A novel route to synthesize Freidinger lactams by microwave irradiation

The incorporation of a Freidinger-like lactam structure into the backbone of peptides has been proven to be an useful strategy in the design of a variety of conformationally restricted targets. Several different strategies have been developed toward Freidinger lactams but no one resulted to be completely facile. Here, we report an efficient strategy that involves the iodo-derivatives in side chain of an appropriate amino acid used as electrophilic agent, and the standard solid phase peptide synthesis assisted by microwave irradiation. The methodology developed could be useful to perform Freidinger-like lactams with defined stereochemistry for routine use in solid phase peptide chemistry.