Efficient stereocontrolled synthesis of 2-benzimidazolyl- and 2-indolyl-C-nucleosides

We report herein the synthesis of β-2-benzimidazolyl- and β-2-indolyl-C-nucleosides and their α-anomers in a stereoselective way. The stereocontrol was observed either in the reduction step (hemiacetal to diol) of the protected heterocycles (1b–d), or in the intramolecular Mitsunobu cyclisation of the free heterocyclic diols obtained from the hemiacetals 1a and 1e.