Example C: Synthesis of 2,6-difluoro-3-(propylsulfonamido)benzoic acid
An aqueous 1N NaOH solution (150 mL, 150 mmol) was added to a 4:1 THF/MeOH (250 mL, 0.2 M) solution of methyl 2,6-difluoro-3-(N-propylsulfonyl)benzoate (20.0 g, 50.1 mmol). The reaction mixture was stirred at room temperature overnight. Most of the organic solvent was removed under vacuum (water bath temperature 35 °C). To the residue, 1N HCl (150 mL) was slowly added, and the resulting solid was filtered and washed with water (4 x 50 mL). Subsequently, the solid was washed with ether (4 x 15 mL) to afford 2,6-difluoro-3-(propylsulfonamido)benzoic acid as a white solid (10.7 g, 77% yield).
1H NMR (400 MHz, d6-DMSO) δ 9.74 (s, 1H), 7.57-7.50 (m, 1H), 7.23-7.17 (m, 1H), 3.11-3.06 (m, 2H), 1.79-1.69 (m, 2H), 0.98 (t, J = 7.4 Hz, 3H).
m/z (APCI-neg) M-1 = 278.0.
![Benzoic acid,3-[bis(propylsulfonyl)aMino]-2,6-difluoro-, Methyl ester](/CAS/20150408/GIF/1186193-95-2.gif)
