Palladium PEPPSI complexes: Synthesis and catalytic activity on the Suzuki-Miyaura coupling reactions for aryl bromides at room temperature in aqueous media
Two new palladium complexes with pyrazole derived ligands 2a–2b have been easily prepared and well characterized by elemental analysis, 1H NMR, 13C NMR, and IR spectra. Their detailed structures are determined by a single-crystal X-ray analysis of 2a. The two compounds were successfully applied to the Suzuki coupling reactions of aryl bromides with phenylboronic acid, in aqueous solution at room temperature under air, giving the desired coupled products in good to excellent yields with catalyst loadings as low as 0.01–0.05 mol-%.
A novel Pd@imine-SiO2 catalyst was prepared and found to exhibit excellent catalytic activity in a Suzuki-Miyaura cross-coupling reaction under aqueous media at room temperature.
A highly active cobalt catalyst system has been developed for the cross-coupling reactions of arylmagnesium reagents and aryl bromides. In the presence of 1 mol% CoCl2, 2 mol% IPr·HCl and 2 mol% NaO
t
Bu, a wide range of (hetero)biaryls are prepared in 51–99% yields at room temperature within a short reaction time.
Abstract
A Pd-Co bimetallic alloy encapsulated in melamine-based dendrimer supported on magnetic nanoparticles denoted as γ-Fe2O3@MBD/Pd-Co was synthesized by a facile co-complexation-reduction method and characterized sufficiently. The catalytic evaluation of γ-Fe2O3@MBD/Pd-Co showed promising results in the Mizoroki-Heck and Buchwald-Hartwig amination reactions of various iodo-, bromo- and challenging chloroarenes in aqueous media. The synergetic cooperative effect of both Pd and Co and dispersion of the catalyst in water due to the encapsulation of γ-Fe2O3 by melamine-based dendrimer lead to high catalytic performance compared with the monometallic counterparts. The dispersion of the magnetic catalyst also facilitates the recovery and reuse of the catalyst by ten consecutive extraction and final magnetic isolation with no loss of catalytic activity, keeping its structure unaltered. Remarkably, this is the first paper on the use of palladium-cobalt bimetallic catalyst for Buchwald-Hartwig amination reaction and the first magnetically recyclable Pd/Co bimetallic catalyst in the Mizoroki-Heck coupling reactions.
The nanoalloy structure greatly improves the catalytic activity for electrocatalytic N2 reduction and Suzuki–Miyaura coupling reactions under ambient conditions.
Four air and moisture-stable palladium(II)-Schiff base complexes,N,N′-bis(α-methylsalicylidene)propane-1,3-diamine palladium(II) (2a),N,N′-bis(4-methyl-α-methylsalicylidene)propane-1,3-diamine palladium(II) (2b),N,N′-bis(3,5-di-tert-butylsalicylidene)propane-1,3-diamine palladium(II) (2c), andN,N′-bis(4-methoxy-salicylidene)propane-1,3-diamine palladium(II) (2d), have been successfully synthesised and characterised by CHN elemental analyses and conventional spectroscopic methods. These complexes were investigated as catalysts in the phosphine-free Mizoroki-Heck cross-coupling reactions of aryl bromides with methyl acrylate.
A New Nanomagnetic Pd-Co Bimetallic Alloy as Catalyst in the Mizoroki-Heck and Buchwald–Hartwig Amination Reactions in Aqueous Media