C(=O)([O-])O.[Na+].S([O-])([O-])=O.[Na+].[Na+].[Br:12][C:13]1[CH:18]=[C:17]([F:19])[CH:16]=[CH:15][C:14]=1[S:20](Cl)(=[O:22])=[O:21].[CH3:24]I>O.O1CCOCC1.CN(C=O)C>[Br:12][C:13]1[CH:18]=[C:17]([F:19])[CH:16]=[CH:15][C:14]=1[S:20]([CH3:24])(=[O:22])=[O:21]Sodium hydrogen carbonate (1.59 g, 18.87 mmol) and sodium sulfite (1.59 g, 12.58 mmol) were heated in water (10 mL) at 70° C. for 5 min. A mixture of 2-bromo-4-fluoro-benzene sulfonyl chloride (1.72 g, 6.29 mmol) in dioxane (15 mL) was added to the base solution and stirred at 70° C. overnight. The solvents were removed in vacuo, DMF (15 mL) and methyl iodide (0.43 mL, 6.85 mmol) were added and reaction mixture stirred at 40° C. overnight. The reaction mixture was concentrated in vacuo, EtOAc (10 ml) added, washed with water (90 ml) and concentrated in vacuo to leave a colourless oil. The resulting oil was purified by flash chromatography (0-10% EtOAc in petroleum ether (40:60) followed by 100% MeOH) to afford 2-bromo-4-fluoro-1-(methylsulfonyl)benzene as an orange oil (1.3 g, 81%).
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