Hydrochloric Acid → (4-Ethoxy-3-fluorophenyl)boronic acid

Participants

Reaction Conditions

Reaction Steps

100 ml of a THF solution of 22.8 g (104 mmol) of 3-fluoro-4-ethoxybromobenzene was dropped, while stirring, at 40 to 60° C. to 3.03 g (124.8 mmol) of dried turnings magnesium, and refluxed under heating after dropping for one hour. The solution was cooled by a coolant to −70° C. and, a THF solution of 16 ml (132.5 mmol) of trimethyl borate (THF: 70 ml) was dropped under stirring. After stirring at −70° C. for 3 hours, and further stirring at a room temperature for 20 hours, the reaction solution was cooled to 5° C., and 50 ml of 6M hydrochloric acid was added. After separating the organic layer, the aqueous layer was extracted with 100 ml of ethyl acetate. After mixing the organic layer, it was washed with water and then with an aqueous saturated sodium chloride solution successively and, after drying over anhydrous magnesium sulfate, concentrated under a reduced pressure, to obtain 22.3 g of crude 3-fluoro-4-ethoxyphenyl boronic acid. The obtained crude boronic acid derivative was used without purification for a second step.

Provenance & Evidence