The Application of Freidinger Lactams and their Analogs in the Design of Conformationally Constrained Peptidomimetics

Peptides exist in solution as an equilibrium mixture of conformers. The backbone conformational constraints are of interest as a means of limiting degrees of freedom and thereby constraining a synthetic peptide into the bioactive conformation. This concept plays an important role in the design of peptidomimetics in the drug development process. In the early eighties, Freidinger proposed the concept of protected lactam-bridged dipeptides, which was a milestone in the design of conformationally constrained peptides. These types of compounds, now widely known as Freidinger lactams, have been of interest to many medicinal and peptide chemists. This review seeks to present the various applications that Freidinger lactams and their hetero-, fused- and unsaturated analogs have found in the design of conformationally constrained peptidomimetics in different therapeutic areas.