GeCl2‑Mediated Ring Contraction toward Endofullerenes

Germanium­(II) dichloride dioxane complex (GeCl2·dioxane) is often utilized as a source of molecular germylene, i.e., GeCl2, which is known to undergo oxidative 1,4-addition to conjugated substrates. Inspired by this nature resembled to carbenes, we demonstrated a CC bond formation from two carbonyl moieties engaged in an aromatic macrocycle. This germylene-mediated reaction enables us to realize efficient synthesis of endo[60]­fullerenes through the consecutive ring contraction of open-[60]­fullerenes.