Stereoselective synthesis of 4′-selenonucleosides via seleno-Michael reaction as potent antiviral agents

Based on the hypothesis that the bulky selenium atom, with 4p orbitals, can sterically hinder the approach of a cellular kinase to 5′-OH for phosphorylation, 4′-selenonucleosides with one-carbon homologation were designed and synthesized via a novel seleno-Michael reaction, with the stereoselectivity controlled by steric effects. 5′-Homo-4′-selenonucleosides (n = 2) demonstrated potent antiherpes simplex virus (HSV-1) activity, indicating that the bulky selenium atom might play a key role in preventing phosphorylation by cellular kinases, resulting in no antiviral activity.