Increasingly remote stereocenters are being targeted in asymmetric aminocatalysis. Application of the HOMO-raising activation concept to δ,δ-disubstituted 2,4-dienones confirms the powerful potential of the trienamine strategy. A cinchona-based primary amine catalyst enables the extension of this activation mode to a highly selective asymmetric Diels-Alder reaction of enones with electron-deficient dienophiles (see scheme; TFA: trifluoroacetic acid).
Extending the aminocatalytic HOMO-raising activation strategy: Where is the limit?
Angew. Chem. Int. Ed. 2012, 51, 5290-5292.