1,1-Dimethylethyl (3aR,4R,6R,6aS)-4-[2-[acetyl[(1,1-dimethylethoxy)carbonyl]amino]-6-ethoxy-9H-purin-9-yl]-3a-ethynyltetrahydro-2-oxo-6-[[[tris(1-methylethyl)silyl]oxy]methyl]furo[3,4-d]oxazole-3(2H)-carboxylate

N-[6-Ethoxy-9-[(3aR,4R,6R,6aS)-3a-ethynylhexahydro-2-oxo-6-[[[tris(1-methylethyl)silyl]oxy]methyl]furo[3,4-d]oxazol-4-yl]-9H-purin-2-yl]acetamide