((3aR,4R,6R,6aR)-6-(6-amino-9H-purin-9-yl)-2,2-dimethyltetrahydrofuro[3,4-d][1,3]dioxol-4-yl)methyl (N2,Nd,Nw-tris(tert-butoxycarbonyl)-L-arginyl)sulfamate