Preparation of oxytocin, arginine-vasopressin and its deamino-analogue serves as an example of use of 2,4,6-trimethylbenzyl group for protection of the cysteine sulfur atom in the peptide synthesis. This modified benzyl group is sufficiently stable under conditions of solvolytic removal of common amino-protecting groups and it can be cleaved off under mild conditions with liquid hydrogen fluoride or trifluoromethanesulfonic acid.
[8-Arginine]deamino-1-carba-vasopressin and its 7-glycine derivative were prepared by condensation of the amino-terminal, cyclic part of the molecule with carboxy-terminal tripeptide amides. Replacement of proline by glycine in the position 7 results in a substantial decrease in the vasopressin-like activities, the oxytocin-like activities remaining unchanged.