2,4(1H,3H)-Pyrimidinedione, 1-[2-deoxy-5-O-[4-(2,2-dimethyl-1-oxopropoxy)-2-oxido-1,3,2-dioxaphosphorinan-2-yl]-.beta.-L-erythro-pentofuranosyl]-5-fluoro- AIDS-149884 AIDS149884 NSC685581