5′-O-(1-Hydroxy-20,20-dimethyl-1-oxido-2-oxa-15,16,17,18-tetraaza-1-phospha-20-silaheneicos-15-en-1-yl)thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidylyl-(3′→5′)-thymidine

2-Amino-7,9-dihydro-7-(2-propyn-1-yl)-9-[(2R,3R)-tetrahydro-3-hydroxy-5-(1-oxopropyl)-2-furanyl]-1H-purine-6,8-dione