2,2-dimethylthiopropionic acid S-(2-((4-(4-benzyl-3-ethoxymethyl-5-isopropyl-2,6-dioxo-3,6-dihydro-2H-pyrimidine-1-carbonyl)phenoxy)-(5-(5-methyl-2,4-dioxo-3,4-dihydro-2H-pyrimidin-1-yl)-2,5-dihydrofuran-2-ylmethoxy)phosphoryloxy)ethyl) ester