The perbenzylated d-ribofuranosyl fluoride is allowed to react with Grignard reagents of aromatic heterocycles such as thiophene, pyrrole, and indole in THF to afford the corresponding β-C-nucleosides in moderate yields. The present process can be also applied to perbenzylated d-glucopyranosyl fluoride and perbenzylated 2-deoxy-d-ribofuranosyl fluoride as sugar donors.
A 2,3,5-tri-O-benzyl-D-ribose reacts with lithium salts of thiophenes or furans to give the corresponding 2-ribosylthiophenes or furans, which are then treated with p-toluenesulfonic acid, affording 2-ribofuranosylthiophenes or furans (C-nucleosides) in good yield and in a stereoselective manner.