Absolute structure determination of (2 R,1′ S)-2-(1′-benzyl-2′-hydroxyethylamino)-4-phenylbutanoic acid

Abstract

Crystallization-induced asymmetric transformation was employed to prepare a labile γ-oxo-α-aminoacid ( 3) with a new stereogenic center in high diastereomeric and enantiomeric purity. Compound 3 was reduced to a stable compound, (2 R,1′ S)-2-(1′-benzyl-2′-hydroxyethylamino)-4-phenylbutanoic acid ( 4), which crystallizes in space group P2 1. Upon deprotonation, 4 becomes a tridentate monoanionic chelating ligand, 4 −H, which reacts with copper nitrate yielding [Cu( 4 −H)(H 2O) 2]NO 3·H 2O ( 5). Complex 5 crystallizes in space group P2 1 and has a rare composition among crystallographically characterized mononuclear five-coordinate transition metal complexes. The absolute structure determination of 5 allowed by inference the assignment of absolute configuration to compound 3.