5′-O-[[[6-[[(1,6-Dihydro-6-oxo-3-pyridazinyl)carbonyl]amino]hexyl]oxy]hydroxyphosphinyl]thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine

5′-O-[Hydroxy[[6-[[1-oxo-3-(2,3,6,9-tetrahydro-3-methyl-2,6-dioxo-1H-purin-8-yl)propyl]amino]hexyl]oxy]phosphinyl]thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine

5′-O-[Hydroxy[[6-[[2-(1,2,3,6-tetrahydro-1,3-dimethyl-2,6-dioxo-9H-purin-9-yl)acetyl]amino]hexyl]oxy]phosphinyl]thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine

5′-O-[[[6-[[[1-Ethyl-1,2,3,4-tetrahydro-7-(1-methylethyl)-2,4-dioxopyrido[2,3-d]pyrimidin-5-yl]carbonyl]amino]hexyl]oxy]hydroxyphosphinyl]thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine

5′-O-[[[6-[[[7-Cyclopropyl-1,2,3,4-tetrahydro-1-(2-methylpropyl)-2,4-dioxopyrido[2,3-d]pyrimidin-5-yl]carbonyl]amino]hexyl]oxy]hydroxyphosphinyl]thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine

5′-O-[[[6-[[3-(3,4-Dihydro-2,4-dioxo-1(2H)-quinazolinyl)-1-oxopropyl]amino]hexyl]oxy]hydroxyphosphinyl]thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine

5′-O-[[[6-[[2-(1,4-Dihydro-2,4-dioxo-3(2H)-quinazolinyl)acetyl]amino]hexyl]oxy]hydroxyphosphinyl]thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine

5′-O-[Hydroxy[[6-[[[1,2,3,4-tetrahydro-3-(1-naphthalenyl)-2,4-dioxo-7-quinazolinyl]carbonyl]amino]hexyl]oxy]phosphinyl]thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine

5′-O-[[[6-[[(3-Ethyl-1,2,3,4-tetrahydro-2,4-dioxo-7-quinazolinyl)carbonyl]amino]hexyl]oxy]hydroxyphosphinyl]thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine

5′-O-[Hydroxy[[6-[[(1,2,3,4-tetrahydro-5-methyl-2,4-dioxopyrido[2,3-d]pyrimidin-7-yl)carbonyl]amino]hexyl]oxy]phosphinyl]thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine

5′-O-[Hydroxy[[6-[[(1,2,3,4-tetrahydro-1-methyl-2,4-dioxopyrido[2,3-d]pyrimidin-6-yl)carbonyl]amino]hexyl]oxy]phosphinyl]thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine

5′-O-[Hydroxy[[6-[[(1,2,3,4-tetrahydro-2,4-dioxopyrido[2,3-d]pyrimidin-6-yl)carbonyl]amino]hexyl]oxy]phosphinyl]thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine

5′-O-[[[6-[[3-(3,4-Dihydro-2,4-dioxo-1(2H)-pyrimidinyl)-1-oxopropyl]amino]hexyl]oxy]hydroxyphosphinyl]thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine

5′-O-[[[6-[[2-(3,4-Dihydro-2,4-dioxo-1(2H)-pyrimidinyl)acetyl]amino]hexyl]oxy]hydroxyphosphinyl]thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine

5′-O-[Hydroxy[[6-[[(1,2,3,4-tetrahydro-1-methyl-2,4-dioxo-5-pyrimidinyl)carbonyl]amino]hexyl]oxy]phosphinyl]thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine

5′-O-[Hydroxy[[6-[[(1,2,3,4-tetrahydro-3-methyl-2,4-dioxo-5-pyrimidinyl)carbonyl]amino]hexyl]oxy]phosphinyl]thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine

5′-O-[Hydroxy[[6-[[(1,2,3,6-tetrahydro-2,6-dioxo-4-pyrimidinyl)carbonyl]amino]hexyl]oxy]phosphinyl]thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine

5′-O-[Hydroxy[[6-[[(1,2,3,4-tetrahydro-2,4-dioxo-5-pyrimidinyl)carbonyl]amino]hexyl]oxy]phosphinyl]thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine