O6-<2-(4-nitrophenyl)ethyl>-9-<3',5'-O-(1,1,3,3-tetraisopropyldisiloxane-1,3-diyl)-2'-O-<(trifluoromethyl)sulfonyl>-β-D-ribofuranosyl>guanine

N-(6-(4-nitrophenethoxy)-9-((6aR,8R,9R,9aR)-2,2,4,4-tetraisopropyl-9-(methoxy-13C)tetrahydro-6H-furo[3,2-f][1,3,5,2,4]trioxadisilocin-8-yl)-9H-purin-2-yl)-2-phenoxyacetamide