N1-(9-fluorenylmethoxycarbonylthiourea)-N2,N3-bis[2-(4-nitrophenyl)ethoxycarbonyl]-N4-(4-monomethoxytrityl)spermine
N1-(4-monomethoxytrityl)-N2,N3-bis[2-(4-nitrophenyl)ethoxycarbonyl]spermine
N1,N4-bis(4-monomethoxytrityl)-N2,N3-bis[2-(4-nitrophenyl)ethoxycarbonyl]spermine
N1,N4-bis(tert-butoxycarbonyl)-N2,N3-bis[2-(4-nitrophenyl)ethoxycarbonyl]spermine
N4,N8-bis (N-CBZ-5-aminopentyl)-N1,N12-bis (tert-butyloxycarbonyl) spermine