9-[5-(hydroxymethyl)tetrahydro-2-furanyl]-1,9-dihydro-6H-purin-6-one & {(2R,4R)-4-[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]-1,3-dioxolan-2-yl}methanol AIDS-107987 AIDS107987 ddI & BCH-13520