Open-cage fullerenes with carbonyl functional groups on the rim of the orifice are ideal precursors for the extension of fullerene π-systems. Unlike isopropylphenylaniline, which reacts selectively with the lactone moiety on the rim of the orifice, phenylenediamine reacts with the adjacent carbonyl and imino groups on a pentagon to form a quinoxaline moiety. Further dehydroxylative aromatization connects the fullerene cage π-system with the quinoxaline π-system. Both the NMR and UV-Vis spectra revealed an evident effect after the extension of the fullerene cage π-system.