2-Bromo-5-(trifluoromethyl)pyridine → 5-(Trifluoromethyl)-2-vinylpyridine

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Reaction Steps

To a solution of vinylmagnesium bromide in THF (1M, 7.38 mL, 7.38 mmol) in THF (29 mL) was added anhydrous zinc bromide (1.66 g, 7.38 mmol) at −78° C. After one hour at this temperature, the mixture was warmed to room temperature. After one hour, tetrakis(triphenylphosphine)palladium(0) (147 mg) and 2-bromo-5-trifluoromethylpyridine (1 g, 4.42 mmol) were added and the mixture heated at 50° C. for 5.25 hours. The mixture was diluted with ammonium chloride solution (10%, 29 mL) and extracted with ethyl acetate (70 mL×2). The combined organic extracts were dried over magnesium sulphate, evaporated and purified by column chromatography (SPE column, silica), eluting with cyclohexane, followed by cyclohexane/ethyl acetate (95:5 v/v), then (9:1 v/v). This afforded the title compound.

Provenance & Evidence