To a solution of diethyl 2-methyl-4-(2-nitrophenyl)-6-hydroxymethyl-1,4-dihydropyridine-3,5-dicarboxylate (1.95 g) in pyridine (25 ml) was dropwise added a solution of benzoyl chloride (2.0 g) in methylene chloride (5 ml) over 5 minutes at 5° to 6° C. with stirring. The resultant mixture was stirred for 15 minutes at the same temperature and then at room temperature for 2 hours, and followed by stirring at 50° C. for an hour and a half. After the reaction was over, the pyridine was distilled off and to the residue was added ethyl acetate and water. The ethyl acetate layer was separated, washed with dil. hydrochloric acid twice and then aqueous solution of sodium bicarbonate, and dried over magnesium sulfate. The solvent was removed and the residue was soon crystallized by treating with diethyl ether and collected by filtration. These crude crystals were washed with a mixture of diethyl ether and a small amount of ethyl acetate to give crystals, which was recrystallized from ethyl acetate (25 ml) to give powders of diethyl 2-methyl-4-(2-nitrophenyl)-6-benzoyloxymethyl-1,4-dihydropyridine-3,5-dicarboxylate, m.p. 156° to 157° C.
