-6-(1-methylethenyl)-2-cyclohexen-1-ol, with ethyl bromoacetate gave ethyl [3S,7S,1(10)E,4Z]-3-alkoxy-6-oxo-13-nor-1(10),4-germacradien-12-oate stereoselectively, which was converted into a natural (−)-4,5-cis-3β-hydroxygermacranolide.
中间体的直接捕获,由 (1R,4S,6S)-4-alkoxy-1-ethenyl-3-methyl-6-(1-methylethenyl)-2-cyclohexen-1-ol 的阴离子oxy-Cope 重排产生,用
溴乙酸乙酯立体选择性地得到 [3S,7S,1(10)E,4Z]-3-alkoxy-6-oxo-13-nor-1(10),4-germacradien-12-oate
乙酯,将其转化为天然 (-)-4,5-cis-3β-hydroxygermacranolide。