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

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

1-{(2R,4R,5S)-5-(tert-Butyl-dimethyl-silanyloxymethyl)-4-[2-oxo-3-(triphenyl-λ5-phosphanylidene)-propyl]-tetrahydro-furan-2-yl}-5-methyl-3-(2-trimethylsilanyl-ethoxymethyl)-1H-pyrimidine-2,4-dione

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