4′-Aza-3′,5′-dihomothymidine and Derivatives

A series of 3′-branched 4′-azanucleoside analogues have been prepared. These compounds comprise three asymmetric atoms, two carbons and one nitrogen. They constitute nucleoside analogues imparted with a “flickering configuration”, the nitrogen inversion replacing a D-L epimerization of their natural congeners. The 1′,3′-cis and 1′,3′-trans isomers have been separated and their configuration established by 1H NMR and the X-ray diffraction structure of one crystalline example. The configurations of the frozen invertomers were assessed by low temperature 1H NMR experiments assisted by molecular mechanics simulations. None of these compounds exhibited any significant in vitro antiviral activity.