SYNTHESIS OF 4-METHYLTHIO ANALOGS OF FLT AND AZT AND THEIR EVALUATIONAGAINST HIV

Silylated 4-methylthiouracil and 4-methylthiothymine were condensed in the presence of TMS triflate with methyl ro-5-O-(4-phenylbenzoyl)-D-e rythro-pentofuranoside (3) and methyl 3-azido-5-O diphenylsilyl)-2,3-d ideoxy-D-erythro-pentofuroside (8), respectively, to give the correspo nding nucleosides which were deprotected. The 3'-azido nucleoside was reduced with triphenylphosphine to the corresponding 3'-amino nucleosi de. The 3'-amino nucleoside was abo obtained by condensation of 4-meth ylthiothymidine with a 3-phthalimido sugar 14 followed by deprotection . The 4-methylthio analogue 11 of AZT showed moderate activity against HIV.