Mechanism of reductive elimination. Reaction of alkylpalladium(II) complexes with tetraorganotin, organolithium, and Grignard reagents. Evidence for palladium(IV) intermediacy

Journal Article · Wed Aug 15 04:00:00 EDT 1979 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00511a031· OSTI ID:5854141

Milstein, D; Stille, J K

Coupling products are obtained in good yields from the reaction of tetraorganotin compounds or Grignard reagents and organohalogenopalladium(II) complexes provided that a benzyl bromide is present. Low yields are obtained in the absence of the benzyl bromides, in which case other decomposition pathways (e.g., ..cap alpha.. elimination) take place, even in the presence of electron acceptors (e.g., oxygen, m-dinitrobenzene). The first step in the reaction of benzylhalogenobis(triphenylphosphine)-palladium(II) complexes with MeM (M = SnMe/sub 3/, MgBr) is metathesis of the benzyl ligand rather than the halogen. This unique carbon-for-carbon transmetalation takes place at 25/sup 0/C and is facilitated by electron-donating substituents on the benzyl ligand. The products of this reaction subsequently react at higher temperature in the presence of a benzyl bromide to afford ethylbenzene. Optically active chloro-(..cap alpha..-deuteriobenzyl)bis(triphenylphosphine)palladium yields, upon reaction with tetramethyltin in the presence of p-nitrobenzyl bromide, optically active ..cap alpha..-deuterioethylbenzene in which overall retention of configuration at carbon has resulted. cis-dimethylbis(triphenylphosphine)palladium(II) reacts with benzyl bromide at 25/sup 0/C to afford ethylbenzene and bromomethylbis(triphenylphosphine)palladium(II) rather than ethane. When optically active ..cap alpha..-deuteriobenzyl bromide is used in this reaction, optically active ..cap alpha..-deuterioethylbenzene is formed, and inversion of configuration at carbon takes place. The reductive elimination process is proposed to take place preferentially from a palladium(IV) intermediate with retention of configuration at carbon.

• Research Organization: Colorado State Univ., Fort Collins
• OSTI ID: 5854141
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 101:17; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
400202* -- Isotope Effects
Isotope Exchange
& Isotope Separation
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
CHEMICAL REACTIONS
COMPLEXES
DATA
DATA FORMS
DEUTERIUM
EXPERIMENTAL DATA
GRIGNARD REAGENTS
HYDROGEN ISOTOPES
INFORMATION
ISOLATED VALUES
ISOTOPE EFFECTS
ISOTOPES
LIGHT NUCLEI
LITHIUM COMPOUNDS
MAGNESIUM COMPOUNDS
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
PALLADIUM COMPLEXES
STABLE ISOTOPES
TIN COMPOUNDS
TRANSITION ELEMENT COMPLEXES