A facile and regio- and stereo-selective preparation of bicyclic guanidines by iodocyclization of 3-(alk-2-enyl)-2-(substituted amino)-1-imidazolin-4-ones

Abstract The iodocyclization of 3-(alk-2-enyl)-2-(substituted amino)-1-imidazolin-4-ones proceeded in regio- and stereo-selective manners to give bicyclic guanidines, imidazo[1,2- a ]imidazole and/or imidazo[1,2- a ]pyrimidine, in good yields. The regiochemistry of the cyclization depended mainly on the kind of substituents of the alkenyl moieties and was interpretable by the PM3 MO calculations of the iodonium ion intermediates.