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Amphoteric Character of 2-Vinyloxiranes: Synthetic Equivalents of β,γ-Unsaturated Aldehydes and a Vinylogous Enolate
We thank Professor Batey and his group for providing the allyl and crotyltrifluoroborates. This work was supported by the National Science and Engineering Research Council (NSERC) and the University of Toronto. S.G.O. thanks NSERC for a post-graduate scholarship.
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.