A green way to γ-lactams through a copper catalyzed ARGET-ATRC in ethanol and in the presence of ascorbic acid

A ‘green’ ARGET-ATRC, for the CuCl[PMDETA] catalysed cyclo-isomerization of N-allyl-α-polychloroamides to γ-lactams is described. The process works efficiently (yields 78-96%), uses a bio-solvent, as ethanol, and exploits the reducing feature of ascorbic acid to limit, at a low level (2-4%), the amount of catalyst. To preserve the efficacy of the catalytic cycle, addition of Na₂CO₃ is essential, which quenches the HCl released during the CuCl[PMDETA] regeneration step. Profitable features of the process are: mild reaction temperatures (25-37 °C), relatively short reaction times (usually 5 h) and low solvent volumes (2 mmol of substrate/mL of ethanol). The method, upon stoichiometric adjustment, was also used for the synthesis of α,β-unsaturated-γ-lactams from N-(2-chloroallyl)-α-polychloroamides, via a tandem process involving an ATRC and a reductive [1,2]-elimination.     

Decisive role of water in efficient noncatalyzed synthesis of polyfunctional 1H-1,2,3-triazoles proceeding from γ-hydroxypropynals

A highly efficient method was developed for the synthesis of new polyfunctional 1H-1,2,3-triazoles by the reaction of γ-hydroxypropynals with trimethylsilyl azide in water at room temperature without catalyst. The addition of trimethylsilyl azide to γ-hydroxypropynals occurs regioselectively: Previously unknown hydroxyalkyl-1H-1,2,3-triazolecarbaldehydes have been isolated in 69-96% yields with the prevalence of 1,5-isomers and the content of minor 1,4-isomers equal 9-21%. In the reaction of γ-hydroxypropynals with sodium azide in DMSO the formation of 4-hydroxyalkyl-1H-1,2,3-triazole-5-carbaldehydes is accompanied by the dimerization of initial aldehydes into the corresponding 1,3-dioxolanes.     

Mast cells play a key role in Th2 cytokine-dependent asthma model through production of adhesion molecules by liberation of TNF-α

Mast cells are well recognized as key cells in allergic reactions, such as asthma and allergic airway diseases. However, the effects of mast cells and TNF-α on T-helper type 2 (Th2) cytokine-dependent asthma are not clearly understood. Therefore, an aim of this study was to investigate the role of mast cells on Th2 cytokine-dependent airway hyperresponsiveness and inflammation. We used genetically mast cell-deficient WBB6F1/J-Kitw/Kitw-v (W/Wv), congenic normal WBB6F1/J-Kit+/Kit+ (+/+), and mast cell-reconstituted W/Wv mouse models of allergic asthma to investigate the role of mast cells in Th2 cytokine-dependent asthma induced by ovalbumin (OVA). And we investigated whether the intratracheal injection of TNF-α directly induce the expression of ICAM-1 and VCAM-1 in W/Wv mice. This study, with OVA-sensitized and OVA-challenged mice, revealed the following typical histopathologic features of allergic diseases: increased inflammatory cells of the airway, airway hyperresponsiveness, and increased levels of TNF-α, intercellular adhesion molecule (ICAM)-1, and vascular cellular adhesion molecule (VCAM)-1. However, the histopathologic features and levels of ICAM-1 and VCAM-1 proteins in W/Wv mice after OVA challenges were significantly inhibited. Moreover, mast cell-reconstituted W/Wv mice showed restoration of histopathologic features and recovery of ICAM-1 and VCAM-1 protein levels that were similar to those found in +/+ mice. Intratracheal administration of TNF-α resulted in increased ICAM-1 and VCAM-1 protein levels in W/Wv mice. These results suggest that mast cells play a key role in a Th2 cytokine-dependent asthma model through production of adhesion molecules, including ICAM-1 and VCAM-1, by liberation of TNF-α.     

Metathesis of 1-butene and 2-butene to propene over Re_2O_7 supported on macro-mesoporous γ-alumina prepared via a dual template method

Macro-mesoporous γ-alumina support(MMA) was prepared by a sol-gel route in aqueous medium using pseudo-boehmite as aluminum source and polystyrene microspheres and Pluronic P123 as hard and soft dual templates,respectively.MMA had a BET specific surface area of about 259 m2 g-1,total pore volume of about 1.61 cm3 g-1,macropore diameter of about 102 nm,and mesopore diameter of about 14 nm.Re2O7/MMA and conventional Re2O7/Al2O3 were prepared by a incipient-wetness impregnation method,and their catalytic performances in the metathesis of 1-butene and 2-butene were tested in a fixed-bed tubular reactor.The result showed that Re2O7/MMA possessed higher activity and far longer working life-span than conventional Re2O7/Al2O3.     

