Synthesis of novel pyrimidine nucleoside analogues

Two new tetrazolopyrimidinedeoxynucleosides were synthesized and their physico-chemical data are described. Results of preliminary analyses of their biological properties are also reported.     

Synthesis of 4-nitromethylene-1,4-dihydropyrimidine derivatives as pyrimidine nucleoside analogues

The synthesis of 4-nitromethylene-1,4-dihydropyrimidine derivatives as pyrimidine nucleoside analogues was developed, starting from 3-nitropyran-2-one N-functionalized amidines. Primary amines were reacted with amidines yielding 4-nitromethylene-1,4-dihydropyrimidine derivatives. In an initial survey, several 4-nitromethylene-1,4-dihydropyrimidines turned into 4-nitromethylene-1,2,3,4-tetrahydropyrimidine derivatives under different reduction conditions. The reduction reaction also induced a change in the exocyclic double bond configuration from (E) to (Z), due to an intramolecular hydrogen bond.     

Synthesis of some analogues of nucleoside 5′-triphosphates

Reaction of propane -1,3- disulphonyl chloride with the appropriate 5' - amino - 5'.- deoxyribonucleoside gave 5' - deoxy -5′-(3- sulphopropanesulpho5' - Deoxy - 5' - p- sulphaminobenzenesulphonylaminothymidine (8) was obtained by treatment of 5' - p- aminobenzenesulphonylamino - 5' -deoxythymidine (10) with SO₃,-triethylamine. This reaction gave also some 5'-p- aminobenzenesulphonylamino - 5' - deoxy - 3' - O - sulphothymidine (12). Compounds 2 and 3 were inactive when tested for inhibitory activity against E.coli RNA polymerase holoenzyme. Compounds 1 and 8 inhibited E.coli DNA polymerase I non-competitively at relatively high concentrations. Compound 4 was without significant inhibitory activity against HSV-1 DNA polymerase.     

Enzyme-catalyzed synthesis of nucleoside triphosphates from nucleoside monophosphates

Syntheses of adenosine 5′-triphosphate (ATP) from adenosine 5′-monophosphate (AMP) and ribavirin 5′-triphosphate (RTP) from ribavirin 5′-monophosphate (RMP) (1) were performed using enzymes as catalysts. Synthesis of ATP is based on acetyl phosphate as the phosphate donor, and acetate kinase (Bacillus stearothermophilus, EC 2.7.2.1), adenylate kinase (porcine muscle, EC 2.7.4.3), and inorganic pyrophosphatase (yeast, EC 2.6.1.1) as the catalysts. Three reactions on a 150-mmol scale provided ATP as its barium salt in 82% yield and 67% purity. Synthesis of RTP used phosphoenol pyruvate (PEP) as the phosphate donor, and pyruvate kinase (rabbit muscle, EC 2.7.1.40) and adenylate kinase (rabbit muscle) as the catalysts. A gram-scale reaction provided RTP as its barium salt in 93% yield and 97% purity. This work demonstrates the utility of the autoxidationresistant acetate kinase fromB. stearothermophilus, the value of pyrophosphatase in controlling the level of pyrophosphate in the reactions and the ability of adenylate kinase to accept at least one substrate other than a derivative of adenosine.     

Synthesis of novel pyrimidine nucleoside analogues owning multiple bases/sugars and their glycosidase inhibitory activity

A series of novel nucleoside analogues having dual bases (pyrimidine and triazole) and sugars have been synthesized by CuAAC reaction of azido sugars with propynylated pyrimidines. These compounds were evaluated for their in vitro α-glucosidase inhibitory activity. In this series, compounds 4b, 4d, 8a, 8b, 8c, 8e, 8g, 8h, and 8i exhibited very good inhibition of α-glucosidase enzyme. Nucleoside analogues 8a, 4b, 8h, and 8c displayed 47.4%, 41.8%, 39.4%, and 34.6% inhibition, respectively, comparable to the standard drug acarbose (53.4%).     

Phosphoramidate analogues of diribonucleoside monophosphates

The synthesis of thio, seleno, and imino analogues of diribonucleoside phosphoramidates is described.     

Synthesis of novel C-2 substituted pyrimidine nucleoside analogs

A series of 2-(2-oxoalkylidene)-4(1H)-pyrimidinone nucleoside analogs were synthesized by the addition of the lithium enolates of methylketones to 2,5′- and 2,2′-anhydrouridines and to 2,5′-anhydrothymidines. Alternatively, 2-thiouridine was alkylated with bromomethyl ketones to yield 2-(2-oxoalkyl)thio-4(1H)-pyrimidinone ribofuranosides in good yields. These intermediates were subsequently transformed into the title compounds via an Eschenmoser sulfur extrusion reaction. The 2-(2-oxoalkylidene)-4-(1H)-pyrimidinone nucleoside analogs exhibit enol proton signals in their ¹H nmr spectra indicative of hydrogen bonding between N-3 and keto oxygen. These structures offer functional groups with potential for Watson-Crick hydrogen bonding.     

