Synthesis of the a-Tocopherol Metabolite

Experiments performed by Corwin and Schwarz (1960) gave evidence that the a-tocopherol metabolite (X) (Fig. 7) exerts tocopherol-like activity in the respiratory decline test. In order to mal e some material available for further biological testing, the tritium-labeled y-lactone (X) was synthesized following the lines given by Weichet et al. (1959)  

The ethynyl-7-lactone (XI), prepared from levulinic acid as indicated in Fig. 7, was partially tritiated to give the labeled vinyl-7-lactone (XII). 

Condensation with trimethylhydroquinone in the presence of BFa, ZnCU and acetic anhydride yielded the ehroman derivative (XIII). Subsequent acid hydrolysis and oxidation under acid conditions gave the desired racemic 7-lactone (X) (specific activity of 164 Mc/mg). 

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