Synthesis of C₆₀(O)₃: An Open-Cage Fullerene with a Ketolactone Moiety on the Orifice

Four isomers are currently known for the trioxygenated fullerene derivative C60(O)3, three regioisomers with all of the oxygen addends as epoxy groups and the unstable ozonide isomer with a 1,2,3-trioxlane ring. Here we report the synthesis of an open-cage isomer for C60(O)3 with a ketolactone moiety embedded into the fullerene skeleton through a three-step procedure mediated by fullerene peroxide chemistry. Two fullerene skeleton carbon–carbon bonds are cleaved in the process. The open-cage derivative C60(O)3 can be converted back to C60 through deoxygenation with PPh3. Single crystal X-ray structure confirmed the open-cage structure.