[Br:1]Br.[C:3]1([N:9]2[CH:13]=[CH:12][CH:11]=[N:10]2)[CH:8]=[CH:7][CH:6]=[CH:5][CH:4]=1.O.C([O-])(O)=O.[Na+]>C(O)(=O)C.C(OCC)(=O)C>[Br:1][C:12]1[CH:11]=[N:10][N:9]([C:3]2[CH:4]=[CH:5][CH:6]=[CH:7][CH:8]=2)[CH:13]=1A solution of bromine (1.1 g, 6.94 mmol) in acetic acid (10 mL) was added to a mixture of 1-phenylpyrazole (Aldrich, 1 g, 6.94 mmol) in acetic acid (10 mL). This mixture was warmed to 100° C. in a pressure tube for 8 h. The material was cooled to ambient temperature, poured into ice and H2O neutralized with excess saturated, aqueous NaHCO3. Ethyl acetate (50 mL) was added and the layers were separated. The aqueous layer was extracted with EtOAc (2×15 mL) and the combined organic extract was dried over Na2SO4 and concentrated under reduced pressure to give a crude solid. Purification by column chromatography (SiO2, 50% hexanes-EtOAc) provided the title compound (1.5 g, 6.72 mmol, 97% yield). MS (DCl/NH3) m/z 223, 225 (M+H)+.
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