1-(tert-Butoxycarbonyl)-5-{[4-(tert-butoxycarbonyl)piperazin-1-yl]sulfonyl}-1H-indol-2-ylboronic acid (2-3, 1.88 g, 3.69 mmol, 2.0 equiv) was added in four equal portions at 30 minute intervals to a solution of 3-iodo-1H-quinolin-2-one (1-3, 0.500 g, 1.84 mmol, 1 equiv), lithium chloride (0.235 g, 5.54 mmol, 3.00 equiv), tetrakis(triphenylphosphine)palladium (0.107 g, 0.093 mmol, 0.050 equiv), and aqueous sodium carbonate solution (2 M, 4.61 mL, 9.22 mmol, 5.00 equiv) in dioxane (50 mL) at 90° C. The reaction mixture was heated for 2 h at 90° C. following the final addition. The mixture was then partitioned between brine (100 mL) and EtOAc (2×100 mL). The combined organic layers were dried over sodium sulfate and concentrated. A solution of the residue in dichloromethane (100 mL) was treated with trifluoroacetic acid (100 mL), and the resulting mixture was stirred for 45 minutes, then concentrated. The residue was purified by reverse-phase liquid chromotography (H2O/CH3CN gradient w/0.1% TFA present) to give 3-[5-(piperazin-1-ylsulfonyl)-1H-indol-2-yl]quinolin-2(1H)-one (2-4) as a yellow solid. 1H NMR (500 MHz, DMSO-d6) δ 12.23 (br s, 1H), 12.11 (s, 1H), 8.62 (s, 1H), 8.00 (br s, 1H), 7.77 (d, 1H, J=7.8 Hz), 7.74 (d, 1H, J=8.6 Hz), 7.56 (t, 1H, J=7.8 Hz), 7.51 (s, 1H), 7.44 (d, 1H, J=8.6 Hz), 7.40 (d, 1H, J=8.1 Hz), 7.27 (t, 1H, J=7.8 Hz), 2.77 (m, 4H), 2.71 (m, 4H).
