Copper-catalyzed carbene insertion and ester migration for synthesis of polysubtituted pyrroles

Copper–catalyzed carbene insertion/ester migration/cyclization of enaminones and α-diazo compounds occurred efficiently, affording 2-ester polysubstituted pyrroles under mild conditions in moderate to good yields. Substituents functionality are well tolerated and 13C-labelled experiments demonstrated 1,2-ester migration during the reaction.