Nucleosides biological activity

Pyrido[3,4-d]pyrimidine-2,4-dione synthesis, 3, 215 Pyridopyrimidines, 3, 201 iV-alkylations, 3, 206 biological activity, 3, 260-261 1-electron reductions, 3, 207 IR spectra, 3, 204 mass spectra, 3, 204 MO calculations, 3, 204 NMR, 3, 202, 203 nucleophilic substitution, 3, 213 8-nucleosides synthesis, 3, 206 physical properties, 3, 201-205 protonation, 3, 206 radical reactions, 3, 215 reactions with water, 3, 207 reduced... 

Pronucleotides as efficient tools for the delivery of biologically active nucleoside monophosphates 98SL233. 

Preparation of 2-fluorofuranoses is also important in relation to the synthesis of biologically active 2 -fluoro derivatives of nucleosides (see Section 111,4). Su and coworkers prepared the 2-triflates 236 and 239 through acid-catalyzed methanolysis of 3,5-di-O-benzyl-1,2-(9-isopropylidene-a-D-ribofuranose [to give 235 (major) and 238] and subsequent triflylation. On treatment with fluoride ion, the anomer 236 afforded exclusively the furan derivative 237, whereas the a anomer 239 gave the 2-fluoro compound 240... 

The preparation of nucleosides by reaction between carbohydrates and heterocyclic bases is fundamental to the study of the important biological activity... 

This type of substitution reaction is useful forthe synthesis of biologically active nucleosides. 1-Deoxy-l-nitroribose reacts with 2,4-bis(trimethylsilyloxy)pyrimidine in the presence of FeCl3 in MeCN to give the nucleoside in 77% yield (Eq. 7.30).34... 

Kitagawa and coworkers have used this strategy for the preparation of pseudo-nucleosides exhibiting various biological activities. The synthesis of (-)-aristeromycin from D-glucose is demonstrated in Scheme 7.17.90... 

Moffett and coworkers203 reported the synthesis of several 4-/3-D-ribofuranosylpyrazoles, such as 284(a-c), by 1,3-dipolar cycloaddition of diazoalkanes to the alkenic C-glycosyl compound 283, followed by dehydrogenation of the resulting pyrazolines. In view of the known biological activities of several nucleosides containing the... 

Potentially tautomeric pyrimidines and purines are /V-alkylated under two-phase conditions, using tetra-n-butylammonium bromide or Aliquat as the catalyst [75-77], Alkylation of, for example, uracil, thiamine, and cytosine yield the 1-mono-and 1,3-dialkylated derivatives [77-81]. Theobromine and other xanthines are alkylated at N1 and/or at N3, but adenine is preferentially alkylated at N9 (70-80%), with smaller amounts of the N3-alkylated derivative (20-25%), under the basic two-phase conditions [76]. These observations should be compared with the preferential alkylation at N3 under neutral conditions. The procedure is of importance in the derivatization of nucleic acids and it has been developed for the /V-alkylation of nucleosides and nucleotides using haloalkanes or trialkyl phosphates in the presence of tetra-n-butylammonium fluoride [80], Under analogous conditions, pyrimidine nucleosides are O-acylated [79]. The catalysed alkylation reactions have been extended to the glycosidation of pyrrolo[2,3-r/]pyrimidines, pyrrolo[3,2-c]pyridines, and pyrazolo[3,4-r/]pyrimidines (e.g. Scheme 5.20) [e.g. 82-88] as a route to potentially biologically active azapurine analogues. 

Example 63 Meier in his studies on potential prodrugs derived from biologically active nucleoside monophosphates used the cyclic chlorophosphites 2-chloro-4-ff-l,3,2,-benzodioxa-phosphinines for the synthesis of the cyclic phosphotriesters having two ligands of different hydrolytic stability benzy-loxy and aryloxy [102]. 

Most biologically active purines or purine nucleosides must be anabolized to 5 -nucleotides to exert their effects. "The 5 -nucleotides are in some cases further phosphorylated to the di- and triphosphates and the number of potential sites of action of these compounds is obviously greater than the number of potential sites of action of compounds metabolized only to the monophosphate level. But even... 

The discovery of the polyoxin group (1) of antifungal nucleoside antibiotics (2) spurred the attention of synthetic chemists as well as biologists for a number of reasons. Their unusual structural features combined with unique biological activity fostered studies on many fronts (3). During their studies on the biosynthesis of the polyoxins, Isono, Crain and McCloskey (4) discovered three novel acidic nucleosides which they called octosyl acid A, B and C,... 

The 2-aminochromene moiety can influence the other types of biological activity. A series of pyrimidine nucleosides 313, containing a 2-amino-5,6,7,8-tetrahydrochromene fragment, reveal activity against Leishmania donovani (06BML5047) (IC50 about 1-10 p). 

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