Aniline → 2-(4-Tert-butyl-benzenesulfonylamino)-4-fluoro-benzoic acid

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Reaction Steps

2-Amino-4-fluorobenzoic acid (25 g, 161 mmol) was added to a solution of sodium bicarbonate (54.1 g, 645 mmol) in water (2.4 L) at room temperature and was stirred until homogeneous. The resultant solution was heated to 60° C. in an oil bath. 4-tert-Butylbenzenesulfonyl chloride (45.0 g, 193 mmol), dissolved in 200 mL p-dioxane, was subsequently added dropwise to the stirring aniline solution in a steady stream over a 30 min period. The reaction mixture was stirred at 60° C. overnight. The following day, upon LCMS verification of consumption of the aniline, the solution was poured in a slow stream into one liter of rapidly stirring 2 M HCl/H2O. The resultant precipitate was collected by vacuum filtration, washed thoroughly with water, and dried in vacuo to afford 46 g of 2-(4-tert-butyl-benzenesulfonylamino)-4-fluoro-benzoic acid as an off-white solid (82% yield): HPLC retention time=2.68; MS (ES) M+H expected 352.0, found 352.0.

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