Isolation and characterization of unsymmetrical C(60)Me(5)O(3)H, a cage-opened bisepoxide ketone: tautomerism involving a fullerene cage bond.

Bisepoxide ketone C(60)Me(5)O(3)H, possessing a nine-membered hole in the cage, has been isolated from the reaction of C(60)Cl(6) 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 EI mass spectrometry.