1-[(1R,2R,4S)-5-O-(tert-butyldiphenylsilyl)-2,3-dideoxy-2-fluoro-2-phenylselanyl-4-thio-β-D-pentofuranosyl]thymine

(+)-9-[(1R,2R,4S)-5-O-(tert-butyldiphenylsilyl)-2,3-dideoxy-2-fluoro-2-phenylselenyl-4-thio-β-D-ribofuranosyl]-6-chloro-2-fluoropurine

N4-benzoyl-1-[(1R,2R,4S)-5-O-(tert-butyldiphenylsilyl)-2,3-dideoxy-2-fluoro-2-phenylselanyl-4-thio-β-D-pentofuranosyl]-5-fluorocytosine