[Br:1]Br.[Cl:3][C:4]1[CH:5]=[C:6]([C:10]([O:12][CH2:13][CH3:14])=[O:11])[NH:7][C:8]=1[CH3:9].CCN(CC)CC.OS([O-])=O.[Na+]>C(Cl)Cl>[Br:1][C:5]1[C:4]([Cl:3])=[C:8]([CH3:9])[NH:7][C:6]=1[C:10]([O:12][CH2:13][CH3:14])=[O:11]Bromine (0.56 ml, 11 mmol) was added to a solution of 1 g (5.3 mmol) of ethyl 4-chloro-5-methyl-1H-pyrrole-2-carboxylate (WO2006087543) and 0.8 ml (5.7 mmol) Et3N in CH2Cl2. After stirring at room temperature for 2 h, aqueous NaHSO3 was added and the CH2Cl2 was removed and the aqueous residue was partitioned between water and EtOAc. The EtOAc layer was separated and washed with brine. The EtOAc layer was dried over anhydrous MgSO4, and the solvent was removed to give 1.5 g of the product as a solid. MS (ES) (MH+): 240 for C8H9BrClNO2; NMR (d6-DMSO): 1.3 (t, 3H), 2.2 (s, 3H), 4.2 (q, 2H), 12.3 (s, 1H).
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