“…Recently (Dyson et al, 1991a), an efficient synthesis of benzyl 3,5-di-Q-benzyl-2-deoxy-1-thio-o-erythro-pentofuranoside which could be used in the synthesis of 4"-thlo-z -deoxynucleoside analogues was described. Other suitable sugar syntheses have since been reported by others (Uenishi et al, 1991;Shaw-Ponter et al, 1996). Many 4'-thio-2'-deoxynucleoside analogues have since been synthesized (Dyson et al, 1991b;Secrist et al, 1991;Walker et al, 1994;Rahim et al, 1996) and in particular, several such pyrimidine nucleoside analogues have been shown to possess significant antiviral (usually antiherpesvirus) activity (Dyson et al, 1991b;Walker et el., 1994;Rahim et al, 1996).…”