3-Hydroxymethyl-1-(cytosine-1-yl)-2,5-dioxabicyclo[2.2.1]heptane 4-Amino-1-(3-hydroxymethyl-2,5-dioxa-bicyclo[2.2.1]hept-1-yl)-1H-pyrimidin-2-one AIDS-096913 AIDS096913