5-[[(1R)-2-[6-[[[[9-[(2R)-2,11-Dimethyl-5-[[[(1-methylethoxy)carbonyl]oxy]methoxy]-5-oxido-9-oxo-3,6,8,10-tetraoxa-5-phosphadodec-1-yl]-9H-purin-6-yl]amino]methyl]amino]-9H-purin-9-yl]-1-methylethoxy]methyl]-2,4,6,8-tetraoxa-5-phosphanonanedioic Acid 1,9-Bis(1-methylethyl) Ester 5-Oxide;