作者:M.Carmen Fernández、Marı́a Ruiz、Vicente Ojea、José M. Quintela
DOI:10.1016/s0040-4039(02)01275-3
日期:2002.8
Olefination of alpha-silyl-, alpha-phosphoryl- and alpha-stannyl-stabilised phosphonate carbanions derived from cyclo-[L-AP4-D-Val] Li(+)4b-d(-) allow a (Z)-selective access to the alpha, beta-substituted vinylphosphonates 7A-E that have been transformed into enantiomerically pure 4-alkylidene AP4 derivatives 12A,B and 13A,C. According to semi-empirical (PM3) calculations, the preference for like topologies in the intermediate adducts of the phosphonate addition step accounts for the highly (Z)-selective course of the 'tin-Peterson-like' olefination. (C) 2002 Elsevier Science Ltd. All rights reserved.