Nucleosides. 139. Synthesis and anticytomegalovirus and antiherpes simplex virus activity of 5'-modified analogues of 2'-fluoroarabinosylpyrimidine nucleosides

An efficient synthesis of 3-fluoro-5-thio-xylofuranosyl nucleosides of thymine, uracil, and 5-fluorouracil as potential antitumor or/and antiviral agents

1,2:5,6-Di-O-isopropylidene-alpha-D-glucofuranose by the sequence of mild oxidation, reduction, fluorination, periodate oxidation, borohydride reduction, and sulfonylation gave 3-deoxy-3-fluoro-1,2-O-isopropylidene-5-O-p-toluenesulfonyl-alpha-D-xylofuranose (5). Tosylate 5 was converted to thioacetate derivative 6, which after acetolysis gave 1,2-di-O-acetyl-5-S-acetyl-3-deoxy-3-fluoro-5-thio-D-xylofuranose (7). Condensation of 7 with silylated thymine, uracil, and 5-fluorouracil afforded nucleosides 1-(5-S-acetyl-3-deoxy-3-fluoro-5-thio-beta-D-xylofuranosyl) thymine (8), 1-(5-S-acetyl-3-deoxy-3-fluoro-5-thio-beta-D-xylofuranosyl) uracil (9), and 1-(5-S-acetyl-3-deoxy-3-fluoro-5-thio-beta-D-xylofuranosyl) 5-fluorouracil (10). Compounds 8, 9, and 10 are biologically active against rotavirus infection and the growth of tumor cells.

Simple Transformation of Thymine 1-[3-Hydroxy-2-(phosphonomethoxy)propyl] Derivatives to Their 1-[3-Fluoro-2-(phosphonomethoxy)propyl] Counterparts

A novel method of transformation of HOCH2 group to FCH2 was successfully applied to the preparation of fluorine-containing pyrimidine acyclic nucleoside phosphonates (FPMP compounds) such as (S)- and (R)-1-[3-fluoro-2-(phosphonomethoxy)propyl]thymine (7a, 7b) (FPMPT). The key displacement of hydroxy group with fluorine in 1-{2-[(diisopropoxyphosphoryl)- methoxy]-3-hydroxypropyl}-4-methoxy-5-methylpyrimidin-2(1H)-one (5a, 5b) was performed using perfluorobutane-1-sulfonyl fluoride in the presence of DBU. Novel pyrimidine acyclic nucleoside phosphonates were investigated as inhibitors of thymidine phosphorylase.

Synthesis and properties of oligonucleotide chimeras containing 5'-amino-2'-deoxy-2'-fluoroarabinonucleosides

Oligonucleotide analogues comprised of 2'-deoxy-2'-fluoro-beta-D-arabinose units joined via P3'-N5' phosphoramidate linkages (2'F-ANA(5'N)) were prepared for the first time. Among the compounds prepared were a series of 2'OMe-RNA-[GAP]-2'OMe-RNA 'chimeras', whereby the "GAP" consisted of DNA, DNA(5'N), 2'F-ANA or 2'F-ANA(5'N) segments. The chimeras with the 2'F-ANA and DNA gaps exhibited the highest affinity towards a complementary RNA target, followed by the 5'-amino derivatives, i.e., 2'F-ANA > DNA > 2'F-ANA(5'N) > DNA(5'N). Importantly, hybrids between these chimeras and target RNA were all substrates of both human RNase HII and E. coli RNase HI. In terms of efficiency of the chimera in recruiting the bacterial enzyme, the following order was observed: gap DNA > 2'F-ANA > 2'F-ANA(5'N) > DNA(5'N). The corresponding relative rates observed with the human enzyme were: gap DNA > 2'F-ANA(5'N) > 2'F-ANA > DNA(5'N).

Synthesis of monofluorinated analogues of lysophosphatidic acid

Lysophosphatidic acid (LPA, 1- or 2-acyl-sn-glycerol 3-phosphate) displays an intriguing cell biology that is mediated via interactions both with G-protein coupled seven transmembrane receptors and with the nuclear hormone receptor PPARgamma. Synthesis and biological activities of fluorinated analogues of LPA are still relatively unknown. In an effort to identify receptor-selective LPA analogues and to document in detail the structure-activity relationships of fluorinated LPA isosteres, we describe a series of monofluorinated LPA analogues in which either the sn-1 or the sn-2 hydroxy group was replaced by fluorine, or the bridging oxygen in the monophosphate was replaced by an alpha-monofluoromethylene (-CHF-) moiety. The sn-1 or sn-2 monofluorinated LPA analogues were enantiospecifically prepared from chiral protected glycerol synthons, and the alpha-monofluoromethylene-substituted LPA analogues were prepared from a racemic epoxide with use of a hydrolytic kinetic resolution. The sn-2 and sn-1 fluoro LPA analogues were unable to undergo acyl migration, effectively "freezing" them in the sn-1-O-acyl or sn-2-O-acyl forms, respectively. The alpha-monofluoromethylene LPA analogues were unique new nonhydrolyzable ligands with surprising enantiospecific and receptor-specific biological readouts, with one compound showing a 1000-fold higher activity than native LPA for one receptor subtype.

The FIAU Derivative (2′S)-2′-Deoxy-2′-C-Methyl-5-Iodouridine (SMIU) is a Novel, Less Cytotoxic and Potent anti-HSV and anti-VZV Agent

In this study, the anti-herpetic activities of novel 2′-methyl nucleoside analogues which were substituted at the 5 position of the pyrimidine with a halogen were investigated. The 2′-fluoro-5-iodo-aracytosine (FIAC) congeners (2′S)-2′-deoxy-2′- C-methylcytidine which were substituted with Br or I at the 5 position (SMBC or SMIC); and 2′-fluoro-5-iodo-arauridine (FIAU) congeners (2′S)-2′-deoxy-2′-C-methyluridine which were substituted with Br or I at the 5 position (SMBU or SMIU), proved to have potent antiviral activities against herpes simplex virus type-1 (HSV-1) and varicella-zoster virus (VZV) but not against herpes simplex virus type-2 (HSV-2). SMIU has a higher selective index against HSV-1 than FIAU, and both SMIC and SMIU showed higher inhibitory effects against VZV replication than aciclovir. The four effective compounds were not inhibitory to a thymidine kinase (TK)-negative HSV-1 strain, and this result indicates that phosphorylation of the compounds by HSV or VZV-TK is necessary for the activation of these compounds.

Synthesis of Mimics to 5-(2″-thienyl)-2′,3′-β-Dideoxyuridine Triphosphate

A series of 5′-amido derivatives of 5-(2″-thienyl)-2′,3′,5′-β-trideoxyuridine were prepared. The compounds were tested for their inhibition of cellular DNA polymerase α and α HIV-RT. The succinic fumaric and maleic acid derivatives of 5-(2″-thienyl)-2′,3′,5′-β-trideoxyuridine were investigated. None of the compounds inhibited HIV-RT. The fumaric acid derivative inhibited DNA pol α with IC5033 μg ml−1. The succinic acid derivative was about half as active with IC5076 μg ml−1. The 5′-N-acyl derivatives also were structurally compared to the monomethyl ester of the triphosphate using the Sybyl program.