α-Substituted acylsilanes via a highly selective [1,4]-Wittig rearrangement of α-benzyloxyallylsilane

Abstract

alpha-Benzyloxyallylsilane undergoes efficient [1,4]-Wittig rearrangement to generate an enolate intermediate that can be trapped with various electrophiles, thereby providing a new synthetic approach to substituted acylsilanes.

Recent Advances in the Synthesis of Acylsilanes

“…The Wittig rearrangement reaction of allyl ether compounds can also be applied to synthesize acylsilanes. [28] In 2013, Maleczka and co-workers disclosed a general method for the preparation of acylsilanes through isomerizations of ethers under basic conditions (Scheme 19). [29] The reaction is characterized by high efficiency, mild conditions, and good tolerance with a variety of functional groups.…”

“…The Wittig rearrangement reaction of allyl ether compounds can also be applied to synthesize acylsilanes . In 2013, Maleczka and co‐workers disclosed a general method for the preparation of acylsilanes through isomerizations of ethers under basic conditions (Scheme ) .…”

Molecular Rearrangements: Part 1. Pericyclic Reactions

“…This has been interpreted as evidence for the [1,4]-rearrangement occuring via a concerted pathway. 43 A DFT study on thermal aryl migration in two aryliodonium ylids has suggested that the mechanism in each case is a concerted, single-step process involving a five-membered cyclic transition state, FMO controlled by an intramolecular HOMO-LUMO interaction. The ylids studied were the phenyliodonium ylids of cyclohexane-1,3-dione and 2-amino-1,4-diquinone; the lower energy barrier calculated for the latter is in line with previous experimental observations.…”

Silylcyclopropanes by Selective [1,4]-Wittig Rearrangement of 4-Silyl-5,6-dihydropyrans

“…In 2006, our research group found that (1-trimethylsilyl)­allylbenzyl ether rearranged selectively through the [1,4]-pathway, forming the acylsilane product . The apparent ability of the silyl group to allow (1) selective allylic deprotonation and (2) selective [1,4]-migration of the benzyl group led us to explore more complex acyclic analogues.…”

“…-Wittig rearrangements of allyl ethers generate enolates, whereas the more common [2,3]-and [1,2]-pathways produce alkoxides. 1 In addition, the [1,4]-Wittig pathway is inherently interwoven with the [1,2]-manifold, which typically predominates.…”