Sulfuric Acid → 2-{[3-tert-butyl-1-(2-methylphenyl)-1H-pyrazol-5-yl]amino}benzenesulfonamide

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Reaction Steps

N,N-Dibenzyl-2-{[3-tert-butyl-1-(2-methylphenyl)-1H-pyrazol-5-yl]amino}benzene-sulfonamide (from Step 2, 240 mg, 0.42 mmol) was added to conc H2SO4 (3 mL), and the mixture was vigorously stirred for 20 min. The mixture was poured onto ice, and conc NaOH solution was added until a pH of ˜7.5 was reached. The aqueous layer was extracted 2× with EtOAc, and the combined organic layers were dried with Na2SO4, filtered, and concentrated under reduced pressure. Purification by silica gel flash chromatography using EtOAc/hexane (1:3, v/v) afforded the title compound as a white solid (104 mg, 64%). 1H NMR (δ 400 MHz, CD2Cl2) 61.39 (s, 9H), 2.09 (s, 3H), 4.50 (br, 2H), 6.20 (s, 1H), 7.94 (t, 1H), 7.23 (m, 4H), 7.34 (m, 2H), 7.45 (t, 1H), 7.73 (d, 1H). ES-MS m/z 385.2 (MH+); HPLC RT (min) 3.11.

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