Amphoteric Character of 2-Vinyloxiranes: Synthetic Equivalents ofβ,γ-Unsaturated Aldehydes and a Vinylogous Enolate

Abstract

An interesting alternative to the use of substituted 3-butenals has been discovered for the generation of bishomoallylic alcohols. 2-Vinyloxiranes 1, upon treatment with an appropriate Lewis acid, can act as synthetic equivalents of β,γ-unsaturated aldehydes 2 that can be trapped in situ by a nucleophile to generate the desired alcohol. In the course of this study, it was also found that 2-methyl-2-vinyloxirane can act as an equivalent for dienolate 3 and react in situ with various aldehydes to give δ-hydroxy-α,β-unsaturated aldehydes. LA=Lewis acid.