An illustrative example of a synthetically useful enzyme: horse liver alcohol dehydrogenase.

The enzymes of most general and continuing value in organic synthesis are those that can operate stereospecifically on a wide range of structurally varied substrates. Horse liver alcohol dehydrogenase (HLADH, EC 1.1.1.1), a commercially available NAD(H)-dependent oxidoreductase that catalyses C = O in equilibrium CH(OH) interconversions, is such an enzyme. The scope of applications of enzymes endowed with this degree of versatility is illustrated by the preparative-scale use of HLADH to catalyse specific oxidoreductions of a broad spectrum of alcohol and ketone substrates. Examples are given of enantiomeric distinctions, of discrimination between enantiotopic groups in substrates possessing prochiral centres or in meso compounds, of regiospecific transformations and of combinations of various specificities. The value of the enzyme-derived products as chiral synthetic precursors of molecules of current interest is demonstrated.