Sulfuric Acid → (S)-(+)-6-hydroxy-2,5,7,8-tetramethylchroman-2-methanol

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Reaction Steps

A mixture of 0.59 g of (3S,9aR)-(-)-2,3,4,5,7,9a-hexahydro-5-hydroxy-3,6,8,9-tetramethyl-3,9a-epoxy-1-benzoxepin-7-one, 0.7 g of palladium-on-barium sulfate (5% by weight) and 3 drops of concentrated perchloric acid in 20 ml of methanol was hydrogenated with ca 120 ml of hydrogen under normal pressure. Subsequently, 2 ml of 2-N sulfuric acid were added and air was conducted into the mixture for 15 hours. The reaction mixture was again hydrogenated with ca 25 ml of hydrogen. After removal of the catalyst by filtration over Hyflo, the filtrate was treated with dilute sodium bicarbonate solution and extracted with ether. The combined organic phases were dried over magnesium sulfate. After distillation of the solvent on a rotary evaporator, there were obtained 0.62 g of brown crystals, which, for purification, was chromatographed on Kieselgel with acetic ester/toluene (1/1 parts by volume). The resulting (S)-(+)-6-hydroxy-2,5,7,8-tetramethylchroman-2-methanol crystallized from methylene chloride/hexane at a yield of 487 mg; melting point 126.5°- 128.5°.

Provenance & Evidence