Solid-Phase Synthesis of Conformationally Constrained Peptidomimetics Based on a 3,6-Disubstituted-1,4-diazepan-2,5-dione Core

Starting from a Cl-trytyl linked hydroxylamine, a hydroxamic dipeptide having serine in the second position was prepared by using DMTMM as the coupling agent. Mitsunobu cyclization carried out under microwave heating gave very good yields of a 3,6-disubstituted-perhydro-diazepin-2,5-dione. This heterocycle can be used as a new platform for combinatorial chemistry or as a constraint to rigidify a small peptide.