GENERAL METHOD: Methanol (12.50 mL) was added to a mixture of 3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzaldehyde (1a, 375 mg, 2.50 mmol), pinacol (355 mg, 3.00 mmol) and anhydrous magnesium sulfate (625 mg, 5.00 mmol). The mixture was stirred at room temperature for 6 hours. Upon completion of the reaction, the crude reaction mixture was filtered and then sodium borohydride (47 mg, 1.25 mmol) was added to the filtrate. Subsequently, the reaction mixture was stirred for another 5 hours. After completion of the reaction, the reaction mixture was filtered and the filtrate was concentrated in vacuum to afford the target product 3-hydroxymethylphenylboronic acid pinacol ester (2a) as a white solid (melting point 75-77 °C) in 88% yield (513 mg).1H-NMR (CD3OD-d4) δ ppm: 7.71 (d, J=8.0 Hz, 2H), 7.35 (d, J=7.8 Hz. 2H), 4.62 (s, 2H), 1.34 (s, 12H); 13C-NMR (CD3OD-d4) δppm: 146.23, 135.93, 127.26, 85.19, 65.24, 25.34; 11B-NMR (CDCl3) δppm: 34.82.
