[Br:1][C:2]1[CH:7]=[CH:6][N:5]=[C:4]([N:8]([C:16]([CH:18]2[CH2:20][CH2:19]2)=[O:17])C(=O)OC(C)(C)C)[CH:3]=1.FC(F)(F)C(O)=O.O.C([O-])(O)=O.[Na+]>C(Cl)Cl>[Br:1][C:2]1[CH:7]=[CH:6][N:5]=[C:4]([NH:8][C:16]([CH:18]2[CH2:19][CH2:20]2)=[O:17])[CH:3]=1Dissolve tert-butyl N-(4-bromo-2-pyridyl)-N-(cyclopropanecarbonyl)carbamate (900 mg, 2.8 mmol) in DCM (8 mL), add slowly trifluoroacetic acid (4 mL). Stir the reaction at room temperature for 3 hrs. Pour the reaction mixture to water (50 mL), adjust to pH=7 with saturated NaHCO3 solution. Extract with EtOAc (15 mL×3), combine the organic layers; wash with brine (100 mL), dry over anhydrous Na2SO4. Concentrate under reduced pressure to give the crude product (670 mg) which is used without further purification. MS: (M+1): 243.1.
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