[Br:1][C:2]1[CH:3]=[CH:4][C:5](F)=[N:6][CH:7]=1.[CH2:9]([O:11][C:12]([CH:14]1[CH2:18][CH2:17][N:16]([CH3:19])[C:15]1=[O:20])=[O:13])[CH3:10].C(=O)([O-])[O-].[Cs+].[Cs+].CS(C)=O>C(O)(=O)C>[CH2:9]([O:11][C:12]([C:14]1([C:5]2[CH:4]=[CH:3][C:2]([Br:1])=[CH:7][N:6]=2)[CH2:18][CH2:17][N:16]([CH3:19])[C:15]1=[O:20])=[O:13])[CH3:10]
A mixture of 5-bromo-2-fluoro-pyridine (3.45 g), 1-methyl-2-oxo-pyrrolidine-3-carboxylic acid ethyl ester (5.00 g), cesium carbonate (12.77 g), and dimethyl sulfoxide (10 mL) was stirred at 100° C. overnight. After cooling to room temperature, acetic acid (4.5 mL) was added and the resulting solution was extracted with ethyl acetate. The extract was washed with brine, dried (MgSO4), and concentrated. The residue was chromatographed on silica gel (dichloromethane/ethyl acetate 1:0→1:1) to give the title compound as an oil. Yield: 3.92 g (61% of theory); Mass spectrum (ESI+): m/z=327/329 (Br) [M+H]+.
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