Ribonucleoside and ribonucleotide derivatives in polynucleotide synthesis

Suitably protected ribonucleotide and ribonucleoside derivatives have been employed as versatile intermediates in both oligoribo- and oligodeoxyribonucleotide synthesis by the phosphotriester method. Thus, the barium salt of 5'-O-dimethoxytrityl-2'-O-(o-nitrobenzyl) uridine-3' p-chlorophenyl-phosphate was used to prepare U-U-U as one example of a procedure that has general applicability in the construction of oligoribonucleotides. In addition, ribonucleosides like N4,O2',O3'-tribenzoylcytidine, and ribonucleotides such as the 2',3'-O-bis(dimethoxytrityl) and 2',3'-O-methoxymethylidene derivatives of uridine-5' p-chlorophenyl phosphate, provide a convenient means of introducing 3'- and/or 5'-terminal phosphate residues into oligonucleotides at the phosphotriester level.