Tributyl borate → 2-Fluoropyridine-4-boronic acid

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of n-butyl lithium (3.2 mL, 2.5M, 8.0 mmol) in dry diethyl ether (20 mL) at −78° C. was added a solution of 2-fluoro-4-iodopyridine (1.5 g, 6.7 mmol) in dry ether (10 mL) and the reaction mixture was stirred at −78° C. for 10 min. Tributyl borate (2.4 mL, 2.01 g, 8.7 mmol) was added and the reaction mixture was allowed to stir to room temperature over 2 h. Water (5 mL) was added followed by 2N aqueous sodium hydroxide solution (10 mL) to dissolve the solids. The organic phase was separated. The aqueous phase was acidified to pH 3 using 6N HCl and the resulting white solid was collected by filtration and dried under vacuum to give the title compound, 0.74 g (78%). 1H NMR (d6 DMSO) δ 8.65 (br s, 2H), 8.21 (d, 1H, J=4.8 Hz), 7.59 (t, 1H, J=4.8 Hz), 7.37 (d, 1H, J=1.8 Hz).

Provenance & Evidence