General procedure for the synthesis of 4-formylphenylboronic acid pinacol ester from p-bromobenzaldehyde and pinacol ester of biboronic acid: to a stirred solution of p-bromobenzaldehyde (8 g, 0.15 mol), pinacol ester of biboronic acid (45.7 g, 0.18 mol), and Pd(dppf)Cl2 (5.26 g, 7.5 mmol) in 1,4-dioxane, under argon protection, was KOAc (22.0 g, 0.225 mol) was added. The reaction mixture was stirred at 80 °C for 15 min. After completion of the reaction, the solvent was removed under reduced pressure. The residue was diluted with petroleum ether (500 mL) and the insoluble material was removed by filtration. The filtrate was concentrated under reduced pressure to give the crude product. The crude product was purified by fast chromatography (silica gel, petroleum ether/ethyl acetate, 10:1) to afford 4-(4,4,5,5-tetramethyl-1,3,2-dioxolan-2-yl)benzaldehyde (32.5 g, 95% yield) as a white solid.
