1.4.2 Hydrolysis of Nitriles to Carboxylic Acids

Abstract

AbstractThe synthesis of carboxylic acids from nitriles utilizes two pathways of nitrile biotransformations: direct hydrolysis by nitrilase and bienzymatic hydrolysis by nitrile hydratase and amidase. General procedures consist of using whole cells or isolated enzymes as catalysts in aqueous media with a small fraction of organic cosolvent. These methods afford a number of products that are often difficult to prepare by chemical means such as 3-oxoamides, cyano carboxamides and cyano carboxylic acids, enantiopure 2- and 3-substituted carboxylic acids and carboxamides, and enantiopure (hetero)cyclic carboxylic acids and carboxamides. Stereochemistry is mainly recognized by amidase, but in some cases also by nitrilase and nitrile hydratase. Nitrile hydrolysis has also been employed in chemoenzymatic and multienzymatic methods such as the synthesis of aromatic and heterocyclic amides from aldehydes, the synthesis of enantiopure 2-hydroxy acids from aldehydes, the synthesis of enantiopure 3-hydroxy acids from 3-oxonitriles, and the synthesis of cyclophellitols from benzo-1,4-quinone.