Thymidine, 3'-O-[(1,1-dimethylethyl)dimethylsilyl]-5'-thio-

1-[(2R,4S,5S)-5-(tert-Butyl-diphenyl-silanyloxymethyl)-4-(4-methoxy-benzylsulfanylmethyl)-tetrahydro-furan-2-yl]-5-methyl-1H-pyrimidine-2,4-dione