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Updated: Sep 19, 2025
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Solid-phase Synthesis of [4.4] Spirocyclic Oximes
Published on: February 6, 2019
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Stereospecific Oxidative Contraction of Anomeric Nucleophiles
Santosh Shelar1, Nicholas Ryan1, Timothy Davis1
1Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States.
Organic Letters
|June 18, 2025
Summary
This study introduces a novel single-flask method to convert common hexose sugars into valuable pentose lactones. This efficient chemical transformation provides a new synthetic route for carbohydrate-based molecules.
Area of Science:
- Organic Chemistry
- Carbohydrate Chemistry
- Synthetic Methodology
Background:
- Accessing pentose scaffolds from abundant hexoses is crucial for carbohydrate synthesis.
- Existing methods for hexose to pentose conversion can be lengthy or low-yielding.
Purpose of the Study:
- To develop a concise and efficient oxidative method for transforming hexoses into pentono-1,4-γ-lactones.
- To explore the stereochemical outcomes and scope of this novel transformation.
Main Methods:
- Oxidative ring-contraction of C1-metal(loid) hexosides using an oxidant.
- Generation of a transient chromium(VI) ester intermediate.
- Stereospecific C1-C2 bond cleavage of the glycoside.
Main Results:
- Achieved conversion of hexoses to arabino- and lyxono-configured pentose lactones in a single flask.
- Demonstrated stereospecificity, with α-silyl glucopyranosides yielding γ-lactones (up to 61% yield) and β-isomers yielding α-silyl C2-ketones.
- Showcased tolerance for diverse silyl groups and applicability to galactose, arabinose, and lactose derivatives.
Conclusions:
- Established a streamlined synthetic route from hexoses to pentose frameworks.
- Provided valuable intermediates for oligosaccharide diversification.
- Uncovered novel reactivity for organosilicon and organoboron compounds under oxidative conditions.
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