Bu3SnH mediated oxidative radical cyclisation onto imidazoles and pyrroles

A new protocol using radical cyclisation has been developed for the synthesis of [1,2-c]-fused imidazoles and [1,2-a]-fused pyrroles. The intermediate nucleophilic N-alkyl radicals, generated using Bu3SnH from N-(omega-bromoalkyl) or N-[omega-(phenylselanyl)alkyl] imidazoles and pyrroles, undergo regioselective radical cyclisation onto the azole rings followed by oxidative re-aromatisation, (C) 1999 Elsevier Science Ltd. Ail rights reserved.