Chemoenzymatic synthesis and antiviral evaluation of conformationally constrained and 3′-methyl-branched carbanucleosides using both enantiomers of the same building block

Starting from both enantiomers of a readily available building block, a straightforward enantioselective approach to constrained 3'-methyl-2',3'-alpha-oxirane-fused and 3'-methyl-3',4'-alpha-oxirane-fused carbanucleosides bearing different purine base analogues is described. The title compounds were evaluated as potential antiviral agents against important viruses. None of the new compounds had significant antiviral activity at a concentration of 100 microg/mL, which was the highest concentration tested.

Synthesis and anti-HCMV activity of novel 2',3', 4'-trimethyl branched carbocyclic nucleosides

This article reports the synthesis of novel 2',3',4'-trimethyl branched carbocyclic nucleosides. The introduction of a methyl group in the 2' and 3'-position was accomplished by sequential Horner-Wadsworth-Emmons reaction and isopropenyl magnesiumbromide addition, respectively. The construction of the 4'-quaternary carbon needed was carried out using a [3,3]-sigmatropic rearrangement. Bis-vinyls were successfully cyclized using a Grubbs catalyst II. The natural bases (adenine, cytosine) were efficiently coupled with the use of a Pd(O) catalyst.