Cyclopropanations between C60 and readily available malonates bearing different steroid moieties, I [R = CH2CH2CHMe2, CH2CHEtCHMe2-(R)] and II, by the Bingel-Hirsch protocol has allowed the synthesis of a new series of hybrid functionalized chimeras [III (X1-X2 = C60-fullerene) and IV]. Whereas cycloadducts III showed the expected chem. structures, the presence of the diene moiety in the ergosterol unit of malonate II resulted in the prodn. of the corresponding cycloadduct with an addnl. oxygen mol. A thorough spectroscopical study (1H and 13C NMR, COSY, DEPT, HMQC, and HMBC) allowed the structure of monocycloadduct IV to be unambiguously unraveled as that of an endoperoxide, as a result of the sensitizing effect of the C60 unit, which efficiently promotes the addn. of excited singlet oxygen to the diene moiety of the steroid. Cyclic voltammetry of hybrids III and IV, as well as their electronic spectra, support the exclusive formation of the corresponding monoadducts.