Stereospecific synthesis and biological evaluations of beta-L-pentofuranonucleoside derivatives of 5-fluorouracil and 5-fluorocytosine.

In the search for new chemotherapeutic agents, we have focused our work on the synthesis and the study of several unnatural beta-L-nucleoside analogues. In this paper, we report on the synthesis of beta-L-pentofuranonucleosides (and their 2'-deoxy derivatives) of 5-fluorouracil and their inhibitory effects on the proliferation of several murine and human tumor cells. The corresponding 5-fluorocytosine derivatives were also synthesized and their anti-HIV and anti-HBV activities have been evaluated.