Investigation of a Stereoselective Co-Mediated Rearrangement Reaction (original) (raw)

A stereocontrolled approach to R-alkyl-alkynyl cyclohexanones is reported through a Lewis acid mediated rearrangement reaction of enol ethers bearing an Co-alkyne moiety. The reaction proceeds with high levels of stereoselectivity in the presence of Ti-and B-Lewis acids to provide a range of R,-disubstituted cyclohexanones in high yield although the products are prone to epimerization at the R-position in the presence of the B-promoter system. The potential for an enantioselective variant of this process is outlined, and a rationale for the observed stereochemical trends and detailed structural analyses of the ketone products are described.