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Palladium Complexes Bearing Mesoionic Carbene Ligands: Applications in α‐Arylation, α‐Methylation and Suzuki–Miyaura Coupling Reactions
Author(s) -
Maity Ramananda,
Verma Amit,
van der Meer Margarethe,
Hohloch Stephan,
Sarkar Biprajit
Publication year - 2016
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201501031
Subject(s) - chemistry , mesoionic , palladium , carbene , coupling reaction , combinatorial chemistry , catalysis , homogeneous catalysis , suzuki reaction , organometallic chemistry , organic chemistry , medicinal chemistry
Complexes of mesoionic carbene (MIC) ligands are gaining immense popularity in organometallic chemistry and homogeneous catalysis. We present here a series of palladium(II) complexes that are comprised of MIC donor ligands, and we demonstrate their applications in α‐arylation, α‐methylation, and Suzuki–Miyaura coupling reactions. All the complexes have been structurally characterized by X‐ray crystallographic analysis. These palladium(II) complexes are potent precatalysts and they deliver good to excellent yields for both α‐arylation and Suzuki–Miyaura coupling reactions. A palladium(II) complex bearing two MIC units in a trans fashion is used for chemoselective Suzuki–Miyaura coupling reaction. This complex delivers lower yields in α‐arylation reactions compared with PEPPSI‐type complexes, however, it gives an α‐methylated product when the reaction is conducted in N , N ‐dimethylformamide. Mercury poisoning experiments suggest that the Suzuki–Miyaura coupling reaction likely proceeds via Pd nanoparticles. However, the α‐arylation reaction proceeds homogeneously, as shown by the negative mercury poison test. The present results thus open up new avenues for MIC ligands in catalytic α‐arylation and α‐methylation reactions.