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',S'-trans isomers have been separated and their configuration established by H-1 NMR and the X-ray diffraction structure of one crystalline example. The configurations of the frozen invertomers were assessed by low temperature H-1 NMR experiments assisted by molecular mechanics simulations. None of these compounds exhibited any significant in vitro antiviral activity.