115 research outputs found
Bis[μ-3-ethyl-4-phenyl-5-(2-pyridÂyl)-4H-1,2,4-triazole]bisÂ[dichloridocopper(II)]
The asymmetric unit of the title compound, [Cu2Cl4(C15H14N4)2], contains two halves of two centrosymmetric dinuclear molÂecules, A and B. The conformations of the two crystallographically independent molÂecules are slightly different: in A, the Cu⋯Cu separation is 4.174 (9) Å and the dihedral angle between the triazole and phenyl rings is 74.23 (11)°; these values are 4.137 (9) Å and 68.58 (13)°, respectively, in B. In each molÂecule, the copper(II) ions have a distorted trigonal–bipyramidal coordination geometry with a CuCl2NN′N′′ chromophore. The crystal packing exhibits weak interÂmolecular C—H⋯Cl interÂactions
Additive-Controlled Divergent Synthesis of Tetrasubstituted 1,3-Enynes and Alkynylated 3H-Pyrrolo[1,2-a]indol-3-ones via Rhodium Catalysis
Herein, we report the additive-controlled divergent synthesis of tetrasubstituted 1,3-enynes and alkynylated 3H-pyrrolo[1,2-a]indol-3-ones through rhodium-catalyzed C-H alkenylation/DG migration and [3+2] annulation, respectively. This protocol features rare directing group migration in 1,3-diyne-involved C-H activation, excellent regio- and stereoselectivity, excellent monofunctionalization over difunctionalization, broad substrate scope, moderate to high yields, good functional group compatibility, and mild redox-neutral conditions
GW26-e4017 Intravenous infusion of drag-reducing polymers protects against acute myocardial ischemia and reperfusion injury
Temperature-Controlled Divergent Synthesis of Tetrasubstituted Alkenes and Pyrrolo[1,2-a]indole Derivatives via Iridium Catalysis
We have achieved an Ir(III)-catalyzed temperature-controlled divergent synthesis of tetrasubstituted alkenes and pyrrolo[1,2-a]indole derivatives through C−H alkenylation/DG migration and [3+2] annulation, respectively. This method has various advantageous features: a) excellent regio- and stereoselectivity and good functional group tolerance, b) broad substrate scope and moderate to excellent yields, c) mild redox-neutral reaction conditions and operational simplicity
Chemo-, Regio-, and Stereoselective Assembly of Polysubstituted Furan-2(5H)-ones Enabled by Rh(III)-Catalyzed Domino C–H Alkenylation/Directing Group Migration/Lactonization: A Combined Experimental and Computational Study
Exploring multistep cascade reactions triggered by C–H activation are recognized as appealing, yet challenging. Herein, we disclose a Rh(III)-catalyzed domino C–H coupling of N-carbamoyl indoles and 4-hydroxy-2-alkynoates for the streamlined assembly of highly functionalized furan-2(5H)-ones in which the carbamoyl-directing group (DG) is given a dual role of an auxiliary group and a migrating acylating reagent via the cleavage of stable C–N bonds at room temperature. More importantly, the obtained furan-2(5H)-one skeleton could be further functionalized under air in situ via C5–H hydroxylation by simply switching the solvent or additive, providing fully substituted furan-2(5H)-ones with the installation of an alcohol-based C5 quaternary carbon center. Detailed experimental studies and density functional theory calculations reveal that a Rh(III)-mediated tandem C–H activation/alkyne insertion/DG migration/lactonization accounts for the developed transformation to achieve high functionalities with the observed exclusive selectivity. The potential biological application of the obtained furan-2(5H)-ones as a class of potent PPARγ ligands further highlights the synthetic utility of the developed methodology. This protocol is endowed with several salient features including efficient multistep cascade triggered by C–H activation, excellent chemo-, regio-, and stereoselectivity, high bond-forming efficiency (e.g., two C–C and two C–O bonds), solvent- or additive-controlled product selectivity, good functional-group compatibility, and mild redox-neutral conditions
Chemo- and Regioselective Synthesis of Functionalized 1H-imidazo[1,5-a]indol-3(2H)-ones via a Redox-Neutral Rhodium(III)-Catalyzed [4+1] Annulation between Indoles and Alkynes
Alkynes generally serve as C2 synthons in transition-metal-catalyzed C−H annulations, herein, exploiting electron-deficient alkynes as unconventional C1 synthons, the chemo- and regiospecific synthesis of functionalized 1H-imidazo[1,5-a]indol-3(2H)-ones via a redox-neutral rhodium(III)-catalyzed [4+1] annulation of N-carbamoyl indoles has been achieved. This process is characterized by high chemo- and regioselectivity, broad substrate scope, good tolerance of functional groups, moderate to high yields and mild redox-neutral conditions, thus affording a robust approach to access valuable 1H-imidazo[1,5-a]indol-3(2H)-ones
Photoflexoelectric effect in halide perovskites
Harvesting environmental energy to generate electricity is a key scientific and technological endeavour of our time. Photovoltaic conversion and electromechanical transduction are two common energy-harvesting mechanisms based on, respectively, semiconducting junctions and piezoelectric insulators. However, the different material families on which these transduction phenomena are based complicate their integration into single devices. Here we demonstrate that halide perovskites, a family of highly efficient photovoltaic materials, display a photoflexoelectric effect whereby, under a combination of illumination and oscillation driven by a piezoelectric actuator, they generate orders of magnitude higher flexoelectricity than in the dark. We also show that photoflexoelectricity is not exclusive to halides but a general property of semiconductors that potentially enables simultaneous electromechanical and photovoltaic transduction and harvesting in unison from multiple energy inputs
SalK/SalR, a Two-Component Signal Transduction System, Is Essential for Full Virulence of Highly Invasive Streptococcus suis Serotype 2
BACKGROUND: Streptococcus suis serotype 2 (S. suis 2, SS2) has evolved into a highly infectious entity, which caused the two recent large-scale outbreaks of human SS2 epidemic in China, and is characterized by a toxic shock-like syndrome. However, the molecular pathogenesis of this new emerging pathogen is still poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: 89K is a newly predicted pathogenicity island (PAI) which is specific to Chinese epidemic strains isolated from these two SS2 outbreaks. Further bioinformatics analysis revealed a unique two-component signal transduction system (TCSTS) located in the candidate 89K PAI, which is orthologous to the SalK/SalR regulatory system of Streptococcus salivarius. Knockout of salKR eliminated the lethality of SS2 in experimental infection of piglets. Functional complementation of salKR into the isogenic mutant DeltasalKR restored its soaring pathogenicity. Colonization experiments showed that the DeltasalKR mutant could not colonize any susceptible tissue of piglets when administered alone. Bactericidal assays demonstrated that resistance of the mutant to polymorphonuclear leukocyte (PMN)-mediated killing was greatly decreased. Expression microarray analysis exhibited a transcription profile alteration of 26 various genes down-regulated in the DeltasalKR mutant. CONCLUSIONS/SIGNIFICANCE: These findings suggest that SalK/SalR is requisite for the full virulence of ethnic Chinese isolates of highly pathogenic SS2, thus providing experimental evidence for the validity of this bioinformatically predicted PAI
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