Ring-Expanded Nucleoside Analogues. 1,3-Dioxan-5-yl Pyrimidines

Synthesis of phosphoramidites of isoGNA, an isomer of glycerol nucleic acid

IsoGNA, an isomer of glycerol nucleic acid GNA, is a flexible (acyclic) nucleic acid with bases directly attached to its linear backbone. IsoGNA exhibits (limited) base-pairing properties which are unique compared to other known flexible nucleic acids. Herein, we report on the details of the preparation of isoGNA phosphoramidites and an alternative route for the synthesis of the adenine derivative. The synthetic improvements described here enable an easy access to isoGNA and allows for the further exploration of this structural unit in oligonucleotide chemistry thereby spurring investigations of its usefulness and applicability.

Design and synthesis of carbocyclic versions of furanoid nucleoside phosphonic Acid analogues as potential anti-hiv agents

Novel 5'-norcarbocyclic adenine and guanine phosphonic acid analogues with 6',6'-difluorine moiety were designed and synthesized from commercially available epichlorohydrin 5. A regioselective Mitsunobu reaction successfully proceeded from an allylic functional group 16b at low reaction temperature in polar cosolvent to give purine phosphonate analogues 17 and 24, respectively. The purine nucleoside phosphonate and phosphonic acid analogues were subjected to antiviral screening against HIV-1. Adenine analogue 21 and its SATE prodrug 29 show significant anti-HIV activity in MT-4 cell lines.

Enantiomeric synthesis of D- and L-cyclopentenyl nucleosides and their antiviral activity against HIV and West Nile virus

Enantiomeric synthesis of D- and L-cyclopentenyl nucleosides and their antiviral activity against HIV and West Nile virus are described. The key intermediate (-)- and (+)-cyclopentenyl alcohols (7 and 15) were prepared from D-gamma-ribonolactone and D-ribose, respectively. Coupling of 7 with appropriately blocked purine and pyrimidine bases via the Mitsunobu reaction followed by deprotection afforded the target L-(+)-cyclopentenyl nucleosides (24-28, 31, 33, and 36). D-(-)-Cyclopentenyl nucleosides (1, 40, 43, and 52-56) were also prepared by a similar procedure for L-isomers from 15. The synthesized compounds were evaluated for their antiviral activity against two RNA viruses: HIV and West Nile virus. Among the synthesized D-(-)-nucleosides, adenine (1, neplanocin A), cytosine (55, CPE-C), and 5-fluorocytosine (56) analogues exhibited moderate to potent anti-HIV activity (EC(50) 0.1, 0.06, and 5.34 microM, respectively) with significant cytotoxicity in PBM, Vero, and CEM cells. Also, cytosine (55) and 5-fluorocytosine (56) analogues exhibited the most potent anti-West Nile virus activity (EC(50) 0.2-3.0 and 15-20 microM, respectively). Among L-(+)-nucleosides, only the cytosine (27) analogue exhibited weak anti-HIV activity (EC(50) 58.9 microM).

Solid phase synthesis of carbocyclic l-2'-deoxynucleosides

[reaction: see text] Carbocyclic L-2'deoxynucleosides 17 were synthesized on solid phase in four steps from the appropriately protected intermedate 11. The Mitsunobu reaction was used as a condensation method between the carbocyclic moiety and heterocyclic bases. The regioselectivity of the carbocyclic nucleosides was compared between the solid and solution phase syntheses.

An efficient synthesis of a new series of acyclonucleosides starting from beta-amino alcohols

A series of new acyclonucleosides analogues 3 has been synthesized very efficiently in three steps starting from beta-amino alcohols 1. The key step of this process is a nucleophilic substitution with various nucleophiles on 2,2'-anhydronucleosides 2. The chemo- and stereoselectivities of this reaction are discussed. AM1 calculations sustained the observed chemoselectivity.