(+)-(1S,3S,4S,8S,9R,11S)-11-tert-butoxy-1,4-dimethyl-9-hydroxy-3-(methoxycarbonyl)-7-oxotricyclo<6.3.0.0
4,8>undecane 、
二溴甲烷 在
四氯化钛 、
锌 作用下,
生成
(+)-(1S,3S,4S,5S,7R,8R)-5-tert-butoxy-1,4-dimethyl-7-hydroxy-2-(methoxycarbonyl)-9-methylidenetricyclo<6.3.0.04,8>undecane