Synthesis of cyclic peptides via transition metal catalyzed C-C bond formation

Introduction The correct three-dimensional structure of a peptide is essential for its biological activity. Nature has found many elegant ways to reduce the flexibility of peptides and proteins in order to control their folding and shape to increase affinity as well as selectivity for receptor interaction. Disulfide bridges, thioether (sulfide) bridges and the even more sophisticated multiple chain knotting, are well known ways to control the three dimensional shape. Outstanding examples in this respect are the glycopeptide antibiotic vancomycin and the lantibiotic nisin Z containing a crossed bisthioether ring system (Fig. 1).