Synthesis of 2'-deoxy-2'-fluoroguanyl-(3',5')-guanosine

The protected analogue of 2-amnio-6-chloropurine arabinoside (3b) was subjected to reaction with diethylaminosulfur trifluoride (DAST) and subsequently treated with NaOAc in Ac2O/AcOH to give N2, O3', O5'-triacetyl-2'-deoxy-2'-fluoroguanosine (5a). After deacetylation of the sugar moiety and protection of 5'-OH by a 4,4'-dimethoxytrityl group, this nucleoside component was converted to 2'-deoxy-2'-fluoroguanyl-(3',5')-guanosine (6c, GfpG).     

Synthesis and biological evaluation of 2',3'-didehydro-2',3'-dideoxy-9-deazaguanosine, a monophosphate prodrug and two analogues, 2',3'-dideoxy-9-deazaguanosine and 2',3'-didehydro-2',3'-dideoxy-9-deazainosine

2',3'-Didehydro-2',3'-dideoxy-9-deazaguanosine (1), its monophosphate prodrug (2), and two analogues, 2',3'-dideoxy-9-deazaguanosine (3) and 2',3'-didehydro-2',3'-dideoxy-9-deazainosine (4), have been synthesized from benzoylated 9-deazaguanosine (5). Basic hydrolysis of 5, selective protection of the 2-amino and 5'-hydroxy functions with isobutyryl and silyl groups, respectively, followed by reaction with thiocarbonyldiimidazole gave the cyclic thiocarbonate, which, upon reaction with triethyl phosphite, followed by deprotection, afforded 1. Treatment of 1 with phenyl methoxyalaninylphosphochloridate and N-methylimidazole gave 2. Catalytic hydrogenation of 1 gave 3. Hydrodediazoniation of 1 with tert-butyl nitrite and tris(trimethylsilyl)silane gave 4. Compounds 1-4 were found to be inactive against the human immunodeficiency virus and exhibited minimal to no cytotoxic activity against the L1210 leukemia, CCRF-CEM lymphoblastic leukemia, and B16F10 melanoma in vitro.     

Synthesis of 2',3'-dideoxy-2'-monofluoromethyl azanucleosides

(2S,4S)-Methyl-N-tert-butoxycarbonyl-4-monofluoromethylpyroglutamate 6 was synthesized via a key dehydrofluorination followed by hydrogenation. Compound 6 was converted to (5S,3S)-N-benzyloxycarbonyl-5-tert-butyldimethylsilyloxymethyl-3-monofluoromethyl-2-pyrrolidone 12 over four steps in 62% yield, which was used as a precursor for the synthesis of 2',3'-dideoxy-2'-monofluoromethyl azanucleosides 17-18.     

Synthesis of 2',3'-dideoxy-2',3'-didehydro nucleosides via a serendipitous route

This paper describes a "green" synthesis of 2',3'-unsaturated 2',3'-dideoxynucleosides via an electrochemical reaction. Using this approach d4T, d4U, ddA and ddI can be synthesized in high yields.     

2',3'-didehydro-2',3'-dideoxy-5-chlorocytidine is a selective anti-retrovirus agent

2',3'-Didehydro-2',3'-dideoxy-5-chlorocytidine (D4CC) is, in contrast with 2',3'-dideoxy-5-chlorocytidine (ddClCyd) and 2',3'-didehydro-2',3'-dideoxy-5-chlorouridine (D4CU), a potent and selective inhibitor of the replication of human immunodeficiency virus (HIV) types 1 and 2, simian immunodeficiency virus (SIV) and simian AIDS related virus (SRV). D4CC is a poor inhibitor of the phosphorylation of [5-3H]2'-deoxycytidine (dCyd) by partially purified MT-4 cell dCyd kinase (Ki: 612 microM). The findings that (i) D4CC has little, if any, affinity for MT-4 cell Cyd/dCyd deaminase, (ii) D4CU is not antivirally active and (iii) the antiretroviral action of D4CC can be reversed by dCyd, but not dThd, indicate that D4CC is antivirally active as its Cyd metabolite (D4CC 5'-triphosphate) and does not need to be deaminated (to the corresponding Urd metabolite) to exert its antiretroviral action.     

Synthesis of 2',3'-dideoxy-2'-fluoro-L-threo-pentofuranosyl nucleosides as potential antiviral agents

A series of 2',3'-dideoxy-2'-fluoro-L-threo-pentofuranosyl nucleosides has been synthesized as potential antiviral agents. The synthesized compounds were evaluated against HIV-1, HBV, HSV-1, and HSV-2. Among the synthesized analogues, only the cytosine derivative showed moderate antiviral activity against HIV and HBV.     

