Pyridine → 3-Bromo-4-(dimethylamino)benzonitrile

Participants

Reaction Steps

To a stirred solution of 4-(dimethylamino)benzonitrile (2.19 g) in chloroform (15 mL) was added pyridine (1.2 mL) and a solution of bromine (0.75 mL) in chloroform (15 mL) dropwise over 45 minutes. Upon complete addition, the mixture was stirred for a further 30 minutes. The reaction mixture was diluted with dichloromethane and washed with water, brine and evaporated to afford a yellow oil of 3-bromo-4-dimethylaminobenzonitrile which was dissolved in tetrahydrofuran (25 mL). Meanwhile, a stirred solution of diisopropylamine (2.7 mL) in tetrahydrofuran (50 mL), at −15° C. and under nitrogen, was treated with a solution of n-butyllithium in hexanes (7.70 mL, 2.5M) over 30 minutes, whilst maintaining the temperature below −10° C. After stirring for 30 minutes the mixture was treated with methylpyrazine (1.21 g) over 15 minutes, then stirred for 1 hour. The solution of 3-bromo-4-(dimethylamino)benzonitrile was added over 1 hour, keeping the temperature below −10° C. The reaction mixture was allowed to warm to room temperature over 2 hours, then stood overnight, then treated with water (10 mL). The tetrahydrofuran was removed in vacuo and the resultant mixture was treated with a mixture of water and ethyl acetate (1:1 v/v) and the mixture stirred for 15 minutes. The resultant precipitate was collected by filtration and washed thoroughly with water/ethyl acetate (1:1 v/v) to afford the title compound as a yellow solid (1.0 g). TLC: RF=0.41 (ethyl acetate).

Provenance & Evidence