Effect of Temperature on the Yields of Final Products in the γ-Radiolysis of Formaldehyde Solutions in C1–C3 Alkanols

The effect of temperature on the yields of 1,2-alkanediols in the -radiolysis of the methanol(or ethanol)–formaldehyde (0.9 M) systems and on the yields of 1,2-alkanediols, carbonyl compounds, methanol, and ethanol in the -radiolysis of the 1-propanol(or 2-propanol)–formaldehyde (1 M) systems was studied over the range 373–473 K. It was found that the temperature dependence of the yields of 1,2-butanediol and 2-methyl-1,2-propanediol exhibited maximums at 423 and 373 K, respectively.     

Synthesis of important β-functionalized 5-methyl-1H-pyrazol-3-ol derivatives in the presence of γ-alumina catalyst in aqueous medium

The γ-alumina catalyzed synthesis of a new series of β-functionalized 5-methyl-1H-pyrazol-3-ol derivatives by the multi-component reaction of an aldehyde, ethylcyano acetate, and in situ generated 3-methyl-1H-pyrazol-5(4H)-one obtained from hydrazine monohyrade and ethyl acetoacetate in aqueous medium is described. The present reaction forms an important variant of the Yonemitsu-type multi-component reaction. The salient features of this present environmentally benign method are: recyclability of the catalysts, mild reaction condition, excellent yields of product, and the use of aqueous medium in the reaction.     

Matrix-isolated NF: Radiative rates of b 1Σ+→a 1Δ, b 1Σ+→X 3Σ−, and a 1Δ→X 3Σ−, in solid argon

Lifetimes of NF b ¹Σ⁺ (2.33 ms) and a ¹Δ (2.85 s) in solid argon have been determined by pulsed laser excitation of the b state. The integrated (0,0) band intensities of the b→X, b→a, and a→X transitions are 1.00, 2.9±0.6, and 2.7±0.6, in relative units. It is concluded that cascading from b ¹Σ⁺ to a ¹Δ is purely radiative within these error limits. While the b→X and a→X transition rates compare favorably with gas-phase data and theoretical calculations, the b→a transition rate is enhanced by four orders of magnitude in the matrix.     

Greener and practical synthesis of 4,4′-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ol)s through a conventional heating and a mechanochemical procedure

A new catalytic application of 4,4′-trimethylenedipiperidine for the efficient synthesis of 4,4′-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ol)s is developed. According to the principles of green chemistry, the reaction was performed by conventional and non-conventional processes: (a) in the refluxing ethanol using a catalytic amount of organocatalyst; (b) at room temperature in the presence of organocatalyst in a planetary ball mill under solvent-free conditions. The organocatalyst could be reused up to 10 runs, and a negligible reduction of catalytic activity was detected. A variety of substituted 4,4′-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ol)s were obtained in good–to-excellent yields under eco-friendly conditions. 4,4′-Trimethylenedipiperidine is commercially available and easy to handle and storage, less toxic, non-flammable, as well as it shows high thermal stability and good solubility in water. The current methodology has merits including (a) wide substrate-scope and high yields of the desired products in the short reaction times, (b) avoiding the use of hazardous solvents and acidic and metal-containing catalysts, (c) minimize the generation of hazardous waste, and (d) simple workup process. Based on great potential as a promising organocatalyst, we hope it can be used as a greener alternative to piperidine for other organic transformations.     

Weakly bound oxygen and its role in stability of solid solutions La1−x Sr x FeO3−δ

In the present study high-temperature X-ray diffraction, thermal analysis, and mass-spectrometry have been employed for investigation of samples in the La_1?x Sr _x FeO_3?δ family (0 ≤ x ≤ 1), the materials being solid solutions having perovskite structure. It has been shown that the loss of oxygen by the samples on heating to 1200°C in air (0 ≤ x ≤ 1) or in vacuum (x < 0.75) does not result in structural rearrangement of the solid solutions, but causes an increase in the lattice parameters. Heating of the compositions with x ≥ 0.75 in vacuum affords phases with ordered vacancies. The observed structural evolutions (growth of the unit cell parameter and vacancy ordering) are reversible, and on re-oxidation (on cooling in air or additional heating of the “vacuum” samples in air atmosphere) the original parameters of the oxides are recovered. The amount of oxygen evolved on heating increases in vacuum or in helium atmosphere, as compared to air, and also grows with rising strontium content, but under experimental conditions does not reach the maximum possible value (δ = x/2).     

