Oligouridylates up to the pentamer were obtained by the polymerization of uridine-5'-phosphorimidazolide in aqueous solution using Pb2+ ion catalyst. The resulting oligouridylates were fully characterized by sequential enzyme and alkaline digestions. The internucleotide linkages of the oligomers were mainly 2'-5'. The yields of the 2'-5'linked dimer, trimer, tetramer and pentamer were 14.2, 6.0, 2.0 and 0.4%, respectively.
