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Both enantiomers of the isomer of neplanocin where the C-4′ hydroxymethyl has been displaced to the 6′-position (that is, 6′-isoneplanocin) have been prepared in 5 steps from known, protected iodocyclopentenones. Both products were evaluated against a number of DNA and RNA viruses and found to be inactive. This observation is suggested to be due to the displacement of the C-4′ hydroxymethyl of neplanocin (in the D-like form) away from the lysine425of S-adenosylhomocysteine hydrolase, which is important for inhibition by neplanocin and, in turn, its antiviral activity. [ABSTRACT FROM PUBLISHER]

To extend the potential of 5′-noraristeromycin (and its enantiomer) as potential antiviral candidates, the enantiomers of the carbocyclic 5′-nor derivatives of 5′-methylthio-5′-deoxyadenosine and 5′-phenylthio-5′-deoxyadenosine have been synthesized and evaluated. None of the compounds showed meaningful antiviral activity. [ABSTRACT FROM AUTHOR]

Abstract: As a surrogate for 4′-hydroxy-5′-noraristeromycin and related carbocyclic nucleosides, an efficient, enantiodivergent synthetic route to both enantiomers of 5-(6-amino-9H-purin-9-yl)-3,3-difluorocyclopentane-1,2-diol (6 and ent-6) has been developed from a common starting material ((+)-(1R,4S)-4-hydroxy-2-cyclopenten-1-yl acetate, 10). Both compounds were assayed versus a series of viruses. The only response found was for compound 6 toward vaccinia and cowpox (EC50 of 143 and 94μM, respectively) and human cytomegalovirus (EC50 of 6.2μM). Both compounds were non-cytotoxic. While not as active as cidofovir toward the orthopox viruses and ganciclovir toward cytomegalovirus, compound 6 offers a new structural prototype upon which to build for uncovering new agents effective against these viral types. [Copyright &y& Elsevier]

Abstract: Missing among the unsaturated carbocyclic nucleosides is the 1′,6′-double bond isomer of neplanocin A. A practical synthesis of this compound and its 2′-deoxy derivative is reported from readily accessible cyclopentenols. [Copyright &y& Elsevier]

The 1′,6′-isomer of neplanocin A possesses biological properties that have not been optimised through rationally conceived analogues. In that direction, this Letter reports the use of the Ullmann reaction to achieve enantiomeric 3-deaza-1′,6′-isoneplanocin and 3-bromo-3-deaza-1′,6′-isoneplanocin. These four compounds showed significant Ebola activity that is not specifically due to their inhibition of S -adenonosylhomocysteine hydrolase, as might have been expected for 3-deazaadenine carbocyclic nucleosides. For some members of this group, antiviral activity was also found against human cytomegalovirus, hepatitis B, norovirus, and measles. [ABSTRACT FROM AUTHOR]

Enzymatic resolution of (±)-1-acetoxy-4-(nitromethyl)-2-cyclopentene (4) provides entry into a facile 10-step route to carbanucleosides and a practical 7-step procedure to 5′-nor-1′-homo carbanucleosides. These routes are illustrated for adenine derivatives but they are adaptable to any heterocyclic base. [Copyright &y& Elsevier]

Abstract: A synthetic route to (1S,2S,3R,5S)-3-(6-amino-9H-purin-9-yl)-5-fluorocyclopentane-1,2-diol (that is, the 4′-fluoro derivative of 4′-deoxy-5′-noraristeromycin, 3) is described via a fluorinated cyclopentanol, which is in contrast to existing schemes where fluorination occurred once the purine ring was present. Compound 3 was assayed versus a number of viruses. A favorable response was observed towards measles (IC50 of 1.2μg/mL in the neutral red assay and 14μg/mL by the visual assay) but this was accompanied by cytotoxicity in the CV-1 host cells (21–36μg/mL). Among the viruses unaffected by 3 were human cytomegalovirus and the poxviruses (vaccinia and cowpox), which are three viruses that were inhibited by the 4′,4′-difluoro analog of 3 (that is, 2). [Copyright &y& Elsevier]