AIDS-050449 AIDS050449 Methyl [5-(5-methyl-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)-2,5-dihydrofuran-2-yl]methyl 2,2'-(5-oxo-1,3-dioxolane-4,4-diyl)diacetate d4T deriv.