stratification, the organic layer was evaporated to dryness to a pale yellow solid, then add 30mL of absolute ethanol, evaporated again. The mixture was hot beaten with ethanol, cooled to 0-5 ° C, stirred for 1-2 hours, filtered and drained. The filter cake was vacuum dried to give 9.6 g of a white powder in 93.1% yield. HPLC: 99.9% ) Has an HPLC area of 0.03%.

Comparative Example:

According to the preparation example of Compound A in original patent CN 101683334A, 10.0 g (0.0224 mol) of (S) -1- (3-ethoxy-4- methoxyphenyl) -2- (methylsulfonyl) N-acetyl-L-leucinate and 4.6 g (0.0224 mol) of 3-acetylaminophthalic anhydride were placed in a 250 mL three-necked flask and 50 mL of acetic acid was added thereto. The mixture was heated at 75 to 80 ° C and the reaction was incubated for 18 hours. The reaction mixture was cooled to 40-50 ° C and the temperature of the water bath was controlled to 40-50 ° C. The reaction mixture was vortexed to glacial acetic acid without any significant fraction. 150 mL of ethyl acetate was added and the mixture was stirred to dissolve. 100 mL of water was added and the mixture was stirred 10 ~ 30 minutes, standing stratification, the organic layer was added 100mL water, stirred for 10 to 30 minutes, allowed to stand for stratification, the organic layer was added 100g 8% sodium bicarbonate solution, stirred for 10 to 30 minutes, The organic layer was added with 100g of 8% sodium bicarbonate solution and stirred for 10-30 minutes. The layers were separated and the organic layer was added with 100 mL of water. The mixture was stirred for 10-30 minutes, and the layers were separated. The organic layer was further added with 100 mL of water and stirred 10 ~ 30 minutes, standing stratification, the organic layer was evaporated to dryness to a pale yellow solid, then add 30mL of absolute ethanol, evaporated again. 68mL of anhydrous ethanol and 34mL of acetone were added to the solid, heated to 60-65 ° C, stirred to make it fully dissolved, and then cooled to 0-5 ° C and stirred for 1 to 2 hours, filtered and drained, and the filter cake was dried under vacuum to give 8.6 Class g white powder, yield 83.4%, HPLC: 99.7% with an HPLC area of deacetylated impurity (4) of 0.22%.