A stereoselective synthesis of trisubstituted alkenes. Part 1. Nickel-catalysed coupling of Grignard reagents with 5-alkyl-2,3-dihydrofurans
作者:Philip J. Kocieński、Martin Pritchard、Sjoerd N. Wadman、Richard J. Whitby、Clive L. Yeates
DOI:10.1039/p19920003419
日期:——
5-Alkyl-2,3-dihydrofurans 3a–j prepared by the alkylation of 5-lithio-2,3-dihydrofuran 2 with primary alkyl bromides and iodides, undergo Ni0-catalysed coupling with Grignard reagents to give homoallylic alcohols. The yield and stereoselectivity depend on the structure of the Grignard reagent with the best results being obtained with long chain primary Grignard reagents and Grignard reagents lacking
通过5-lithio-2,3-二氢呋喃2与伯烷基溴化物和碘化物的烷基化反应制得的5-烷基-2,3-二氢呋喃3a – j与Niignyard试剂进行Ni 0催化偶联,得到均丙醇。产率和立体选择性取决于格氏试剂的结构,使用长链伯氏格氏试剂和缺少β-氢的格氏试剂(Me,Ph,Me 3 SiCH 2)可获得最佳结果。5-(1-羟基烷基)-2,3-二氢呋喃20和21是偶联反应的不良底物。提出了用于偶合以及竞争性还原和异构化反应的机理。