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Although radical ion chain pathways have long been recognized in the field of synthetic organic chemistry and are expected to be operative in various reactions, it is somewhat complicated to verify their involvement, since counting the number of electrons is not straightforward. Herein, a series of bis‐styrenes is designed and synthesized to investigate electron transfer events by using radical cation [4+2] cycloadditions as probes. It is demonstrated that the intramolecular single electron transfer seems to be ineffective, while the intermolecular variants are highly effective. Therefore, a truly catalytic amount of electricity is enough for full conversions, confirming that chain pathways were definitely involved. [ABSTRACT FROM AUTHOR]

Mitochondria is an important drug target for ailments ranging from neoplastic to neurodegenerative diseases and metabolic diseases. Here, we describe the synthesis of chloroquine analogs and show the results of mitochondrial ATP inhibition testing. The 2,4-dinitrobenzene-based analogs showed concentration-dependent mitochondrial (mito.) ATP inhibition. The most potent mito. ATP inhibitor was found to be N-(4-((2,4-Dinitrophenyl)amino)pentyl)-N-ethylacetamide (17). [ABSTRACT FROM AUTHOR]

The use of Ru(II) catalysts, which are less expensive than the established Rh2(OAc)4, for the synthesis of enaminones via coupling of α-diazocarbonyl compounds with thioamides is described. [ABSTRACT FROM AUTHOR]

The petrophysical characterization of tight gas sands can be affected by clay minerals, gas adsorption, microfractures, and the presence of high-density minerals. In this study, we conducted various petrophysical, petrographic, and high-resolution image analyses on Saudi Arabian tight sand in order to understand how a complex pore system responds to measurement tools. About 140 plug samples extracted from six wells were subjected to routine core analyses including cleaning, drying, and porosity–permeability measurements. The porosity–permeability data was used to identify hydraulic flow units (HFU). In order to probe the factors contributing to the heterogeneity of this tight sand, 12 subsamples representing the different HFUs were selected for petrographic study and high-resolution image analysis using SEM, quantitative evaluation of minerals by scanning electron microscope (QEMSCAN), and micro-computed tomography (µCT). Nuclear magnetic resonance (NMR) and electrical resistivity measurements were also conducted on 56 subsamples representing various lithofacies. NMR porosity showed good agreement with other porosity measurements. The agreement was remarkable in specific lithofacies with porosity ranging from 0.1% to 7%. Above this range, significant scatters were seen between the porosity methods. QEMSCAN results revealed that samples with <7% porosity contain a higher proportion of clay than those with porosity >7%, which are either microfractured or contain partially dissolved labile minerals. The NMR T2 profiles also showed that samples with porosity <7% are dominated by micropores while samples with porosity >7% are dominated by macropores. Analysis of the µCT images revealed that pore throat sizes may be responsible for the poor correlation between NMR porosity and other porosity methods. NMR permeability values estimated using the Shlumberger Doll Research (SDR) method are fairly correlated with helium permeability (with an R2 of 0.6). Electrical resistivity measurements showed that the different rock types fall on the same slope of the formation factors versus porosity, with a cementation factor of 1.5. [ABSTRACT FROM AUTHOR]

Catalytic performance of two magnetically recoverable copper(I) complexes is reported for the synthesis of 1,2,3-triazole derivatives. Boronic acids and alkyl halides, in the presence of either catalyst, react with terminal alkynes and NaN3, forming 1,2,3-triazole derivatives in good yields. Both catalysts are easily recoverable and show a high potential of reusability. [ABSTRACT FROM AUTHOR]

