Biocatalytic transformation of racemates into chiral building blocks in 100% chemical yield and 100% enantiomeric excess

Biocatalytic techniques, which lead to the highly efficient transformation of a racemate into a single stereoisomeric product in (theoretically) 100% chemical yield and 100% enantiomeric excess are reviewed and their specific merits and limitations are discussed. The processes known so far can be cl assified into the following categories: (i) A range of methods are based on the improvement of classic kinetic resolution processes, for instance rera cemization followed by repeated resolution, dynamic resolution and follow-u p reactions, such as stereoinversion reactions. (ii) On the contrary, more elegant solutions are derived by employing enantioconvergent processes, whi ch are based on the transformation of each enantiomer through stereochemica lly different pathways, which can be achieved by using combined chemo- and/ or biocatalysis. (iii) Finally, a novel type of process for the deracemizat ion of compounds possessing a sec-alcohol and -amino group makes use of a c yclic oxidation-reduction sequence, which is combined in a cyclic mode. (C) 1999 Elsevier Science Ltd. All rights reserved.