Stereochemical Outcomes in Reductive Cyclizations To Form Spirocyclic Heterocycles
作者:Matthew A. Perry、Richard R. Hill、Justin J. Leong、Scott D. Rychnovsky
DOI:10.1021/acs.orglett.5b01422
日期:2015.7.2
Reductive lithiation and cyclization of N-Boc α-amino nitriles are often highly stereoselective. The alkyllithium intermediates are formed with varying levels of selectivity, but the alkyllithium geometry does not play a major role in the overall stereoselectivity. The final configuration is determined in the cyclization reaction, where both retention and inversion pathways are observed. Where strong
N -Bocα-氨基腈的还原锂化和环化通常具有很高的立体选择性。形成的烷基锂中间体具有不同的选择性水平,但烷基锂的几何形状在总体立体选择性中不发挥主要作用。最终构型是在环化反应中确定的,在该反应中观察到了保留和转化途径。在产物中存在强烈的热力学偏好的地方,动力学控制的烷基锂环化有利于更稳定的产物。