New pyrrole-based amino acids for the synthesis of peptidomimetic constrained scaffolds

A new family of pyrrole-based amino acids have been prepared through the microwave assisted Paal–Knorr reaction of 1–4 ketoesters derived from the corresponding β-ketoester with a functional homologation. The carboxylic group is located in position 3 of the pyrrole, whereas the amino group, protected with the Cbz moiety, is present on the side chain in positions 1 or 2. These compounds were used to prepare constrained oligopeptides.