1-(.beta.-D-Arabinofuranosyl)-5-fluoro-2-thiocytosine 2-Thio-5-fluorocytosine arabinoside 4-Amino-1-((2R,3S,4S,5R)-3,4-dihydroxy-5-hydroxymethyl-tetrahydro-furan-2-yl)-5-fluoro-1H-pyrimidine-2-thione AIDS-164974 AIDS164974