Isolation and characterization of unsymmetrical C60Me5O3H, a cage-opened bisepoxide ketone: Tautomerism involving a fullerene cage bond

Bisepoxide ketone C60Me5O3H, possessing a nine-membered hole in the cage, has been isolated from the reaction of C60Cl6 with methyllithium followed by hydrolysis, It is a tautomer of the recently isolated bisepoxide fullerenol, this tautomerism being the first example. involving a cage C-C bond, and may be driven by cage strain. Like the fullerenol, the ketone gives a high C-58(+) fragmentation ion intensity during El mass spectrometry.