To a solution of 1H-pyrrolo[3,2-c]pyridine (5-azaindole) (1 g, 8.47 mmol, 1.0 eq.) in anhydrous THF (10 mL) was slowly added NaH (60% dispersed in mineral oil) (0.24 g, 10.2 mmol, 1.2 eq.) at 0 °C. The reaction mixture was stirred at 0°C for 30 min. Subsequently, benzenesulfonyl chloride (1.80 g, 10.2 mmol, 1.2 eq.) was added slowly and dropwise at the same temperature. The reaction mixture was gradually warmed to room temperature and stirring was continued for 1 hour. Upon completion of the reaction, the reaction was quenched by the addition of saturated aqueous NaHCO3 solution (30 mL) and then extracted with ethyl acetate (3 x 30 mL). The organic phases were combined and dried with anhydrous Na2SO4. The solvent was removed by concentration under reduced pressure to give 1-benzenesulfonyl-5-azaindole (1.52 g, 5.88 mmol, 69.4% yield) as a yellow solid. The product was confirmed by NMR hydrogen spectroscopy (400 MHz, CDCl3): δ 6.75 (d, J = 3.6Hz, 1H), 7.48 (t, J = 8Hz, 2H), 7.55-7.61 (m, 2H), 7.89-7.93 (m, 3H), 8.49 (d, J = 6Hz, 1H), 8.88 (s, 1H). Electrospray ionization mass spectrometry (ESIMS) analysis showed a molecular ion peak m/z 259.1 ([M+H]+), which is consistent with the theoretical molecular weight C13H10N2O2S.
![1-(Phenylsulfonyl)-1H-pyrrolo[3,2-c]pyridine](/CAS/20150408/GIF/109113-39-5.gif)