154070-66-3Relevant articles and documents
Metal Complexes of Biologically Important Ligands, LXVII. - Synthesis of α-Amino Acids from Palladium(II)- and Rhodium(III)-Coordinated Imines and Oximes of α-Oxocarboxylates
Kraemer, Roland,Wanjek, Herbert,Polborn, Kurt,Beck, Wolfgang
, p. 2421 - 2428 (2007/10/02)
The bis-chelate complexes Pd1)=NOR2>2 (1) and Pd1)=NR2>2 (2, R2 optically active substituent) are synthesized by template condensation of an α-oxocarboxylic acid with a hydroxylamine or amine component, respectively.Similarly, the Rh(III) complexes Cp*Rh(Cl) (3a: R = H, 3b: R = Me) were obtained from α-oxocarboxylic acids and optically active 1-phenylethylamine.Catalytic hydrogenation of 1 and 2 gives directly the free α-amino acids with, in case of 2, ee's between 0 and 36percent.Nucleophilic attack by the carbanions of RC(O)CH2CO2Et and H2NCH(CO2Et)2 at the imino carbon atom of 3a leads to the α-amino carboxylato complexes 4 and 5. - Compounds 4a and 5 have been characterized by X-ray diffraction.Reaction of 3a with NaBH4 or NaBD4 followed by decomposition of the complex with HCl yields N-substituted glycine and N-substituted α-deuterioglycine, respectively.The diastereoselectivity (70:30) of the α-deuteration could be determined by NMR spectroscopy. - Key Words: Palladium complexes / Rhodium complexes / α-Amino acids / 2-Iminocarboxylate as ligand / Chiral glycine