1-(3-Benzyloxymethyl-4,5-O-isopropylidene- 2-cyclopentenyl)uracil 1-(6-((Benzyloxy)methyl)-2,2-dimethyl-4,6a-dihydro-3aH-cyclopenta[d][1,3]dioxol-4-yl)-2,4(1H,3H)-pyrimidinedione AIDS-130653 AIDS130653 NSC608452