Ln(III)/Chiral Brønsted Acid Catalyzed Asymmetric Cascade Ring Opening/Aza-Piancatelli Rearrangement of D-A Cyclopropanes.

The first Lewis acid and chiral Brønsted acid cooperatively catalyzed asymmetric cascade ring opening/aza-Piancatelli rearrangement reaction of furyl-substituted donor-acceptor cyclopropanes is achieved, enabling the construction of functionalized aminocyclopentenones bearing α-quaternary carbon stereocenters in high yields with excellent enantio- and diastereoselectivities under remarkably low catalyst loading of 0.2-1.2 mol %.