Asymmetric organocatalysis mediated by a,a-L-diaryl prolinols: recent advances

This feature article illustrates progress in asymmetric organocatalysis achieved by using readily available a,a-L-diaryl prolinols from 2009 up to middle 2012. This class of bifunctional organocatalysts has shown the ability to catalyze a variety of reactions such as epoxidation, cyclopropanation, a-sulfenylation of active methines, cross conjugate addition, direct aldol, cycloaddition and desymmetrization reactions. The most striking feature of these promoters is to enable either non-covalent or covalent activation of the reagents, thus distinguishing themselves as a rare example of organic promoters capable of encompassing alternative mechanistic pathways, namely enamine/iminium catalysis and Brønsted acid/base catalysis.