Synthesis and Fluoride-Promoted Wittig Rearrangements of α-Alkoxysilanes
摘要:
[GRAPHICS]Lewis acid-catalyzed reaction of allyl and benzyl trichloroacetimidates with alpha-silyl alcohols was found to be a general method for the synthesis of alpha-alkoxysllanes. Upon exposure to CsF, these alpha-alkoxysilanes could be made to undergo [2,3]-Wittig rearrangement with an efficiency similar to that realized by the analogous but inherently more toxic alpha-alkoxystannanes.
Methyllithium-Promoted Wittig Rearrangements of α-Alkoxysilanes
作者:Robert E. Maleczka,、Feng Geng
DOI:10.1021/ol990912+
日期:1999.10.1
[formula: see text] The Wittig rearrangements of alpha-alkoxysilanes, promoted by the action of methyllithium were studied. Depending on both the substrate and reaction conditions employed, [2,3]-, [1,2]-, or [1,4]-Wittigrearrangements can be realized. These rearrangements were shown to be initiated by either Si/Li exchange or deprotonation alpha to the silane. Furthermore the sigmatropic shifts can
Studies on the deprotonation and subsequent [1,4]-Wittig rearrangement of α-benzyloxyallylsilanes
作者:Edith N. Onyeozili、Robert E. Maleczka
DOI:10.1016/j.tetlet.2006.07.018
日期:2006.9
Upon exposure to s-BuLi, benzyloxyallylsilane undergoes an unusually rapid and efficient [1,4]-Wittig rearrangement. Herein we describe efforts aimed at trapping the intermediate alpha-carbanion with an electrophile prior to rearrangement. The results of these experiments indicate that alpha-deprotonation and bond reorganization are separate events. Findings herein further indicate that the future success of benzyloxyallylsilanes in [1,4]-Wittig rearrangements will likely hinge on the acidity of the benzylic protons. (c) 2006 Elsevier Ltd. All rights reserved.