[CH3:1][N:2]1[CH:6]=[CH:5][C:4]([C:7]2[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=2)=[N:3]1.[CH3:13][N:14]1[C:18]([C:19]2[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=2)=[CH:17][CH:16]=[N:15]1.C1C(=O)N([Br:32])C(=O)C1>C(#N)C>[Br:32][C:5]1[C:4]([C:7]2[CH:8]=[CH:9][CH:10]=[CH:11][CH:12]=2)=[N:3][N:2]([CH3:1])[CH:6]=1.[Br:32][C:17]1[CH:16]=[N:15][N:14]([CH3:13])[C:18]=1[C:19]1[CH:20]=[CH:21][CH:22]=[CH:23][CH:24]=1The mixture of isomers, 1-methyl-3-phenyl-1H-pyrazole and 1-methyl-5-phenyl-1H-pyrazole (1.0 g, 6.3 mmol) and NBS (1.1 g, 6.3 mmol) are combined in acetonitrile (25 ml), stirred and heated to 70° C. for 1 hr. The solution is concentrated and the crude product is purified by chromatography using a hexane-ethyl acetate gradient (100% hexane to 25% ethyl acetate in hexane) to elute 4-bromo-1-methyl-3-phenyl-1H-pyrazole (504 mg, 34% yield) and 4-bromo-1-methyl-5-phenyl-1H-pyrazole (295 mg, 20% yield), respectively:
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