Nucleosides and related organic compounds are usually phosphorylated by phosphoryl chloride, 1) polyphosphoric acid [2][3][4] and various organic phosphorus compounds. [5][6][7][8] Because phosphorylation with these agents is accompanied by various side reactions, protection of other functional groups is necessary and complicated procedures are typically required.Sodium cyclo-triphosphate, Na 3 P 3 O 9 (P 3m ), is a simple and efficient inorganic phosphorylating agent. One of the authors reported the phosphorylation of nucleosides 9) and nucleotides 10) by P 3m . The 2Ј-and 3Ј-OH groups of the b-D-ribofuranosyl unit on nucleosides and nucleotides were selectively phosphorylated in high yield without the need for protection of the other hydroxyl groups. The main phosphorylated products were 2Ј-and 3Ј-monophosphate esters of the nucleosides and nucleotides. We also reported that alkylamines, 11) aminoalcohols, 12) and carbohydrates [13][14][15][16][17][18] are readily phosphorylated with P 3m to give the corresponding triphosphate derivatives. Unfortunately, phosphorylated carbohydrates are easily decomposed to monophosphate derivatives. 9,10,[13][14][15][16][17][18] We have developed new inorganic phosphorylating reagents, imido-cyclo-triphosphates, Na 3 P 3 O 9Ϫn (NH) n . Compared with the P-O-P linkage, the P-NH-P linkage is stable and difficult to hydrolyze. 19) We therefore explored the use of imido-cyclo-triphosphates for the phosphorylation of biologically important compounds. Monoimido-cyclo-triphosphate (MCTP), diimido-cyclo-triphosphate (DCTP), and triimidocyclo-triphosphate (TCTP), shown in Fig. 1, were synthesized. Our current interest is to disclose the phosphorylation mechanism by MCTP and DCTP. TCTP did not react even under strict conditions such as pH 13 and 70°C.MCTP is a six-membered ring composed of one P-NH-P and two P-O-P linkages. We recently demonstrated that the phosphorylation of methylamine 20) and amino acids 21) proceeded with MCTP. More recently, we reported that D-glucose, D-glucuronic acid and 2-deoxy-D-glucose reacted with MCTP to form 1-O-diphosphoramidophosphono-b-D-aldoses stereoselectively.22) Organic compounds containing amino or hydroxyl group were easily phosphorylated by MCTP. We also reported that D-glucose and gluco-oligosaccharides reacted with DCTP.
23)In the present work, we chose MCTP and first studied the reaction of nucleosides with MCTP in aqueous solution, followed by phosphorylation of nucleotides, in order to synthesize triphosphate derivatives of nucleosides and nucleotides.
Results and DiscussionPhosphorylation of Adenosine (1), Guanosine (2), Cytidine (3) and Uridine (4) with MCTP Nucleosides used in the present study are shown in Fig. 2. Phosphorylation was carried out essentially according to the previously described The phosphorylation of nucleosides (adenosine, guanosine, cytidine, and uridine) and nucleotides (adenosine 5-monophosphate, guanosine 5-monophosphate, cytidine 5-monophosphate and uridine 5-monophosphate) has been achieved using inorganic monoi...