Hydrogen production from coke oven gas over LiNi/γ-Al2O3 catalyst modified by rare earth metal oxide in a membrane reactor

The performance of LiNi/r-Al2O3 catalysts modified by rare earth metal oxide (La2O3 or CeO2) packed on BCFNO membrane reactor was discussed for the partial oxidation of methane (POM) in coke oven gas (COG) at 875 ◦C. The NiO/r-Al2O3 catalysts with different amounts of La2O3 and CeO2 were prepared with the same preparation method and under the same condition in order to compare the reaction performance (oxygen permeation, CH4 conversion, H2 and CO selectivity) on the membrane reactor. The results show that the oxygen permeation flux increased significantly with LiNiREOx/r-Al2O3 (RE = La or Ce) catalysts by adding the element of rare earth especially the Ce during the POM in COG. Such as, the Li15wt%CeO29wt%NiO/ -Al2O3 catalyst with an oxygen permeation flux of 24.71 ml·cm−2·min−1 and a high CH4 conversion was obtained in 875 ◦C. The resulted high oxygen permeation flux may be due to the added Ce that inhibited the strong interaction between Ni and Al2O3 to form the NiAl2O4 phase. In addition, the introduction of Ce leads up to an important property of storing and releasing oxygen.     

Does a Concerted Non‐Insertive Mechanism Prevail over a σ‐Insertive Mechanism in Catalytic Cyclohydroamination by Magnesium Tris(oxazolinyl)phenylborate Compounds? A Computational Study

The present study comprehensively explores alternative mechanistic pathways for intramolecular hydroamination of 2,2-dimethyl-4-penten-1-amine (1) by [{To(M)}MgMe] (To(M)=tris(4,4-dimethyl-2-oxazolinyl)phenylborate) (2) with the aid of density functional theory (DFT) calculations. A single-step amidoalkene → cycloamine conversion through a concerted proton transfer associated with N-C ring closure has been explored as one possible mechanism; its key features have been described. This non-insertive pathway evolves via a six-centre TS structure featuring activation of the olefin unit towards nucleophilic amido attack outside the immediate vicinity of the metal centre by amino proton delivery and describes a viable mechanistic variant for alkaline-earth metal-mediated aminoalkene hydroamination. However, herein is presented sound evidence for the operation of the Mg-N amido σ-bond insertive mechanism, its turnover-limiting activation barrier is found to be 5.0 kcal mol(-1) lower than for the non-insertive mechanism, for the cyclohydroamination of 2,2-disubstituted 4-aminoalkenes by a [{To(M)}Mg-NHR] catalyst. The operative mechanism involves rapid equilibria of the {To(M)}Mg-amidoalkene resting state 3 with its amine adduct, easily accessible and thermodynamically disfavoured, hence reversible, 1,2-olefin insertion into the Mg-N amido σ-bond with ring closure at 3, linked to turnover-limiting Mg-C azacycle tether aminolysis by an adduct substrate molecule, followed by facile cycloamine liberation to regenerate the active catalyst species 3. The following aspects are in support of this scenario: 1) the derived rate law is consistent with the experimentally obtained empirical rate law; 2) the reasonable agreement between the computationally estimated and the observed value of the primary KIE; 3) the assessed effective activation barrier for turnover-limiting aminolysis matches empirically determined Eyring parameters remarkably well; and 4) the observed resistance of isolated 3 to undergo amidoalkene cycloamine/cycloamido transformation until further quantities of substrate is added is consistently explained. The herein unveiled insights into the structure-reactivity relationships will undoubtedly govern the rational design of alkaline-earth metal-based catalysts and likely facilitate further advances in the area.     

The 3,4-dihydro-N-oxo-3-ethyl-2,1-benzoxazinium cation in the synthesis of β- and γ-substituted arylbutanes and 1-aryl-2-butenes

The reaction of 3,4-dihydro-N-oxo-3-ethyl-2,1-benzoxazinium salts with reagents with nucleophilic and basic character can be used to obtain - or -substituted arylbutanes and trans-1-aryl-2-butenes. The reactions proceed regiospeciflcally and are regulated by the nature of the reagents used.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 550–554, April, 1992.     

Thio-sugars. Part 5: From d-glucal to 3-deoxy-(1→2)-2-S-thiodisaccharides through isolevoglucosenone—a simple approach

A new synthesis of isolevoglucosenone and its stereoselective functionalization into 3-deoxy-(1-2)-2-S-thiodisaccharides is described. The base-catalyzed conjugate addition of 1-thiosugars to isolevoglucosenone followed by the reduction of the C-4 keto function constitute a new two-step general approach to these classes of biologically important thio-sugars.     

