1-(2,5-Dideoxy-2-fluoro-5-thio-.beta.-D-arabinofuranosyl)-5-iodocytosine 105281-20-7 4-Amino-1-((2R,3S,4R,5S)-3-fluoro-4-hydroxy-5-mercaptomethyl-tetrahydro-furan-2-yl)-5-iodo-1H-pyrimidin-2-one 5'-SH-FIAC AIDS-191192 AIDS191192