Method for the sterospecific preparation of 2' or 3' deoxy and 2',3'-dideoxy-.beta.-L-pentafuranonucleoside compounds. 2' or 3' deoxy and 2',3'-dideoxy-.beta.-L-pentofuranonucleoside compounds are also described. Finally, the invention concerns the use of these compounds, and particularly 2',3'dideoxy-.beta.-L-fluorocytidine, as drugs, and especially as anti-viral agents.