Brønsted base catalysts.

Chiral organic Brønsted bases have emerged as highly efficient catalysts for enantioselective transformations. Since their early use in enantiomeric separation processes, chiral organic Brønsted base catalysis has advanced significantly to include both natural and designed catalysts. Insight into the mode of action of the organocatalysts has promoted modifications in catalyst structures to expand the application to numerous asymmetric reactions. Bifunctional catalysts, containing both Brønsted base and H-activating functionalities, have proven to be very applicable to an array of reaction types. The development of Brønsted base catalysts containing or not containing H-activating moieties, has greatly impacted asymmetric organocatalysis. This overview illustrates the recent developments in this emerging field.