Solid phase synthesis of oligoribonucleotides using the 1-[(2-chloro-4-methyl)phenyl]-4-methoxypiperidin-4-yl (Ctmp) group for the protection of the 2'-hydroxy functions and the H-phosphonate approach.

The solid phase synthesis of oligoribonucleotides using the H-phosphonate approach and the 1-[(2-chloro-4-methyl)phenyl]-4-methoxypiperidin-4-yl (Ctmp) and dimethoxytrityl (DMTr) groups, respectively, for the protection of the 2'- and 5'-hydroxy functions is described. The use of a new reagent, tris-(1,1,1,3,3,3-hexafluoro-2-propyl) phosphite for the preparation of nucleoside H-phosphonate units is also discussed in detail.