[Cl:1][C:2]1[CH:7]=[C:6]([Cl:8])[CH:5]=[CH:4][C:3]=1[C:9]1[C:10]([C:18]#[N:19])=[CH:11][C:12]2[N:13]([CH:15]=[CH:16][N:17]=2)[CH:14]=1.[N+:20]([O-])([OH:22])=[O:21].O>OS(O)(=O)=O>[Cl:1][C:2]1[CH:7]=[C:6]([Cl:8])[CH:5]=[CH:4][C:3]=1[C:9]1[C:10]([C:18]#[N:19])=[CH:11][C:12]2[N:13]([C:15]([N+:20]([O-:22])=[O:21])=[CH:16][N:17]=2)[CH:14]=1To a solution of 6-(2,4-dichloro-phenyl)-imidazo[1,2-a]pyridine-7-carbonitrile (3.07 g, 6.10 mmol, prepared according to Example 3, Step 2.3) in concentrated H2SO4 (55 mL) was added a freshly prepared mixture of fuming HNO3 in H2SO4 (1:2, v/v, 2.55 mL) at RT. The reaction mixture was stirred at RT for 2 h then cautiously added to cold water (300 mL) and extracted with DCM (5×). The combined organic fractions were dried over Na2SO4, filtered, and evaporated to dryness to give the crude 6-(2,4-dichloro-phenyl)-3-nitro-imidazo[1,2-a]pyridine-7-carbonitrile as a brown solid (533 mg). MS: 333 [M+1]+; HPLC: AtRet=1.57.
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