Amides as radical precursors in heterocyclic chemistry

In this project the use of amides as precursors for imidoyl radicals in heterocyclic chemistry has been developed. Amides were converted to thioamides, which function as precursors for imidoyl radical equivalents. Also, a novel protocol for the synthesis of imidoyl selanides was developed for the purpose of using these as imidoyl radical precursors. The precursors were used in a study of intramolecular oxidative cyclisation of imidoyl radicals onto electron deficient pyrroles and indoles. The imidoyl radical equivalents derived from thioamides did not cyclise onto heteroarene double bonds. In contrast, imidoyl radicals derived from imidoyl selanides did cyclise 6-exo onto activated heteroarenes, but yields were generally low due mainly to competing reduction of the imidoyl radical, but also due to adduct formation with isobutyronitrile radicals originating from the initiator. [Continues.]