2 - phenethylpiperidines bearing urea , thiourea , and amidine substituents in the ortho - position of the phenethyl moiety have been synthesized and demonstrate useful antiarrhythmic properties . these novel compounds are prepared by reaction of appropriately substituted o - amino - phenethylpiperidines with appropriately substituted phenyl isothiocyanates , phenyl isocyanates , or phenyl imino esters .