Chiral phosphoric acid-catalyzed enantioselective synthesis of biphenyl-bridged ε-sultams via the Friedel–Crafts reactions of cyclic N-sulfonylimines with indolizines

Abstract

A highly enantioselective aza-Friedel–Crafts arylation of biphenyl-bridged seven-membered cyclic N-sulfonylimines with indolizines was developed, affording a wide range of chiral indolizine modified biphenyl-bridged ε-sultams in excellent yields (up to 99% yield) and enantioselectivities (up to 99% ee) by utilizing chiral phosphoric acid organocatalysis. Furthermore, scale-up reactions and diversified synthetic transformations of the desired ε-sultams without the loss of stereochemical purity substantiated their potential utility values.