Water → 4-(3-chloro-9-(benzenesulfonyl)-9H-pyrido[2,3-b]indol-6-yl)phenol

To a solution of 3-chloro-6-(4-methoxyphenyl)-9-(benzenesulfonyl)-9H-pyrido[2,3-b]indole (222 mg, 1.11 mmol, 1eq.) in CH2Cl2 at 0° C., BBr3 (4.46 ml, 1M in CH2Cl2 4.46 mmol) was added dropwise. After 3 h at room temperature, the reaction mixture is hydrolysed with H2O and extracted with AcOEt (3×50 ml), dried with MgSO4, then filtered. The solvents were removed under reduced pressure and the crude material was purified by flash chromatography (CH2Cl2 then AcOEt) to afford 4-(3-chloro-9-(benzenesulfonyl)-9H-pyrido[2,3-b]indol-6-yl)phenol (409 mg, 0.94 mmol, 85% yield. 1H NMR 1H ((CD3)2CO, 300 MHz), δ 8.67 (d, 1H, J=2.3 Hz), 8.45-8.51 (m, 4H), 8.16-8.20 (m, 2H), 7.93 (dd, 1H, J=2.1 Hz, 8.9 Hz), 7.54-7.68 (m, 5H), 6.98 (d, 2H, J=8.6 Hz).