.alpha.-1-(5,6-Di-O-acetyl-2,3-dideoxy-3-phthalimido-D-ribo-hexofuranosyl)uracil 133488-33-2 2,4(1H,3H)-Pyrimidinedione, 1-[5,6-di-O-acetyl-2,3-dideoxy-3-(1,3-dihydro-1,3-dioxo-2H-isoindol-2-yl)-.alpha.-D-ribo-hexofuranosyl]- AIDS-002533 AIDS002533 DiOAcPhthN-D-ribo-ddU deriv.