Synthesis of 2',3'-dideoxy-3'-fluoro-L-ribonucleosides as potential antiviral agents from D-sorbitol

2',3'-Dideoxy-3'-fluoro-L-ribonucleosides were synthesized as potential antiviral agents. The key intermediate, methyl 5-O-benzoyl-2,3-dideoxy-3-fluoro-L-ribofuranoside, which was prepared from D-sorbitol, was condensed with pyrimidine and purine bases to obtain the respective nucleosides. Among them, the cytosine analogue 2',3'-dideoxy-3'-fluoro-alpha-L-cytidine showed a moderate anti-HBV activity.     

Synthesis and polymerase incorporation of 5'-amino-2',5'-dideoxy-5'-N-triphosphate nucleotides

Owing to the markedly increased reactivity of amino functional groups versus hydroxyls, the 5′-amino-5′-deoxy nucleoside and nucleotide analogs have proven widely useful in biological, pharmaceutical and genomic applications. However, synthetic procedures leading to these analogs have not been fully explored, which may possibly have limited the scope of their utility. Here we describe the synthesis of the 5′-amino-2′,5′-dideoxy analogs of adenosine, cytidine, guanosine, inosine and uridine from their respective naturally occurring nucleosides via the reduction of 5′-azido-2′,5′-dideoxy intermediates using the Staudinger reaction, and the high yield conversion of these modified nucleosides and 5′-amino-5′-deoxythymidine to the corresponding 5′-N-triphosphates through reaction with trisodium trimetaphosphate in the presence of tris(hydroxymethyl)aminomethane (Tris). We also show that each of these nucleotide analogs can be efficiently incorporated into DNA by the Klenow fragment of Escherichia coli DNA polymerase I when individually substituted for its naturally occurring counterpart. Mild acid treatment of the resulting DNA generates polynucleotide fragments that arise from specific cleavage at each modified nucleotide, providing a sequence ladder for each base. Because the ladders are generated after the extension, the corresponding products may be manipulated by enzymatic and/or purification processes. The potential utility of this extension–cleavage procedure in genomic sequence analysis is discussed.     

Synthesis of 2',3'-dideoxy-2'-fluoro-3'-thioarabinothymidine and its 3'-phosphoramidite derivative

An efficient method for the synthesis of 5'-O-monomethoxytrityl-2',3'-dideoxy-2'-fluoro-3'-thioarabinothymidine [(5'MMT)araF-T(3'SH), (5)] and its 3'-phosphoramidite derivative (6) suitable for automated incorporation into oligonucleotides, is demonstrated. A key step in the synthesis involves reaction of 5'-O-MMT-2,3'-O-anhydrothymidine (4) (Eleuteri, A.; Reese, C.B.; Song, Q. J. Chem. Soc. Perkin Trans. 1 1996, 2237 pp.) with sodium thioacetate to give (5'-MMT)araF-T(3'SAc) (5) (Elzagheid, M.I.; Mattila, K.; Oivanen, M.; Jones, B.C.N.M.; Cosstick, L?nnberg, H. Eur. J. Org. Chem. 2000, 1987-1991). This nucleoside was then converted to its corresponding phosphoramidite derivative, 6, as described previously ((a) Sun, S.; Yoshida, A.; Piccirilli, J.A. RNA, 1997, 3, 1352-1363; (b) Matulic-Adamic, J.; Beigelman, L. Helvetica Chemica Acta 1999, 82, 2141-2150: (c) Fettes, K.J.; O'Neil, I.; Roberts, S.M.; Cosstick, R. Nucleosides, Nucleotides and Nucl. Acids 2001, 20, 1351-1354).     

Synthesis and anti-HIV evaluation of new 2',3'-dideoxy-3'-thiacytidine prodrugs

A series of anti-HIV prodrugs possessing various polyaminated side arms have been developed. The incorporation of a N-Boc protected monoamine or diamine side arm into the backbone of the 2',3'-dideoxy-3'-thiacytidine 1 (BCH-189) provided an increase in antiviral potency, which could be several orders magnitude greater than the parent drug (1) depending on the cell culture systems used (MT-4 or MDMs). Twenty six 2',3'-dideoxy-3'-thiacytidine prodrugs which differ from each other by the length, the nature of the 5'-O function and the 5'-O or/and N-4 position on the nucleoside moiety were synthesized. Among this new series of prodrugs, several congeners (12c and 12a) were found to inhibit HIV-1 replication in cell culture with 50% effective concentrations EC50 of 10 and 50 nM respectively, in MT-4 cells. Compound 12c was found more active on infected MDMs cells with 50% effective concentration of 0.01 nM. The synthesis and the antiviral properties of these compounds are discussed.     

