Crystal structure of 4-(naphthalen-2-yl)-2-oxo-6-phenyl-1,2-di-hydro-pyridine-3-carbo-nitrile.

The synthesis and crystal structure of the title compound, C22H14N2O, are described. The title compound was synthesized by a three-component one-pot reaction in DMSO involving chalcone, cyano-acetamide and elemental sulfur as catalyst. The compound was characterized by spectroscopic methods and single-crystal X-ray diffraction. The structure consists of inversion-related dimers produced by N-H⋯O hydrogen bonding, which further inter-act through π-π contacts.

DABCO-Catalyzed DMSO-Promoted Sulfurative 1,2-Diamination of Phenylacetylenes with Elemental Sulfur and o-Phenylenediamines: Access to Quinoxaline-2-thiones.

The oxidative amination of alkynes typically requires transition metal catalysts and strong oxidants. Herein, we alternatively utilize DABCO as a sulfur-activating catalyst to achieve the sulfurative 1,2-diamination of phenylacetylenes with elemental sulfur and o-phenylenediamines. DMSO was found to be particularly suitable for use as a terminal oxidant for this three-component process. A mechanistic study has shown that this cascade reaction is triggered by the addition of active sulfur species to the triple bond of phenylacetylenes.

Sulfur-Promoted Oxidative Condensation of Chalcones with Unsubstituted Cyanoacetamide in DMSO: Access to 3-Cyanopyrid-2-ones.

Elemental sulfur and DABCO were found to be an excellent combination to promote a one-pot cascade of condensation-oxidative cyclization of chalcones and unsubstituted cyanoacetamide in DMSO to provide 3-cyanopyrid-2-ones.

Synthesis and crystal structure of peptide dimethyl biphenyl hybrid C52H60N6O10·0.25H2O.

The synthesis and crystal structure of peptide 6,6'-dimethyl biphenyl hybrid are described. The title compound was synthesized by reaction between 6,6'-dimethyl-[1,1'-biphen-yl]-2,2'-dicarbonyl dichloride in CH2Cl2, amine HN-proline-phenyl-alanine-alanine-COOMe and Et3N at 273 K under N2 atmosphere and characterized by single-crystal X-ray diffraction. The asymmetric unit contains one peptide mol-ecule and a quarter of a water mol-ecule. A disorder of a methyl and meth-oxy-carbonyl group of one alanine residue is observed with occupancy ratio 0.502 (6):0.498 (6). The structure is consolidated by intra- and inter-molecular hydrogen bonds.

Crystal structure of a tripeptide biphenyl hybrid C50H56N6O10·0.5H2O.

A peptide biphenyl hybrid compound {systematic name: dimethyl 2,2'-[((2S,2'S)-2,2'-{[(2S,2'S)-1,1'-([1,1'-biphen-yl]-2,2'-dicarbon-yl)bis-(pyrrolidine-1,2-diyl-2-carbon-yl)]bis-(aza-nedi-yl)}bis-(3-phenyl-propano-yl))bis-(aza-nedi-yl)](2S,2'S)-dipropionate hemihydrate}, C50H56N6O10·0.5H2O, was prepared by coupling of [1,1'-biphen-yl]-2,2'-dicarbonyl dichloride, tri-ethyl-amine and the tripeptide Pro-Phe-Ala in CH2Cl2 at 273 K under an N2 atmosphere. In the crystal, the asymmetric unit contains the peptide biphenyl hybrid accompanied by one-half of a water mol-ecule. A C atom of one of the proline rings is disordered between two positions in a 0.746 (11):0.254 (11) ratio. An important structural aspect of peptide compounds is their capacity to self-associate mediated by inter-molecular and intra-molecular hydrogen bonding. This characteristic can be useful in understanding the inter-actions between peptides and biomacromolecular targets, as well as to explain peptide properties.

Crystal structures of 2-(2-bromo-5-fluoro-phen-yl)-8-eth-oxy-3-nitro-2H-thio-chromene and 2-(2-bromo-5-fluoro-phen-yl)-7-meth-oxy-3-nitro-2H-thio-chromene.

Two thio-chromene com-pounds containing Br and F atoms, namely 2-(2-bromo-5-fluoro-phen-yl)-8-eth-oxy-3-nitro-2H-thio-chromene (C17H13BrFNO3S, A) and 2-(2-bromo-5-fluoro-phen-yl)-7-meth-oxy-3-nitro-2H-thio-chromene (C16H11BrFNO3S, B), were prepared via the condensation reaction between 2-mer-capto-benzaldehyde and nitro-styrene derivatives. In both com-pounds, the thio-chromene plane is almost perpendicular to the phenyl ring. In the structure of A, mol-ecules are assembled via π-π stacking and C-H⋯O and C-F⋯π inter-actions. In the crystal packing of B, mol-ecules are linked by C-H⋯F, C-H⋯O, C-H⋯π and π-π inter-actions.

Periodic projector augmented wave density functional calculations on the hexachlorobenzene crystal and comparison with the experimental multipolar charge density model.

The projector augmented wave (PAW) methodology has been used to calculate a high precision electron density distribution ρ(r) for the hexachlorobenzene crystal phase. Implementing the calculation of the crystallographic structure factors in the VASP code has permitted one to obtain the theoretical multipolar ρ(r). This electron density is compared with both the DFT electron density and the experimental multipolar model obtained from high-resolution X-ray diffraction data. This comparison has been carried out in intra- and intermolecular regions within the framework of the quantum theory of atoms-in-molecules (QTAIM) developed by Bader and co-workers. The characterization of the electron density in both C-Cl and Cl···Cl regions, as well as within the atomic basins, shows similar features for the three models. As a consequence, the observation of charge depletion and charge concentration regions around the halogen nuclei (along the C-Cl bonding axis and in the perpendicular plane, respectively) underlines the nature of halogen bonding in terms of electrophilic and nucleophilic interactions.

The nature of halogen...halogen interactions: a model derived from experimental charge-density analysis.

Slightly attractive: The attractive and anisotropic nature of the ClCl interaction in C(6)Cl(6) is experimentally demonstrated from an expansion of the electron density rho(r) around the chlorine nuclei. The interaction is explained in a model in which there is a bonding attraction involving electron-deficient (see picture, blue) and electron-rich (red) regions of adjacent Cl atoms.