N(OC(C)(C)C)=O.[CH2:8]([O:10][C:11]([C:13]1[N:14]=[CH:15][N:16]([C:18]2[CH:23]=[CH:22][C:21](N)=[CH:20][CH:19]=2)[CH:17]=1)=[O:12])[CH3:9]>CN(C)C=O.[Cl-].[Na+].O>[CH2:8]([O:10][C:11]([C:13]1[N:14]=[CH:15][N:16]([C:18]2[CH:23]=[CH:22][CH:21]=[CH:20][CH:19]=2)[CH:17]=1)=[O:12])[CH3:9]Tert-butyl nitrite (535 mg, 5.19 mmol) in dry dimethylformamide (15 ml) was heated to 65° C. under nitrogen and then 1-(4-aminophenyl)imidazole-4-carboxylic acid ethyl ester (see part (ii)) (800 mg, 3.463 mmol) in dry dimethylformamide (5 ml) was added over 10 minutes. The mixture was heated at 65° C. for a further 20 minutes and then cooled to room temperature. The mixture was poured into saturated brine (50 ml) and extracted with dichloromethane (3×20 ml). The combined organic layers were dried (MgSO4) and concentrated under reduced pressure. Purification by flash chromatography on silica gel eluting with dichloromethane gave the title compound (520 mg, 70%) as an off-white solid.
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