Hydrochloric Acid → HCID 22285289, compound

Participants

Reaction Conditions

Reaction Steps

2,2,6,6-Tetramethylpiperidine (8.61 mL, 7.23 g, 51.2 mmol) was added dropwise with stirring to a mixture of 2.5 M solution of n-butyllithium in hexanes (19.6 mL, 49 mmol) and THF (130 mL) at −78° C. 2-(2-Fluoro-phenyl)pyridine (8.06 g, 46.5 mmol) in THF (25 mL) was added dropwise with stirring to the resulting solution at −78° C., and the mixture was stirred at the same temperature for 2 h. Trimethyl borate (10.5 mL, 9.67 g, 93 mmol) was added at −78° C., and the mixture was stirred for a further 10 min before being allowed to warm to room temperature. 2 N Hydrochloric acid (12 mL) was added, then the mixture was stirred for 30 min at room temperature, and was concentrated in vacuo. The residual material was stirred with 2 N hydrochloric acid (130 mL) for 1 h. The mixture was adjusted to pH 14 by addition of 2 N sodium hydroxide solution, and was then washed with diethyl ether. Concentrated hydrochloric acid was added to the aqueous phase with ice-bath cooling, until the pH was ˜8, precipitating a white solid. The slurry was stirred at 0° C. for 1 h, and was then filtered, yielding the residual boronic acid as a sticky white solid. This was refluxed in diethyl ether overnight, and was then filtered, affording 2-fluoro-3-(pyridin-2-yl)benzeneboronic acid as a white powder (3.4 g, 34%). m/z (ES+) 218 (M++H).

Provenance & Evidence