2,2-Dimethyl-propionic acid 4-[1-([2-(6-amino-purin-9-yl)-ethoxymethyl]-{1-[4-(2,2-dimethyl-propanoyloxy)-phenyl]-2-methoxycarbonyl-ethoxy}-phosphinoyloxy)-2-methoxycarbonyl-ethyl]-phenyl ester AIDS-162991 AIDS162991