3′-Azido-3′, 5′-dideoxythymidine 5′-phosphonate and 3′, 5′-dideoxy-5′- difluoromethylenethymidine 5′-phosphonate were prepared by multistep syntheses. The nucleoside 5′-phosphonates were converted to their triphosphates and triphosphate mimics (P3Ms) containing β, γ-difluoromethylene, β, γ-dichloromethylene, or β, γ-imodo by condensation with pyrophosphate or pyrophosphate mimics, respectively. Inhibition of HIV ...