To a mixture of 5-chloro-3-phenylsulfinylindole-2-carboxylic acid (0.096 g, 0.3 mmol), triethylamine (0.061 g, 0.6 mmol), 4-aminomethylpyridine (0.043 g, 0.4 mmol) in dry dimethylformamide was added benzotriazol-1-yloxytris(dimethylamino)phosphonium hexafluorophosphate (BOP reagent) (0.155 g, 0.35 mmol). The mixture was stirred at room temperature under nitrogen for three days. Following evaporation, the residue was partitioned between ethyl acetate and water. The ethyl acetate phase was separated and washed with dilute hydrochloric acid. The acidic extract was neutralized with aqueous sodium bicarbonate and the product extracted into ethyl acetate. The ethyl acetate extract was washed well with aqueous sodium bicarbonate, then brine, and dried over magnesium sulfate. Evaporation afforded a solid residue which was recrystallized from ethyl acetate to give the title compound, mp 233°-235° C. Anal. Calcd for C21H16ClN3O2S: C, 61.54; H, 3.93; N, 10.25. Found: C, 61.39; H, 3.95; N, 10.36. NMR (DMSO-d6) δ9.62 (1H, t, J=6 Hz), 8.53 (2H, d, J=6 Hz), 7.80 (1H, d, J=2 Hz), 7.67 (2H, m), 7.64 (2H, d, J=9 Hz), 7.44-7.54 (3H, m), 7.33 (3H, m), 4.60 (2H, dq, J=9, 6 Hz).
