To a slurry of 2-fluoro-4-formylbenzoic acid (0.600 g, 3.57 mmol) in 10 mL anhydrous DCM under nitrogen was added 3 drops DMF, followed by oxalyl chloride (0.380 mL, 4.28 mmol). The reaction was allowed to stir under N2. The reaction was allowed to stir for 4 h and concentrated in vacuo to a yellow oil. This material was dissolved in 10 mL THF and was added via pipette to a slurry of 2-amino-4-(phenylthio)phenol hydrochloride (0.906 g, 3.57 mmol) and diisopropylethylamine (1.55 mL, 8.92 mmol) in THF at 0° C. The bright yellow slurry was allowed to stir overnight. The mixture was treated with 1N HCl and DCM, and the organic layer was extracted 1×DCM. The organics were dried, filtered, and concentrated in vacuo. The orange oil was dissolved in 5 mL DCM, and a thick yellow precipitate resulted. This was collected by filtration, rinsing with DCM to give 2-fluoro-4-formyl-N-(2-hydroxy-5-(phenylthio)phenyl)benzamide as a bright yellow solid. MS (ESI) m/z: Calculated: 367.1; Observed: 366.0 (M−−1).
