Organocatalytic asymmetric [3+2] cycloaddition of N-2,2,2-trifluoroethylisatin ketimines with 3-alkenyl-5-arylfuran-2(3H)-ones

Abstract

A highly diastereo- and enantioselective [3+2] cycloaddition reaction of N-2,2,2-trifluoroethylisatin ketimines and 3-alkenyl-5-arylfuran-2(3H)-ones was developed with 1 mol% thiourea–tertiary amine as the catalyst. A series of spiro[pyrrolidin-3,2′-oxindoles] bearing four consecutive stereocenters, including two vicinal spiro-quaternary chiral centers, were efficiently obtained with excellent results (up to >99% yield, >20 : 1 dr, and >99% ee).