(A) new method for β-functionalization of α,β-unsaturated ketone using β-phosphonium salt methyl enol ethers메틸 에놀 에테르의 β-포스포늄염을 이용한 α,β-불포화 케톤의 새로운β-위치 작용기화
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.