Regio- and Stereoselective Synthesis of Vinylallenes by 1,5-(SN′′)-Substitution of Enyne Acetates and Oxiranes with Organocuprates
作者:Martin Purpura、Norbert Krause
DOI:10.1002/(sici)1099-0690(199901)1999:1<267::aid-ejoc267>3.0.co;2-v
日期:1999.1
substitution patterns react with organocuprates regioselectively under 1,5-(SN2′′)-substitution to provide vinylallenes 11 and 12. With lithium dimethylcuprate, reduced vinylallenes originating from a (formal) transfer of a hydride ion to the substrate are formed in some cases. The products are usually obtained as mixtures of (E/Z)isomers; however, pure (E)-vinylallenes are formed occasionally. The 1,5-substitutions
具有不同取代模式的烯炔乙酸酯 2、4、6 和 8 以及烯炔环氧乙烷 10 在 1,5-(SN2'')-取代下与有机铜酸盐区域选择性地反应以提供乙烯基丙二烯 11 和 12。使用二甲基铜酸锂,还原在某些情况下,会形成源自氢化物离子(正式)转移到基材上的乙烯基丙二烯。产品通常以 (E/Z) 异构体的混合物形式获得;然而,偶尔会形成纯 (E)-乙烯基丙二烯。1,5-取代也可以用催化量的铜试剂进行。手性醋酸烯炔(S)-2a与tBu2CuLi·LiCN的反应对映选择性地进行,使这种转化构成了远程立体控制的新案例。