Asymmetric Hetero-Diels-Alder Reactions of Danishefsky's and Brassard's Dienes with Aldehydes

The asymmetric hetero-Diels-Alder reactions of three Danishefsky"s dienes and two Brassard"s dienes with aldehydes that have been performed in our group are presented. (R)-1,1¢-Bi-2-naphthol [(R)-BINOL] and its derivatives complexed with tetraisopropoxytitanium(IV) [Ti(Oi-Pr)4] were efficient catalytic systems for the reactions with Danishefsky"s dienes, proceeding via a ­Mukaiyama aldol pathway. Meanwhile, tridentate Schiff base ligands complexed with Ti(Oi-Pr)4 or copper(II) triflate [Cu(OTf)2] were efficient for the reactions of Brassard's dienes, following the Diels-Alder pathway.