Seven-Membered Rings

There continues to be an active pursuit of new synthetic methods to prepare seven-membered heterocyclic compounds containing one, two or three of the heteroatoms N, O or S. The focus of the majority of the literature has been on aromatic systems containing at least one N atom and has often been driven by the search for new heterocycles with biological activity and the total synthesis of natural products. New synthetic methods of interest include transition metal-catalyzed, dipolar cycloaddition, cascade, and C–H functionalization processes; various traditional chemistry methods have also been popular. This year has also seen an increasing number of reports on the synthesis and application of heterocyclic compounds containing four or five N, O, or S atoms. Reviews on the chemistry of 2,4-azepanediones (15SC1823), 1,5-benzodiazepines (15IJCS46), benzothiazepines (15RA70619), and 1,5-benzothiazepines (15IJPC31) have been published.