1-(2',3'-Dideoxy-2'-fluoro-.beta.-D-threo-pentofuranosyl)cytosine 119555-47-4 2'-F-ddaraC 2(1H)-Pyrimidinone, 4-amino-1-(2,3-dideoxy-2-fluoro-.beta.-d-threo-pentofuranosyl)- AIDS-000446 AIDS000446 Ro 31-6840