Does the anti-hepatitis B virus activity of (+)-5'-noraristeromycin exist in its 4'-epimer and 4'-deoxygenated derivatives?

To begin an exploration of the structural parameters responsible for the activity of (+)-5'-noraristeromycin toward hepatitis B virus (HBV), three derivatives varied at the C-4' position have been prepared and evaluated. The syntheses began with a Mitsunobu coupling reaction of an appropriate cyclopentanol with 6-chloropurine. The products of these reactions were synthetically altered by standard ammonolysis and deprotection procedures to give the desired products. Evaluation of the new derivatives indicated that removal of the C-4' hydroxyl of (+)-5'-noraristeromycin increased its potency toward HBV by approximately 10-fold.