Abstract
Reaction of 2', 3'-di- or 2', 3', 5'-tri-O-protected guanosine (I, IX) with phosphorus trichloride in ethyl methyl ketone, cyclohexanone or benzaldehyde afforded the corresponding N2-(1-phosphono)alkylguanosine derivative (IIa-c). The structure of the aglycon (IIIa) was determined definitely by the X-ray diffraction method. A similar reaction in dioxane resulted in no modification of the guanine moiety, while the reaction in tetrahydrofuran gave 4-(inosin-2-yl)amino-4-phosphonobutyl hydrogen phosphonate (VII). None of the reactions in acetylacetone, benzoquinone, naphthoquinone and anthraquinone modified the guanine base. An alternative preparation of guanosine 5'-monophosphate was accomplished by the reaction of isopropylideneguanosine(IX) with phosphorus trichloride in anthraquinone in a stream of oxygen, followed by hydrolysis and deblocking.
