<4-N-acetyl-1-<2',5'-bis-O-(tert-butyldimethylsilyl)-β-D-ribofuranosyl>cytosine>-3'-spiro-5''-<4''-amino-1'',2''-oxathiole 2'',2''-dioxide>
<4-N-acetyl-1-<2',5'-bis-O-(tert-butyldimethylsilyl)-β-D-xylofuranosyl>cytosine>-3'-spiro-5''-<4''-amino-1'',2''-oxathiole 2'',2''-dioxide>
4-N-acetyl-1-<2',5'-bis-O-(tert-butyldimethylsilyl)-3'-C-cyano-3'-deoxy-β-D-xylo-pentofuranosyl>cytosine