Boron trifluoride etherate → alpha-Tocopherol

Beteiligte Stoffe

Reaktionsschritte

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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