9.7 g of 2-nitratoethyl acetoacetate, 7.6 g of 2-nitrobenzaldehyde and 0.2 g of piperidine in 40 ml of benzene were heated at reflux under azeotropic dehydration conditions for 3 hours. The mixture was treated in a manner similar to that of Referential Example 1, there was obtained the residue, to which was added 7.7 g of 2-cyanoethyl 3-aminocrotonate. The mixture was taken up in 40 ml of isopropyl alcohol and heated at reflux for 3 hours. The isopropyl alcohol was evaporated under reduced pressure, and the residue was applied to a silica gel column chromatography (eluent: dichromomethane) and recrystallized from a mixture of dichromethane and diethyl ether to give 14.3 g of 2,6-dimethyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-(2-cyanoethyl) ester 5-(2-nitratoethyl) ester.
