I. Introduction
In recent years the importance of the application of enantiomerically pure building blocks for the manufacture of many chiral products has been recognised. Enantiopure cyanohydrins are valuable structures for the chemical synthesis of compounds such as ~-hydroxyketones, ~-hydroxyacids, fl-aminoalcohols and pyrethroid pesticides. Several methods have been described for the enantiospecific addition of hydrogen cyanide to aldehydes or ketones. These methods can be divided into two main groups, those involving chiral chemical reagents [1] and those having enzymes as catalysts [2,3].