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Coordination compounds Pd(L1)Cl$_{2}$, Pd(L2)Cl$_{2}$, and Pd(L3)Cl$_{2}$ have been synthesized from optically pure $\alpha $-amino-oxime ligands L1–L3 based on $(R)$-limonene. Structures of the new palladium complexes are characterized and described by NMR spectroscopy and X-rays. These $\alpha $-amino-oxime ligands were then evaluated in the palladium-catalysed allylation of 1,3-dioxo compounds.

An effective method of grafting functionalities onto lignin based on glycerol carbonate has been developed. This biobased grafting reagent reacts with lignin without generating co-products. Alkenyl groups were added to the glycerol carbonate moiety from 1,3-butadiene chemistry using the nickel-catalysed hydroalkoxylation reaction and the newly developed nickel-catalysed telomerisation reaction under solvent-free conditions. The high-atom economical reactions lead to three different sets of glycerol carbonate ethers with various chain lengths that can be separated from the catalyst to avoid lignin contamination with metals. Kraft, organosolv and soda lignins, without prior purification, were grafted via ether functions using these linkers in a clean and efficient procedure. The technical and modified lignins were characterised by NMR, IR and SEC, and their thermal properties were determined by DSC. The glass transition temperatures of the modified lignins are significantly reduced, opening up possibilities of shaping, for example, on hot presses. In addition, these modifications offer the possibility of inserting new reactive functions within the lignin, including unsaturations and alcohols, allowing a new range of lignin-based resins to be developed. [ABSTRACT FROM AUTHOR]

The growing interest of industry in the field of bi(hetero)arene compounds motivated us to synthesize these compounds via a homogeneous catalytic route using Pd PEPPSI-type complexes through direct arylation. In this study, new Pd PEPPSI-type complexes bearing NHC spectator ligands were synthesized and characterized using spectroscopic techniques, such as 1HNMR, 13C NMR, MS spectrometry, FTIR spectroscopy and elemental analysis (PEPPSI = pyridine enhanced precatalyst preparation stabilization and initiation). All the synthesized Pd(II) complexes were stable. The catalytic properties of these complexes were evaluated in the direct C5 mono-arylation of furan, 2-acetylthiophene and N-methylpyrrole-2-carboxaldehyde derivatives with a wide variety of (hetero)aryl halides. This environmentally attractive procedure was found to be tolerant of a wide variety of functional groups on the aryl halides and good yields were obtained in the presence of 1 mol% catalyst loading at 150 °C for 2 hours. In addition, the conversions for substrates containing electron-withdrawing groups were higher than those for substituents containing electron-donating groups. [ABSTRACT FROM AUTHOR]

• Herein, we reported the synthesis of nine new PEPPSI-Pd(II)–N-heterocyclic carbene (NHC) complexes 3a-h containing benzimidazole core and examined their catalytic activities in the direct arylation of heteroaromatic species with aryl bromides and arylchlorides. • Their structures were elucidated by 1H and 13C NMR spectroscopy, FT-IR spectroscopy, and elemental analysis methods. • Further, direct arylation reaction, using KOAc as base and DMAc as solvent under inert conditions, were carried out with the synthesized complexes in the presence of various aryl bromides and chlorides. Herein, we reported the synthesis of nine new PEPPSI-Pd(II)–N-heterocyclic carbene (NHC) complexes 3a-h containing benzimidazole core and examined their catalytic activities in the direct arylation of heteroaromatic species with aryl bromides and arylchlorides. Nine new Pd benzimidazole complexes were synthesized and their structures were elucidated by 1H and 13C NMR spectroscopy, FT-IR spectroscopy, and elemental analysis methods. In the 13C NMR spectra, N C HN peaks of Pd(II) complexes were observed between 159.7–161.5 ppm. Further, direct arylation reaction, using KOAc as base and DMAc as solvent under inert conditions, were carried out with the synthesized complexes in the presence of various aryl bromides and chlorides, and 2-acetyl furan, and furfuryl acetate 2-acetylthiophene and N-methylpyrrole-2- carboxaldehyde. Moreover, moderate to hig yields were obtained in the direct arylation of heteroarenes and aryl bromides under 1 mol% catalyst loading at 150 °C for 2 h loading conditions. The results showed that electron-donating and electron-withdrawing substituents on the aryl halides might produce coupling products in good yields in the presence of complexes 2a-d. Taken together, our findings are expected to contribute to the synthesis and design of palladium complexes containing benzimidazole core structures. [ABSTRACT FROM AUTHOR]

A dinuclear nickel complex with ( S )-limonene based amino-oxime ligand has been isolated and its crystal structure determined. The resolved structure of dichloridobis-{(2 S ,5 R )-2-methyl-5-(prop-1-en-2-yl)-2-[(pyridin-2-yl)methyl-amino]-cyclo-hexan-1-one oxime}dinickel(II), [Ni 2 Cl 2 (C 16 H 23 ClN 3 O) 2 ], at 100 K has monoclinic ( P 2 1 ) symmetry. The two Ni II ions in the dinuclear complex are each coordinated in a distorted octa-hedral environment by three nitro-gen atoms, a terminal chloride and two μ bridging chlorides. Each oxime ligand is coordinated to nickel(II) by the three nitro-gen atoms, leading to two five-membered chelate rings, each displaying an envelope conformation. In the crystal, numerous inter-molecular and intra-molecular hydrogen bonds lead to the formation of a three-dimensional network structure., (© Homrani et al. 2021.)