Synthesis Of 6-Alkoxy-5-bromo-5,6-dihydropyrimidine Nucleosides Using Dibutyltin Alkoxide-Bromine

The pyrimidine nucleosides (1–3), on reaction with bromine and dibutyltin oxide in appropriate alcohols gave the titled compounds (5–7), which were characterised by derivatisation to 8–10, 1-H and 13C NMR. The reported method of bromination of nucleosides in presence of DBTO under neutral and mild conditions facilitates the isolation of acid-labile 6-alkoxy-5-bromo-5,6-dihydro addition compounds of nucleosides which are otherwise difficult to obtain.