Alkyne hydroarylation in ionic liquids catalyzed by palladium(II) complexes

Electron-poor hemilabile dicationic palladium NHC complexes - synthesis, structure and catalytic activity

We present a new class of dicationic palladium NHC complexes with two carbene ligands bearing different aryl substituents and a hemilabile pyrimidyl group. They can either be synthesized from the imidazolium salts via the silver transmetalation route to a halide-free palladium(ii) precursor or by direct deprotonation by palladium acetate. For four complexes we could determine their solid-state structures by X-ray diffraction experiments. Insight gained by NMR spectroscopy and DFT calculations revealed that in solution the two potentially bidentate ligands interchange between chelating and non-chelating coordination modes. The preference of these coordination modes is governed by the steric influence of the different ligands. The complexes were shown to be active catalysts for the hydroarylation of alkynes, and their performance was rationalized by DFT calculations.

The Synthesis of 2-Aminobenzoxazoles Using Reusable Ionic Liquid as a Green Catalyst under Mild Conditions

A facile, green, and efficient method for the direct oxidative amination of benzoxazoles using heterocyclic ionic liquid as catalyst has been developed. The reaction proceeded smoothly at room temperature and gave the desirable 2-aminobenzoxazoles with good to excellent yields (up to 97%). The catalyst 1-butylpyridinium iodide can be easily recycled and reused with similar efficacies for at least four cycles.

Reusable ionic liquid-catalyzed oxidative esterification of carboxylic acids with benzylic hydrocarbons via benzylic Csp3–H bond activation under metal-free conditions

A protocol for oxidation of the Csp³–H bond in benzylic hydrocarbons with carboxylic acids using ionic liquid as reusable catalyst has been reported.

Reusable ionic liquid-catalyzed oxidative coupling of azoles and benzylic compounds via sp3 C–N bond formation under metal-free conditions

The heterocyclic ionic liquid-catalyzed direct oxidative amination of benzylic sp³ C–H bonds via intermolecular sp³ C–N bond formation for the synthesis of N-alkylated azoles under metal-free conditions is reported for the first time.

Dinuclear gold(I) complexes with propylene bridged N-heterocyclic dicarbene ligands: synthesis, structures, and trends in reactivities and properties

Four novel dinuclear N-heterocyclic dicarbene gold(I) complexes with a propylene linker between the carbene moieties have been synthesized and their luminescence and electrochemical properties, together with their reactivity towards bromine oxidative addition, have been screened. All the complexes emit in the solid state in the blue-green spectral range (400-500 nm) with appreciable intensities (Φ(em) up to ≈10%). In cyclic voltammetry, the Au(I)/Au(0) peak splits at low temperature into two separate peaks relative to the couples Au(I)-Au(I)/Au(I)-Au(0) and Au(I)-Au(0)/Au(0)-Au(0), thus indicating the presence of an Au···Au interaction in the dinuclear complex. Oxidative addition of bromine affords as a major or unique product Au(II)-Au(II) complexes most likely as a consequence of the interaction between the two gold centres favoured by the propylene linker.

An efficient palladium catalyst system for the oxidative carbonylation of glycerol to glycerol carbonate

Glycerol carbonate can be readily synthesized from the oxidative carbonylation of glycerol catalyzed by PdCl(2)(phen) (phen=1,10-phenanthroline) with the aid of CuI. High conversion (95 %) and selectivity (98 %) are achieved and the turnover frequency (TOF) reaches 455 h(-1). Furthermore, a new zeolite-Y-confined Pd catalyst, PdCl(2)(phen)@Y, has been successfully prepared by a ''flexible ligand'' method. The structure and composition of the heterogeneous catalyst have been characterized by atomic absorption spectroscopy, elemental analysis, N(2) sorption, XRD, FTIR, solid-state NMR, and X-ray photoelectron spectroscopy. This catalyst exhibits a comparable activity to its homogeneous counterpart and could be reused five times without significant decrease in activity. This is the most efficient heterogeneous system for synthesizing glycerol carbonate by the oxidative carbonylation of glycerol to date.