Rhodium(II) catalyzed intermolecular double C-alkylation: a method for the synthesis of tetraindoles and indolophanes

Double C-alkylation of cyclic diazoamides or bis-diazoamides with indoles or bis-indoles has been achieved to synthesize tetraindole derivatives using rhodium(II) acetate as a catalyst under mild reaction conditions with complete regioselectivity. The intermolecular double C-alkylation reaction strategy was successfully applied to synthesize indolophanes in moderate yield with excellent regiocontrol. The structure and stereochemistry of macrocycles were unequivocally confirmed with the help of single-crystal X-ray structure analyses.