2.1.31. N-(4-(N-(6-methoxypyridin-3-yl)sulfamoyl)phenyl)formamide (309)

970 mg of 287 (3.57 mmol) were dissolved in CH₂Cl₂ (100 mL), pyridine (5 mL) and formic acid (15 mL) and stirred at room temperature. After 24 h, the reaction mixture was poured onto ice and treated with 2N HCl and 5% NaHCO₃. The organic layers were washed to neutrality with brine, dried over anhydrous Na₂SO₄, filtered and evaporated to dryness to afford 555 mg (52%) of 309. The crude reaction product was purified by crystallization in methanol (368 mg, 34%). M.p.: 189–193 °C (MeOH). IR (KBr): 3349, 3273, 1698, 1592, 823 cm⁻¹. ¹H NMR (400 MHz, CD₃OD): δ 3.82 (3H, s), 6.69 (1H, d, J = 8.8), 7.42 (1H, dd, J = 8.8 and 2.8), 7.62 (2H, d, J = 8.8), 7.70 (2H, d, J = 8.8), 7.71 (1H, d, J = 2.8), 8.31 (1H, s). ¹³C NMR (100 MHz, Acetone-D6): δ 52.8 (CH₃), 110.6 (CH), 118.9 (2CH), 128.0 (C), 128.4 (2CH), 133.9 (C), 134.8 (CH), 141.6 (CH), 142.3 (C), 159.6 (C), 161.9 (CH). HRMS (C₁₃H₁₃N₃O₄S + H⁺): calcd 308.0703 (M + H⁺), found 308.0700.