The Aldol Reaction: Organocatalysis Approach

At the beginning of this century, a large number of research groups focused their studies on the use of small metal-free organic molecules as organocatalysts. A large number of powerful asymmetric organocatalytic bond-forming reactions have now been developed. Organocatalysis allows for the chemo-, regio-, diastereo-, and enantioselective synthesis of molecules that were not readily available through traditional methods. Research in this area has advanced rapidly over the past decade because of the versatility, simplicity, and safety of organocatalytic reactions. This chapter addresses the significant achievements in asymmetric syntheses focused on organocatalytic nucleophilic addition to C=O bonds, namely aldol reaction which is one of the most fundamental reactions in synthetic organic chemistry. In addition, it is also an essential biological process involved in glycolysis, gluconeogenesis, and the Calvin cycle, covering the literature from 1971 to 2012. The description is subdivided based on various classes of catalysis: enamine, Brønsted acid, hydrogen-bond, Brønsted base, bifunctional, phase transfer, and supported organocatalysis.