Triisopropyl borate → 5-(1-(Tert-butyldimethylsilyloxy)-2-methylpropan-2-yl)-2-fluoropyridin-3-ylboronic acid

Participants

Reaction Conditions

Reaction Steps

n-Butyllithium (1.66 M in hexane) (Aldrich, St. Louis, Mo.; 0.429 mL, 0.712 mmol) was added (dropwise over 1 min) to a solution of 5-(1-(tert-butyldimethylsilyloxy)-2-methylpropan-2-yl)-2-fluoropyridine (183.5 mg, 0.647 mmol) in THF (3.3 mL) at −78° C., and the resulting yellow solution was stirred at −78° C. for 1 h. Tri-isopropyl borate (Aldrich, St. Louis, Mo.; 0.179 mL, 0.777 mmol) was then added, and the resulting mixture was stirred at −78° C. for 1 h. The reaction mixture was subsequently partitioned between EtOAc (50 mL) and water (30 mL) (1 N HCl (about 200 μL) was added to bring the pH of the aqueous layer to 6.5). The organic layer was separated, and the aqueous layer was extracted with EtOAc (30 mL). The combined organic extracts were dried over sodium sulfate, filtered, and concentrated in vacuo to provide 5-(1-(tert-butyldimethylsilyloxy)-2-methylpropan-2-yl)-2-fluoropyridin-3-ylboronic acid (228.0 mg, 0.697 mmol, 108% yield) as a colorless oil. m/z (ESI, +ve) 328.3 (M+H)+.

Provenance & Evidence