The aldol reaction is one of the most important and effective methodologies for the straightforward construction of carbon–carbon bonds in synthetic organic chemistry.This reaction unites two carbonyl compounds to form a β-hydroxy-carbonyl product, where one carbonyl compound acts as a nucleophilic donor via its enolate or enol form and the other, a ketone or an aldehyde, acts as an electrophilic acceptor. The importance of the enantioselective aldol reaction in constructing chiral building blocks for complex small-molecule synthesis has spurred continuous efforts toward the development of direct catalytic variants.

Asymmetric Aldol reaction

Cinchona alkaloid catalysts are the most favoured catalysts in enantioselective aldol reactions. These catalysts are highly enantioselective and provide high yields. Most of the catalyst can be recycled easily. Often a combination of aldol reaction and decarboxylation, called decarboxylative aldol reaction, can be performed under mild reaction conditions to synthesize valuable enantiomerically pure intermediates of synthetic interest, especially for medicinal and agrochemical applications. A lot of examples can be reviewed in our free of charge Chiral Catalyst Search Data Base.

Application

The cinchona alkaloid based chiral catalyst enables, for instance the synthesis of the active pharmaceutical ingredient Funapide through asymmetric aldol reaction with low (1 mol%) catalyst loading.

Example from literature

Highly enantioselective direct aldol reaction catalyzed by cinchona derived primary amines. (Zheng et al.; Org. Biomol. Chem. 2007, 5, 2913 – 2915.)