A DFT Study on Hetero-Diels-Alder Reactions Catalyzed by Cobalt Complexes:Lewis Acidity Enhancement as a Consequence of Spin Transition Caused by Lewis Base Coordination

摘要

Among the various chiral Schiff base transition-metal complexes,the cobalt complexes with acacen-and salen-type ligands have been successfully employed as chiral Lewis acid catalysts,for example,for the enantioselectIVe hetero-Diels-Alder reaction,the carbonyl-ene reaction,1,3-dipolar cycloaddition of nitrones,and ring opening of epoxides.For these enantioselectIVe catalyses,high efficiency and high stereoselectIVity were realized,and specific catalytic actIVity of the cobalt complexes was achieved.