Diaryl ethers form an important class of organic compounds, both in life sciences and in the polymer industry. In general, diaryl ethers can be synthesized by means of copper-catalyzed Ullmann diaryl ether coupling, palladium-catalysed Buchwald-Hartwig reaction, nucleophilic aromatic substitution, arylboronic acid diaryl ether coupling, oxidative coupling, and nucleophilic aromatic addition to metal-arene complexes. This review covers the progress in diaryl ether synthesis since 1999, with literature coverage through September 2005.

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.