The Direct Mechanocatalytic Suzuki–Miyaura Reaction of Small Organic Molecules

• Published in: Angewandte Chemie International Edition Vol. 61; no. 34; pp. e202205003 - n/a
• Main Authors: Pickhardt, Wilm, Beaković, Claudio, Mayer, Maike, Wohlgemuth, Maximilian, Kraus, Fabien Joel Leon, Etter, Martin, Grätz, Sven, Borchardt, Lars
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 22-08-2022
• Edition: International ed. in English
• Subjects: Abrasion; Ball Milling; Bromides; Catalysis; Catalysts; Chemical reactions; Coupling (molecular); Cross coupling; Direct Mechanocatalysis; Iodides; Mechanochemistry; Organic chemistry; Palladium; Substrates; Transition-Metal Catalysis; X ray photoelectron spectroscopy; Ball Milling; Cross-Coupling; Transition-Metal Catalysis; Mechanochemistry; Direct Mechanocatalysis
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202205003

The molecular Suzuki cross‐coupling reaction was conducted mechanochemically, without solvents, ligands, or catalyst powders. Utilizing one catalytically active palladium milling ball, products could be formed in quantitative yield in as little as 30 min. In contrast to previous reports, the adjustment of milling parameters led to the complete elimination of abrasion from the catalyst ball, thus enabling the first reported systematic catalyst analysis. XPS, in situ XRD, and reference experiments provided evidence that the milling ball surface was the location of the catalysis, allowing a mechanism to be proposed. The versatility of the approach was demonstrated by extending the substrate scope to deactivated and even sterically hindered aryl iodides and bromides.
Utilizing polymer milling vessels and liquid‐assisted grinding, direct mechanocatalytic Suzuki coupling was conducted successfully without abrading the palladium catalyst. Various target molecules were synthesized in good yields within 1 h. In situ XRD and parameter studies provided deep insight into the mechanism of direct mechanocatalysis.