N[C:2]1[C:10]2[NH:9][C:8](=[O:11])[NH:7][C:6]=2[CH:5]=[C:4]([C:12]([F:15])([F:14])[F:13])[CH:3]=1.[I-:16].[Cs+].II.N(OCCC(C)C)=O>C(Cl)Cl.[Cu]I>[I:16][C:2]1[C:10]2[NH:9][C:8](=[O:11])[NH:7][C:6]=2[CH:5]=[C:4]([C:12]([F:15])([F:14])[F:13])[CH:3]=1
(Analogous to the procedure described in Heterocycles, 2001, 55, 461-464). To a solution of 4-amino-6-(trifluoromethyl)-1,3-dihydro-2H-benzimidazol-2-one from step (a) above (0.76 g, 3.5 mmol) in 20 mL of DCM was added CsI (0.91 g, 3.5 mmol), I2 (0.44 g, 1.75 mmol), and CuI (0.2 g, 1.06 mmol). To the mixture was added isoamyl nitrite (2.8 mL, Aldrich) and the reaction mixture was heated at 60° C. with stirring for 3 h. The reaction mixture was cooled to room temperature, filtered, and the filtrate was diluted with EcOAc (60 mL). The solution was washed with 25% NH4OH (2×30 mL), 5% Na2S2O3 (20 mL) and brine, dried over MgSO4 and filtered. The filtrate was evaporated and the residue was purified by silica gel column chromatography, eluting with 30% EtOAc/hexane to give the title compound as a brown solid. MS (ESI, pos. ion) m/z: 329 (M+1)
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