To a mixture of toluene-4-sulfonic acid 2-(4-amino-3-benzenesulfonylmethyl-phenoxy)-ethyl ester (11.7 g, 25.3 mmol) of in ethanol (350 mL) and 1.0 N hydrochloric acid (425 mL) was dropwise added sodium nitrite (2.67 g, 38.7 mmol) in water (50 mL). After stirring at ambient temperature for 1.5 hours, solid sodium carbonate was added to basic pH. The reaction mixture was stirred for an additional 2 hours. It was then solvent evaporated and extracted with warm ethyl acetate. The organic phase was washed with water and brine, dried with anhydrous magnesium sulfate, filtered and concentrated. The residue was purified by flash chromatography with 2% methanol in chloroform to yield toluene-4-sulfonic acid 2-(3-benzenesulfonyl-1H-indazol-5-yloxy)-ethyl ester as an orange solid (9.54 g, 79.5%): MP: 174-7° C.; Mass Spectrum (−EI, [M−H]−) m/z 471. 1HNMR (500 MHz, DMSO-d6): δ14.11 (s, 1H), 7.96-7.98 (m, 2H), 7.74-7.77 (m, 2H), 7.62-7.66 (m, 1H), 7.53-7.59 (m, 3H), 7.39 (d, 2H, J=8.05 Hz), 7.24 (d, 1H, J=2.32 Hz), 6.97-7.00 (m, 1H), 4.35-4.37 (m, 2H), 4.21-4.23 (m, 2H), 2.33 ppm (s, 3H).
