Synthesis
GENERAL PROCEDURE: A 1 M solution (375 μL, 375 μmol) of phenylmagnesium bromide (PhMgBr) THF (375 μL, 375 μmol) was added dropwise to a solution of diisopropylaminoborane (DIPAB, 863 mg, 7.5 mmol) and magnesium shavings (182 mg, 7.5 mmol) in tetrahydrofuran (THF, 4 mL) under nitrogen protection at room temperature. After 10 min of reaction, 30 mL of anhydrous THF was added, followed by 4-bromo-1,2-dichlorobenzene (5 mmol). The reaction mixture was cooled to 0 °C and quenched by slow addition of methanol (7 mL). After 1 h of reaction, the volatile solvent was removed by distillation under reduced pressure and the resulting solid was dissolved in a 1 N hydrochloric acid/methanol (7:3, v/v) mixture. After stirring at room temperature for 1 h, ethyl acetate (100 mL) was added for extraction, and the organic phase was washed sequentially with 1 N hydrochloric acid (30 mL) and saturated saline (3 x 30 mL). The organic phase was concentrated under reduced pressure to give the crude product, which was purified by recrystallization from water (H2O) to give the target product 3,4-dichlorophenylboronic acid.
References
[1] Tetrahedron, 2019, vol. 75, # 2, p. 164 - 171
