Synthesis and application of C-2-symmetrical bis-beta-amino alcohols basedon the octahydro-cyclopenta[b]pyrrole system in the catalytic enantioselective addition of diethylzinc to benzaldehyde

Asymmetric catalytic ethylation of benzaldehyde utilizing a series of new, tetradental bis-beta-amino alcohols based on the octahydro-cyclopenta[b]pyr role system - derived from an industrial waste material - is presented. Att ention is focused on steric aspects of the catalyst(-precursor) structure. Furthermore, the catalytic efficiency of the ethylene-bridged, C-2-symmetri cal bis-beta-amino alcohols is compared to related 'monomeric' structures. Potent chiral ligands, which are highly effective even at concentrations of below 2 mol%, have been developed reaching excellent enantioselectivities up to 100% ee, (C) 1999 Elsevier Science Ltd. All rights reserved.