Studies On Synthetic Methods Of Nucleoside Polyphosphate Analogues

Nucleoside polyphosphates exist in large numbers in organisms,participate in various important biological activities,and are also widely used in biology,medicine and other fields.The chemical synthesis of nucleoside polyphosphates has always been a well-recognized challenge in organophosphorus chemistry.At present,finding a universal method that is compatible with a huge range of nucleoside polyphosphate analogs is still a challenge.It is still no general method suitable for the synthesis of all such compounds.It is of great significance to develop new methods for the synthesis of such compounds.The chapters 2-4 of this master’s thesis studied(1)a novel method for one-pot preparation of nucleoside polyphosphate by onium salt type condensation reagent activation of nucleoside monophosphate,(2)synthesis of 5-hydroxymethyl2’-deoxycytidine triphosphate,(3)a novel method for synthesis of P~1,P~4-modifieddinucleoside tetraphosphate from nucleoside phosphoramidite.The detailed research works were summarized as follows.1.The chapter 2 focused on the synthesis of nucleoside polyphosphate from nucleoside monophosphate activated ester.In this chapter,the coupling of nucleoside monophosphate-7-azabenzotriazole(OAt)ester with pyrophosphate were firstly studied,and the reaction was confirmed to be thermally activated. The reactivity of HATU,Py Br OP,Py AOP,Py BOP and AOP to nucleoside monophosphate and their corresponding activated esters was investigated,and the best onium salt condensation reagent was screened out as Py AOP.9 nucleoside triphosphates and 3 nucleoside diphosphate sugars were efficiently prepared by using Py AOP to activate nucleoside monophosphates and then couple them with phosphate donors in a one-pot reaction.This study provides a new method for the activation of nucleoside monophosphates and the synthesis of nucleoside polyphosphate compounds.2.The chapter 3 focused on new chemical routes to 5-hydroxymethyl 2’-deoxycytidine triphosphate.Our research group has reported the synthetic route of this compound based on acetyl group protection in the early study,but the phosphorylation and deprotection steps in this route were problematic such as low yield,poor reproducibility and difficult purification.We have established method for the rapid conversion of 3’,5’-di TBS deoxythymidine into 5-(2-cyanoethyl)hydroxymethyl-2’-deoxyuridine.On this basis,two synthetic routes to 5-hydroxymethyldeoxycytidine triphosphate based on cyanoethyl-protected were attempted.The first synthetic route directly phosphorylates the nucleoside to obtain the nucleoside monophosphate,which is then converted to nucleoside triphosphate.The second synthetic route adopts a fully protected strategy,using P(III)phosphorylation reagent to convert nucleosides into fully protected nucleoside phosphoramides,followed by deprotection and coupling to furnish nucleoside triphosphate.The first synthetic route reduces reaction steps while improving the overall yield.Although the second synthetic route requires more reaction steps and separation operations,the overall yield is 9%higher than the reported route.3.The chapter 4 focused on synthesis of P~1,P~4-modified nucleoside tetraphosphate from nucleoside phosphoramidite.Our research group has established a new method for the synthesis ofα-P modified nucleoside triphosphates from nucleoside phosphinamides.In this method,a linear P(V)-P(V)-P(III) intermediate is formed by coupling nucleoside phosphoramidite and pyrophosphate,and then trivalent phosphorus is oxidized to pentavalent phosphorus by using an oxidation reagent to introduce heteroatoms.Finally,the protection groups are sequentially removed to obtain the target product.This study also found that the nucleoside phosphoramidite is highly reactive.The P(III)-P(V)-P(V)-P(III)tetraphosphate by-product is detected during coupling. The tetraphosphate by-products can be purged by raising the pyrophosphate to 3 equivalent and absence of activating reagents.Therefore,we in turn utilized the high reactivity of nucleoside phosphoramidites.By changing the ratio of nucleoside phosphoramidite and pyrophosphate,the linear P(III)-P(V)-P(V)-P(III) tetraphosphate intermediate is generated,which is oxidated and deprotected sequentially to obtain P~1,P~4-modifiednucleoside tetraphosphate.By this method,4 P~1,P~4-dithiodinucleoside tetraphosphates and 2 P~1,P~4-diselenodinucleoside tetraphosphates were efficiently synthesized,which provided an efficient and general method for synthesizing such compounds.