Stereoselective SN2' additions of organocuprates to homochiral acyclic vinyloxiranes
作者:James A. Marshall、Joseph D. Trometer、Darryl G. Cleary
DOI:10.1016/0040-4020(89)80067-5
日期:1989.1
Additions of various methylcopper reagents to the homochiral acyclic vinyloxiranes A14, A15, B6–B9, and C5, C6 were performed in order to evaluate E/Z and syn/anti preferences. The unsubstituted oxiranes A14 and A15 gave a mixture of SN2 and SN2' substitution products with the four reagents examined, LiMe2Cu, LiMeCuCN, BrMgMe2Cu, and LiMeCuI · BF3. The more highly substituted systems B6–B9 derived
为了评估E / Z和syn / anti偏好,向同手性无环乙烯基氧杂环戊烷A14,A15,B6-B9和C5,C6添加了各种甲基铜试剂。未取代的环氧乙烷A14和A15给出了S N 2和S N 2'取代产物与所检验的四种试剂LiMe 2 Cu,LiMeCuCN,BrMgMe 2 Cu和LiMeCuI·BF 3的混合物。衍生自香叶醇的取代度更高的系统B6-B9和衍生自神经醇的C5,C6仅产生S N 2'产物。这 (Z)-烯丙醇衍生物B8和C6以及LiMeCuCN给出了最佳的抗/合成比(分别为99:1和97:3)。在这两种情况下,新成立的双键是专门Ë。