Synthesis of bicyclic pyrimidine derivatives as ATP analogues

A highly efficient and general solid-phase synthesis of bicyclic pyrimidine derivatives that target purine dependent proteins is reported. The synthesis of the key intermediate, 4,6-disubstituted-5-amino-pyrimidine, involved reduction of the corresponding nitro derivatives using 1,1'-dioctyl-viologen in a triphasic milieu. The mild reduction conditions enable the use of any acid labile solid support as well as a wide range of combinatorial substituents, thus enabling the synthesis of large libraries of highly diverse bicyclic pyrimidines. Alternative reduction conditions with tin(II) chloride and structure-reactivity studies are discussed as well.     

新型类嘌呤脱氧核糖核苷类化合物的合成

以1,3,5-三-O-苯甲酰基-2-脱氧-2-β-氟-α-D-核糖为原料,通过溴代、与4-氯吡咯[2,3-d]嘧啶的钠盐偶合、4-氯的氨基化等反应,设计合成了一系列具有新型结构的4-取代-9-(2′-脱氧-2′-β-氟-β-D-呋喃糖基)吡咯[2,3-d]嘧啶类化合物,其化学结构经核磁共振、高分辨率质谱分析确证;并且初步探讨了反应条件和反应机理.结果表明,以无水四氢呋喃为溶剂,密闭高压回流反应,反应产率较高.     

High-throughput synthesis of HepDirect prodrugs of nucleoside monophosphates

A high-throughput phosphoramidite method for HepDirect prodrug synthesis was optimized on seven representative nucleosides, adenosine, inosine, guanosine, uridine, cytidine, AICA-riboside, and thymidine, each on a 5 mg scale. The variables optimized included (1) reaction time, (2) reaction temperature, (3) activating agent, (4) solvent, (5) purification method, and (6) stoichiometry. Preparative HPLC with mass-based fraction collection and yield determination from an ELSD standard curve enabled high-throughput. The optimized conditions for the representative nucleosides required 6 mol equiv of phosphoramidite to nucleoside and resulted in an average HPLC determined yield of 31 +/- 14% and HPLC purity of 93 +/- 3%.     

Synthesis of novel anthracene derivatives of isoxazolino-carbocyclic nucleoside analogues

The synthesis of isoxazolino-carbocyclic nor-nucleosides incorporating an anthracene moiety was properly tuned through nitrosocarbonyl intermediates chemistry, and a variety of analogues were attained starting from stereodefined heterocyclic aminols through the linear construction of purine heterocyclic rings. The synthesis hinges on the exo selective 1,3-dipolar cycloaddition of the stable anthracenenitrile oxide to the N-benzoyl-2,3-oxazanorborn-5-ene and simple elaborations of the cycloadducts. A selection of nucleoside derivatives were initially tested for their inhibitory activity against a variety of viruses, including Hepatitis B and C, Human Papilloma virus as well as Influenza viruses of type A and B. Modest anti-viral activities were observed in Hepatitis assays while the activities in the cases of Influenza viruses were almost negligible. Good anti-viral activity was found for compound 11bC with no cellular toxicity at the dose tested in the case of Human Papilloma virus.     

Synthesis of new nucleoside analogues comprising a methylenecyclobutane unit

Synthesis of eight nucleoside analogues 3-10 with a methylene cyclobutane unit is described. Wittig or Peterson reactions with protected 2-hydroxycyclobutanones 12 and 13 gave E- and Z-derivatives, respectively. After functional modifications the heterocyclic moieties were introduced via a Mitsunobu reaction either on the lateral chain or on the cycle. When adenine was used in this reaction only the N-9 substitution products were obtained. Removal of the protecting groups provided the target products.     

Synthesis of tritium-labeled nucleoside 5′-triphosphates and nucleoside 5′-diphosphates

Tritium-labeled nucleoside 5′-triphosphates (NTPs) nucleoside 5′-diphosphates (NDPs) containing the tritium label in positions 8 (in the purine nucleus) and 5 (in the pyrimidine nucleus) have been obtained by the dehalogenation of the corresponding bromine derivatives with gaseous tritium. The dehalogenation of the Br-NTPs and Br-NDPs was carried out at atmospheric pressure in an aqueous alkaline medium using palladium catalysts (5% Pd/BaSO₄ or α-Pd). The possibility of introducing a tritium label into nucleotides of the adenine series by the heterogenecus isotope exchange reaction with gaseous tritium in the presence of 5% Pd/BaSO₄ has been investigated. For the compounds synthesized, the compositions of the eluents used for the chromatographic isolation of the desired products are given. The molar activities of the compounds synthesized were between 370 and 740 TB_q/mole (10–20 kCi/mole).     

Synthesis of 5-ethylpyrimidine nucleoside analogs

This paper describes the synthesis of acyclic, cyclic, and deoxy sugar nucleosides of 5-ethylpyrimidine, i.e., i) 1-(2-hydroxyethoxymethyl), 1-(2-methoxyethoxymethyl), and 1-ethoxyethyl derivatives of 5-ethyl-uracil and 5-ethylcytosine, ii) 5-ethyl-1-(tetrahydro-2H-pyran-2-yl)- and -1-(tetrahydrofuran-2-yl)uracils, and iii) 5-ethyl-2′-deoxyuridine.