Diastereodivergent construction of bispiro[oxindole-bi-pyrrolidine]s with four consecutive stereocenters via asymmetric [3 + 2] cycloaddition of 2,3-dioxopyrrolidines using identical catalysts

Abstract

A highly enantioselective [3 + 2] cycloaddition between 2,3-dioxopyrrolidines and N-2,2,2-trifluoroethylisatin ketimines with a quinine-derived squaramide catalyst in a diastereodivergence way has been described, which leads to two diastereomeric enantioenriched bispiro[oxindole-bi-pyrrolidine]s (incorporating CF₃ units) with four consecutive stereocenters, including two adjacent spiro-quaternary centers. The reaction afforded the corresponding adducts in good to excellent yields with good to excellent enantioselectivities.