2-(Dimethylamino)ethanol → 2-BROMO-4,5-DIMETHYLPYRIDINE

Participants

Reaction Conditions

Reaction Steps

71.3 g (0.8 mol) of 2-(dimethylamino)ethanol are initially charged in 500 ml of n-hexane, and the mixture is cooled to 0° C. 1.0 liter (1.6 mol) of n-butyllithium solution (1.6 M in n-hexane) is added slowly, and the mixture is stirred at 0° C. for 15 min. A solution of 17.9 g (166.7 mmol) of 3,4-lutidine in 500 ml of n-hexane is then added dropwise, and the mixture is stirred at 0° C. for 1 h. The mixture is then cooled to −78° C., and a solution of 331.7 g (1.0 mol) of carbon tetrabromide in 1.0 liter of THF is added. The reaction mixture is stirred at −78° C. for 1 h and then allowed to warm to RT. The mixture is cooled again to 0° C., and 1.5 liters of water are slowly added dropwise. The phases are separated, and the organic phase is washed with water, dried over magnesium sulfate and concentrated under reduced pressure. The residue is initially prepurified on about 1 kg of silica gel (mobile phase: cyclohexane/ethyl acetate 9:1, then 7:3). The product-containing fractions are combined and concentrated under reduced pressure. The residue is then purified again on silica gel (mobile phase: cyclohexane/ethyl acetate 9:1). The product obtained in this manner contains about 10% of the regioisomeric 2-bromo-3,4-dimethylpyridine.

Provenance & Evidence