926031-21-2Relevant academic research and scientific papers
Synthesis of C2-symmetric benzimidazolium salts and their application in palladium-catalyzed enantioselective intramolecular α-arylation of amides
He, Weiping,Zhao, Wei,Zhou, Bihui,Liu, Haifeng,Li, Xiangrong,Li, Linlin,Li, Jie,Shi, Jianyou
, (2016)
A series of C2-symmetric chiral benzimidazolium salts, the precursor of N-heterocyclic carbene ligands, were designed and synthesized from 1,2-dibromobenzene. In situ prepared corresponding carbenes were tested in the asymmetric palladium-catal
Synthesis of 3,3-disubstituted oxindoles by palladium-catalyzed asymmetric intramolecular α-arylation of amides: Reaction development and mechanistic studies
Katayev, Dmitry,Jia, Yi-Xia,Sharma, Akhilesh K.,Banerjee, Dipshikha,Besnard, Celine,Sunoj, Raghavan B.,Kuendig, E. Peter
supporting information, p. 11916 - 11927 (2013/09/23)
Palladium complexes incorporating chiral N-heterocyclic carbene (NHC) ligands catalyze the asymmetric intramolecular α-arylation of amides producing 3,3-disubstituted oxindoles. Comprehensive DFT studies have been performed to gain insight into the mechanism of this transformation. Oxidative addition is shown to be rate-determining and reductive elimination to be enantioselectivity-determining. The synthesis of seven new NHC ligands is detailed and their performance is compared. One of them, L8, containing a tBu and a 1-naphthyl group at the stereogenic centre, proved superior and was very efficient in the asymmetric synthesis of fifteen new spiro-oxindoles and three azaspiro-oxindoles often in high yields (up to 99 %) and enantioselectivities (up to 97 % ee; ee=enantiomeric excess). Three palladacycle intermediates resulting from the oxidative addition of [Pd(NHC)] into the aryl halide bond were isolated and structurally characterized (X-ray). Using these intermediates as catalysts showed alkene additives to play an important role in increasing turnover number and frequency. Copyright
New chiral N-heterocyclic carbene ligands in palladium-catalyzed α-arylations of amides: Conformational locking through allylic strain as a device for stereocontrol
Jia, Yi-Xia,Katayev, Dmitry,Bernardinelli, Gerald,Seidel, Thomas M.,Kuendig, E. Peter
supporting information; scheme or table, p. 6300 - 6309 (2010/07/14)
New Enders/Herrmann-type chiral N-heterocyclic carbene (NHC) ligands have been developed and applied in asymmetric palladium-catalyzed intramolecular α-arylations of amides. The best ligands feature the bulky tert-butyl group and ortho-substituted aryl gr
