Bromide ion → (2-(2,4-Difluorophenoxy)-5-(trifluoromethyl)phenyl)boronic acid

Participants

Reaction Conditions

Reaction Steps

To a suspension of magnesium (0.083 g, 3.42 mmol) in tetrahydrofuran (1.00 mL) was added 0.5 mL of a solution of Example 275a (1.099 g, 3.11 mmol) in tetrahydrofuran (1.5 mL). The reaction mixture was warmed (about 40-50° C.) until reaction commenced. The remaining solution of starting bromide was added dropwise. The reaction mixture was stirred at ambient temperature for 1 hour. The resulting solution was added dropwise to a solution of trimethyl borate (0.696 mL, 6.23 mmol) in tetrahydrofuran (1.5 mL) at 0° C. The reaction mixture was stirred at ambient temperature for 1 hour, quenched with ice water and then neutralized with 2 M HCl. The mixture was extracted with ethyl acetate. The combined organics were washed with saturated aqueous sodium chloride, dried over anhydrous sodium sulfate, filtered, and concentrated. The residue was purified by flash chromatography (silica gel, 10-33% ethyl acetate/hexanes gradient) to provide the title compound (650 mg, 66% yield).

Provenance & Evidence