Comparing and taming the reactivity of HWE and Wittig reagents with cyclic hemiacetals

被引：5

作者：

Carrillo, Jokin ^{[1
]}

Costa, Anna M. ^{[1
]}

Sidera, Mireia ^{[1
]}

Vilarrasa, Jaume ^{[1
]}

机构：

[1] Univ Barcelona, Fac Quim, Dept Quim Organ, E-08028 Barcelona, Catalonia, Spain

来源：

TETRAHEDRON LETTERS | 2011年 / 52卷 / 40期

关键词：

Lactols; Wittig and HWE reactions; Oxa-Michael cyclisation; ASYMMETRIC-SYNTHESIS; STABILIZED CARBANIONS; FORMAL SYNTHESIS; AMPHIDINOLIDE C; OLEFINATION; TETRAHYDROFURANS; DERIVATIVES; PRECURSOR; FRAGMENT; KETONES;

D O I：

10.1016/j.tetlet.2011.07.121

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

A practical solution to the formation of mixtures of E/Z and open/cyclic isomers in the reaction of (2R,4S)-4-hydroxy-2-methylpentanal (as its hemiacetal, a lactol) with conjugated phosphoranes (stabilised Wittig reagents) and Horner-Wadsworth-Emmons reagents is disclosed. The HWE reaction has a strong bias to give oxolanes. On the other hand, stabilised Wittig reagents give unsaturated carboxyl derivatives of configuration E (major) and oxolanes (minor); the latter can be avoided by addition of CF3CH2OH or using morpholine amide phosphorane. (C) 2011 Elsevier Ltd. All rights reserved.

引用

页码：5153 / 5156

页数：4