Linear Stereo‐co‐oligopeptides with Alternating <scp>D</scp>‐ and <scp>L</scp>‐Residues. I. Synthesis and Mass Spectrometric Behavior of the Members of a Series with Valine Residues

Abstract

Abstract The synthesis of the protected stereo‐co‐oligopeptides with alternating D ‐ and L ‐valine residues Boc‐( D ‐Val) m ‐( L ‐Val‐ D ‐Val) n ‐OMe (m = 0; n = 1,2,3,4,6,8, and m = 1; n = 1,2,3,4) is described. The synthesis has been carried out by using conventional solution methods. The co‐oligopeptides up to the nonapeptide (m = 1; n = 4) have been prepared in a stepwise fashion. The dodecapeptide (m = 0; n = 6) and the hexadecapeptide (m = 0; n = 8) have been prepared by condensation of smaller peptides, and the criteria used for assessing their stereochemical purity are discussed. Preliminary characterization data are presented. Even the co‐oligopeptides with six or more residues, up to the dodecapeptide included, have given EI/MS. showing the molecular ion peak. The possible reasons for this uncommon behavior are examined.