Dehydrooligopeptides. I. The Facile Coupling of α-Amino Acids with α-Dehydroamino Acids to Dehydrodipeptides

Abstract

Abstract N-Cbz- or N-Tos-α-dehydroamino acid (DHA) and its ester were prepared by the condensation of 2-oxo carboxylic acid or ester with benzyl carbamate or p-toluenesulfonamide. Subsequently, the N-protected DHA and its N-free ester thus obtained were coupled with several l-α-amino acid esters and N-protected (Boc or Cbz)-l-α-amino acid respectively by the usual peptide synthetic methods to give a number of different types of dehydrodipeptide. The configurations of all the new DHA and dehydrodipeptides obtained were shown to have (Z)-geometry.