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A deprotonation pathway to reactive [B]CH2 boraalkenes
Karel Škoch1, Chaohuang Chen1, Constantin G Daniliuc1
1Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraβe 40, 48149 Münster, Germany. erker@uni-muenster.de.
Dalton Transactions (Cambridge, England : 2003)
|May 6, 2022
Summary
New boraalkenes were synthesized and reacted with sulfur, carbon dioxide, and sulfur dioxide to form novel boron-containing heterocycles. These compounds also reacted with Lewis acidic boranes and gold complexes.
Area of Science:
- Organoboron Chemistry
- Synthetic Organic Chemistry
- Heterocyclic Chemistry
Background:
- Boron-containing compounds, particularly boraalkenes, are valuable synthetic intermediates.
- Understanding the reactivity of boraalkenes is crucial for developing new synthetic methodologies.
- Previous studies have explored the cycloaddition and Lewis acid-mediated reactions of boron compounds.
Purpose of the Study:
- To synthesize novel boraalkenes with specific aryl substituents (ArF: C6F5 or FpXyl).
- To investigate the reactivity of these boraalkenes with various reagents, including elemental sulfur, carbon dioxide, sulfur dioxide, Lewis acidic boranes, and gold complexes.
- To explore the formation of new boron-containing heterocycles and organometallic complexes.
Main Methods:
- A three-step reaction sequence involving B-methylation, hydride abstraction, and deprotonation was employed to synthesize the boraalkenes.
- Reactions of the synthesized boraalkenes with elemental sulfur, carbon dioxide, and sulfur dioxide were performed to study cycloaddition reactions.
- The addition of Lewis acidic boranes (e.g., HB(C6F5)2) and reaction with [(Me2S)AuCl] were conducted to explore complex formation.
Main Results:
- The synthesized IMes(ArF)B=CH2 boraalkenes successfully reacted with elemental sulfur to yield thiaborirane products.
- [2+2] cycloaddition reactions with CO2 and SO2 resulted in the formation of four-membered boron-containing heterocycles.
- Boraalkenes readily added Lewis acidic boranes at the exocyclic methylene carbon, leading to adducts that could reduce carbon monoxide.
- Complexation with [(Me2S)AuCl] yielded the corresponding (boraalkene)AuCl complexes.
Conclusions:
- The developed synthetic route provides access to a range of functionalized boraalkenes.
- These boraalkenes exhibit versatile reactivity, participating in cycloaddition, Lewis acid-mediated reactions, and organometallic complexation.
- The study highlights the potential of boraalkenes as building blocks for novel heterocyclic compounds and organometallic chemistry.
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