Enantioselective Organocatalytic Michael Additions of Aldehydes to Enones

Significance

The authors report that the addition of an appropriate achiral cocatalyst is important for the regioselectivity (Michael versus aldol additions) in the described reaction. Various cocatalysts with hydrogen bond donors were tested and those with adjacent hydrogen bond donors (i.e. catechol derivatives) provided the best results. NMR experiments showed that the imidazolidin­one catalyst likely produced an enamine with E configuration, which was preformed and a competent nucleophile in the Michael addition.