Simple organocopper reagents are shown to undergo anti-stereoselective 1,4-addition to menthyloxy-substituted lactone 1 in the presence of BF3.OEt2; the Lewis acid causes partial epimerisation of the acetal centre after conjugate addition. Enolate alkylation of the adducts leads to di- and trisubstituted lactones that are converted, in favourable cases, into di- and trisubstituted cyclopentenones.
已显示简单的
有机铜试剂在
BF3.OEt2存在下,经薄荷醇氧基取代的内酯1进行抗立体选择性的1,4-加成;加入共轭物后,
路易斯酸引起
缩醛中心的部分差向异构化。加合物的
乙醇酸酯烷基化导致二和三取代的内酯,在有利的情况下,它们被转化为二和三取代的
环戊烯酮。