Methylglyoxal → (RS)-2-methyl-3-(2,2,2-trifluoroethyl)-4-oxocyclopent-2-en-1-ol

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Reaction Conditions

Reaction Steps

98.8 g of the ethyl 4,4,4-trifluorobutyrylacetate thus obtained was added to 250 ml of a 10% sodium hydroxide solution and vigorously stirred for 12 hours. The pH value of the reaction solution was brought 7.5 with a 10% aqueous sulfuric acid solution. Then 250 ml of toluene, 2.86 g of sodium hydrogencarbonate and 6.43 g of hydrosulfite were added to the solution under an atmosphere of nitrogen and warmed to 37° C. 90 g of methyl glyoxal was added over 1 hour and allowed to react for 12 hours. After 50 g of sodium chloride was added to the solution, the mixture was extracted three times with ethyl acetate. The ethyl acetate layers were combined and dried over anhydrous magnesium sulfate. After removal of the drying agent, the solvent was removed under reduced pressure. The obtained residue was mixed with 450 ml of 5% sodium hydroxide solution and vigorously stirred under ice-water cooling. The pH of the solution was adjusted to 7.3 with a 10% hydrochloric acid solution and then extracted three times with ethyl acetate. The ethyl acetate layer was combined and dried over anhydrous magnesium sulfate. After removal of the drying agent, the solvent was removed under reduced pressure. The obtained residue was distilled under reduced pressure to afford 45 g of the desired (RS)-2-methyl-3-(2,2,2-trifluoroethyl)-4-oxocyclopent-2-en-1-ol in a yield of 50%. (b.p. 100°-133° C., 0.52 mmHg)

Provenance & Evidence