Azobisisobutyronitrile → 2-(4-Fluoro-2-methoxy-phenyl)-5-(5-methoxymethyl-3-phenyl-isoxazol-4-yl)-[1,3,4]oxadiazole

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Reaction Conditions

Reaction Steps

To a solution of 2-(4-fluoro-2-methoxy-phenyl)-5-(5-methyl-3-phenyl-isoxazol-4-yl)-[1,3,4]oxadiazole (1.95 g, 5.56 mmol) in carbon tetrachloride (20 ml) was added N-bromo succinimide (990 mg, 5.56 mmol) and 2,2′-azobis(2-methylpropionitrile) (46 mg, 0.28 mmol) and the reaction mixture was stirred for 4 h at 70° C. Further 2,2′-azobis(2-methylpropionitrile) (46 mg, 0.28 mmol) was added and stirring was continued for another 14 h at 70° C. N-Bromo succinimide (378 mg, 2.12 mmol) was added and the mixture stirred for another 4 h at 90° C. After the reaction mixture was cooled to 0° C. the suspension was filtered off and was washed with dichloromethane (30 mL) and aqueous sodium hydrogencarbonate (1 N).It was extracted with dichloromethane and dried over sodium sulfate resulting in crude material (1.66 g). A part of this light brown solid (200 mg) was dissolved in tetrahydropyran (2 mL), sodium methoxide (30% in methanol, 0.43 ml, 2.32 mmol) was added and the resulting mixture was stirred for 1 h at ambient temperature. It was diluted with ethyl acetate (20 mL) and washed aqueous ammonium chloride (saturated). The aqueous layers were extracted with ethyl acetate and the combined organic layers were dried over sodium sulfate. Purification by chromatography (SiO2, heptane:ethyl acetate:dichloromethane=70:10:20 to 40:40:20) afforded the title compound (25 mg, 14%) as a white solid. MS: m/e=382.3 [M+H]+.

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