To a solution of diethyl 2-methyl-4-(2-nitrophenyl)-6-formyl-1,4-dihydropyridine-3,5-dicarboxylate (2.0881 g) in ethanol (20 ml) was gradually added sodium borohydride (0.1892 g) under stirring and the resultant mixture was further stirred at room temperature for an hour. The solution was acidified with dilute hydrochloric acid and stirred at room temperature for 30 minutes. After the resultant solution was filtered, the filtrate was concentrated under reduced pressure and extracted with ethyl acetate. The extract was washed with water and dried and then the solvent was removed to give orange oil (1.8596 g) of diethyl 2-methyl-4-(2-nitrophenyl)-6-hyroxymethyl-1,4-dihydropyridine-3,5-dicarboxylate. After the crude, product was dissolved in ethanol, the solution was filtered. The filtrate was concentrated under reduced pressure and the oily residue was allowed to stand for 3 days. Thus obtained crystals were recrystallized from ether to give pure product, m.p. 112° to 113° C.