Acyclic nucleoside analogues. III. Synthesis of new 2',3'-dideoxy-2',3'-didehydronucleoside analogues

The coupling of 5-acetoxy-1,1-dimethoxypent-2-ene with cytosine and thymine trimethylsilyl derivatives, as well as the reaction of 5-acetoxy-1-bromopent-2-ene with adenine sodium salt, yielded acyclic analogues of the corresponding nucleosides containing 5'-acetoxy groups. They were deprotected with a saturated methanolic solution of ammonia to the target analogues of nucleosides, which were characterized with 1H NMR, IR, and UV spectra. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 6; see also http://www.maik.ru.     

Synthesis and biological evaluation of polyaminated 2',3'-dideoxy-3'-thiacytidine prodrugs.

The syntheses and biological evaluation of polyaminated 2',3'-dideoxy-3'-thiacytidine have been performed. A new lead was found to increase the in vitro antiviral potency (syncitia formation on MT-4 cell line) of two order magnitude greater than the parent nucleoside drug. Moreover, the in vitro activity on HIV macrophages was found to be more than 3 log greater than the activity of the parent drug 1.     

Synthesis and antiviral evaluation of 2',3'-dideoxy-2'-fluoro-3'- C-hydroxymethyl-beta-D-arabinofuranosyl pyrimidine nucleosides

The synthesis and anti-HBV and anti-HIV activity of a number of 2',3'-dideoxy-2'-fluoro-3'-C-hydroxymethyl-beta-D-arabinofuranosyl pyrimidine nucleosides are reported.     

Synthesis of 3'-thioamido-modified 3'-deoxythymidine-5'-triphosphates and their use as chain terminators in Sanger-DNA sequencing

The thioamide derivatives 3'-deoxy-5'-O-(4,4'-dimethoxytrityl)-3'-[(2-methyl-1-thioxo- propyl)amino]thymidine 1 and 3'-deoxy-5'-O-(4,4'-dimethoxytrityl)-3'-((6-([(9H-(fluo-ren-9- ylmethoxy)carbonyl]-amino)-1-thioxohexyl)amino) thymidine 2 were synthesized by regioselective thionation of their corresponding amides 7 and 8 with 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide (Lawesson's reagent). The thioamides were converted into the corresponding 5'-triphosphates 3 and 4. Compound 3 was chosen for DNA sequencing experiments and 4 was further labelled with fluorescein.     

Synthesis of dihydrothymidine and thymidine glycol 5'-triphosphates and their ability to serve as substrates for Escherichia coli DNA polymerase I

5,6-Dihydrothymidine 5'-triphosphate (DHdTTP) was synthesized by catalytic hydrogenation of thymidine 5'-triphosphate (dTTP). Thymidine glycol 5'-triphosphate (dTTP-GLY) was prepared by bromination of dTTP followed by treatment with Ag2O. The modified nucleotides were extensively purified by anion-exchange high-performance liquid chromatography (HPLC). Alkaline phosphatase digestion of DHdTTP and dTTP-GLY gave the expected products (5,6-dihydrothymidine and cis-thymidine glycol), the identities of which were confirmed by reverse-phase HPLC using authentic markers. HPLC analysis of the alkaline phosphatase digested DHdTTP revealed that DHdTTP was a mixture of C5 diastereoisomers [(5S)- and (5R)-DHdTTP]. Despite the significant distortion of the pyrimidine ring in DHdTTP, it was incorporated in place of dTTP during primer elongation catalyzed by Escherichia coli DNA polymerase I Klenow fragment. The rate of incorporation of DHdTTP was about 10-25-fold lower than that of dTTP. On the other hand, dTTP-GLY, which also has a distorted pyrimidine ring, did not replace dTTP, and no elongation of the primer was observed. In order to study the preference of incorporation of the diastereoisomers of DHdTTP into DNA, salmon testes DNA, activated by exonuclease III, was used as a template for DNA polymerase I Klenow fragment in the presence of [3H]DHdTTP (S and R mixture) and normal nucleotides. After enzymatic digestion of the DNA to nucleosides, the products were analyzed by HPLC. The ratio of the isomers incorporated into DNA (S:R = 73.27) was virtually the same as that of the [3H]DHdTTP substrates (S:R = 79.21).(ABSTRACT TRUNCATED AT 250 WORDS)