tert-Butanol → 3,3-Dibromo-1H-pyrrolo[2,3-b]pyridin-2(3H)-one

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Reaction Steps

Technical (90%) pyridinium tribromide (220.4 g, 0.62 mol) was added portionwise over a period of 30 min to a stirred suspension of 7-azaindole (1, 27.13 g, 0.23 mol) in t-BuOH (1.36 L). The mixture was stirred at r.t for 3 h, and more pyridinium tribromide (73.3 g, 0.21 mol) was added in one portion. After additional stirring at r.t. for 2 h, the solvent was evaporated under reduced pressure. The residue was separated between water:AcOEt=1:1 (4.2 L). The aqueous layer was extracted with AcOEt (2×800 mL). Combined organic solutions were washed with water (2×500 mL), brine, dried (MgSO4) and concentrated to dyness in vacuum. The residue was triturated with CH2Cl2 (1500 mL) for 20 min. The solid was filtered off, washed with CH2Cl2 (250 mL) and dried in vacuum to afford 2 (49.85 g, 75%) as yellow powder. 1H NMR (400 MHz, DMSO-d6) δ 7.16 (dd, J=7.4, 5.1 Hz, 1H), 7.98 (dd, J=7.4, 1.5 Hz, 1H), 8.19 (dd, J=5.1, 1.5 Hz, 1H), 11.97 (bs, 1H).

Provenance & Evidence