Acetic Anhydride → HCID 20277273, compound

Participants

Reaction Steps

To a solution of isopropyl ester of 4-(2-cyanophenyl)-6-formyl-5-methoxycarbonyl-2-methyl-1,4-dihydropyridine-3-carboxylic acid (3.90 g) in acetic acid (20 ml) were added hydroxylamine hydrochloride (0.88 g) and sodium acetate (1.30 g), and the mixture was stirred for an hour at ambient temperature. To the reaction mixture was added acetic anhydride (3.97 g) with stirring, and the stirring was continued for an hour at ambient temperature and for additional 4 hours at 95°~100° C. After the reaction mixture was allowed to stand at ambient temperature, the acetic acid was removed by distillation under reduced pressure. The resultant residue was diluted with water, neutralized with an aqueous solution of sodium bicarbonate and then extracted twice with ethyl acetate. After the combined extract was washed twice with water and dried, the solvent was removed by distillation under reduced pressure to give an oil, which was allowed to stand overnight and pulverized with a small amount of ethyl ether. The powder was washed with isopropyl ether and recrystallized from methanol to give yellowish-orange crystals of isopropyl ester of 6-cyano-4-(2-cyanophenyl)-5-methoxycarbonyl-2-methyl-1,4-dihydropyridine-3-carboxylic acid (1.99 g), mp 198°~200° C.

Provenance & Evidence