Synthesis and biological activity of 5-(trifluoromethyl)- and 5-(pentafluoroethyl)pyrimidine nucleoside analogues

Various 5-substituted perfluoroalkylpyrimidine nucleoside analogues have been synthesized, and their biological activity against L1210, S-180, Vero cells, and herpes simplex virus type 1 (HSV-1) was evaluated. The 5-trifluoromethyl derivatives, 7 and 9, showed significant antiviral activity against HSV-1 with ED50 values of 7 and 5 microM, respectively. In addition, the unblocked nucleoside 9 was found to be about 64-fold less toxic to the host Vero cells and gave a favorable therapeutic index of 64 against HSV-1 in vitro.