Ammonium Chloride → 5-Butyl-4-methyldihydro-2(3H)-furanone, trans-

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Reaction Conditions

Reaction Steps

In 20 ml of anhydrous ether, 1.98 g of copper iodide (10.4 mmol were suspended. To the resultant suspension, 20.8 ml of n-propyl lithium solution (1 N, 20.8 mmol) were added dropwise under an argon atmosphere with cooling at -50° C. The reacted solution was added dropwise to 25 ml of anhydrous ether solution containing 1.0 g of epoxide (6.94 mmol) obtained in step [C'] under an argon atmosphere at -60° C. Next, the temperature of the reacted solution was raised from -60° C. to -20° C. over three hours. After that, the solution was poured into a saturated aqueous ammonium chloride solution, followed by stirring for thirty minutes. Next, the solution was filtered to remove insoluble substances. The obtained filtrate was extracted with ether. The resultant extract was then washed with water and a saturated aqueous sodium chloride aqueous solution, in this order, dried with anhydrous magnesium sulfate, and filtered. The obtained filtrate was concentrated, and the obtained residue was dissolved in 20 ml of methanol. To the obtained solution was then added 20 ml of a 10% aqueous sodium hydroxide solution, followed by stirring at room temperature for three hours. Next, the methanol in the solution as distilled off under reduced pressure, and the obtained residue was extracted twice with diethyl ether and then the organic layer was separated from the obtained extract. Also, the residual aqueous layer was acidified with dilute hydrochloric acid, and then extracted five times with diethyl ether. The obtained extract was combined with the organic layer obtained before. The combined organic layer was dried with anhydrous magnesium chloride, and concentrated to obtain a crude product. This crude product was purified via silica gel column chromatography (n-hexane:ethyl acetate=10:1 to 5:1), and distilled under reduced pressure to obtain 823 mg of trans-whisky lactone (yield: 76.2%). This product exhibited the same physical properties as that of the trans-whisky lactone obtained in Example 1.

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