Practical approach for the stereoselective introduction of β-arabinofuranosides

Xiangming Zhu, Sameer Kawatkar, Yu Rao, Geert J. Boons*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

A practical approach for the stereoselective introduction of β-arabinofuranosides has been developed on the basis of locking an arabinosyl donor in a conformation in which nucleophilic attack from the β face is favored. The new glycosyl donor was designed by analyzing optimized geometries of low-energy conformers of the arabinofuranosyl oxacarbenium ion. The Newman projection of the E3 conformer indicated that nucleophilic attack from the α face is disfavored because an eclipsed H-2 will be encountered. On the other hand, an approach from the β face was expected to be more favorable, because it will experience only staggered substituents. The arabinofuranosyl oxacarbenium ion could be locked in the E3 conformation by employing a 3,5-O-di-tert-butylsilane protecting group, which places C-5 and O-3 in a pseudoequatorial orientation, resulting in a perfect chair conformation of the protecting group. The new glycosyl donor gave excellent β selectivities in a range of glycosylations with glycosyl acceptors having primary and secondary alcohols. The attractiveness of the new methodology was demonstrated by the chemical synthesis of a fragment of arabinogalactan, which is an important constituent of the primary plant cell wall.

Original languageEnglish
Pages (from-to)11948-11957
Number of pages10
JournalJournal of the American Chemical Society
Volume128
Issue number36
DOIs
Publication statusPublished - 13 Sept 2006
Externally publishedYes

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