Highly efficient Heck olefin arylation in the presence of iminophosphine–palladium(0) complexes

Abstract

The Heck coupling of aryl bromides with olefins such as styrene or butyl acrylate is efficiently catalysed by the iminophosphine-palladium(0) complex [Pd(dmfu)(P-N)] (dmfu = dimethyl fumarate; P-N = 2-(PPh 2)C 6 H 4-1-CH NC 6 H 4 OMe-4) (1) in polar solvents. With activated aryl bromides such as 4-bromoacetophenone turnover numbers of up to 20,000 can be achieved at 140 • C in 2 h. The presence of electron-donating groups leads to decreased reaction rates, nevertheless, high substrate conversions can be obtained in reasonable reaction times. Kinetic studies indicate that complex 1 is only a precursor of the actual catalytic species. Experiments aimed to demonstrate the intervention of metallic palladium did not lead to conclusive findings.

Palladium(II) Complexes of Monodentate Phosphine Ligands and Their Application as Catalyst in Suzuki-Miyaura C-C Coupling Reaction at Room Temperature

“…Our catalysts are also effective towards the coupling of 2-bromoanisole, 2-bromotoluene and 2bromoacetophenone, which have bulkymethoxy, -ethyl and -aceto group at ortho position respectively, giving corresponding biaryls as major product up to 68% conversion (entry 1-4, 13-16, and 25-28) and steric effect of these substituents on the C-Br bond were well tolerated. In general, the reaction rate slows down in the presence of the electronically deactivated aryl halides, which have electronreleasing groups such as -methoxy and -methyl group on the phenyl ring for the SM coupling reactions (14,29). However, the coupling of these deactivated aryl bromides with phenylboronic acid gave desired coupling product moderate to good yields by all catalysts.…”

Density Functional Theoretical Study on the Mechanism of Alcoholysis of Acylpalladium(II) Complexes

“…The other mechanism commences with reversible formation of intermediate I1 followed by inner-sphere attack of the alkoxide ligand (OCH 3 ) at the carbon atom of the palladium-bound carbonyl group (reductive elimination via a Meisenheimer intermediate I2 or insertion pathway) [17][18][19][20]. The Suzuki [21][22][23][24][25][26], Heck [27][28][29][30][31][32], Stille [33][34][35][36] and Buchwald-Hartwig [20,[37][38][39] couplings are modern methods in organic synthesis. The award of the 2010 Nobel Prize was due to the very high importance of such methods.…”

[PdCl2{8-(di-tert-butylphosphinooxy)quinoline)}]: a highly efficient catalyst for Suzuki–Miyaura reaction

“…For instance, we have recently reported that palladium complexes containing iminophosphine ligands such as 1 ( Fig. 1) are efficient and versatile catalysts in the Suzuki, 13 Stille 14 and Heck 15 coupling reactions.…”