Chemistry of Open‐Cage Fullerenes: o ‐Phenylenediamine‐Induced Orifice Expansion and its Nucleophilic Dichlorination through a Nitroso Intermediate

Abstract One amino group of o‐phenylenediamine undergoes nucleophilic addition to the carbonyl moiety of an open‐cage fullerene containing a 9‐membered ring orifice. Subsequent intramolecular cyclization under mild conditions generated a novel open‐cage fullerene derivative featuring an enlarged 12‐membered orifice. The unreacted amino group in this o‐phenylenediamine adduct could be selectively oxidized to form a nitroso group, which was subsequently reduced back to an amino group using hydrochloric acid. This reduction process simultaneously induced dichlorination on the adjacent aromatic ring.