Regioselective synthesis of pentathiepino-fused pyrroles and indoles

Treatment of simple pyrroles, pyrrolidines and indoles with S₂Cl₂ and Dabco in chloroform at room temperature gives their fused pentathiepino derivatives 4, 6 and 8 in extensive cascade reactions; the reaction profile is changed and the regioselectivity enhanced when the S₂Cl₂ and Dabco are premixed and equilibrated before the heterocycle is added.