Abstract
Thiation of the 2', 5'-di-O-trityl-3'-O-acetyluridine or 3', 5'-di-O-trityl-2'-O-acetyluridine with phosphorus pentasulfide in refluxing toluene containing 20-30% pyridine afforded corresponding"4-thio"derivative in good yield. These "4-thio" derivatives were converted to the cytidine counterparts by the reaction with methanolic ammonia. 2', 5'-Di-O-trityl-3'-O-methanesulfonyluridine was also converted to cytidine derivative by similar manner. In addition, phosphorylation and dinucleoside monophosphate synthesis using titled compounds were described.
