Organocatalytic Enantioselective Protonation of Enol Derivatives

The proton is the smallest functional group in organic synthesis and it is extremely challenging to control it in terms of enantioselectivity. In recent years, the use of organocatalysts has witnessed rapid developments and has become the state-of-art in enantioselective protonation of transient enolate. The key prochiral enolate can be generated via various reaction types. Herein we review recent reports of organocatalytic enantioselective protonation of transient enolate, classifying them according to the type of enolate precursors.