Various analogues of the anti-HIV-1 agent TSAO-T, [1-[2',5'-bis-O-(tert-butyldimethylsilyl)-beta-D-ribofuranosyl]thymine]-3'-spiro-5"-(4"-amino-1",2"-oxathiole-2",2"-dioxide) have been synthesized in which the 5'-TBDMS group has been replaced by alkyl-, alkenyl- or aromatic ether groups, substituted amines, carbamoyl or (thio)acyl groups. The compounds synthesized were evaluated for their inhib...