4-Iodo-7-azaindole

Synthesis

Part 2: Synthesis of 4-iodo-1H-pyrrolo[2,3-b]pyridine: To a mixture of 4-chloro-1H-pyrrolo[2,3-b]pyridine (12.9 g, 84.3 mmol) and NaI (40 g, 168 mmol) in acetonitrile (150 mL) was slowly added acetyl chloride (12.6 mL, 176 mmol). The reaction mixture was stirred at 80 °C for 4 days, followed by removal of excess acetonitrile by distillation under reduced pressure. To the residue was added 300 mL of 10% K2CO3 (aqueous solution) and extracted with CH2Cl2 (3 x 100 mL). The combined organic phases were washed sequentially with 10% sodium bisulfite (aqueous) and saturated brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure to give the crude product (22.2 g). The crude product was dissolved in THF (150 mL) and 1 M NaOH (100 mL) was added. The mixture was stirred at room temperature for 2 h. The solvent was subsequently evaporated under reduced pressure, diluted with water and extracted with CH2Cl2. The organic phase was washed with saturated saline, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The resulting brown solid was purified by silica gel column chromatography and recrystallized with acetonitrile to give pure 4-iodo-1H-pyrrolo[2,3-b]pyridine (9.75 g, 48% yield). Mass spectrum (ES+): 245 [MH+].

References

[1] Journal of Medicinal Chemistry, 2018,
[2] Tetrahedron Letters, 2007, vol. 48, # 9, p. 1527 - 1529
[3] Patent: US2004/186124, 2004, A1. Location in patent: Page/Page column 14
[4] Patent: US2011/282056, 2011, A1. Location in patent: Page/Page column 16
[5] Patent: WO2014/121883, 2014, A1. Location in patent: Page/Page column 54