Information acquisition and fluid characterization of oil reservoirs are one of the most challenging and scientifically demanding areas in the oil exploration industry. Herein, we report a single-step solvothermal method for the synthesis of highly-stable hydrophilic and hydrophobic superparamagnetic iron oxide nanoparticles (SPIONs). The functionalization of SPIONs was achieved using polyethylene glycol (PEG-400) and oleylamine (OLA) for water/oil phases of the reservoir, respectively. For comparison, uncoated SPIONs were also prepared by coprecipitation. Stability of hydrophilic SPIONs was monitored in deionized (DI) water and artificial seawater (ASW), while stability of hydrophobic SPIONs was investigated in model oil (cyclohexane-hexadecane 1:1). Several physicochemical techniques were utilized to characterize the phase and functionalization of SPIONs. Transmission electron microscopy (TEM) images display the spherical shape nanoparticles (NPs) having particle diameters 11.6 ± 1.4, 12.7 ± 2.2, and 9.1 ± 3.0 nm for PEG-Fe 3 O 4 , OLA-Fe 3 O 4 , and Fe 3 O 4 , respectively. Spin-spin (T 2 ) relaxation measurements were performed by an Acorn Area analyzer to demonstrate contrasting ability of the contrast agents. The transverse relaxivity (r 2 ) values for PEG-Fe 3 O 4 (66.7 mM −1  s −1 ) and OLA-Fe 3 O 4 (49.0 mM −1  s −1 ) were 2.07 and 1.53 times higher than Fe 3 O 4 (32.2 mM −1  s −1 ) NPs, respectively. The (i) enhanced NMR T 2 -relaxation with optimum SPIONs concentration, (ii) excellent relaxivity properties due to their ultra-small size, and (iii) long-term stability in various continuous phases, suggest them to be promising T 2 -contrast agents for oil reservoir applications. [ABSTRACT FROM AUTHOR]

The synthesis of a copper(I)-complexed magnetic nanoparticle catalyst is described. The catalyst was characterized using Fourier transform infrared spectroscopy (FT–IR), energy-dispersive X-ray spectroscopy (XPS), atomic absrobtion spectroscopy (AA), thermogravimetric analysis (TGA), vibrating sample magnetometery (VSM), X-ray photoelectron spectroscopy (XPS), scanning electron miscroscopy (SEM) and transmission electron microscopy (TEM). The catalyst coupled thioamides and diazocarbonyl compounds to produce diverse enaminones. The catalyst reduced the reaction times and temperature and provided enaminones in high yields and selectivity. Moreover, the catalyst can be separated by a magnet and recycled. [ABSTRACT FROM AUTHOR]

The development of operationally simple and cost-effective methods for C C bond formation reactions are highly important in pharmaceutical, agrochemical and material research. In this article we describe the first copper-catalyzed cross-coupling reaction of thioamides with acceptor/acceptor-substituted and acceptor-only substituted α-diazocarbonyl compounds to yield enaminones. The reaction shows broad substrate scope in terms of thioamides and diazocarbonyl compounds. Primary, secondary and tertiary thioamides all give enanminones when reacted with α-diazodiesters, α-diazoketoesters, α-diazodiketones, α-diazoketoamides, α-diazoesteramides, α-diazoketosulfones and α-diazomonoketones. [ABSTRACT FROM AUTHOR]

Enaminones can be prepared via the Rh2(OAc)4-catalyzed coupling of α-diazocarbonyl compounds with thioamides. However, rhodium is the most expensive and least abundant among the dominant precious metals used for catalysis. Furthermore, a very limited substrate scope is known for the intermolecular rhodium catalyzed coupling reaction. Therefore, there is a need to find a more economical catalyst substitute with a broad substrate scope. In this paper, we describe the use of Ru(II) catalysts for the synthesis of enaminones. The reaction can be performed efficiently with the Grubbs first-generation catalyst or [(Ph)3P]3RuCl2 in a sealed tube. Both catalysts are much less expensive than Rh2(OAc)4. Secondary and tertiary thioamides, when reacted with α-diazodiesters, α-diazoketoesters, α-diazodiketones, and α-diazomonoketones give enaminones. Primary thioamides give thiazole derivatives when reacted with α-diazomonoketones. However, with other diazo compounds, primary thioamides also give enaminones. All enaminones are obtained in good yields and with good diastereoselectivity. Accordingly, the method described in this paper is an efficient and economical alternative to the Rh2(OAc)4-catalyzed coupling process. [ABSTRACT FROM AUTHOR]

