Example 159 A Synthesis of 4-(pyridin-4-yl)benzoic acid: To a mixed solvent of acetonitrile (40 mL) and water (40 mL) was added 4-carboxyphenylboronic acid (1.66 g, 10 mmol), 4-bromopyridine (1.72 g, 11 mmol), potassium carbonate (5.5 g, 40 mmol), and bis(triphenylphosphine)palladium(II) chloride (400 mg, 0.37 mmol). The reaction mixture was degassed and displaced three times with nitrogen. Subsequently, the mixture was stirred at 100 °C for 24 hours. Upon completion of the reaction, the reaction suspension was filtered while hot and the filtrate was concentrated to half of the original volume. The concentrated aqueous phase was washed with dichloromethane, and then the pH of the aqueous phase was adjusted with 1 M hydrochloric acid to 3. The precipitated solid was collected by filtration, washed with water, and finally dried under vacuum to give 1.8 g of the white solid product, 4-(pyridin-4-yl)benzoic acid, in 90% yield.LC-MS (ESI) m/z: 200(M+1)+.
