Synthetic Intermediates and Transformations of a-Tocopherol

Synthetic Intermediates and Transformations of a-TocoPHEROL A. Trimethyephytylhydroquinones as Synthetic Intermedutes 

The preparation of a-tocopherol consists in condensing trimethylhydro-quinone with phytol or isophytol (Fig. 3). Under specified experimental 

a-ToCOPHKHOU AND 3,4-DEliyDUO-a-ToOOPHEHOL FROM TkIMETHYE-phytylbenzoquinonb 

Totally racemic 3,4-dehydro-a-tocopherol (Karrer et al., 1940) is a vitamin E active compound. We prepared it from trimethyphytylbenzo- 

A reaction of special interest found in our laboratories is the reductive cyclization of trimethylphytylbenzoquinone into a-tocopherol by means of a series of acidic reagents, e.g., boron trifluoride in petroleum ether (Fig. 12). This transformation which probably involves a hydride transfer reaction, can also be achieved with a-tocopherylquinone (Issidorides, 19. il) and 

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