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Cross-Coupling between Arylboronic Acids and Terminal Alkynes in Water Microdroplets.
Sandeep Bose1, Mohammad Mofidfar1, Richard N Zare1
1Department of Chemistry, Stanford University, Stanford, California 94305, United States.
This study introduces a novel, catalyst-free cross-coupling reaction in water microdroplets, efficiently forming C-C bonds for synthesizing internal aryl alkynes. This green chemistry approach is suitable for pharmaceutical drug preparation.
Area of Science:
- Organic Chemistry
- Green Chemistry
- Reaction Engineering
Background:
- Traditional C-C bond formation often requires harsh conditions and catalysts.
- Developing sustainable synthetic methods is crucial for environmental protection and pharmaceutical manufacturing.
Purpose of the Study:
- To develop a mild, catalyst-free method for C-C bond formation.
- To synthesize internal aryl alkynes using water microdroplets.
- To elucidate the reaction mechanism for this novel coupling.
Main Methods:
- Electrospraying a mixture of terminal alkyne and arylboronic acid in water-acetonitrile.
- Utilizing mass spectrometry (MS) and tandem mass spectrometry (MS2) for product analysis.
- Conducting in situ reaction studies and radical experiments to determine the mechanism.
Main Results:
- Achieved C(sp2)-C(sp) coupling reaction products within milliseconds.
- Identified phenylacetylene and 4-methoxyphenylboronic acid as reactants.
- Determined the reaction mechanism through detailed studies.
Conclusions:
- The developed method provides a sustainable and environmentally benign pathway for synthesizing internal aryl alkynes.
- This approach is suitable for preparing building blocks for pharmaceutical drugs.
- Water microdroplets enable efficient, catalyst-free C-C bond formation under mild conditions.
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