Additions of structurally diverse α-ketonitriles to aromatic and aliphatic prochiral aldehydes yielding highly enantioenriched acylated cyanohydrins were achieved using a combination of a titanium salen dimer and an achiral or chiral Lewis base. In most cases high yields and high enantioselectivities were observed. The ee was moderate in the initial part of the reaction but increased over time. This
straightforward process for the preparation of optically active protected cyanohydrins, important building blocks for the synthesis of drugs and agrochemicals, has been established. Lipase B from Candida Antarctica (CAL-B) catalysed the kinetic resolution of racemic cyanohydrin acetates under mild conditions. The resulting labile cyanohydrins were reprotected either by an enzyme-catalysed route involving the