Sustainable Ligand‐Free Heterogeneous Palladium‐Catalyzed Sonogashira Cross‐Coupling Reaction in Deep Eutectic Solvents. Issue 7 (11th February 2020)

• Record Type: Journal Article
• Authors: Messa, Francesco; Dilauro, Giuseppe; Perna, Filippo M.; Vitale, Paola; Capriati, Vito; Salomone, Antonio
• Is Part Of: ChemCatChem. Volume 12:Issue 7(2020)
• Page Start: 1979
• Page End: 1984
• Publication Date: 2020-02-11
• Subjects: Deep Eutectic Solvents -- Sonogashira reaction -- Alkynes -- Heterocycles -- Green chemistry; Catalysis -- Periodicals; 541.39505
• DOI: 10.1002/cctc.201902380
• Languages: English
• ISSNs: 1867-3880

Abstract

Abstract: The commercially available and cheap Pd/C was found to promote Sonogashira couplings in the environmentally friendly choline chloride/glycerol eutectic mixture in the absence of external ligands. Under heterogeneous conditions, (hetero)aryl iodides were successfully coupled with both aromatic and aliphatic alkynes in yields ranging from 50 to 99 % within 3 h at 60 °C. The aforementioned catalytic system proved to be effective also towards electron‐rich iodides, which are notoriously known to be poorly reactive in Pd‐catalyzed Sonogashira coupling reactions. The eutectic mixture and the catalyst could easily and successfully be recycled up to four times with an E‐factor as low as 24.4. Abstract : Sustainable, ligand‐free Pd/C‐catalyzed Sonogashira cross‐couplings of (hetero)aryl iodides with terminal aromatic and aliphatic alkynes have been successfully achieved in the environmentally responsible and recyclable choline chloride‐glycerol (1 : 2 mol mol −1 ) eutectic mixture to afford functionalized alkynes in 50–99 % yield and with a broad substrate scope.