反应详情

A mixture of 2-nitrobenzaldehyde (3.023 g), benzyl acetoacetate (3.802 g) and piperidine (272.5 mg) in benzene (10 ml), was treated in a substantially similar manner that of Example 1-(11) to give a brown oil (6.94 g) of benzyl 2-(2-nitrobenzylidene)acetoacetate, which was further treated with ethyl 3-amino-4,4-diethoxycrotonate (4.34 g) to give a dark brown oil (10.3 g). This oil was purified by column chromatography on silica-gel and the resultant oil (3.8 g) was crystallized to give crystals (1.65 g) of benzyl 2-methyl-4-(2-nitrophenyl)-5-ethoxycarbonyl-6-diethoxymethyl-1,4-dihydropyridine-3-carboxylate, m.p. 103° to 103.5° C. (recrystallized from a mixture of diisopropyl ether and n-hexane).