Synthesis
Preparation of 3-amino-N-phenylbenzenesulfonamide (12): to a solution of 3-nitro-N-phenylbenzenesulfonamide (255.5 mg, 0.919 mmol) in tetrahydrofuran (THF, 4 mL) was added tin chloride dihydrate (SnCl2-2H2O, 1.015 g, 4.486 mmol). The reaction mixture was placed in a microwave reactor and was first heated at 135 °C for 1 min at a power of 75 Watt, then the power was adjusted to 15 Watt and the temperature was maintained at 135 °C for a further 14 min. Upon completion of the reaction, it was cooled to room temperature, diluted with ethyl acetate (EtOAc, 20 mL) and washed with saturated aqueous sodium bicarbonate (NaHCO3) (10 mL), followed by stirring for about 12 hours. The reaction mixture was extracted with ethyl acetate (75 mL), the organic layer was washed sequentially with water (75 mL), saturated sodium chloride (NaCl) aqueous solution (2 x 75 mL), dried with anhydrous magnesium sulfate (MgSO4) and concentrated under reduced pressure to give a yellow residue. The residue was purified by silica gel column chromatography (eluent: 0-4% gradient of methanol (MeOH) in dichloromethane (CH2Cl2)) to afford the target product 3-amino-N-phenylbenzenesulfonamide (178 mg, 78% yield). The product characterization data were as follows: 1H NMR (DMSO-d6, 300 MHz): δ 5.57 (s, 2H), 6.69 (d, J = 8.1 Hz, 1H), 6.84 (d, J = 7.5 Hz, 1H), 6.95 (s, 1H), 6.99 (t, J = 7.5 Hz, 1H), 7.07 (d, J = 8.1 Hz, 2H). 7.12 (t, J = 8.1 Hz, 1H), 7.21 (t, J = 8.1 Hz, 2H), 10.12 (s, 1H). Mass spectrum (ESI, cation mode) m/z: 249 ([M+H]+).
References
[1] Patent: US2007/293494, 2007, A1. Location in patent: Page/Page column 23; 24
[2] Archiv der Pharmazie, 2008, vol. 341, # 2, p. 99 - 112
[3] Journal of the American Chemical Society, 1946, vol. 68, p. 1039,1040, 1044
[4] Org. Synth. Coll. Vol., 1941, vol. I, p. 52
[5] Fortschr. Teerfarbenfabr. Verw. Industriezweige, vol. 10, p. 807
