Triisopropyl borate → (2-(Pyridin-4-yl)-4-(trifluoromethyl)phenyl)boronic acid

Participants

Reaction Conditions

Reaction Steps

A 250-mL round bottom flask was charged with 4-(2-bromo-5-(trifluoromethyl)phenyl)pyridine (0.242 g, 0.801 mmol), Ether (6.16 ml), and triisopropyl borate (0.223 ml, 0.961 mmol). The flask was cooled to −78° C. for 10 minutes, after which butyllithium (2.5M in hexanes) (0.385 ml, 0.961 mmol) was added dropwise. After 30 minutes the dry-ice bath was removed, and 2N aq NaOH (10 mL), and the resulting biphasic mixture was stirred vigorously. After 1 h, the mixture was diluted with water, and the layers separated. The ether was then extracted with water (×2) and the water layers were combined, and washed with ether. The ether layers were back-extracted once more, and all aqueous layers combined and neutralized to ˜pH=7 with 1N aq HCl to give a clear solution. The aqueous was extracted with DCM (×3) and the combined organics were dried over sodium sulfate, filtered and concentrated. The dried residue was taken up in DCM, and concentrated to give (2-(pyridin-4-yl)-4-(trifluoromethyl)phenyl)boronic acid (0.136 g, 0.509 mmol, 63.6% yield) as an off-white solid. [M+H]+=268.1

Provenance & Evidence