Organocatalytic Enantioselective Decarboxylative Protonation Reaction of Meldrum's Acid Derivatives under PTC Conditions

摘要

An original organocatalyzed enantioselective protonation sequence of a transient quaternary ammonium enolate species has been developed by starting from readily available disubstituted Meldrum's acid derivatives and phenols. Under phase-transfer-catalytic (PTC) conditions, chiral nonracemic 2-aryl propionic ester derivatives were obtained in good isolated yields with enantioselectivities up to 70 % ee. The usefulness of the approach was demonstrated by the synthesis of enantioenriched (S)-ibuprofen.