Selective Synthesis of Cis-1 and Cis-2 Bisaziridino[60]fullerenes in the Presence of Stoichiometric Amounts of Cu(OTf)2.

The development of methods for the selective functionalization of C60 fullerene to form bis-adducts with a specified symmetry remains an urgent task. A strategy for the targeted synthesis of regioisomeric cis-1 and cis-2 bis-6,6-aziridinofullerenes using stoichiometric amounts of Cu(OTf)2 as a controlling reagent is proposed for the first time in this work. It is shown that the reaction between C60 and organic azides in chlorobenzene at 100 °C in the presence of 100 mol % Cu(OTf)2 leads to the exclusive formation of cis-1 regioisomers in the case of linear or aromatic azides (butyl, octyl, and benzyl azides) with yields of 30-35%. Conversely, the use of branched or bulky azides (tert-butyl, isobutyl, cyclohexyl, and cycloheptyl azides) gives selectively the cis-2 regioisomers with comparable yields. The structure and regiochemistry of the obtained compounds were unambiguously established by mass spectrometry (APCI) together with 1H and 13C NMR spectroscopy combined with quantum chemical calculations. A plausible mechanism is proposed, and it involves the coordination of Cu(II) with nitrogen atom of a monoaziridine fragment, thereby directing the attack of the second nitrene intermediate. The developed approach paves the way for the precision synthesis of bisaziridinofullerenes with a specified addition pattern for applications in molecular electronics and asymmetric catalysis.