Synthesis of novel nucleosides and stereoselectivity of N-glycosidation

An efficient synthetic route for novel nucleosides has been realized. We report the formation of α-isomers in spite of neighboring group participation by the benzoyl group at the 2-position in N-glycosidation as well as discuss the stereoselectivity observed. We also found that non-silylated pyrimidin-2(1H)-ones and pyrimidin-2(1H)-thiones having aromatic structures reacted with 1-fluororibose in the presence of a Lewis acid to give the corresponding nucleosides in good to high yield.