5'-O-dimethoxytrityl-3'-O-[2-(4-nitrophenyl)ethoxy-N,N-diisopropyl]-2'-deoxyribofuranosyl-3-guanyl-N,N-bis[2-(4-nitrophenyl)ethoxycarbonyl]urea phosphoramidite
5'-O-dimethoxytrityl-2'-deoxyribofuranosyl-3-guanyl-N,N-bis-[2-(4-nitrophenyl)ethoxycarbonyl]urea
2'-deoxyribofuranosyl-3-guanyl-N,N-bis-[2-(4-nitrophenyl)ethoxycarbonyl]urea
5',3'-O-(1,1,3,3-tetraisopropyldisiloxane-1,3-diyl)-2'-deoxyribofuranosyl-3-guanyl-N,N-bis-[2-(4-nitrophenyl)-ethoxycarbonyl]urea