tert-Butyl 4-[2-phenyl-1-(phenylsulfonyl)-1H-indol-4-yl]-1-piperazinecarboxylate (30 mg, 0.058 mmol) was dissolved in CH2Cl2 (1 mL) followed by addition of HCl in ether (1 mL). The reaction was shaken for 2 h at room temperature. The resulting precipitate was filtered off and washed with ether giving 20 mg of the desired compound (80%). 1H NMR (270 MHz, DMSO-d6) δ 9.02 (br, 1H), 7.90-7.80 (m, 3H), 7.75-7.55 (m, 3H), 7.32 (s, 1H), 7.22 (t, J=8 Hz, 1H), 6.79 (d, J=8 Hz, 1H), 3.35-310 (m, 8H). MS (ESI+) for m/z 418 (M+H)+.
