5-Bromo-4-chloro-1H-pyrrolo[2,3-b]pyridine

Synthesis

5-Bromo-4-chloro-1-(triisopropylsilyl)-7-azaindole (4.1 g, 10.57 mmol) was dissolved in tetrahydrofuran (THF, 80 mL) at room temperature. Subsequently, tetrabutylammonium fluoride (TBAF, 1.1 eq.) was added to the reaction system and the reaction was stirred for 1 hour at room temperature. Upon completion of the reaction, the reaction mixture was poured into water and extracted with dichloromethane (DCM). The organic phases were combined, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to give the crude product. The crude product was suspended in a 10:1 solvent mixture of hexane and dichloromethane and filtered to afford the target compound 5-bromo-4-chloro-1H-pyrrolo[2,3-b]pyridine (2.20 g, 89.9% yield).

References

[1] Patent: WO2009/89352, 2009, A1. Location in patent: Page/Page column 59
[2] ChemMedChem, 2014, vol. 9, # 2, p. 277 - 281
[3] Patent: US2007/129364, 2007, A1. Location in patent: Page/Page column 77-78
[4] Bioorganic and Medicinal Chemistry Letters, 2012, vol. 22, # 15, p. 5150 - 5156
[5] Patent: WO2018/191587, 2018, A1. Location in patent: Paragraph 0155; 0158