143141-23-5

1227270-32-7

4.2.7 Synthesis of 2-iodo-1H-pyrrolo[2,3-b]pyridine (7): 7-azaindole-1-benzenesulfonamide (509 mg, 1.97 mmol) was dissolved in tetrahydrofuran (THF, 20 mL) in a dry and nitrogen purged round bottom flask. The reaction solution was cooled to -60°C, followed by the slow addition of lithium diisopropylammonium (LDA, 1.97 mL, 3.95 mmol, 2M THF solution). After maintaining stirring at -60°C for 15 min, a THF (10 mL) solution of iodine (752 mg, 2.96 mmol) was added. The reaction mixture was gradually warmed to room temperature and stirred overnight. Upon completion of the reaction, the reaction was quenched by the addition of water (5 mL). The reaction mixture was diluted with ethyl acetate (EtOAc) and washed sequentially with 5% sodium thiosulfate solution, water and saturated sodium chloride solution. The organic layer was dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. The crude product was purified by rapid chromatography on a silica gel column with cyclohexane/EtOAc (85:15) as eluent to give a mixture of 6 and 6'. The mixture was dissolved in 1,4-dioxane (10 mL) and sodium tert-butoxide (380 mg, 3.95 mmol) was added. The reaction mixture was stirred and refluxed for 2 hours. After cooling to room temperature, the reaction was quenched with water (20 mL) and extracted with EtOAc. The organic layer was washed with saturated sodium chloride solution, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to give 418 mg of light orange solid product in 87% yield. The product was structurally confirmed by 1H NMR (300 MHz, DMSO-d6) and 13C NMR (75 MHz, DMSO-d6).