rac-(1-isobutyl-2-oxo-pyrrolidin-3-yl)-triphenyl-phosphonium bromide 、 (6S,7S)-7-allyloxycarbonylamino-3-formyl-8-oxo-4-oxa-1-aza-bicyclo[4.2.0.] oct-2-ene-2-carboxylic acid allyl ester 生成 (E)-(6S,7S)-7-Allyloxycarbonylamino-3-(1-isobutyl-2-oxo-pyrrolidin-3-ylidenemethyl)-8-oxo-4-oxa-1-aza-bicyclo[4.2.0.] oct-2-ene-2-carboxylic acid allyl ester