Iron-catalyzed redox radical cyclizations of 1,6-dienes and enynes.
Treatment of 1,6-dienes and enynes with FeCl(3) or Fe(Pc) in the presence of NaBH(4) and air or O(2) causes radical cyclization to give five-membered carbo or heterocyclic compounds, into which a halogen atom or hydroxyl group was introduced.