5'-{3-[(3'R)-5'-(4,4'-Dimethoxytrityl)-3'-deoxythymidin-3'-yl]-2-oxopropyl}-3'-O-[2-cyanoethoxy(diisopropylamino)phosphino]-5'-deoxythymidine

3-Benzyloxymethyl-1-[(2R,4R,5S)-5-(tert-butyl-dimethyl-silanyloxymethyl)-4-(2-imidazol-1-yl-2-oxo-ethyl)-tetrahydro-furan-2-yl]-5-methyl-1H-pyrimidine-2,4-dione

(E)-3'-O-Acetyl-5'-{3-[(3'R)-3-benzyloxymethyl-5'-O-(tert-butyldimethylsilyl)-3'-deoxythymidin-3'-yl]-2-oxopropylidene}-5'-deoxythymidine

2-Cyanoethyl {5'-[(E)-3-((3'R)-3-benzyloxymethyl-5'-O-tert-butyldimethylsilyl-3'-deoxythymidin-3'-yl)-2-oxopropylidene]-5'-deoxythymidin-3'-O-yl}(3'-acetylthymidin-5'-O-yl)phosphinate