Abstract: Isoguanosine (4b) was synthesized by a one-pot reaction involving a condensation of-5-amino-l-(BD-ribofuranosyl) imidazole-4-carboxamide (2) with benzoyl isothiocyanate, treatment of the resulting thiourea derivative with DCC furnished 5-(N'- benzoylcarbamoyljaminoimidazole-4-carbonitrile (3b) which was then annulated with ethanolic ammonia to affordisoguanosine in a 68% yield from lb.-
