Step 1: In a 2L three-necked round-bottomed flask, a nitrogen inert atmosphere was established and maintained. A solvent mixture of 2-propanol/water (800mL/40mL) with pyridine-4-boronic acid (30g, 244mmol, 1.0 eq.), Na2CO3 (77.3g, 729mmol, 3.0 eq.), Pd(OAc)2 (5.46g, 24.3mmol, 0.1 eq.), PPh3 (12.75g, 48.7 mmol, 0.2 equiv) and m-bromobenzaldehyde (45 g, 243 mmol, 1.0 equiv). The reaction mixture was placed in an oil bath at 80 °C and the reaction was stirred for 48 hours. After completion of the reaction, the solid was removed by filtration and the filtrate was concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography with the eluent ethyl acetate/petroleum ether (1:1, v/v) to give 30 g of 3-(pyridin-4-yl)benzaldehyde, the product was in the form of an orange oil.
