.beta.-D- 2',3'-Didehydro-2',3'-dideoxy-5-fluorocytidine .beta.-D-D4FC 134379-77-4 5F-D4C AIDS-000572 AIDS000572 D-d4FC DFC DPC 817 Dexelvucitabine RA 131423 RVT Reverset (TM) d4FC