Ring-opening reaction of cyclopropanated [60]fullerenes: unexpected transformation of methano[60]fullerenes having an electron-donating group on the methano-bridge carbon

A series of novel transformations of 60]fullerene derivatives were found, starting from methano60]fullerenes with an electron-donating group on the methano-bridge carbon. Aminomethano60]fullerenes, in situ generated by the treatment of their trifluoromethanesulfonic acid salts with a base, were readily converted into 1-acyl-1,2-dihydro60]fullerenes via the ring opening of the cyclopropane moiety. The aldehyde/ketones thus obtained were easily hydrolyzed to give 1,2-dihydro60]fullerene in the presence of hydroxide anions.