[Cl:1][C:2]1[CH:3]=[CH:4][C:5]2[N:6]([C:8]([CH3:15])=[C:9]([C:11]([F:14])([F:13])[F:12])[N:10]=2)[N:7]=1.[Br:16]N1C(=O)CCC1=O.N(C(C)(C)C#N)=NC(C)(C)C#N>C(#N)C>[Br:16][CH2:15][C:8]1[N:6]2[N:7]=[C:2]([Cl:1])[CH:3]=[CH:4][C:5]2=[N:10][C:9]=1[C:11]([F:14])([F:13])[F:12]A mixture of 6-chloro-3-methyl-2-(trifluoromethyl)imidazo[1,2-b]pyridazine x35 (3.45 g, 1 eq, 14.64 mmol), N-bromosuccinimide (NBS; 2.87 g, 1.1 eq, 16.11 mmol) and azo-bis-iso-butyronitrile (AIBN; 240 mg, 0.1 eq, 1.5 mmol) in acetonitrile (50 ml) is refluxed for 2 hours. After cooling to room temperature, the solvent is removed under reduced pressure and the crude product is purified by preparative chromatography on silicagel (CH2Cl2) affording 3-(bromomethyl)-6-chloro-2-(trifluoromethyl)imidazo[1,2-b]pyridazine x36.
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