Concerning the chemistry of vitamin E. 7. The stereospecific cyclization of (3'R, 7'R, 11'R)-alpha-tocopherolquinone

Stereospecific cyclizations of (3′R, 7′R, 11′R)-α-tocopherolquinone (2) are reported: Treatment with conc. sulfuric acid in methanol at 0-5° gave (2R, 4′R, 8′R)-α-tocopherol (1a) with complete retention of configuration at C-3′.