Constructing a coplanar heterojunction through enhanced π-π conjugation in g-C3N4 for efficient solar-driven water splitting

Adjusting the electronic structure of graphitic carbon nitride（g-C₃N₄） photocatalyst through π-π conjugation is an effective method to achieve efficient photogenerated carrier separation. One key challenge ofπ-π conjugation control is to tune the degree of such conjugation without destroying the g-C₃N₄structure. Herein we report a conceptual design that achieves a coplanar heterojunction by enhancing theπ-π conjugation via the doping of crystalline g-C...     

Opening of the epoxide bridge in 3a,6-epoxyisoindol-1-ones by the action of BF3⋅Et2O in acetic anhydride*

The opening of the epoxide bridge in N-substituted 2,3,7,7a-tetrahydro-3a,6-epoxyisoindol-1-ones by the action of BF₃⋅Et₂O in acetic anhydride at 25°C over 1 h proceeds through an S_N1 mechanism. The allylic type cation formed in the first step is stabilized by the addition of an acetoxy group at C-5 in the isoindole system to give a mixture of cis and trans isomers of 5,6-diacetoxy-2,3,5,6,7,7a-hexa-hydroisoindol-1-ones, which are aromatized under these conditions over 24 h to give 2,3-dihydro-1H-isoindol-1-ones.     

Formation of a 1-D metal–water chain and a 2-D water–sulfate layer containing cyclic water octamers in a 3-D supramolecular network

A new tetranuclear complex, {[Cu(phen)(OH)]₄(H₂O)₂}?·?(SO₄)₂?·?8H₂O (1) (phen = 1,10-phenanthroline), has been synthesized and characterized by elemental analysis, UV-Vis, IR, TG, and single-crystal X-ray diffraction. Complex 1 exhibits a 3-D supramolecular network with a 1-D metal–water chain consisting of tetranuclear hydroxo-bridged copper(II) clusters and water octamers and a 2-D water–sulfate layer containing cyclic water octamers with five types of O–H?···?O hydrogen-bonding motifs. The free ligand and its complex were screened for antibacterial activity against Gram-positive and Gram-negative bacteria.     

(±)-1-Tetralone-3-carboxyl­ic acid and (±)-1-tetralone-2-acetic acid: hydrogen bonding in two γ-keto acids

The crystal structure of (±)-4-oxo-1,2,3,4-tetra­hydro­naph­thalene-2-carboxylic acid (C₁₁H₁₀O₃) involves projection of the carboxyl group nearly orthogonal to the aromatic plane and hydrogen bonding of the acid groups by centrosymmetric pairing across the a edge and the center of the chosen cell [O⃛O = 2.705 (2) Å]. Intermolecular C—H⃛O=C close contacts to translationally related mol­ecules are found for both the ketone (2.55 Å) and the acid (2.67 Å). In (±)-1-oxo-1,2,3,4-tetra­hydro­naph­thalene-2-acetic acid (C₁₂H₁₂O₃), the aggregation involves centrosymmetric carboxyl dimers mutually hydrogen bonded across the bc face and the a edge of the chosen cell [O⃛O = 2.674 (2) Å]. A 2.60 Å close C—H⃛O=C contact is found to the carboxyl group of centrosymmetrically related mol­ecule.     

Synovial fluid of patients with rheumatoid arthritis induces ��-smooth muscle actin in human adipose tissue-derived mesenchymal stem cells through a TGF-��1-dependent mechanism

Rheumatoid arthritis (RA) is a chronic, inflammatory autoimmune disorder that causes the immune system to attack the joints. Transforming growth factor-β1 (TGF-β1) is a secreted protein that promotes differentiation of synovial fibroblasts to α-smooth muscle actin (α-SMA)-positive myofibroblasts to repair the damaged joints. Synovial fluid from patients with RA (RA-SF) induced expression of α-SMA in human adipose tissue-derived mesenchymal stem cells (hASCs). RA-SF-induced α-SMA expression was abrogated by immunodepletion of TGF-β1 from RA-SF with anti-TGF-β1 antibody. Furthermore, pretreatment of hASCs with the TGF-β type I receptor inhibitor SB431542 or lentiviral small hairpin RNA-mediated silencing of TGF-β type I receptor expression in hASCs blocked RA-SF-induced α-SMA expression. Small interfering RNA-mediated silencing of Smad2 or adenoviral overexpression of Smad7 (an inhibitory Smad isoform) completely inhibited RA-SF-stimulated α-SMA expression. These results suggest that TGF-β1 plays a pivotal role in RA-SF-induced differentiation of hASCs to α-SMA-positive cells.