Boron trifluoride etherate → alpha-Tocopherol

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The reaction of isophytol or phytol with TMHQ is well known. One method that has been employed with phytol is described in Japan Kokai No. 73 48,472 [Chem. Abstr. 79, 105067m (1973)]. It was discovered that a similar method could also be applied successfully in condensation of TMHQ with dehydrophytol. Essentially, 2.5 grams TMHQ and 0.1 gram aluminum powder were placed in a flask to which was added 35 mls. of ethyl acetate containing 1 ml. of boron trifluoride etherate. While stirring, 4 grams of dehydrophytol was added slowly and the mixture was refluxed for 4 hours at 80°. This gave 5.0 grams of crude dehydrotocopherol (dehydro-Vitamin E) after work-up and removal of unreacted starting materials. A portion of the dehydrotocopherol obtained (1.0 gram) was conveniently hydrogenated in 30 mls. glacial acetic acid containing 0.5 gram of 5% Pd on BaSO4. Shaking for 8 hours under 52 psig H2 pressure and ambient temperature provided 1.0 gram of crude α-tocopherol (Vitamin E). The present invention has been described with reference to the use of beta-myrcene to produce chloromyrcene (3-chloro-6-methylene-2-methylocta-1,7-diene) which is then coupled with 3,7-dimethyloctyl magnesium chloride. The invention is equally applicable to the use of alpha-myrcene, or alpha- or beta-ocimene.

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