1210906-15-2

Conditions: temp:100.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Triethylamine (1.14 mL, 8.18 mmol) and propylphosphonic anhydride (cyclic trimer) (ca. 1.7 M solution in ethyl acetate, 4.8 mL, 8.18 mmol) were added in this order to a solution of 5-bromo-2-(trifluoromethoxy)benzaldehyde (2.00 g, 7.43 mmol) and hydroxyamine hydrochloride (568 mg, 8.18 mmol) in DMF (7.5 mL), and the mixture was stirred at 100° C. for 8 hours. The reaction solution was poured to a saturated sodium bicarbonate aqueous solution, followed by extraction with ethyl acetate. The obtained organic layer was washed with brine and dried over anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure. The obtained residue was purified by silica gel column chromatography [elute: hexane/ethyl acetate=100/0-98/2] to obtain the title compound (1.71 g, yield: 86%). followed by extraction with ethyl acetate The obtained organic layer was washed with brine dried over anhydrous sodium sulfate the solvent was distilled off under reduced pressure The obtained residue was purified by silica gel column chromatography [elute: hexane/ethyl acetate=100/0-98/2]