A 4'-C-ethynyl-2',3'-dideoxynucleoside analogue highlights the role of the 3'-OH in anti-HIV active 4'-C-ethynyl-2'-deoxy nucleosides

J Med Chem. 2004 Oct 7;47(21):5041-8. doi: 10.1021/jm049550o.


4'-C-ethynyl-2'-deoxynucleosides belong to a novel class of nucleoside analogues endowed with potent activity against a wide spectrum of HIV viruses, including a variety of resistant clones. Although favorable selectivity indices were reported for several of these analogues, some concern still exists regarding the 3'-OH group and its role in cellular toxicity. To address this problem, we removed the 3'-OH group from 4'-C-ethynyl-2'-deoxycytidine (1a). This compound was chosen because of its combined high potency and low selectivity index. The removal of the 3'-OH was not straightforward; it required a different synthetic approach from the one used to synthesize the parent compound. Starting with glycidyl-4-methoxyphenyl ether, the target 4'-C-ethynyl-2',3'-dideoxycytidine analogue (rac-1h) was obtained after 13 steps. In a cellular assay, rac-1h was completely inactive (0.001-10 microM) against HIV(LAI), demonstrating the critical importance of the 3'-OH for antiviral activity. To determine whether the role of the 3'-OH was essential for the phosphorylation of the compound by cellular kinases or for inhibition of DNA polymerization, we synthesized and tested the 5'-triphosphate (rac-1h-TP) for its ability to inhibit HIV reverse transcriptase (RT). rac-1h-TP was slightly more potent than AZT-5'-triphosphate against wild-type HIV RT, suggesting that the role of the 3'-OH is crucial only for the activation of the drug by cellular kinases. The lipase-catalyzed resolution of rac-1h into ent-1h (beta-D-dideoxyribo) and ent-14 (beta-L-dideoxyribo) and the synthesis of the corresponding 5'-triphosphates established the stereochemical assignment based on HIV RT's preference for the beta-D-enantiomer, which was confirmed by assaying against the M184V variant, an RT mutant with a marked preference for incorporating nucleosides in the D-configuration.

MeSH terms

  • Alkynes / chemical synthesis*
  • Alkynes / chemistry
  • Alkynes / pharmacology
  • Anti-HIV Agents / chemical synthesis*
  • Anti-HIV Agents / chemistry
  • Anti-HIV Agents / pharmacology
  • Binding Sites
  • Cell Line
  • Crystallography, X-Ray
  • DNA, Viral / chemistry
  • Dideoxynucleosides / chemical synthesis*
  • Dideoxynucleosides / chemistry
  • Dideoxynucleosides / pharmacology
  • HIV Reverse Transcriptase / antagonists & inhibitors
  • HIV Reverse Transcriptase / chemistry
  • HIV-1 / drug effects
  • HIV-1 / genetics
  • Humans
  • Models, Molecular
  • Molecular Structure
  • Organophosphates / chemical synthesis
  • Organophosphates / chemistry
  • Organophosphates / pharmacology
  • Phosphorylation
  • Phosphotransferases / chemistry
  • Prodrugs / chemical synthesis
  • Prodrugs / chemistry
  • Prodrugs / pharmacology
  • Stereoisomerism
  • Structure-Activity Relationship
  • Zalcitabine / analogs & derivatives*
  • Zalcitabine / chemical synthesis*
  • Zalcitabine / chemistry
  • Zalcitabine / pharmacology


  • 6-amino-3-(5-ethynyl-5-(hydroxymethyl)oxolan-2-yl)-3-hydroxypyrimidin-2-one
  • Alkynes
  • Anti-HIV Agents
  • DNA, Viral
  • Dideoxynucleosides
  • Organophosphates
  • Prodrugs
  • Zalcitabine
  • Phosphotransferases
  • HIV Reverse Transcriptase