Trimethyl orthoformate → 1-(2,6-Dichloro-4-trifluoromethylphenyl)-5-methoxymethylideneamino-3-(1,2,4-oxadiazol-3-yl)-4-trifluoromethylsulfonylpyrazole

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Reaction Steps

To 5-amino-1-(2,6-dichloro-4-trifluoromethylphenyl)-3-(1,2,4-oxadiazol-3-yl)-4-trifluoromethylsulfonylpyrazole (1.00 g, 2.02 mmol) and 10 ml of trimethyl orthoformate was added p-toluenesulfonic acid monohydrate (0.05 g) with stirring at room temperature. The mixture was stirred with heating at reflux for 59 hours. The reaction mixture was cooled to room temperature and then concentrated under reduced pressure. The residue was dissolved in 50 ml of toluene and then concentrated under reduced pressure. After this procedure was repeated once again, the resulting concentrated residue was purified by subjecting to silica gel column chromatography [eluent: mixed solvent of ethyl acetate and chloroform (volume ratio=1:20)]. The resulting crystal was washed with hexane and filtered to obtain 124 mg (0.46 mmol) of the title compound as a colorless crystal. Yield 23.0%.

Provenance & Evidence