Adenosine, 5′-O-[bis(4-methoxyphenyl)phenylmethyl]-P(O)-(2-cyanoethyl)-2′-O-(2-methoxyethyl)-5-methyl-P-thiouridylyl-(3′→5′)-N-benzoyl-3′-O-[(1,1-dimethylethyl)diphenylsilyl]-2′-O-(2-methoxyethyl)-5-methyl-