The main aim of this study is to constrain the range of reservoir properties observed in various depositional environments of the fine-grained sandstones of the early Silurian middle Qusaiba Member, Qalibah Formation, northwestern Saudi Arabia. Facies analysis, micro-X-ray fluorescence (μXRF), lamina-scale permeability measurements, automated helium porosity-permeability measurement, and pore system visualization were integrated to observe variations in these various environments. Seven main facies were recognized and interpreted to be deposited in an offshore "turbiditic-influenced" to lower shoreface paleoenvironments. These facies include current rippled siltstone (F1); Contorted silty sandstone (F2); current rippled fine-grained sandstone (F3); planar-laminated fine-grained sandstone (F4); Bioturbated to current-rippled argillaceous siltstone to silty sandstone (F5); Current rippled silty sandstone (F6); bioturbated sandstone (F7) facies. These facies were clustered into several fabric classes; 1) contorted fabrics associated with load casts flame structure that is characteristic of F2: These typically revealed slightly higher porosity and permeability values than the surrounding media with a spherical and relatively low anisotropy. 2) Planar-laminated fabrics in F4 that overlain by cryptic bioturbation: It comprises of clay mineral-rich laminae with higher porosity and permeability and the quartz-rich laminae with lower porosity and permeability probably due to abundant calcite cement associated with detrital quartz. Higher anisotropy, associated with this fabric, was observed. Cryptic bitourbated interval showed relatively low permeability. 3) In F7, three types of rock fabrics were observed, (1) Vertical sand-filled Piscichnus trace fossil: The burrow fill shows significantly higher porosity and permeability values than the laminated matrix; this fabric reveals an elliptical and highly anisotropic variance map. (2) Horizontal sand-filled Thalassinoides burrow (with iron oxide cement).: The internal core of this fabric was highly porous and permeable compared to the laminated fabric. Thalassinoides fabric had the most elliptical and highest anisotropic variance map in F7. (3) Entirely laminated fabric with bed-parallel gypsum veins: The permeability of the veins was slightly higher than that of the matrix, this resulted in a less anisotropic variance map. μCT scanning was used for F5 and F6; In the F5 facies, more significant porosity associated with quartz-rich lamina than iron oxide (e.g., siderite) and gypsum-rich lamina were observed probably due to higher chlorite alignment in the iron oxide-rich lamina. We found lower porosity and permeability within the vertical mud-filled burrows (Piscichnus) than the laminated fabric; this was also observed in the 3D pore system imaged by μCT scanning. These findings could have significant implications for different fabric types in fluid flow conduits in argillaceous sandstone and siltstone systems. • Effect of small-scale fabrics on permeability was examined in fine-grained sediments. • Lamination and deformation are the main factors controlling μm to mm-scale permeability of turbiditic deposits. • Bioturbation has an impact on permeability of lower shoreface sediments. [ABSTRACT FROM AUTHOR]

The total synthesis of two decahydroquinoline poison frog alkaloids ent-cis-195A and cis-211A were achieved in 16 steps (38% overall yield) and 19 steps (31% overall yield), respectively, starting from known compound 1. Both alkaloids were synthesized from the common key intermediate 11 in a divergent fashion, and the absolute stereochemistry of natural cis-211A was determined to be 2R, 4aR, 5R, 6S, and 8aS. Interestingly, the absolute configuration of the parent decahydroquinoline nuclei of cis-211A was the mirror image of that of cis-195A, although both alkaloids were isolated from the same poison frog species, Oophaga (Dendrobates) pumilio, from Panama. [ABSTRACT FROM AUTHOR]

Smoking-cessation drugs bind many off-target nicotinic acetylcholine receptors (nAChRs) and cause severe side effects if they are based on nicotine. New drugs that bind only those receptors, such as α 6 β 2* nAChR, implicated in nicotine addiction would avoid the off-target binding. Indolizidine (-)-237D (IND (-)-237D), a bicyclic alkaloid, has been shown to block α 6 β 2* containing nAChRs and functionally inhibit the nicotine-evoked dopamine release. To improve the affinity of indolizidine (-)-237D for α 6 β 2*, we built a library of 2226 analogs. We screened virtually the library against a homology model of α 6 β 2 nAChR that we derived from the recent crystal structure of α 4 β 2 nAChR. We also screened the crystal structure of α 4 β 2 nAChR as a control on specificity. We ranked the compounds based on their predicted free energy of binding. We selected the top eight compounds bound in their best pose and subjected the complexes to 100 ns molecular dynamics simulations to assess the stability of the complexes. All eight analogs formed stable complexes for the duration of the simulations. The results from this work highlight nine distinct analogs of IND (-)-237D with high affinity towards α 6 β 2* nAChR. These leads can be synthesized and tested in in vitro and in vivo studies as lead candidates for drugs to treat nicotine addiction. [ABSTRACT FROM AUTHOR]