Pinacol → 2-Fluoro-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine

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Reaction Conditions

Reaction Steps

A solution of 2-bromo-6-fluoropyridine (1.0 g) in tetrahydrofuran (10 ml) was cooled to −78° C. under argon atmosphere, and thereto was added a solution of n-butyl lithium (2.59 M hexane solution, 2.24 ml) in tetrahydrofuran (10 ml). The mixture was stirred at the same temperature for 45 minutes, and thereto was added dropwise a solution of triisopropoxyborane (1.28 g) in tetrahydrofuran (10 ml). The mixture was stirred at the same temperature for 2 hours, warmed, and further stirred at room temperature for one hour. Subsequently, a solution of pinacol (0.91 g) in tetrahydrofuran (10 ml) was added dropwise thereto, and stirred at room temperature for 20 minutes. Insoluble materials were filtered off. The filtrate was extracted with 2.5% sodium hydroxide, and the extract was cooled to 0° C., and was made weakly acidic with 2N aqueous hydrochloric acid solution. It was extracted with diethyl ether, washed with a small amount of brine, and dried over magnesium sulfate. The solvent was evaporated under reduced pressure and the residue was solidified with hexane to give 6-fluoro-2-pyridylboronic acid pinacol ester (850 mg) as a colorless solid. APCI-Mass m/Z 224 (M+H).

Provenance & Evidence