3',5'-O,O-bis(dimethoxytrityl)-dithymidilyl-3',5'-phosphorofluoridate

(2R,3S,5R)-2-((bis(4-methoxyphenyl)(phenyl)methoxy)methyl)-5-(5-methyl-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)tetrahydrofuran-3-yl (((2R,3S,5R)-3-hydroxy-5-(5-methyl-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)tetrahydrofuran-2-yl)methyl) methyl phosphate

dithymidylyl-3',5'-phosphoroselenoate

methyl 5'-O-dimethoxytrityl-N3-benzoylthymidin-3'-yl N3,3'-O-dibenzoylthymidin-5'-yl phosphate