Hydrochloric Acid → 3-(Trifluoromethyl)-1,2-oxazol-5-amine

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Reaction Steps

Sodium metal (0.48 g, 0.0210 mole, 1.5 eq.) was added to dry methanol (28 ml) and 97% hydroxylamine hydrochloride (1.50 g, 0.0210 mole, 1.5 eq.), obtained from Nakarai Chemicals, was then added to the resulting solution with ice cooling. After being stirred at room temperature for 15 minutes, 3-methoxy-3-(trifluromethyl)acrylonitrile (2.12 g, 0.0140 mole) was added and heated under reflux for 16 hours. To the solution was then added 36% hydrochloric acid (3.54 g, 0.0350 mole, 2.5 eq.) and it was heated under reflux for 1 hour. Methanol was distilled off at atmospheric pressure over 1 hour by using a distillation apparatus equipped with a fractionating column. Water (28 ml) was added to the residue and it was extracted with methylene chloride after pH being adjusted above 11 with 48 sodium hydroxide. The extract was dried with anhydrous sodium sulfate and it was distilled at atmospheric pressure and then under reduced pressure at room temperature by using a distillation apparatus equipped with a fractionating column to give the crude title compound (0.8968 g). This product was purified by column chromatography on silica gel to give the title compound (0.2201 g, 10.3%) and 3-trifluoromethyl-5-aminoisoxazole (0.4738 g, 22.3%).

Provenance & Evidence