(-)-.beta.-L-FTC (-)-2',3'-Dideoxy-5-fluoro-3'-thiacytidine (-)-FTC .beta.-L-(-)-(2R,5S)-5-Fluoro-1-[2-(hydroxymethyl)-1,3-oxathiolan-5-yl]cytosine 143491-57-0 4-Amino-5-fluoro-1-[(2R,5S)-(hydroxymethyl)-1,3-oxathiolan-5-yl]-2(1H)-pyrimidinone 524W91 AIDS-004782 AIDS004782 BW524W91 Coviracil Emtricitabine Emtriva FTC