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

Crystallization-induced asymmetric transformation was employed to prepare a labile gamma-oxo-alpha-aminoacid (3) with a new stereogenic center in high diastereomeric and enantiomeric purity. Compound 3 was reduced to a stable compound, (2R,1'S)-2-(1'-benzyl-2'-hydro-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))(H2O)(2)]NO3-H2O (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. (C) 2004 Elsevier B.V. All rights reserved.