Thiosugars. Part 5: synthesis and biological activity of 1-(4-thio- -arabinofuranosyl)-5-halopyrimidine nucleosides

1-O-Acetyl-2,3,5-tri-O-benzyl-4-thio- -arabinofuranoside (6) was transformed in two steps into the 1-(4-thio- -arabinofuranosyl)-5-halopyrimidine nucleosides 10, 11 and 12, obtained as anomeric mixtures which were separable in the case of 10 and 11. No in vitro antiviral activity against HIV-1 and HIV-2, TK+- and TK− VZV and CMV has been found for 10, 11 and 12.