Copper-Catalyzed Enantioselective Coupling between Allyl­boronates and Phosphates Using a Phenol–Carbene Chiral Ligand: Asymmetric Synthesis of Chiral Branched 1,5-Dienes

Details of the Cu-catalyzed enantioselective allyl–allyl coupling reaction between allylboronates and (Z)-allylic phosphates using a new chiral N-heterocyclic carbene (NHC) ligand containing a phenolic hydroxy group are presented. The copper catalysis delivers enantio­enriched chiral 1,5-dienes with a tertiary stereogenic center. Compatibility with various functional groups and the use of earth-abundant and relatively low-toxicity copper as a metal are attractive features of this protocol. The utility of the chiral phenol–NHC ligand for enantioselective copper catalysis with organoboron compounds is demonstrated and enantiodiscrimination models are discussed.

Syntheses and structures of discrete copper(II) and cadmium(II) supramolecular complexes based on 1,4-diacylthiosemicarbazone ligands

Thiosemicarbazides and their metal complexes have attracted considerable interest because of their biological activities and their flexibility, which allows the ligands to bend and rotate freely to accommodate the coordination geometries of various metal centres. Discrete copper(II) and cadmium(II) complexes have been prepared by crystallization ofN-[2-(2-hydroxybenzoyl)hydrazinecarbonothioyl]propanamide (H3L) with Cu(CH3COO)2or Cd(NO3)2in a dimethylformamide/methanol mixed-solvent system at room temperature, affording the complexes di-μ-acetato-bis{μ4-1-[(2-oxidophenyl)carbonyl]-2-(propanamidomethanethioyl)hydrazine-1,2-diido}tetracopper(II) dimethylformamide disolvate, [Cu4(C11H10N3O3S)2(C2H3O2)2]·2C3H7NO, (I), and bis{μ2-[(2-hydroxyphenyl)formamido](propanamidomethanethioyl)azanido}bis[(4,4′-bipyridine)nitratocadmium(II)] dihydrate, [Cd2(C11H12N3O3S)2(NO3)2(C10H8N2)2]·2H2O, (II). Complex (I) consists of four CuIIcations, two μ4-bridging trianionic ligands and two μ2-bridging acetate ligands, while complex (II) is composed of two CdIIcations, two μ2-bridging monoanionic ligands, two nitrate ligands and two 4,4′-bipyridine ligands. These discrete complexes are connected by hydrogen bonds and van der Waals interactions to form a three-dimensional supramolecular architecture. Compared with (I), the phenolic hydroxy group and hydrazide N atom of the thiosemicarbazide ligand of (II) are not involved in coordination and lead to a binuclear CdIIcomplex. This different coordination mode may be attributed to the larger ionic radius of the CdIIion compared with the CuIIion.

Cinnarizinium 3,5-dinitrosalicylate

The title compound [systematic name: 4-diphenylmethyl-1-(3-phenylprop-2-en-1-yl)-piperazin-1-ium 2-carboxy-4,6-dinitrophenolate], C26H29N2+·C7H3N2O7−, is the dinitrosalicylate salt of a tertiary amine. Deprotonation of the carboxylic acid group occurred on the phenolic hydroxy group. The diazacyclohexane ring adopts a chair conformation. Intramolecular O—H...O and intermolecular C—H...O and N—H...O hydrogen bonds are observed. The N—H...O hydrogen bonds are bifurcated at the H atom and connect the cinnarizinium and 3,5-dinitrosalicylate ions together. Intermolecular C—H...O hydrogen bonds connect the components into layers perpendicular to the crystallographicaaxis.

The Heck Reaction of Protected Hydroxychromones: on route to Natural Products

The Heck reaction has been successfully extended to the bromochromones with an adjacent protected phenolic hydroxy group which offers a new methodology to various naturally occurring derivatives including tricyclic O-heterocycles. Phosphine-free coupling conditions are found to be effective. Surprisingly, the methoxymethyl protecting group is unstable in several cases but benzyl proved to be an ideal protecting group which could be selectively cleaved by boron trihalides in good yields.

Crystal Structures, Antioxidation, and DNA Binding Properties of SmIII Complexes

The dinuclear SmIII complexes with 1:1 metal to ligand stoichiometry were prepared from Sm(NO3)3·6H2O and three anionic tetradentate Schiff-base ligands derived from 8-hydroxyquinoline-2-carboxyaldehyde with benzoylhydrazine, 2-hydroxybenzoylhydrazine, and isonicotinylhydrazine, respectively. All the ligands and complexes can bind strongly to calf thymus DNA through intercalation with the binding constants at 105–106 M–1, but complexes present stronger affinities to DNA than ligands. All the ligands and complexes have strong abilities of antioxidation, but complexes and ligands containing an active phenolic hydroxy group show stronger scavenging effects on hydroxyl radical, and SmIII complex containing N-heteroaromatic substituent shows stronger scavenging effects for superoxide radical.