Synthesis and application of C2-symmetrical bis-β-amino alcohols based on the octahydro-cyclopenta[ b]pyrrole system in the catalytic enantioselective addition of diethylzinc to benzaldehyde

Abstract

Asymmetric catalytic ethylation of benzaldehyde utilizing a series of new, tetradental bis-β-amino alcohols based on the octahydro-cyclopenta[ b]pyrrole system—derived from an industrial waste material—is presented. Attention is focused on steric aspects of the catalyst(-precursor) structure. Furthermore, the catalytic efficiency of the ethylene-bridged, C 2-symmetrical bis-β-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.