Synthesis of heterocycles via group VI Fischer carbene complexes

Metal carbene complexes of group 6 are reactive toward a wide array of heteroatom-containing substates, allowing access to a grest variety of mono- and polyheterocycled compounds. In most cases, four- to seven-membered rings are successfully formed in a single step and with high selectivity. Among them, the facile azepine ring formation seems of particular relevance in terms of both mechanistic and synthetic purposes.