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. ; Peter Kundig, E. (2013) Synthesis of 3,3-disubstituted oxindoles by palladium-catalyzed asymmetric intramolecular α-arylation of amides: reaction development and mechanistic studies Chemistry - A European Journal, 19 (36). pp. 11916-11927. ISSN 0947-6539

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Official URL: http://onlinelibrary.wiley.com/doi/10.1002/chem.20...

Related URL: http://dx.doi.org/10.1002/chem.201301572

Abstract

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.

Item Type:Article
Source:Copyright of this article belongs to John Wiley and Sons, Inc.
Keywords:Arylation; Asymmetric Catalysis; N-Heterocyclic Carbenes; Oxindoles; Palladium
ID Code:109752
Deposited On:02 Aug 2017 09:10
Last Modified:02 Aug 2017 09:10

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