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An Efficient Synthetic Approach to trans ‐(NHC) 2 Pd(R)Br Type Complexes and Their Use in Suzuki–Miyaura Cross‐Coupling Reactions
Author(s) -
Kumar Anuj,
Prakasham A. P.,
Gangwar Manoj Kumar,
Vishnoi Pratap,
Butcher Raymond J.,
Ghosh Prasenjit
Publication year - 2017
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.201700017
Subject(s) - chemistry , palladium , reagent , ligand (biochemistry) , medicinal chemistry , stereochemistry , catalysis , biphenyl , coupling reaction , crystal structure , crystallography , organic chemistry , biochemistry , receptor
Mixed organohalidopalladium complexes of the type trans ‐(NHC) 2 Pd(R)Br were conveniently obtained from trans ‐(NHC) 2 PdBr 2 type complexes by a ligand‐substitution reaction. In particular, the trans ‐[1‐( 1S )‐menthyl‐4‐(R 1 )‐1,2,4‐triazol‐5‐ylidene] 2 Pd(R 2 )Br [R 1 = Et, R 2 = CH 2 Ph ( 3a 1 ); R 1 = Et, R 2 = o ‐OMeC 6 H 4 ( 3a 2 ); R 1 = R 2 = CH 2 Ph ( 3b 1 ); R 1 = CH 2 Ph, R 2 = o ‐OMeC 6 H 4 ( 3b 2 )] complexes were obtained from the corresponding palladium(II) precursor complexes, 2a , b , by reaction with the respective Grignard reagents, in good to excellent yields (74–93 %). Three of the four mixed organohalidopalladium complexes, 3a 1 , a 2 , b 1 , have been structurally characterized by single‐crystal X‐ray diffraction, which revealed the trans disposition of the NHC ligands around the palladium center. The use of these mixed organohalidopalladium complexes in the Suzuki–Miyaura cross‐coupling reaction was established for all of the complexes, 3a 1 – b 2 , which yielded the desired cross‐coupled products upon treatment with various ArB(OH) 2 [Ar = 1‐naphthyl, 4‐(1,1′‐biphenyl), 9‐phenanthrenyl, 4‐FC 6 H 4 , and 2,6‐Me 2 C 6 H 3 ] compounds, in the presence of NaOH as a base, in CH 3 CN, in three hours, under reflux conditions.