Asymmetric Benzylic Allylic Alkylation Reaction of 3-Furfural Derivatives by Dearomatizative Dienamine Activation.

The dearomatizative dienamine-type ortho-quinodimethane species are smoothly generated between 2-alkyl-3-furfurals and chiral secondary amine catalysts, which undergo asymmetric benzylic allylic alkylation reactions with 2-nitroallylic acetates efficiently. A spectrum of densely functionalized 3-furfural derivatives are delivered in moderate to high yields with good to excellent diastereo- and enantioselectivity (up to 98 % yield, >19:1 d.r., >99 % ee). The latent transformations allow the facile production of some enantioenriched architectures, such as 1,1,2,2-tetraarylethanes and triarylmethanes, which are not easily available from other protocols.

Remote Asymmetric Oxa-Diels-Alder Reaction of 5-Allylic Furfurals via Dearomatizative Tetraenamine Catalysis.

A previously unreported activation mode is developed through the generation of dearomatizative tetraenamine species between 5-allylic furfurals and a bifunctional amine-thiourea catalyst. The very remote ζ,η-alkenes perform as effective HOMO-raised dienophiles in inverse-electron-demand oxa-Diels-Alder cycloadditions with isatin-derived oxadiene substrates, delivering multifunctional spirocyclic oxindoles incorporating a dihydropyran skeleton in moderate to high yields with good to excellent enantio- and diastereoselectivity.