Step 1: Synthesis of 1,2-difluoro-4-methanesulfonylbenzene; a mixture of thionyl chloride (12.73 mL, 0.175 mol) and methanesulfonic acid (28.4 mL, 0.438 mol) was heated and refluxed overnight, and subsequently cooled to 80 °C. At this temperature, 1,2-difluorobenzene (8.64 mL, 88 mmol) and trifluoromethanesulfonic acid (0.675 mL, 8.8 mmol) were added dropwise. The reaction mixture was continued to be heated at 120 °C for 3 h, after which it was cooled to room temperature and poured into ice water (200 mL). The mixture was extracted three times with ethyl acetate, the organic extracts were combined and dried over sodium sulfate, filtered and the solvent evaporated. The product was purified by fast chromatography using 15% ethyl acetate/hexane as eluent to afford 1,2-difluoro-4-methylsulfonylbenzene (9.98 g, 59% yield) as a white solid.1H NMR (300 MHz, CDCl3) δ 3.27 (s, 3H), 7.70-7.84 (m, 2H), 8.02-8.09 (m, 1H).
