A solution of 2-(2-tritylaminothiazol-4-yl)-(Z)-2-isopropoxyiminoacetic acid (3.06 g, 6.5 mmol), 1-hydroxybenzotriazole (1.01 g, 7.47 mmol) and N,N'-dicyclohexylcarbodiimide (1.47 g, 7.15 mmol) in dimethylacetamide (36 ml) was stirred at room temperature for 3 hours. To the solution was added a solution of 7β-amino-3-[(1-amino-1H-tetrazol-5-yl)thiomethyl]-3-cephem-4-carboxylic acid (2.35 g, 7.15 mmol) and triethylamine (1.44 g, 14.2 mmol) in dimethylacetamide (18 ml) and water (2.4 ml) and the mixture was stirred at room temperature for 17 hours. Then the mixture was treated in a manner similar to that described in Example 6, (c) to give pale brown powder of 7β-[2-(2-tritylaminothiazol-4-yl)-(Z)-2-isopropoxyiminoacetamido]-3-[(1-amino-1H-tetrazol-5-yl)thiomethyl]-3-cephem-4-carboxylic acid (3.10 g, 61%).
