2,5-Dibromopyridine → 5-Bromo-2-ethylpyridine

Participants

Reaction Steps

Into a 1000-mL 3-necked round-bottom flask (1 atm) purged and maintained with an inert atmosphere of nitrogen, was placed 2,5-dibromopyridine (20 g, 84.43 mmol, 1.00 equiv), Pd(PPh3)4 (9.7 g, 8.39 mmol, 0.10 equiv) and tetrahydrofuran (500 mL). To the resulting mixture was then added diethylzinc (46.2 mL) dropwise with stirring at −78° C. The resulting solution was stirred overnight at room temperature. The reaction was then quenched by the addition of water (10 mL). The resulting mixture was then concentrated under vacuum. The resulting solution was diluted with ethyl acetate (200 mL). The resulting solution was extracted with 4N HCl (2×200 mL) and the aqueous layers combined. The pH value of the solution was adjusted to pH 14 with aqueous LiOH. The resulting solution was extracted with ethyl acetate (2×200 mL) and the organic layers combined. The resulting residue was applied onto a silica gel column with ethyl acetate/petroleum ether (4.6/95.4) to yield 5-bromo-2-ethylpyridine as colorless oil.

Provenance & Evidence