1,4-Dioxane → 3-(3,5-Difluoro-pyridin-2-yl)-4-fluorophenylboronic acid

Participants

Reaction Conditions

Reaction Steps

To 2-(5-bromo-2-fluorophenyl)-3,5-difluoropyridine (0.746 g, 2.59 mmol), and bis(neopentyl glycolato)diborane (0.704 g) was added dry 1,4-dioxane (9 ml) and dry dimethylsulfoxide (1.1 ml) followed by potassium acetate (0.542 g) and dichloro[1,1′-bis(diphenylphosphino)ferrocene]palladium(II) dichloromethane adduct (0.080 g). The mixture was thoroughly degassed with nitrogen and then stirred at 85° C. for 24 h. On cooling to ambient temperature 1N aqueous sodium hydroxide (24 ml) was added and the mixture stirred for 30 min. Diethyl ether was added and the aqueous phase separated and washed with diethyl ether. The organics were discarded. The aqueous phase was filtered then acidified to pH 5 by addition of 2N aqueous hydrochloric acid (12 ml). The resulting solid was collected by filtration, washed with water and dried in vacuo at 60° C. to afford 4-fluoro-3-(3,5-difluoropyridin-2-yl)phenylboronic acid (0.618 g) as a colourless solid: δH (400 MHz, DMSO) 8.69 (1H, d, J 2), 8.21 (2H, s), 7.94-8.14 (3H, m), 7.34 (1H, dd, J 11 and 8).

Provenance & Evidence