N-bromobutanimide → 7-bromo-5,8-dichloro-3,4-dihydroisoquinolin-1(2H)-one

Participants

Reaction Steps

To a solution of 5,8-dichloro-3,4-dihydroisoquinolin-1(2H)-one (253e, 40 g, 0.186 mol) in concentrated sulfuric acid (200 mL) at 60° C. was added N-bromosuccinimide (49.7 g, 0.279 mol) in portions. Stirring was continued at 60° C. for 2 hours, then more N-bromosuccinimide (5 g. 28 mmol) was added. After stirring at 60° C. for 1 hour more, the mixture was poured onto ice water (500 mL), then extracted with dichloromethane (3×500 mL). The combined organic extracts were washed with saturated aqueous sodium chloride solution (800 mL), dried over sodium sulfate, and concentrated in vacuo. The residue was stirred in ethyl acetate (40 mL) and petroleum ether (20 mL), and the resulting solids collected by filtration and dried under vacuum to give 7-bromo-5,8-dichloro-3,4-dihydroisoquinolin-1(2H)-one (253f, 41 g, 75% yield) as an off-white solid.

Provenance & Evidence