Synthesis of 6-O-cyclopyrimidine nucleosides and their physicochemical properties.

Treatment of 5-iodopyrimidine nucleosides with sodium methoxide afforded 6:2'-, 6:5'- and novel 6:3'-O-cyclopyrimidine nucleosides. The rates of cyclization and ring-opening, and the UV-, CD-, mass- and 13C-NMR spectra of the cyclonucleosides were compared with regard to their isomers.