Tetrahydrofuran → 7-Formyl-3,11,15-trimethyl-2,6,10,14-hexadecatetraen-1-ol tetrahydropyranyl ether

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Reaction Steps

In 300 ml of anhydrous tetrahydrofuran was suspended 58.6 g of (E)-4-methyl-6-(2'-tetrahydropyranyloxy)-4-hexen-1-yltriphenylphosphonium iodide [R. Tschesche and J. Reden, Ann. 853 (1974)]. To this suspension was added dropwise the equimolar amount of a n-butyllithium-hexane solution at -20° C. in a stream of nitrogen. The mixture was stirred, and to this was further added 25.4 g of (E)-1,1-dimethoxy-6,10-dimethyl-5,9-undecadien-2-one (prepared in Referential example 1) in 50 ml of anhydrous tetrahydrofuran. The reaction mixture was stirred at room temperature for 3 hours, and, after addition of ice-water, extracted with n-hexane. The so obtained crude oil was suspended in 300 ml of 50% acetic acid, and stirred at room temperature for 2 hours. There was obtained 28.0 g of 7-formyl-3,11,15-trimethyl-2,6,10,14-hexadecatetraen-1-ol tetrahydropyranyl ether from the n-hexane extract. The obtained product was dissolved in 200 ml of ethanol and, after addition of 1.5 g of sodium borohydride, stirred for 2 hours under ice-cooling. This was treated with dilute acetic acid and, after addition of water, extracted with n-hexane. The resultant was dissolved in 200 ml of methanol. To this was added 200 mg of p-toluenesulfonic acid, and the resulting solution was allowed to stand overnight and neutralized with an aqueous sodium hydrogencarbonate solution. After evaporation of the methanol, the residue was extracted with ether, and from the extract was obtained an oil. The so obtained oil was then chromatographed on silica gel to yield 18.2 g of a mixture of the (E,Z,E) and (E,E,E) isomers of 7-hydroxymethyl-3,11,15-trimethyl-2,6,10,14-hexadecatetraen-1-ol.

Provenance & Evidence