Diethyl Ether → 5-Bromo-2-ethylpyridine

Participants

Reaction Steps

A solution of ethylmagnesium bromide in dry ether (3M; 100 ml, 0.30 mol) was added dropwise to a stirred, ice-cooled solution of anhydrous zinc chloride (40.9 g, 0.30 mol) in dry tetrahydrofuran (500 ml) under nitrogen and the resulting solution stirred for a further 1 hour before the sequential addition of tetrakis (triphenylphosphine)palladium(0) (1.0 g, 0.87 mmol) and a solution of 2,5-dibromopyridine (50 g, 0.21 mol) in dry tetrahydrofuran (200 ml). The resulting yellow suspension was stirred at room temperature for 18 hours, quenched by the addition of water (200 ml) and evaporated under reduced pressure. The residue was partitioned between dichloromethane (500 ml) and a suspension of ethylenediaminetetraacetic acid (200 g) in water (1 l). The organic phase was separated, combined with a dichloromethane extract (500 ml) of the aqueous phase, dried (MgSO4) and evaporated under reduced pressure. Distillation under reduced pressure of the residue gave the title compound (28.8 g) as a colourless oil, b.p. 123-124° C./8 kPa (60 mm Hg). δ(CDCl3): 1.30(3H,t), 2.80(2H,q), 7.10(1H,d), 7.70(1H,dd), 8.60(1H,d).

Provenance & Evidence