1-(2-tert.-butoxycarbonylaminothiazol-4-yl)-3-methyl-1(Z)-butenecarboxylic acid 、 3-acetoxymethyl-7-aminoceph-3-em-4-carboxylic acid 以93%的产率得到7-[1-(2-tert.-Butoxycarbonylaminothiazol-4-yl)-3-methyl-1(Z)-butenecarboxamido]-3-acetoxymethyl-3-cephem-4-carboxylic acid