(4-Allyloxycarbonylmethyl-5-oxo-[1,3]dioxolan-4-yl)-acetic acid 5-(5-methyl-2,4-dioxo-3,4-dihydro-2H-pyrimidin-1-yl)-2,5-dihydro-furan-2-ylmethyl ester AIDS-050447 AIDS050447 d4T deriv.