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

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Reaction Conditions

Reaction Steps

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 5 N 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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