Catalyst-free racemic and H2O/CPA-catalyzed asymmetric regio-reversed domino processes of triketone enones with azlactones

Abstract

Regio-reversed domino processes of triketone enones with azlactones have been established. Opposite to the previous β-addition-triggered domino processes, this protocol is initiated by a regio-reversed α-addition. Under catalyst-free conditions, the domino reaction readily occurred, leading to the formation of a variety of bicyclic furofurans bearing vicinal quaternary carbons in good to excellent yields. In addition, a catalytic asymmetric version was achieved using chiral phosphoric acid catalysis, in which H₂O played a crucial role in enantio-control. Notably, all the prepared enantio-enriched products could be further recrystallized to ensure excellent enantioselectivity.