To a solution of 2-amino-3-chloro-5-bromopyridine (2.0 g, 9.64 mmol) in 1,4-dioxane (20 mL) was added pinacol ester of bisboronic acid (2.94 g, 11.57 mmol), potassium acetate (2.84 g, 28.92 mmol), and 1,1'-bis(diphenylphosphino)ferrocene-palladium dichloride (705 mg, 0.96 mmol). The reaction mixture was purged with nitrogen for 2 minutes and subsequently heated to 100 °C and kept for 4 hours. After completion of the reaction, the mixture was concentrated to dryness under vacuum. The resulting viscous material was diluted with water and extracted with ethyl acetate (2 x 50 mL). The organic layers were combined, dried with anhydrous sodium sulfate and again concentrated to dryness under vacuum. The resulting crude product was purified by column chromatography (silica gel, 100-200 mesh, 30% ethyl acetate in hexane solution) to afford the target product 3-chloro-5-(4,4,5,5-tetramethyl-1,3,2-boronic acid pinacol ester-2-yl)pyridin-2-amine (2.0 g, 84% yield). The product was confirmed by NMR hydrogen spectrum (400 MHz, chloroform-d): δ 8.32 (d, J=1.6 Hz, 1H), 7.84 (d, J=1.6 Hz, 1H), 5.09 (s, 2H), 1.32 (s, 12H).
