A solution of 2-bromo-5-nitropyridine (4.23 g, 0.02 mol) and the alkyne prepared in Step (a) (4.0 g, 0.019 mol) in 7.9 mL of triethylamine and 100 mL of acetonitrile is degassed by bubbling in dry nitrogen for 15 minutes, and 0.27 g (0.0004 mol) of bis(triphenylphosphine)palladium chloride and 0.07 g (0.0004 mol) of cuprous iodide are added. The flask is flushed with nitrogen and the mixture is stirred at room temperature for 6 hours. The solvent is removed under reduced pressure and the residue is partitioned between 100 mL of dichloromethane and 100 mL of saturated aqueous sodium bicarbonate. The aqueous layer is extracted with 50 mL of dichloromethane and the combined organic layers are washed with 50 mL of water and dried (sodium sulfate), and the solvent is removed in vacuo. The residue is chromatographed (silica gel, 1% methanol/99% dichloromethane) to give the title compound, containing 0.3 mol of water; mp 133°-134° C.
