Free-Radical Synthesis and Functionalization of Heterocycles

The venerable Minisci reaction allows for direct access to functionalized heterocycles. This process has lately seen an interesting renaissance and is discussed in this volume. Addition of heteroatom-centered radicals onto unsaturated systems constitutes another powerful method to construct heterocycles. Examples of such a strategy are proposed along with the formation of various heterocycles relying on homolytic substitution at sulfur, phosphorus and selenium. Additionally free-radical functionalization of reactive functional groups including isonitriles, isothiocyanates and related unsaturated systems which offer a straightforward route towards useful aromatic and non-aromatic heterocycles are discussed. Finally, as metals are able to trigger single electron transfer both in reductive and oxidative modes this provides another possibility for the synthesis of heterocycles. Significant research efforts have focused on the use of samarium, copper and other metals to access a broad variety of heterocycles in a single pot process, starting from readily available raw material. Examples and mechanistic insights are discussed by experts in this area.