Sodium Chloride → 4-Tetrahydropyranyloxy-2-(6-tetrahydropyranylcarboxyhexyl)cyclopent-2-en-1-one

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Reaction Steps

To a stirred solution of 5.59 g. (24.6 mmoles) of 4-hydroxy-2-(6-carboxyhexyl)cyclopent-2-en-1-one (Example 2) and 20.7 g. (246 mmoles) of dihydropyran in 100 ml. of methylene chloride at 20° C. is added 47 mg. (0.246 mmoles) of p-toluenesulfonic acid monohydrate in one portion. The temperature is maintained at 20°-25° C. by cooling and is stirred for one hour at that temperature. The solution is diluted with 200 ml. of ether and poured into a mixture of 40 ml. of saturated sodium bicarbonate solution, 40 ml. of saturated sodium chloride solution, and 80 ml. of water. The phases are separated, and the aqueous phase is extracted with additional ether. The total extract is washed successively with water and saturated sodium chloride solution, dried over potassium carbonate, and freed of volatile matter by concentration at reduced pressure to give an oil, λmax.MeOH =223 mμ(9500); νmax. 1730 (ester carbonyl group), 1705 (ketone carbonyl group), and 1030 cm-1 (tetrahydropyranyloxy groups).

Provenance & Evidence