A solution of 2-chloro-5-bromopyridine (386 mg, 2 mmol) in THF (6 mL) was cooled to -78C and tert-butyl bromide (1.17 mL, 2 mmmol) was added dropwise under nitrogen. After 5 min at -78C, the brown solution was treated with a solution of the appropriate electrophilic reagent (3 mmol) in THF (4 mL). The reaction medium was then allowed to warm to room temperature (1 h) and the mixture was hydrolyzed with H2O (10 mL) at 0C. The aqueous layer was then extracted with Et2O. The organic layer (MgSO4) was dried and the solvent was evaporated under reduced pressure. The crude product was purified by column chromatography. Eluent: hexane-ethyl acetate (90:10). Compound - Chloro-4-methyl-5-bromopyridine in 50% yield.
