Synthesis of uridine oligonucleotide by the reaction of unprotected uridine with tri-(imidazolyl-(1)) phosphine.

Uridine oligonucleotide was synthesized by the reaction of unprotected uridine with tri-(imidazolyl-(1))phosphine and the successive oxidation of the resulting cyclic phosphite with iodine and water. The uridine oligonucleotide obtained from this reaction contained both 3'-5'linkage and 2'-5'linkage. The type of the phosphodiester linkage was resulted at the oxidative ring-opening reaction, and it was controlled by polynucleotides and various divalent metal cations.