To a suspension of 3-(3-methoxypyridin-2-yl)aniline (0.34 g), N,N′-bis(tert-butoxycarbonyl)thiourea (563 mg) and diisopropylethyl-amine (0.681 ml) in dichloromethane (15 ml) was added 1-methyl-2-chloropyridinium iodide (565 mg), and the mixture was stirred for 18 hours. The mixture was diluted with dichloromethane, washed with water and brine, dried over magnesium sulfate and evaporated under reduced pressure. The residue was crystallized from methanol. The precipitate was collected by filtration, washed with methanol and dried to give N,N′-bis(tert-butoxycarbonyl)-N″-(3-(3-methoxypyridin-2-yl)phenyl)guanidine (512 mg).
