Chiral (Pyridine)-(Imidazoline) NCN′ Pincer Palladium(II) Complexes: Convenient Synthesis via C–H Activation and Characterization

Abstract

A series of aryl-based chiral NCN′ pincer palladium-(II) complexes 4a−k were synthesized via C−H activation of the (pyridyl)-(imidazolinyl)benzene ligands, which proceeded smoothly with PdCl 2 as the palladium source in the presence of Et 3 N or NaHCO 3 base in toluene under reflux. All of the complexes have been characterized by elemental analysis and 1 H and 13 C{ 1 H} NMR spectroscopy. In addition, the molecular structures of complexes 4a, 4c, and 4f have been determined by X-ray singlecrystal diffraction analysis. The obtained chiral Pd pincers were applied to catalytic asymmetric reactions of acrylonitrile and dichloroacetonitrile with sulfonimines. With a catalyst loading of 5 mol % and the assistance of AgOAc, these complexes acted as active but moderately stereoselective catalysts for the aforementioned reactions.

Base-Promoted Annulated Aromatization of Aryl Acetylenes with Dimethyl Sulfoxide to Access Symmetrical/Unsymmetric m-Terphenyl

“…Polycyclic aromatic hydrocarbons (PAHs) are nonpolar hydrocarbons with unique structures and photoelectric properties . PAHs with m -terphenyl and its derivatives as the core skeleton exhibit significant potential in catalysis, , materials, and biomedicine . For example, a cyclometallic compound utilizing 1,3-bis­(2-pyridyl)­benzene as a ligand (Figure a) has been employed for unsymmetric catalysis. , This ligand could also be used as a synthesizer to construct multivalent glycoconjugates (Figure b) .…”

“…PAHs with m -terphenyl and its derivatives as the core skeleton exhibit significant potential in catalysis, , materials, and biomedicine . For example, a cyclometallic compound utilizing 1,3-bis­(2-pyridyl)­benzene as a ligand (Figure a) has been employed for unsymmetric catalysis. , This ligand could also be used as a synthesizer to construct multivalent glycoconjugates (Figure b) . [n]­Cyclo-meta-phenylene (Figure c) with conjugated π-electrons shows great potential in organic light-emitting diodes (OLEDs) .…”

Novel Copper(II) Complexes with Dipinodiazafluorene Ligands: Synthesis, Structure, Magnetic and Catalytic Properties

“…Chiral pyridines are of great interest from many points of view [1] and are being actively investigated as ligands in coordination chemistry [2][3][4][5], as chiral auxiliary [6][7][8][9][10][11][12], as biologically active compounds [13,14], including anticancer agents [15], as building blocks in the design of receptors for enantioselective recognition [16], chiral coordination frameworks [17], luminescent materials [18,19], and calamitic liquid crystals [20]. The coupling of a pinane carbon frame and pyridine ring system in one molecule generates an extensive group of pinane-pyridine hybrids (pinopyridines) [21][22][23][24][25][26][27][28][29][30][31][32][33].…”