(3aS,5S,6R,6aS)-5-((R)-2,2-Dimethyl-[1,3]dioxolan-4-yl)-2,2,6-trimethyl-tetrahydro-furo[2,3-d][1,3]dioxole

5'-O-(3-benzoylpropionyl)-3'-deoxy-3'-dihydroxyphosphinylmethyl-2'-O-acetyl uridylyl-(3'<*>5')-2',3'-O-isopropylidene uridine pyridinium salt

3'-deoxy-3'-dihydroxyphosphinylmethyl-2'-O-acetyl uridylyl-(3'<*>5')-2',3'-O-isopropylidene uridine pyridinium salt