Hydrochloric Acid → 4-Hydroxy-2,3-dimethylcyclopent-2-en-1-one

Participants

Reaction Conditions

Reaction Steps

In a reaction vessel, water (100 ml) and 5-methyl-2-furylmethylcarbinol (5 g) were charged, and the pH value was adjusted to 5.5 with an aqueous 1/3N NaOH solution and an aqueous 1/3N HCl solution. The temperature was elevated up to 100° C. to reflux, and the mixture was stirred under reflux for 16 hours while maintaining the pH value of 4.0 to 5.7 by the addition of an aqueous 1/3N NaOH solution and an aqueous 1/3N HCl solution. After cooling to 50° C., concentrated hydrochloric acid (10 g; corresponding to 0.9N) was added, and stirring was continued at 50° C. for 22 hours. After cooling, the reaction mixture was neutralized with an aqueous 20% NaOH solution and an aqueous 1/3N NaOH solution. Then, sodium chloride (30 g) was added thereto, and the mixture was extracted with toluene (50 ml) five times. The extract was concentrated at 60° C. under reduced pressure to remove toluene, whereby an oily substance (4.4 g) was obtained. The crude product was subjected to column chromatography with silica gel (60 g) (developing solvent, ethyl acetate-n-hexane (1:2 by volume)), and the objective fraction was concentrated to obtain 2-methyl-3-methyl-4-hydroxy-2-cyclopentenone (3.2 g). Yield, 64%.

Provenance & Evidence