CONCEPTS FOR LIGAND DESIGN IN ASYMMETRIC CATALYSIS - A STUDY OF CHIRAL AMINO THIOL LIGANDS

A series of new chiral sulfur-nitrogen chelate ligands, derived from a mino acids, has been synthesised rationally. Fruitless experiments int o catalytic asymmetric conjugate additions and desymmetrisation of mes o-epoxides led us to analyse our ligands in the catalytic asymmetric a ddition of diethylzinc to aromatic aldehydes. These latter experiments were successful with chiral benzylic alcohols being obtained in up to 82% enantiomeric excess. (C) 1998 Elsevier Science Ltd. All rights re served.