Water → 2-Propargyl-3-hydroxy-3-methyl-4-cyclopentenone

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In a reaction vessel, water (1600 ml), anhydrous sodium acetate (0.4 g) and 5-methyl-2-furylpropargylcarbinol (20 g) were charged, and the temperature was elevated to reflux. The pH value was adjusted to 4.5 with an aqueous 0.5 N acetic acid solution, and the mixture was stirred under reflux for 13 hours while maintaining a pH value of 4.0 to 5.0 by the addition of an aqueous 1/3 N NaOH solution. Then, the reaction mixture was cooled to 40° C., neutralized with an aqueous 1/3 N NaOH solution and, after addition of sodium chloride (300 g), extracted with methyl isobutyl ketone (400 ml) five times. From the extract, methyl isobutyl ketone was removed by distillation at 60° c. under reduced pressure to give an oily substance (16 g), which was subjected to distillation under reduced pressure to obtain 2-propargyl-3-hydroxy-3-methyl-4-cyclopentenone (14.8 g). Yield, 74%. B.P., 115°-132° C./0.1 mmHg. nD25 1.5124. C13NMR spectrum (CDCl3, internal standard TMS, δ ppm, 22.6 MHz): 206.2 (1-C); 167.8 (5-C); 130.7 (4-C); 82.0 (--CH2 -C≡CH); 78.5 (3-C); 70.6 (--CH2 --C≡CH); 57.0 (2-C); 23.4 (--CH3); 14.7 (--CH2 --C≡CH).

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