Stabilization and first direct spectroscopic evidence of the o-quinone methide derived from vitamin E.

[reaction: see text] The o-quinone methide (2) derived from vitamin E (1) can be stabilized at low temperatures in a complex with the highly polar N-methylmorpholine-N-oxide (5). The lifetime of 2 can thus be prolonged from less than 10 s to several minutes. In the complex formed, 2 adopts a zwitterionic, aromatic structure with the exocyclic methylene group in perpendicular arrangement to the ring plane, stabilized by the negatively charged oxygen in 5.