3'-Spiro nucleosides, a new class of specific human immunodeficiency virus type 1 inhibitors: Synthesis and antiviral activity of [2',5'-bis-O-(tert- butyldimethylsilyl)-β-D-xylo- and -ribofuranose]-3'-spiro-5''-[4''-amino- 1'',2''-oxathiole 2'',2''-dioxide] (TSAO) pyrimidine nucleosides

Article abstract of DOI:10.1021/jm00093a002

A series of 3'-spiro nucleosides have been synthesized and evaluated as anti-HIV-1 agents. Reaction of O-mesyl-cyanohydrins of furanos-3'-ulosyl nucleosides with base afforded [1,[2',5'-bis-O-(tert-butyldimethylsilyl)-β- D-xylo- and -ribofuranosyl]]-3'-spiro-5''-[4''-amino-1'',2''-oxathiole 2'',2''-dioxide] derivatives of thymine, uracil and 4-N-acetylcytosine 11 and 12. Desilylation of 11 and 12 gave the full deprotected 3'-spiro xylo- and ribofuranosyl nucleosides 13 and 14 or the partially 5'-O-deprotected-3'- spiro β-D-xylo- and -ribo-nucleosides 15 and 16, or 2'-O-deprotected-3'- spiro β-D-ribo-nucleoside 17. 2'-Deoxygenation of 17 afforded 2'-deoxy-3'- spiro β-D-erythro-pentofuranosyl derivative 18. These 3'-spiro derivatives were evaluated for their anti-HIV-1 activity. All 3'-spiro nucleosides having a xylo configuration did not show any anti-HIV-1 activity. 3'-Spiro ribo- nucleosides with none or only one silyl group at C-2' or C-5' or the 2'-deoxy derivative were also inactive at subtoxic concentrations. However, 3'-spiro ribo-nucleosides having two silyl groups at C-2' and C-5' were potent and selective inhibitors of HIV-1. None of the nucleoside analogues that showed anti-HIV-1 activity proved inhibitory to the replication of HIV-2 or SIV.