烯丙醇在Re 2 O 7的存在下进行转座反应,从而可以通过用一种亲电亲和剂捕获一种异构体来控制平衡。当捕获基团是醛或酮时,可能会发生其他电离,从而导致形成环氧碳鎓离子。通过将双分子亲核加成至中间物来终止该过程,为合成各种含氧杂环化合物提供了一种通用的方法。了解序列中各步骤的相对速率会导致设计反应,从而创建多个具有良好至极佳控制水平的立体中心。
Highly stereoselective tandem cyclizations of 5-hexenyllithiums: preparation of endo-2-substituted bicyclo[2.2.1]heptanes and 3-substituted trans-bicyclo[3.3.0]octanes
作者:William F. Bailey、Atmaram D. Khanolkar、Kaustubh V. Gavaskar
DOI:10.1021/ja00047a013
日期:1992.10
diolefinic alkyl iodides by low-temperature lithium-iodine exchange, proceeds via two highly stereoselective and totally regiospecific 5-exo-trig ring closures to deliver bicyclic alkyllithiums. Trapping of the organolithium product by addition of an electrophile cleanly affords functionalized bicyclic molecules in good yield. In this way both endo-2-substituted bicyclo[2.2.1]heptanes and 3-substituted