Synthesis of (MeO)₂Bn₂C₇₀: Regiochemistry of 2-fold Additions to C₇₀ with Addends That Are Preferential for Ortho...

Three C₇₀ tetraadducts, 2,10-(MeO)₂-5,9-Bn₂C₇₀ (6), 1,56-Bn₂-2,57-(MeO)₂C₇₀ (7, 2 o'clock isomer), and 1,41-Bn₂-2,58-(MeO)₂C₇₀ (8, 12 o'clock isomer), were obtained from the reaction of C₇₀ with MeO^- and BnBr (benzyl bromide). The structures of 6-8 were resolved via single-crystal X-ray diffraction and spectroscopic characterizations. Computational calculations on the electrophilic Fukui functions f_k⁺, the stability of reaction intermediates, and activation barriers for the key processes of the reaction were performed to rationalize the regioselectivity of the reaction. A conversion of the 5 and 12 o'clock intermediates to the 2 o'clock intermediate was proposed to account for the regioselectivity related to the 2-fold additions at the two distinctive polar regions of C₇₀. Electrochemical study showed a similar electron deficiency for the 2 and 12 o'clock isomers, while the 2,5,9,10-tetraadduct was more electron deficient with respect to the 2 and 12 o'clock isomers.