A mixture of 3-bromo-4-chloronitrobenzene (5.17 g, 21.9 mmol) and pyridine-3-boronic acid 1,3-propanediol cyclic ester (4.27 g, 26.2 mmol) in ethanol (30 ml) and toluene (30 ml) together with 2 N Na2CO3 solution (13.9 ml) was degassed with a stream of nitrogen for 10 min. Tetrakis(triphenylphosphine)palladium(0) (0.3 g, 0.26 mmol) was added and the reaction was heated at reflux for over 24 h. The mixture was concentrated under reduced pressure to remove the organic solvents and water (100 ml) was added. This was extracted with ethyl acetate (200 ml) and then washed with brine (75 ml), dried (MgSO4), and concentrated under reduced pressure while dry loading onto silica. The resulting crude residue was purified by column chromatography (silica gel, 50% Et2O/CH2Cl2), to yield the title compound (3.53 g, 69%): 1H NMR (360 MHz, CDCl3) δ 7.42-7.48 (1H, m), 7.70 (1H, d, J 8.7 Hz), 7.81 (1H, dt, J 8.0, 1.8 Hz), 8.17-8.27 (2H, m), 8.68-8.77 (2H, m).
