1,3-Dipolar Cycloaddition of Aza-Propargylglycine with Aryl Azides

Significance

An aza-propargylglycine residue immobilized onto rink amide peptide 1 was treated with aryl iodides, NaN₃, and CuI in the presence of l-proline to give the corresponding aza-1,2,3-triazole-4-alanine residues 2 in 58-82% conversion. After removal of N-benzylidene, the resulting azapeptides 3 were elongated and deprotected to give analogues of [aza-1,2,3-triazole-4-alanine⁴] growth hormone releasing peptide-6 (GHRP-6) 4 in 5-11% overall yields based on initial resin loading.