1,2-cis-Selective glucosylation enabled by halogenated benzyl protecting groups.
Dancan K Njeri1, Claude J Pertuit1, Justin R Ragains1
1Department of Chemistry, Louisiana State University, 232 Choppin Hall, Baton Rouge, LA 70803, USA.
Organic & Biomolecular Chemistry
|March 21, 2020
Summary
Researchers developed a new method for 1,2-cis-selective O-glucosylation using electron-withdrawing groups and basic solvents. This approach enhances selectivity in glycosylation reactions, offering broad applicability in carbohydrate chemistry.
Area of Science:
- Organic Chemistry
- Carbohydrate Chemistry
- Synthetic Chemistry
Background:
- Achieving stereoselective glycosylation, particularly 1,2-cis(α)-selective O-glucosylation, remains a significant challenge in carbohydrate chemistry.
- Traditional methods often lack the desired selectivity, necessitating complex protecting group strategies or leading to difficult-to-separate mixtures of anomers.
Purpose of the Study:
- To systematically investigate the use of electron-withdrawing protecting groups and Lewis basic solvents/additives to achieve 1,2-cis(α)-selective O-glucosylation.
- To establish a correlation between the electronic properties of protecting groups and the observed stereoselectivity in O-glucosylation reactions.
Main Methods:
- Employed thioglucosides and glucosyl trichloroacetimidates as glycosyl donors.
- Utilized a range of alcohol acceptors to test the generality of the developed methodology.
- Systematically varied electron-withdrawing protecting groups and Lewis basic solvents/additives to probe their influence on stereoselectivity.
Main Results:
- Successfully achieved 1,2-cis(α)-selective O-glucosylation using the designed approach.
- Demonstrated a clear correlation between the electron-withdrawing strength of protecting groups and the degree of 1,2-cis selectivity.
- Reported high selectivity across various thioglycosides, glucosyl trichloroacetimidates, and acceptor types.
Conclusions:
- The implementation of electron-withdrawing protecting groups in conjunction with Lewis basic solvents/additives is an effective strategy for controlling stereoselectivity in O-glucosylation.
- The established correlation provides a valuable guideline for designing future glycosylation strategies.
- This approach holds significant potential for broad applicability in the synthesis of complex carbohydrates and glycoconjugates.
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