A highly efficient Friedel-Crafts reaction of 3-hydroxyoxindoles and aromatic compounds to 3,3-diaryl and 3-alkyl-3-aryloxindoles catalyzed by Hg(ClO4)2·3H2O.

A highly efficient Friedel-Crafts reaction of 3-hydroxyoxindoles and aromatic compounds to 3,3-diaryl and 3-alkyl-3-aryloxindoles catalyzed by Hg(ClO4)2·3H2O.