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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.
None:
We report a cross-coupling reaction between terminal alkyne and arylboronic acid to form the C-C bond in water microdroplets under mild, catalyst-free conditions. A solution containing phenylacetylene (50 μM) and 4-methoxyphenylboronic acid (50 μM) in a 4:1 (H2O: ACN) mixture was electrosprayed at +1.5 kV, and the reaction products were analyzed using a mass spectrometer (MS). We observed C(sp2)-C(sp) coupling reaction products within milliseconds, which were characterized by tandem mass spectrometry (MS2). Based on in situ reaction studies and radical experiments, we determined the reaction mechanism for the coupling reaction. Our approach offers a sustainable and environmentally benign pathway for the synthesis of internal aryl alkynes, making it a suitable building block for the preparation of various pharmaceutical drugs.
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