Cyclization of the alkadienyl carbamates 1 to the cis-divinylcyclopentanes 2 with high enantioselectivity and diastereoselectivity has been successfully achieved by (-)-sparteine-induced asymmetric deprotonation. The conversion may be described as a hybrid of a lithium-ene reaction and an Sn ' reaction.
US5223633A
申请人:——
公开号:US5223633A
公开(公告)日:1993-06-29
Asymmetric Synthesis of <i>cis</i>-1,2-Dialkenyl-Substituted Cyclopentanes via (−)-Sparteine-Mediated Lithiation and Cycloalkylation of a 9-Chloro-2,7-nonadienyl Carbamate
作者:Alexander Deiters、Dieter Hoppe
DOI:10.1021/jo015548i
日期:2001.4.1
Herein we report our comprehensive results in enantioselective cyclopentane synthesis via stereogenic allyllithium compounds. The described cycloalkylation reaction starts with a (-)-sparteine-mediated asymmetric deprotonation of the 2,7-alkadienyl carbamate 7e and leads to the enantioenriched (80% ee) and diastereomerically pure (dr = 99:1) cis-1,2-divinyl-cyclopentane 8, by a subsequent cyclization