To a suspension of hydroxylamine hydrochloride (0.30 g, 4.35 mmol) in tetrahydrofuran (6 ml) a saturated NaHCO3 solution (4 ml) was added and the resultant mixture was stirred at ambient temperature for 10 min. To the reaction mixture a solution of crude 3-{3-[(naphthalen-1-ylmethyl)-sulfamoyl]-phenyl}-acryloyl chloride (16a) (0.33 g) in tetrahydrofuran (4 ml) was added and the mixture was stirred at ambient temperature for one hour. The reaction mixture was partitioned between ethyl acetate and 2N HCl. The organic layer was washed successively with water and saturated NaCl, then the solvent was removed. The residue was crystallised from ethyl acetate-acetonitrile affording the title compound (0.13 g, 40%) as a lightly pink crystals. M.p. 177° C. 1H NMR (DMSO-d6, HMDSO) δ: 4.45 (2H, d, J=6.0 Hz); 6.58 (1H, d, J=16.0 Hz); 7.29-8.38 (13H, m); 9.12 (1H, br s); 10.83 (1H, br s). HPLC analysis on Symmetry C8 column: impurities 1.5% (column size 3.9×150 mm; mobile phase acetonitrile-0.1 M phosphate buffer (pH 2.5), 40:60; sample concentration 0.25 mg/ml; flow rate 1.2 ml/min; detector UV 220 nm). Anal. Calcd for C20H18N2O4S, %: C, 62.54; H, 4.70; N, 7.21. Found %: C, 62.81; H, 4.74; N, 7.32.
