Diisopropylamine → 2-Fluoro-5-methoxypyridine-3-boronic acid

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To a 100 mL round-bottomed flask, diisopropylamine (Aldrich, 1.40 mL, 9.99 mmol) was dissolved into THF (6 mL). nBuLi (Aldrich, 2.5 M in hexanes, 3.60 mL, 8.99 mmol) was added slowly at 0° C. The mixture was stirred at 0° C. for 30 min then cooled to −78° C. 2-fluoro-5-methoxypyridine (0.520 g, 4.09 mmol) in 4 mL of THF was added slowly, and the mixture was stirred at that temperature for 40 min. Triisopropyl borate (Aldrich, 2.07 mL, 8.99 mmol) in a total of 4 mL of THF was added slowly and the mixture was stirred at −78° C. for 5 min. The cold bath was removed and the reaction mixture was stirred at room temperature for 1 h. 1 N NaOH (20 mL) was added to the mixture to quench the reaction. The layers were separated and the aqueous phase was treated with 5N HCl to adjust the pH to around 5. The aqueous phase was extracted with EtOAc (2×20 mL). The combined organic phases were dried over sodium sulfate, filtered and concentrated in vacuo to afford 0.593 g of tan color solid. This material was used in the next step without further purification.

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