(2R,3S,5R)-5-(4-benzamido-2-oxopyrimidin-1(2H)-yl)-2-((bis(4-methoxyphenyl)(phenyl)methoxy)methyl)tetrahydrofuran-3-yl (((2R,3S,5R)-3-((tert-butyldimethylsilyl)oxy)-5-(6-isobutyramido-9H-purin-9-yl)tetrahydrofuran-2-yl)methyl) (2-cyanoethyl) phosphate