A mixture of N-(4-formylphenyl)methanesulfonamide (0.161 g, 0.0800 mmol), 2-amino-4,6-dimethoxybenzamide (0.159 g, 0.0800 mmol), NaHSO3 (94%, 0.00460 g, 0.0240 mmol), and p-TsOH.H2O (0.0125 g, 0.120 mmol) in DMA (1.00 mL) was heated at 155° C. for 16 hours. The mixture was diluted with EtOAc (50 mL), washed with water (2×50 mL), then brine (50 mL), dried over Na2SO4, filtered, and the solvent was removed under vacuum. The residue was purified over silica gel (12 g, CH2Cl2/MeOH) and the product was freeze-dried from MeCN/H2O to provide the title compound (0.0341 g, 11%) as a pale yellow solid. 1H NMR (300 MHz, DMSO-d6): δ 11.94 (s, 1H), 10.21 (s, 1H), 8.16 (d, J=8.76 Hz, 2H), 7.30 (d, J=8.76 Hz, 2H), 6.72 (d, J=2.25 Hz, 1H), 6.52 (d, J=2.25 Hz, 1H), 3.89 (s, 3H), 3.85 (s, 3H), 3.09 (s, 3H). MS (ESI) m/z 376 [C17H17N3O5S+H]+.
