2-Methoxyphenylacetic acid (33 mg, 0.20 mmol) and sulfamethazine (55 mg, 0.20 mmol) were dissolved in 4 ml of chloroform. Triethylamine (70 μl, 0.55 mmol) and diisopropylcarbodiimide (50 μl, 0.20 mmol) were added to the reaction mixture. Solution was stirred and refluxed overnight. The reaction mixture was then evaporated to dryness, washed with water and purified on silica using gradient elution (chloroform to 2% methanol in chloroform) to obtain white crystals with the yield of 40%. 1H NMR (CDCl3, 500 MHz): 8.04 (2H, m), 7.54 (2H, m), 7.30 (2H, m), 6.98 (2H, m), 6.60 (1H, s), 3.95 (3H, s), 3.72 (2H, s), 2.33 (6H, s); MS (ESI+): m/z 449 (M+Na)+, 427 (M+H)+.
