title: Carboxyl activation in peptide synthesis using 4-oximino-pyrazol-5-ones.
abstract: 4-Oximino-pyrazol-5-ones 2a, b and their esters with N-protected amino acids 3a, b have been studied for carboxyl activation in peptide synthesis. 2a, b and 3a, b appear to be diastereoisomeric mixtures whose configurations have been assigned on the basis of spectroscopic and X-ray data. Some peptides obtained using these pyrazolone derivatives are reported: no racemization was noted by the Weigand test.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids; D055598:Chemical Phenomena; D002621:Chemistry; D010455:Peptides / Q000138:chemical synthesis*; D011720:Pyrazoles; D013057:Spectrum Analysis
chemical_list: D000596:Amino Acids; D010455:Peptides; D011720:Pyrazoles