Synthesis of Heterocyclic Compounds by Carbenoid Transfer Reactions

Over the last 30 years, the use of diazocarbonyl compounds has been a very fertile field for the development of new synthetic methods for constructing C-C bonds and heterocyclic rings. The reactions of the carbenoids, derived from the diazocarbonyls, offer exciting new strategies for the construction of complex target molecules due to the range of unusual transformations and cascade sequences which can be utilized. This review provides an update of the significant advances in the field since the year 2000 in the synthesis of several heterocycles (pyrrole, aziridines, dihydrofurans, etc.) by inter- and intra-molecular insertions of carbenoid species, generated from α-diazo-β-keto compounds, into carbonhydrogen or heteroatom-hydrogen bonds. New methodologies and unusual synthetic transformations will be highlighted. Although heterocycles have very important uses, the focus of this survey will be directed not to their use but to the methods of preparation.