Based on the discovery of β-D-2′-deoxy-2′-fluorocytidine as a potent anti-hepatitis C virus (HCV) agent, a series of β-D-and l-2′-deoxy-2′-fluororibonucleosides with modifications at 5 and/or 4 positions were synthesized and evaluated for their in vitro activity against HCV and bovine viral diarrhea virus (BVDV). The introduction of the 2′-fluoro group was achieved by either fluorination of 2, 2′-anhydronucleosides with hydrogen fluoride- ...