反应详情

2,1,3-Benzoxadiazol-4-carbaldehyde is reacted with aceto-acetic acid methyl ester in benzene in the presence of catalytic amounts of piperidine and acetic acid. The resultant 2-acetyl-3-(2,1,3-benzoxadiazol-4-yl)-2-propenoic acid methyl ester (crystalline, mixture of Z and E isomers) is cyclized in dioxane under refluxing with an equivalent amount of 3-aminocrotonic acid-(2-dimethylaminoethyl)ester {M.P. 56°; obtained by reaction of aceto-acetic acid-(2-dimethylaminoetyl)ester [B.P.0.01 mm 140°-150°, obtained by reaction of diketen with 2-dimethylaminoethanol at 70°], with ammonia gas at 60°}, to give 4-(2,1,3-benzoxadiazol-4-yl)-1,4-dihydro-5-methoxycarbonyl-2,6-dimethyl-3-pyridine carboxylic acid-(2-dimethylaminoethyl)ester (M.P. 161°).