Selective Michael addition of pyrrole to conjugated alkenes catalyzed by Cr3+-Catsan and ZnCl2

Lewis acid Cr3+-Catsan and ZnCl2 were first used as catalysts for Michael additions of pyrrole to conjugated alkenes. 2-Alkyl and 2,5-dialkyl pyrrole derivatives could be selectively obtained with Cr3+-Catsan and ZnCl2 as catalyst, respectively. The reaction has the advantages of mild reaction conditions, high selectivity, excellent yields.