Highly stereoselective synthesis of novel cyclobutane-fused azanucleosides

Stereoselective syntheses of several 3-azabicyclo[3.2.0]heptane nucleoside analogues have been efficiently completed starting from a homochiral a,b-unsaturated-g-lactam. The target compounds were prepared by condensation of a common bicyclic acetate intermediate with pyrimidine and purine bases under modified Vorbrüggen conditions. The anti-HIV activity of the newly synthesized azanucleosides has been evaluated.