Organocatalytic Enantioselective Protonation of Silyl Enolates Mediated by Cinchona Alkaloids and a Latent Source of HF

Hidden benefits: The enantioselective organocatalytic protonation of silyl enolates has been achieved by using readily available cinchona alkaloid catalysts (1) and a latent source of HF that delivers “at will” the active catalytic hydrogen fluoride salt (1-HF). This approach leads to enantioselective proton transfer with high enantioselectivities of up to 92 % under mild, neutral, and metal-free conditions (see scheme, TMS=trimethylsilyl).