Hydrochloric Acid → 4-Hydroxy-4-methyl-5-(prop-2-en-1-yl)cyclopent-2-en-1-one

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Reaction Conditions

Reaction Steps

In a reaction vessel, water (150 ml) and tri-n-octylmethylammonium chloride (450 mg) were charged, and the pH value was adjusted to 5.5 with an aqueous 1/3 N HCl solution and an aqueous 1/3 N NaOH solution. Then, 5-methyl-2-furylallylcarbinol (11.0 g) was added thereto, and the temperature was elevated up to 100° C. to reflux. The mixture was stirred under reflux for 7 hours while maintaining a pH value of 5 to 5.5 by the addition of an aqueous 1/3 N NaOH solution and an aqueous 1/3 N HCl solution. After cooling to 40° C., sodium chloride (30 g) was added, and the mixture was extracted with toluene (70 ml) five times. From the extract, toluene was removed by distillation at 60° C. under reduced pressure to give an oily substance (10.1 g), which was subjected to chromatography on silica gel (100 g) with a mixture of ethyl acetate-n-hexane (1:2 by volume) as the developing solvent to obtain 2-allyl-3-hydroxy-3-methyl-4-cyclopentenone (7.1 g). Yield, 64.5%.

Provenance & Evidence