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Sustainable Ligand‐Free Heterogeneous Palladium‐Catalyzed Sonogashira Cross‐Coupling Reaction in Deep Eutectic Solvents
Author(s) -
Messa Francesco,
Dilauro Giuseppe,
Perna Filippo M.,
Vitale Paola,
Capriati Vito,
Salomone Antonio
Publication year - 2020
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201902380
Subject(s) - sonogashira coupling , eutectic system , choline chloride , catalysis , aryl , palladium , ligand (biochemistry) , chemistry , coupling reaction , heterogeneous catalysis , environmentally friendly , combinatorial chemistry , organic chemistry , alkyl , biochemistry , receptor , alloy , ecology , biology
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.