Cyanogen-induced synthesis of 18O-labelled β-ribofuranose 1-phosphate and its acid-catalysed hydrolysis

D-Ribose was phosphorylated with HP18O42– in dilute aqueous solution in the presence of cyanogen. In the β-ribofuranose 1-phosphate produced, the oxygen atom of the P–O–C bond was derived mainly from the ribose. This indicated the formation of a reactive intermediate from cyanogen and phosphate, followed by nucleophilic attack of the glycosidic hydroxy-group of the ribose on the phosphorus atom of that intermediate.A study of the hydrolysis of unlabelled β-ribofuranose 1-phosphate in H218O in 0·1N-hydrochloric acid showed that it proceeds with 95% C–O bond fission, suggesting the occurrence of an A1 mechanism.