 A decade later, Elias James Corey introduced an effective aluminum-diamine controller for Diels-Alder reaction.Formation of the active catalyst is achieved by treatment of the bis(sulfonamide) with trimethylaluminum; recovery of the ligand was essentially quantitative.The proposed tetracoordinate aluminum prevent the imide acting as a chelating Lewis base, while enhance the α-vinyl proton of the dienophile and the benzylic proton of the catalyst.