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Palladium Nitrosyl Complexes as Highly Versatile Catalysts for C−H/C−H Oxidative Coupling of Arenes: Application Area and Insight into Mechanism
Author(s) -
Shishilov Oleg N.,
Shamsiev Ravshan S.,
Akhmadulliilya S.,
Flid Vitaly R.
Publication year - 2021
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.202004191
Subject(s) - deprotonation , chemistry , intramolecular force , palladium , catalysis , metalation , oxidative addition , medicinal chemistry , oxidative coupling of methane , reductive elimination , stereochemistry , reaction mechanism , photochemistry , organic chemistry , ion
Abstract Palladium nitrsosyl carboxylates Pd 3 (NO) 2 (CX 3 CO 2 ) 4 (ArH) 2 ( I : X=Cl, Ar=Ph; II : X=F, Ar=Tol) are found to be effective catalysts for C−H/C−H oxidative homocoupling of arenes bearing electron‐donor as well as electron‐withdrawing groups (EWG). Trifluoroacetate complex II is found to be more promising due to higher stability under the reaction conditions. Complex II also shows high performance in intramolecular coupling in diarylsulfides, diarylethers and diarylamines giving corresponding dibenzothiophenes, dibenzofurans and carbazoles with yields ranged from moderate to high. The plausible mechanism is studied by DFT computational analysis basing on Pd 3 linear complexes as major active species. It was found that two deprotonation steps proceed in two different ways: for the first deprotonation S E Ar is most probable pathway while for the second one concerted metalation‐deprotonation (CMD) is preferable. That can explain high tolerance of the system to different substrates: S E Ar is favorable in the presence of electron donor group and EWG facilitate CMD. NO group was found to be involved into the CMD pathway and that is the rate‐determining step with the highest activation barrier.