Imidoyl Radicals in Organic Synthesis

Imidoyl radicals are very attractive intermediates that can be readily prepared by several methods, i.e. H-abstraction from aldimines, homolytic fragmentation of certain imidoylic precursors and addition of both carbon-and heteroatom-centered radicals to isonitriles and isothiocyanates. Imidoyl radicals have been shown to perform smooth intra- and intermolecular additions to double and triple carbon-carbon bonds as well as cyclizations onto aromatic rings, sulfur atoms and cyano groups. They have been therefore efficiently employed in cyclizations, annulations and cascade reactions leading to the construction of various nitrogen-containing heterocyclic compounds. They have also been used as key intermediates in the synthesis of carbonyl compounds, amides and nitriles and as precursors of alkyl radicals in tin-free reactions. In this review we discuss the generation methods, the structural features and, above all, the reactivity of imidoyl radicals with particular attention to their synthetic applications.