Asymmetric hydrogenation of unsaturated peptides.
Eleven unsaturated peptides, containing one or two dehydro-phenylalanyl (dehydro-Phe) residues and a C-terminal L-amino acid have been hydrogenated in the presence of palladium-on-charcoal. Hydrolysis of the saturated peptides thus obtained gave optically active phenylalanine showing the occurrence of asymmetric induction during the hydrogenation. Both mono-unsaturated dipeptides and doubly unsaturated tripeptides with L-Glu, L-Leu and L-Val as chiral end-group afforded L-Phe in 40-50% optical yield. In the case of the tripeptide N-acetyl-(dehydro-Phe)-(dehydro-Tyr)-L-Glu the asymmetric induction was higher (70%) for the unsaturated residue which is farther from the chiral end-group along the peptide chain. The results are discussed on the bases of Prelog rule and the rigid dissymmetric conformation of the dehydropeptides in solution.
D000596:Amino Acids / Q000032:analysis; D002606:Charcoal; D055598:Chemical Phenomena; D002621:Chemistry; D002845:Chromatography; D006865:Hydrogenation; D006868:Hydrolysis; D008968:Molecular Conformation; D010165:Palladium; D010455:Peptides / Q000032:analysis*; D010649:Phenylalanine / Q000032:analysis
D000596:Amino Acids; D010455:Peptides; D002606:Charcoal; D010649:Phenylalanine; D010165:Palladium