5'-O-(4,4'-Dimethoxytrityl)-3'-O-tert-butyldimethylsilyl uridine

for the following products 1-((2R,3R,4S,5R)-5-((bis-(4-Methoxyphenyl)(phenyl)methoxy)methyl)-4-((tert-butyldimethylsilyl)oxy)-3-hydroxytetrahydrofuran-2-yl)pyrimidine-2,4(1H,3H)-dione and 5'-O-(4,4'-Dimethoxytrityl)-3'-O-tert-butyldimethylsilyl uridine