Synthesis of [60]- and [70]Fullerene-Fused Tetrahydroquinoxaline Derivatives by Oxidative [4 + 2] Cycloaddition with Unusual Reactivity and Regioselectivity.

Abstract

The oxidative [4 + 2] reaction of o-phenylenediamine-derived disulfonamides with fullerene C60 and C70 is reported, in which electron-deficient reactants showed high reactivity. The reaction of C70 exhibited unusual regioselectivity, yielding a [5,6]-adduct as the major product, which was characterized by 1H, 13C NMR and single-crystal X-ray diffraction. DFT calculations revealed the reaction is an inverse-electron-demand Diels-Alder (IEDDA) reaction, and the [5,6]-adduct of C70 is a kinetic product.