Enantioselective [3+2] Cyclization of 3-Isothiocyanato Oxindoles with Trifluoromethylated 2-Butenedioic Acid Diesters

The highly efficient organocatalytic enantioselective [3+2] cyclization of 3-isothiocyanato oxindoles with trifluoromethylated 2-butenedioic acid diesters for the synthesis of spirooxindoles possessing a CF3-containing quaternary carbon stereocenter was explored. An enantiodivergent approach for the synthesis of spirooxindoles by regulation of the temperature was demonstrated at different temperatures. The outcome of the reaction featured high diastereo- and enantioselectivities. Several interesting enantioenriched spirooxindole derivatives bearing a trifluoromethyl quaternary carbon stereocenter were synthesized from the products of this reaction.