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Palladium-Catalyzed Isomerization (Palladium-Catalyze + isomerization)

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Chemistry100%

Selected Abstracts

Effect of the Leaving Group on the Rate and Mechanism of the Palladium-Catalyzed Isomerization of Cyclic Allylic Benzoates in Allylic Substitutions

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 5 2006
Christian Amatore
Abstract In chloroform, the reaction of cis -5-phenylcyclohex-2-enyl 4-Z-benzoate (cis - 1Z, Z = NO2, Cl, H, Me, MeO) with Pd0 complexes ligated to PPh3 is reversible and proceeds with isomerization at the allylic position. The rate of isomerization of cis - 1Z to trans - 1Z depends on the catalytic precursor: Pd0(PPh3)4 > {Pd0(dba)2 + 2PPh3} in agreement with an SN2 mechanism in the rate-determining isomerization of the cationic (,3 -allyl)palladium complexes formed in the oxidative addition. For a given precursor, the rate of isomerization of cis - 1Z to trans - 1Z also depends on the substituent Z, i.e., on the leaving group. The isomerization rate follows the same order as the leaving group properties: 4-NO2,C6H4 -CO2,> 4-Cl,C6H4 -CO2, > C6H5 -CO2, > 4-Me,C6H4 -CO2, > 4-MeO,C6H4 -CO2,. The same tendency is found for the equilibrium constant between the neutral cis - 1Z and the cationic (,3 -allyl)palladium complex in DMF. The higher the concentration of the cationic (,3 -allyl)palladium complex, the faster the isomerization of cis - 1Z to trans - 1Z is. The isomerization of cis - 1Z to trans - 1Z and that of the cationic (,3 -allyl)palladium complexes are at the origin of the lack of stereospecificity observed in catalytic nucleophilic allylic substitutions. These isomerizations are affected by both the leaving groups and the Pd0 precursors, which therefore are not "innocent" but may play an important role in palladium-catalyzed nucleophilic substitutions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

ChemInform Abstract: Mild and Efficient Palladium-Catalyzed Isomerization of Baylis,Hillman Acetates.

CHEMINFORM, Issue 39 2009
Jinhyung Park
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Regioselective Control in the Palladium-Catalyzed Isomerization of Methylenecyclopropylcarbinols Using Acetic Acid as a Reagent.

CHEMINFORM, Issue 32 2007
Min Shi
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

ChemInform Abstract: Palladium-Catalyzed Isomerization of Vinyldisilanes to Allyldisilanes.

CHEMINFORM, Issue 20 2001
David M. Hodgson
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]