9-[(2R,4S,5R)-4-(tert-Butyl-dimethyl-silanyloxy)-5-(tert-butyl-dimethyl-silanyloxymethyl)-tetrahydro-furan-2-yl]-2-(trityl-amino)-9H-purin-6-ol

4-{2-[2-Amino-9-((2R,4S,5R)-4-hydroxy-5-hydroxymethyl-tetrahydro-furan-2-yl)-9H-purin-6-yloxy]-ethylamino}-1-((2R,4S,5R)-4-hydroxy-5-hydroxymethyl-tetrahydro-furan-2-yl)-1H-pyrimidin-2-one