Preparation of compound 69b: 3-iodo-1-toluenesulfonyl-1H-indole-5-carbonitrile. 3-Iodo-1H-indole-5-carbonitrile (2 g, 7.40 mmol) was dissolved in DMF (20 mL), and 60% NaH (538 mg, 22.38 mmol) was added in batches at 0 °C, and the reaction mixture was stirred at room temperature for 10 min. Subsequently, a solution of p-toluenesulfonyl chloride (2.2 g, 11.19 mmol) in DMF (4 mL) was added dropwise to the reaction mixture at 0 °C and stirring was continued for 2 h at room temperature. Upon completion of the reaction, the reaction was quenched with ice water (20 mL). The resulting suspension was filtered and the solid was washed with water (10 mL) and dried. The crude product was purified by silica gel column chromatography (eluent: petroleum ether solution of 20% ethyl acetate) to afford 3-iodo-1-toluenesulfonyl-1H-indole-5-carbonitrile (3.0 g, 95.5%) as a brown solid.1H NMR (400 MHz, DMSO-d6): δ 8.30 (s, 1H), 8.13 (d, J = 8.8 Hz, 1H). 7.98 (d, J = 8.4Hz, 2H), 7.87-7.81 (m, 2H), 7.43 (d, J = 8.0Hz, 2H), 2.32 (s, 3H).
