Copper(I)/Ming-Phos-Catalyzed Asymmetric Intermolecular [3 + 2] Cycloaddition of Azomethine Ylides with α-Trifluoromethyl α, β-Unsaturated Esters

Abstract

The employment of α-trifluoromethyl α,β-unsaturated esters as dipolarophiles pose considerable challenge due to expeditious defluorination and intrinsic steric hindrance. The present work provides an efficient access to valuable pyrrolidines bearing a trifluoromethylated all-carbon quaternary stereocenter through copper/M7-catalyzed asymmetric dipolar cycloaddition of α-trifluoromethyl α,β-unsaturated esters with azomethine ylides. The products were obtained in up to 98% yield with up to >20:1 d.r. and 99% ee. A broad substrate scope, good functional group tolerance, high stereoselectivity, as well as diverse synthetically valuable transformations of the products make this approach highly attractive.