1,3-Dibromo-5,5-dimethylhydantoin → 1-Benzenesulfonyl-5-chloro-2-bromomethyl-1H-pyrrolo[2,3-b]pyridine-3-carboxylic acid methyl ester

Participants

Reaction Steps

A mixture of 1-benzenesulfonyl-5-chloro-2-methyl-1H-pyrrolo[2,3-b]pyridine-3-carboxylic acid methyl ester (16.9 g, 46.2 mmol), 1,3-dibromo-5,5-dimethylhydantoin (13.21 g, 46.2 mmol) and 1,1-azobis(cyclohexanecarbonitrile) (1.52 g, 9.3 mmol) in 1,2-dichloroethane (200 mL) was heated under reflux for 90 minutes then stirred at ambient temperature for 16 hours. The reaction mixture was 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 white solid (13.7 g, 61%). LCMS (Method B): RT=4.35 min, M+H+=443/445/447. 1H NMR (400 MHz, CDCl3): 8.46-8.46 (m, 2H), 8.39 (d, J=2.4 Hz, 1H), 8.32 (d, J=2.4 Hz, 1H), 7.64-7.64 (m, 1H), 7.55-7.52 (m, 2H), 5.67 (s, 2H), 4.00 (s, 3H).

Provenance & Evidence