The self-assembly of 4-fold-symmetric porphyrins with Fe or Zn gave a new cubic M$\mathrm{<mrow\; data-mjx-texclass="ORD">8</mrow>}$L$\mathrm{<mrow\; data-mjx-texclass="ORD">6</mrow>}$ cage framework with electron-deficient walls. This cage bound C$\mathrm{<mrow\; data-mjx-texclass="ORD">60</mrow>}$-indene or C$\mathrm{<mrow\; data-mjx-texclass="ORD">60</mrow>}$-anthracene bisadducts selectively, whereas unfunctionalized fullerenes and monoadducts were not encapsulated. The Fe$\mathrm{<mrow\; data-mjx-texclass="ORD">8</mrow>}$L$\mathrm{<mrow\; data-mjx-texclass="ORD">6</mrow>}$ cage also enabled the reaction of C$\mathrm{<mrow\; data-mjx-texclass="ORD">60</mrow>}$ and anthracene to yield the bisadducts selectively under conditions where no reaction was observed in the absence of the cage. These findings have relevance in the context of polymer solar cells, where C$\mathrm{<mrow\; data-mjx-texclass="ORD">60</mrow>}$ bisadducts have found use as electron acceptors, because these adducts currently require laborious and time-consuming syntheses and purification.