N-bromobutanimide → 1H-Pyrrolo[2,3-b]pyridine-3-carboxylic acid, 5-bromo-2-(bromomethyl)-1-(phenylsulfonyl)-, methyl ester

Participants

Reaction Steps

A mixture of 1-benzenesulfonyl-5-bromo-2-methyl-1H-pyrrolo[2,3-b]pyridine-3-carboxylic acid methyl ester (121 g, 296 mmol), NBS (63 g, 354 mmol) and 1,1-azobis(cyclohexanecarbonitrile) (14.4 g, 59 mmol) in 1,2-dichloroethane (1.2 L) was heated under reflux for 90 minutes. The reaction mixture was allowed to cool to ambient temperature and washed with saturated aqueous sodium thiosulfate solution. The organic layer was dried (Na2SO4) then filtered. The filtrate was stirred with flash silica gel, filtered and the filtrate evaporated under reduced pressure. The resultant residue was triturated with diethyl ether/pentane (1:1) to afford the title compound as a white solid (130 g, 90%). 1H NMR (400 MHz, CDCl3): 8.47-8.46 (m, 4H), 7.64-7.64 (m, 1H), 7.54-7.53 (m, 2H), 5.67 (s, 2H), 4.00 (s, 3H).

Provenance & Evidence