Microwave-Assisted Ring Opening of Epoxides with Pyrimidine Nucleobases: A Rapid Entry into C-Nucleoside Synthesis

ABSTRACT Microwave irradiation strongly accelerates the regio­selective nucleophilic ring opening of epoxides by pyrimidine nucleobases. In the presence of tetrabutylammonium bromide (TBAB), various bases were elaborated to determine the proper base in which it can activate N1 rather than N3 for alkylation. It was shown that MgO not only could serve as an eligible base, but also enhanced the selectivity and tendency of N1 for alkylation as compared with N3. The use of microwave irradiation provided dominant regioselective synthesis of N1-β-hydroxyalkylpyrimidines in moderate to good yields with a reaction time of less than 7 minutes.