Stereoselective synthesis of 2-deoxy-2-bromo-hexopyrano-β-nucleosides: solvent-free Lewis acid catalysis

An expedient solvent-free synthesis of 2-deoxy-2-bromo-hexopyrano-β-nucleosides stereo- and regioselectively from protected glycals and unactivated nucleobases using cheaper and easily available reagent systems has been developed. The synthesis is mediated by a Lewis acid and is solvent-free. The substrate scope of the reaction was analysed with ether, ester and silyl-protected glycals as donors and different pyrimidine and purine bases were taken into consideration. This method further finds application in the synthesis of 2-deoxynucleosides.