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 zeta,eta-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.