Aldolases in Organic Synthesis

Abstract

Asymmetric carbon-carbon bond formation in aldol addition reactions is one of the most useful and efficient methods in synthetic organic chemistry. Most of the organic aldol reactions developed recently are stoichiometric and require the use of a metal or metal-like enolate complex to achieve stereoselectivity. Because of the instability of the enolate complex in aqueous solutions, the aldol reactions must be carried out in organic solvents at low temperature. This requirement limits the application of organic aldol reactions to synthesis of molecules soluble in organic solvents. For those compounds containing polyfunctional groups, such as carbohydrates, the synthesis still relies on other methods. The aldol addition reactions catalyzed by aldolases, however, are performed in aqueous solution at neutral pH without protection of the substrate functional groups. It is obvious that both chemical and enzymatic aldol reactions are complementary and the combination of these two approaches will extend the synthetic utility of aldol reactions.