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0 °C

A mixture of 5-cyclopropyl-3-phenyl-isoxazole-4-carboxylic acid (3.72 g, 16 mmol), N,O-dimethylhydroxylamine hydrochloride (2.53 g, 26 mmol), N-methylmorpholine (2.85 mL, 26 mmol) and 4-dimethylaminopyridine (198 mg, 2 mmol) in dichloromethane (50 mL) and DMF (10 mL) was cooled to 0° C. Then 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (3.73 g, 19 mmol) was added and the reaction mixture was stirred at room temperature for 2 h. The reaction mixture was poured into hydrochloric acid (1 N) and extracted with ethyl acetate. The combined organic layers were then washed with a saturated solution of sodium hydrogen carbonate, brine and then dried over sodium sulphate and evaporated to leave a light yellow oil. Purification by chromatography (SiO2, heptane:ethyl acetate=100:0 to 50:50) afforded the title compound (4.03 g, 91%) which was obtained as a colourles oil. MS: m/e=273.0 [M+H]+.

1. extractionextracted with ethyl acetate
2. washThe combined organic layers were then washed with a saturated solution of sodium hydrogen carbonate, brine
3. dry with materialdried over sodium sulphate
4. customevaporated
5. customto leave a light yellow oil
6. customPurification by chromatography (SiO2, heptane:ethyl acetate=100:0 to 50:50)