Pyridine → 5-Bromonaphthalene-2-carbonitrile

温度

0 °C

To a solution of 5-bromo-2-naphthoic acid (4.3 g, 17 mmol)) in dry pyridine (75 mL) at 0° C. was added methanesulfonyl chloride (1.4 mL, 18 mmol). After stirring at 0° C. for 1 h, ammonia gas was bubbled through the solution for 10 min, whilst maintaining the temperature below 5° C. During the gas addition the solution became viscous, so additional dry pyridine (˜30 mL) was added. Excess ammonia was removed in vacuo, the solution again cooled to 0° C., then treated with additional methanesulfonyl chloride (12.5 mL) and allowed to warm to room temperature overnight. The solution was poured onto ice cold water, the mixture stirred for 30 min and the brown precipitate collected by filtration, washed on the sinter with ice cold water, then dried in vacuo. The crude product was dissolved in hot chloroform (˜35 mL) and insoluble material filtered off. The chloroform was removed and the residue dissolved in a minimum volume of ether at reflux. Hexane was added until the solution remained turbid at reflux, the solution filtered rapidly into a pre-heated flask, and allowed to cool slowly to room temperature. The precipitate was collected by filtration, washed with hexane, and dried in vacuo, to yield 5-bromo-2-naphthonitrile. Further crops were obtained by cooling the filtrate at −18° C. overnight.