Synthesis 2024; 56(06): 966-974
DOI: 10.1055/a-2149-4586
paper
Emerging Trends in Glycoscience

C-5 Epimerisation of d-Mannopyranosyl Fluorides: The Influence of Anomeric Configuration on Radical Reactivity

a   School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia
,
b   Centre for Advanced Imaging, The University of Queensland, Brisbane, Queensland 4072, Australia
,
a   School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia
,
Vito Ferro
a   School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia
› Author Affiliations
We thank the Australian Research Council for financial support (DP220102493). N.W.S. is grateful to The University of Queensland (UQ) for a PhD scholarship.


Abstract

The fluorine-directing effect has so far been exploited to provide short and efficient synthetic routes to rare l-ido sugars. However, the importance of anomeric configuration to its success has remained experimentally unverified. We now report on the synthesis of α- and β-configured per-O-benzoylated mannopyranosyl fluorides and initially show that their reactivity towards photo-bromination is strongly dependent on the anomeric configuration. The stereochemical basis of the fluorine-directing effect is then validated by revealing the striking difference in stereoselectivity observed for the free-radical reductions of the isolated 5-C-bromo sugars. This work importantly provides a synthetic route to a donor-functionalised derivative of l-gulose and reveals new insights into the behaviour of glycosyl radicals.

Supporting Information



Publication History

Received: 10 July 2023

Accepted after revision: 07 August 2023

Accepted Manuscript online:
07 August 2023

Article published online:
14 September 2023

© 2023. Thieme. All rights reserved

Georg Thieme Verlag KG
Rüdigerstraße 14, 70469 Stuttgart, Germany