3'-O-{[2-(2-nitrophenyl)propoxy]carbonyl}thymidine

[(4R,5S)-2-Hydroxy-2-oxo-4-((E)-pentadec-1-enyl)-2λ5-[1,3,2]dioxaphosphinan-5-yl]-carbamic acid 1-(2-nitro-phenyl)-ethyl ester

[(4R,5S)-2-(2-Cyano-ethoxy)-2-oxo-4-((E)-pentadec-1-enyl)-2λ5-[1,3,2]dioxaphosphinan-5-yl]-carbamic acid 1-(2-nitro-phenyl)-ethyl ester

N4-{[4-(tert-butyl)phenoxy]acetyl}-2'-deoxy-3'-O-{[2-(2-nitrophenyl)propoxy]carbonyl}cytidine

N6-{[4-(tert-butyl)phenoxy]acetyl}-2'-deoxy-3'-O-{[2-(2-nitrophenyl)propoxy]carbonyl}adenosine