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

Participants

Reaction Conditions

Reaction Steps

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

Provenance & Evidence