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Synthesis of 3,3-Disubstituted Oxindoles by Palladium-Catalyzed Asymmetric Intramolecular -Arylation of Amides: Reaction Development and Mechanistic Studies

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Title Synthesis of 3,3-Disubstituted Oxindoles by Palladium-Catalyzed Asymmetric Intramolecular -Arylation of Amides: Reaction Development and Mechanistic Studies
 
Creator KATAYEV, D
JIA, YX
SHARMA, AK
BANERJEE, D
BESNARD, C
SUNOJ, RB
KUNDIG, EP
 
Subject arylation
asymmetric catalysis
N-heterocyclic carbenes
oxindoles
palladium
HETEROCYCLIC CARBENE LIGANDS
QUATERNARY CARBON CENTERS
ALDOL-TYPE REACTION
ALPHA-ARYLATION
ENANTIOSELECTIVE SYNTHESIS
HECK REACTIONS
3-ALLYL-3-ARYL OXINDOLES
3-SUBSTITUTED OXINDOLES
COMPLEXES SYNTHESIS
IMIDAZOLIUM SALTS
 
Description Palladium complexes incorporating chiral N-heterocyclic carbene (NHC) ligands catalyze the asymmetric intramolecular -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.
 
Publisher WILEY-V C H VERLAG GMBH
 
Date 2014-10-16T06:50:40Z
2014-10-16T06:50:40Z
2013
 
Type Article
 
Identifier CHEMISTRY-A EUROPEAN JOURNAL, 19(36)11916-11927
0947-6539
1521-3765
http://dx.doi.org/10.1002/chem.201301572
http://dspace.library.iitb.ac.in/jspui/handle/100/15478
 
Language en