Application of the Radical Cascade of Acyclic Peptide-Based Precursors into Analogues of Type I (beta)-Turn

Radical cyclizations of di-, tri- and tetrapeptides containing N-2-bromobenzyl,N-methyl-substituted alanine or aspartic acid lead in good yields to (alpha),(beta)-unsaturated (gamma)-lactams. The overall cascade, relying on a hydrogen atom transfer-elimination strategy could serve as a way to incorporate a flat and rigid five-membered ring into the peptide framework.