(A) new method for β-functionalization of α,β-unsaturated ketone using β-phosphonium salt methyl enol ethers

Abstract

Wittig reaction at the $\beta$-position, $\beta$-alkoxycarbonylation, $\beta$-acylation, and $\beta$-sulfenylation of 2-cyclohexen-1-one have been achieved by the reaction of ylides, which were derived from enone ketal via phosphonylation with triphenylphosphine in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) or boron trifluoride etherate (BF$_3$.OEt$_2$), with aldehydes, chloroformates, acyl chlorides, and disulfides, respectively, followed by the hydrolysis. Direct displacement of triphenylphosphonium salt with several nucleophiles provided conjugated addition products in which ketone groups were protected as methly enol ethers.