Inosine, 5′-O-[bis(4-methoxyphenyl)phenylmethyl]-1-(13,13-dimethyl-6,9-dioxo-3,10-dioxa-5,8-diaza-13-silatetradec-1-yl)-3′-O-[(1,1-dimethylethyl)dimethylsilyl]-, 2′-[2-cyanoethyl N,N-bis(1-methylethyl)phosphoramidite]