Summary. The application of the tetraisopropyldisiloxane-K3-diyl (TIPDSi) group for the large-scale preparation of the key components for the chemical synthesis of oligoribonucleotides by the triester approach is described. The key components, N-benzol-2'- 0-tetrahydropyranyl-S'-O-dimethoxytritylnucleoside 3'(p-chlorophenyl, 2-cyanoethyl) phosphates for uridine, cytidine, adenosine and guanosine (1-4), respectively, are ...