[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 (Intermediate 7) 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 was separated and washed with brine. Drying (MgSO4) and removal of solvent gave 1.5 g of 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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