2-[1-((2R,4S,5S)-4-Azido-5-hydroxymethyl-tetrahydro-furan-2-yl)-5-methyl-2-oxo-2,3-dihydro-1H-pyrimidin-4-ylidene]-malonic acid diethyl ester 3'-Azido-2',3'-dideoxy nucleoside AIDS-059321 AIDS059321