Search results for "Imides"

Synthesis of 1,3,5-Trisubstituted Hydantoins by Regiospecific Domino Condensation/Aza-Michael/O→N Acyl Migration of Carbodiimides with Activated α,β-…

2005

[reaction: see text] Carbodiimides and suitably activated alpha,beta-unsaturated carboxylic acids react effectively to afford a vast array of 1,3,5-trisubstituted hydantoins by means of a regiospecific domino condensation/aza-Michael/N--O acyl migration. The reaction works well in very mild conditions (20 degrees C, dichloromethane) with fumaric acid derivatives bearing an electron-withdrawing group in the beta position. Good results have been obtained also with less activated substrates bearing only one electron-withdrawing group in the beta position, using more polar solvents (acetonitrile, DMF), and in the presence of a base (2,4,6-trimethylpyridine). Reactions with asymmetric carbodiimi…

New imidazo[1,2-c]pyrrolo[3,2-e]pyrimidinone derivatives as potential DNA-binders

2008

Conformations and Energetics of Sulfur and Selenium Diimides

2003

The geometries and energetics of different conformations of sulfur and selenium diimides E(NR) 2 (E = S, Se; R = H, Me, 'Bu, C 6 H 3 Me 2 -2,6, SiMe 3 ) have been studied by using various ab initio and DFT molecular orbital techniques. The syn,syn conformation is found to be most stable for parent E(NH) 2 , but in general, the preferred molecular conformation for substituted chalcogen diimides is syn,anti. In the case of E(NH) 2 the present calculations further confirm that syn,syn and syn,anti conformations lie energetically close to each other. From the three different theoretical methods used, B3PW91/6.31G * proved to be the most suitable method for predicting the geometries of chalcogen…

Structural characterization of site-modified nanocapsid with monodispersed gold clusters

2017

AbstractHepatitis E Virus-like particles self-assemble in to noninfectious nanocapsids that are resistant to proteolytic/acidic mucosal delivery conditions. Previously, the nanocapsid was engineered to specifically bind and enter breast cancer cells, where successful tumor targeting was demonstrated in animal models. In the present study, the nanocapsid surface was modified with a solvent-exposed cysteine to conjugate monolayer protected gold nanoclusters (AuNC). Unlike commercially available gold nanoparticles, AuNCs monodisperse in water and are composed of a discrete number of gold atoms, forming a crystalline gold core. Au102pMBA44 (Au102) was an ideal conjugate given its small 2.5 nm s…

Acetylcholine mediates the release of IL-8 in human bronchial epithelial cells by a NFkB/ERK-dependent mechanism

2007

Acetylcholine may play a role in cell activation and airway inflammation. We evaluated the levels of both mRNA and protein of muscarinic M(1), M(2), M(3) receptors in human bronchial epithelial cell line (16HBE). 16HBE cells were also stimulated with acetylcholine and extracellular signal-regulated kinase1/2 (ERK1/2) and NFkB pathway activation as well as the IL-8 release was assessed in the presence or absence of the inhibitor of Protein-kinase (PKC) (GF109203X), of the inhibitor of mitogenic activated protein-kinase kinase (MAPKK) (PDO9805), of the inhibitor of kinaseB-alpha phosphorilation (pIkBalpha) (BAY11-7082), and of muscarinic receptor antagonists tiotropium bromide, 4-Diphenylacet…

Metabotropic glutamate receptors activate phospholipase D in astrocytes through a protein kinase C-dependent and Rho-independent pathway.

2003

Metabotropic glutamate receptors (mGluRs) are G protein-coupled receptors that mediate phospholipase D (PLD) activation in brain, but the mechanism underlying this response remains unclear. Here we used primary cultures of astrocytes as a cell model to explore the mechanism that links mGluRs to PLD. Glutamate activated both phospholipase C (PLC) and PLD with equal potency and this effect was mimicked by L-cysteinesulfinic acid, a putative neurotransmitter previously shown to activate mGluRs coupled to PLD, but not PLC, in adult brain. PLD activation by glutamate was dependent on Ca(2+) mobilization and fully blocked by both protein kinase C (PKC) inhibitors and PKC down-regulation, suggesti…

Formation, Structural Characterization, and Calculated NMR Chemical Shifts of Selenium-Nitrogen Compounds from SeCl4 and ArNHLi (Ar = supermesityl, m…

2004

Supermesityl selenium diimide [Se{N(C6H2tBu3-2, 4, 6)}2; Se{N(mes*)}2] can be prepared in a good yield from the reaction of SeCl4 and (mes*)NHLi. The molecule adopts an unprecedented anti, anti-conformation, as deduced by DFT calculations at PBE0/TZVP level of theory and supported by 77Se NMR spectroscopy and a crystal structure determination. An analogous reaction involving (C6H2Me3-2, 4, 6)NHLi [(mes)NHLi] unexpectedly lead to the reduction of selenium and afforded the selenium diamide Se{NH(mes)}2 that was characterized by X-ray crystallography and 77Se NMR spectroscopy. The Se-N bonds of 1.847(3) and 1.852(3) A show normal single bond lengths. The <NSeN bond angle of 109.9(1)° also indi…

Experimental and Theoretical Investigations of Structural Trends for Selenium(IV) Imides and Oxides: X-ray Structure of Se3(NAd)2

2004

The thermal decomposition of Se(NAd)2 (Ad = 1-adamantyl) in THF was monitored by 77Se NMR and shown to give the novel cyclic selenium imide Se3(NAd)2 as one of the products. An X-ray structural determination showed that Se3(NAd)2 is a puckered five-membered ring with d(Se−Se) = 2.404(1) Å and |d(Se−N)| = 1.873(4) Å. On the basis of 77Se NMR data, other decomposition products include the six-membered ring Se3(NAd)3, and the four-membered rings AdNSe(μ-NAd)2SeO and OSe(μ-NAd)2SeO. The energies for the cyclodimerization of E(NR)2 and RNEO (E = S, Se; R = H, Me, tBu, SiMe3), and the cycloaddition reactions of RNSeO with E(NR)2, RNSO2 with Se(NR)2, and S(NR)2 with Se(NR)2 have been calculated at…

Experimental and Theoretical Investigations of Tellurium(IV) Diimides and Imidotelluroxanes: X-ray Structures of B(C6F5)3 Adducts of OTe(μ-NtBu)2TeNt…

2005

The hydrolysis of tBuNTe(μ-NtBu)2TeNtBu (1) with 1 or 2 equiv of (C6F5)3B·H2O results in the successive replacement of terminal imido groups by oxo ligands to give the telluroxane-Lewis acid adducts (C6F5)3B·OTe(μ-NtBu)2TeNtBu (2) and [(C6F5)3B·OTe(μ-NtBu)2Te(μ-O)]2 (3), which were characterized by multinuclear NMR spectroscopy and X-ray crystallography. The TeO distance in 2 is 1.870(2) Å. The di-adduct 3 involves the association of four tBuNTeO monomers to give a tetramer in which both terminal TeO groups [d(TeO) = 1.866(3) Å] are coordinated to B(C6F5)3. The central Te2O2 ring in 3 is distinctly unsymmetrical [d(TeO) = 1.912(3) and 2.088(2) Å]. The X-ray structure of (C6F5)3B·NH2tBu (4),…