Triphosgene: an efficient carbonylating agent for liquid and solid-phase aza-peptide synthesis. Application to the synthesis of two aza-analogues of the AChR MIR decapeptide.

The N alpha/C alphaH exchange in aza-peptides has the advantage of preserving the side chain. Bis(trichloromethyl)carbonate or triphosgene is a solid, stable phosgene substitute which retains its high reactivity. Temperature and coupling times are greatly reduced with reference to other usually recommended carbonylating agents, while purity and yield are increased. It has been used, in both liquid- and solid-phase procedures, for the synthesis of various aza-analogues of dipeptides, tripeptides and decapeptides containing the alanine, aspartic acid and asparagine aza-residue.