Department of Chemistry, The University of Kansas, 1251 Wesoce Hall Drive, Lawrence, Kansas 66045-75832, United States.
J Org Chem. 2011 May 20;76(10):3968-86. doi: 10.1021/jo200368a. Epub 2011 Apr 14.
A diastereoconvergent formal nucleophilic substitution of bromocyclopropanes with oxygen- and sulfur-based nucleophiles is described. The reaction proceeds via in situ formation of a highly reactive cyclopropene intermediate and subsequent diastereoselective addition of a nucleophile across the strained C═C bond. Three alternative means of controlling the diastereoselectivity of addition have been demonstrated: (1) thermodynamically driven epimerization of enolizable carboxamides, (2) steric control by bulky substituents, and (3) directing effect of carboxamide or carboxylate functions.
本文描述了溴环丙烷与含氧和含硫亲核试剂的非对映选择性亲核取代反应。该反应通过原位形成高活性环丙烯中间体，并随后在张力 C=C 键上进行亲核试剂的非对映选择性加成来进行。已经证明了三种控制加成非对映选择性的替代方法：（1）可烯醇化的酰胺的热力学驱动的差向异构化，（2）大取代基的空间控制，和（3）酰胺或羧酸盐功能的导向效应。
