A novel method for the synthesis of dipyrromethanes by metal triflate catalysis

5-Substituted dipyrromethanes were synthesized by the reaction of N-tosyl imines with excess pyrrole in the presence of metal triflates. High yields of 5-substituted dipyrromethanes were obtained for electron donating and withdrawing substituents by performing the reaction at two different temperatures. The new reaction procedure is simple and anhydrous conditions are not required.