(S)-7-Amino-3-chloromethyl-7-methoxy-5,8-dioxo-5λ
4-thia-1-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid 4-methoxy-benzyl ester 在
乙酰氯 、 potassium iodide 作用下,
生成
(S)-3-Chloromethyl-7-(2-difluoromethylsulfanyl-acetylamino)-7-methoxy-8-oxo-5-thia-1-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid 4-methoxy-benzyl ester