(S)-2-((3S,4aR,4bS,6S,8R,8aR,10aR)-6-Acetoxy-8-methoxycarbonyl-4a,8a-dimethyl-1,5-dioxo-dodecahydro-2-oxa-phenanthren-3-yl)-4,5-dihydro-oxazole-4-carboxylic acid methyl ester 在
三氯溴甲烷 、
1,8-二氮杂双环[5.4.0]十一碳-7-烯 作用下,
以
二氯甲烷 为溶剂,
反应 1.5h,
以80%的产率得到methyl 2-[(2S,4aR,6aR,7R,9S,10aS,10bR)-9-acetyloxy-7-methoxycarbonyl-6a,10b-dimethyl-4,10-dioxo-2,4a,5,6,7,8,9,10a-octahydro-1H-benzo[f]isochromen-2-yl]-1,3-oxazole-4-carboxylate