乙酸异丙烯酯 、
(6R,7R)-3-Acetoxymethyl-7-[5-benzhydryloxycarbonyl-5-(2,4-dichloro-benzoylamino)-pentanoylamino]-8-oxo-5-thia-1-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid benzhydryl ester 在
对甲苯磺酸 作用下,
以62%的产率得到(6R,7R)-3-Acetoxymethyl-7-(acetyl-{5-[acetyl-(2,4-dichloro-benzoyl)-amino]-5-benzhydryloxycarbonyl-pentanoyl}-amino)-8-oxo-5-thia-1-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid benzhydryl ester