Bifunctinoal Phosphonium Salt-Catalyzed Asymmetric Cyclodearomatization of 2-Nitroindoles and 2-Nitrobenzofurans for Constructing CF3-Containing Spiro-Polycycles

An efficient enantioselective dearomative cycloaddition reaction between either 2-nitroindoles or 2-nitrobenzofurans and N-2,2,2-trifluoroethylisatin ketimines by dipeptided phosphonium salt catalysis is firstly established. This protocol provides a new and facile synthetic approach to create a variety of CF3-containing polycyclic spirooxindole derivatives under mild reaction conditions with high yields in excellent diastereo- and enantioselectivities (all >20:1 dr, up to 95% ee).