(6R)-7t-[2-(2-amino-thiazol-4-yl)-acetylamino]-3-hydroxymethyl-8-oxo-(6rH)-5-thia-1-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid 、
双乙烯酮 以to produce 7β-[2-(2-imino-4-thiazolin-4-yl)-acetamido]-3-(3-oxobutyryloxy)methyl-3-cephem-4-carboxylic acid or its salt的产率得到7beta-[2-(2-Imino-4-thiazolin-4-yl)-acetamido]-3-(3-oxobutyryloxy)methyl-3-cephem-4-carboxylic acid