Acceleration of the template-directed reactions of nucleoside 5'-phosphorimidazolides by acylation

Nucleoside-5'-phosphorimidazolides react readily with acylating agents to give N-substituted products that are highly activated. In most cases these acylated derivatives undergo rapid hydrolysis to give nucleoside 5'-phosphates, whether or not a complementary template is present. However, guanosine 5'-phosphorimidazolide reacts with diethyl pyrocarbonate to give a derivative that oligomerizes rapidly and efficiently in the presence of polycytidylic acid and Pb2+. The reaction is complete in about 1 h, whereas the corresponding reaction in the absence of an acylating agent takes several days. However, the final yield of long oligomers is lower when diethyl pyrocarbonate is present.