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Intramolecular interactions in ortho-methoxyalkylphenylboronic acids and their catechol esters
Agnieszka Adamczyk-Woźniak1, Krzysztof M Borys, Karolina Czerwińska
1Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland.
Summary
Researchers synthesized and characterized catechol esters of ortho-methoxyalkylphenylboronic acids using oxygen-17 NMR spectroscopy. The study found no O → B interactions in the esters, indicating weak Lewis acidity and low sugar receptor activity in the parent acids.
Area of Science:
- Organic Chemistry
- Supramolecular Chemistry
- Spectroscopy
Background:
- Boronic acids are important compounds in organic synthesis and medicinal chemistry.
- Understanding the electronic properties and interactions of boronic acids is crucial for their applications.
- Catechol esters offer a way to modify the properties of boronic acids.
Purpose of the Study:
- To synthesize and characterize catechol esters of ortho-methoxyalkylphenylboronic acids.
- To investigate the influence of hydrogen bonding on the properties of these boronic acids and their esters.
- To determine the presence or absence of O → B interactions in the synthesized esters.
Main Methods:
- Synthesis of catechol esters of ortho-methoxyalkylphenylboronic acids.
- Characterization using oxygen-17 Nuclear Magnetic Resonance ((17)O NMR) spectroscopy.
- Comparison of (17)O NMR data with parent boronic acids.
- Crystal structure determination of ortho-methoxyphenylboronic acid catechol ester.
Main Results:
- The synthesized catechol esters were successfully characterized by (17)O NMR spectroscopy.
- Comparison with parent acids revealed insights into intramolecular and intermolecular hydrogen bonding effects.
- Crucially, (17)O NMR data confirmed the absence of O → B interactions in the investigated boronic esters.
- The crystal structure of ortho-methoxyphenylboronic acid catechol ester was determined.
Conclusions:
- The absence of O → B interactions in the catechol esters is linked to the weak Lewis acidity of the parent boronic acids.
- This finding suggests limited potential for these specific boronic acids in applications requiring strong Lewis acidity, such as sugar receptors.
- The study provides valuable spectroscopic and structural data on ortho-methoxyalkylphenylboronic acid derivatives.
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