Regioselective Electrochemical Hydroalkylations of[6o]Fullerene-Fused Furochromenone

Regioselective electrochemical hydroalkylations of[60]fullerene-fused furochromenone with alky halides under different acidic con-ditions unexpectedly afford three types of tetra-functionalized[60]fullerene derivatives in high yields.When acetic acid is used as the proton source,two 1,2,3,4-adducts with retained or rearranged five-membered heterocycle are obtained as major and minor products,respectively.While trifluoroacetic acid is employed as the proton source,1,2,3,16-adducts and 1,2,3,4-adducts,both with the five-membered heterocycle rearranged from[6,6]-junction to[5,6]-junction,are generated.Intriguingly,the obtained 1,2,3,16-adducts can be transformed into 1,2,3,4-adducts accompanied by rearrangement of the fused five-membered heterocycle from[5,6]-junction to[6,6]-junction.These products have been characterized by spectroscopic data and single-crystal X-ray analysis.Moreover,the two 1,2,3,4-adducts with the heterocycle fused to[5,6]-junction or[6,6]-junction show diagnostic UV-vis spectra,which may be useful for the identification of these two types of 1,2,3,4-adducts in the future.A plausible reaction mechanism has been proposed to elucidate the formation of hydroalkylation products in the presence of different acids.