Stereocontrolled Synthesis of Heterocyclic C-Nucleosides. Protecting Group Effect and Molecular Modeling Studies
作者:Dominique Guianvarc'h、Jean-Louis Fourrey、Marie-Elise Tran Huu Dau、Vincent Guérineau、Rachid Benhida
DOI:10.1021/jo016345x
日期:2002.5.1
We report herein a short stereocontrolledsynthesis of heterocyclic C-nucleosides (indole, imidazole, benzimidazole, and 6-iodobenzimidazole). First, condensation of 2-lithiated heterocycles 2-5 with 5-(tert-butyldiphenylsilyl)-2,3-O-isopropylidene-D-gamma-ribonolactone (1) afforded the hemiacetals 6-9 in good yields. Then, borohydride reduction (NaBH(4)) of the protected hemiacetals proceeded stereoselectively
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.