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Palladium‐Nanoparticle‐Catalysed Ullmann Reactions in Ionic Liquids with Aldehydes as the Reductants: Scope and Mechanism
Author(s) -
Calò Vincenzo,
Nacci Angelo,
Monopoli Antonio,
Cotugno Pietro
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200801621
Subject(s) - palladium , mechanism (biology) , scope (computer science) , chemistry , ionic liquid , ionic bonding , nanoparticle , reaction mechanism , catalysis , combinatorial chemistry , organic chemistry , photochemistry , materials science , nanotechnology , computer science , ion , philosophy , epistemology , programming language
An efficient Ullmann‐type reductive homocoupling of aryl, vinyl and heteroaryl halides can be promoted by an aldehyde in tetraalkylammonium ionic liquids under very mild reaction conditions. This simple procedure generates symmetrical biaryls under relatively mild conditions. The ionic liquid is crucial for this process because it behaves simultaneously as a base, ligand and reaction medium. The role of the aldehyde is also discussed and a general mechanism for this unusual reaction is proposed. These results open the way to a new efficient method of Pd‐catalysed dehydrogenation of carbonyl compounds.