Common Reagents Research Articles

A Concise Review on the Synthesis of Pyrazole Heterocycles

Study background: Pyrazole moiety, being called as pharmacophore, plays an important role in many biologically active compounds and therefore represents an interesting template for combinatorial as well as medicinal chemistry. In addition pyrazoles are also used extensively as useful synthons in organic synthesis. These derivatives have wide spread biological activities such as anticancer, analgesic, anti-inflammatory, antimicrobial, antiviral, anticonvulsant, antihistaminic and anti-HIV. The recent success of pyrazole COX-2 inhibitor has further highlighted the importance of these heterocycles in medicinal chemistry. Methodology: The steps included condensation followed by cyclization or MCR, either in a step-wise manner or in one pot has been achieved successfully to obtain this class of heterocycles under different conditions. Phosphorus oxychloride (POCl3 ), dimethyl formamide, acetamide and hydrazine are the most common reagents used for the synthesis of pyrazole appended heterocyclic skeletons. Results: The reaction schemes resulted in the synthesis of heterocyclic appended pyrazoles in potential yields under either simple reaction conditions or microwave irradiation. Conclusion: These protocols provide convenient strategies to annelate different heterocyclic nuclei with widespread bioactive pyrazoles thereby extending the categories of heterocyclic systems. These strategies also provide valuable information for the further design of more active biological agents through various modifications and derivatizations.

CCQM-P58.1: Immunoassay Quantitation of Human Cardiac Troponin I.

The CCQM study P58.1 assessed the equivalence of immunoassay measurements between participating NMIs. The aim of P58.1 was to demonstrate the equivalence of immunoassay measurements to determine the mass concentration of the clinically-relevant protein human cardiac troponin I (cTnI) present at low concentration relative to the protein concentration of the sample matrix. The measurement equivalence was assessed using traceability to a common certified reference material. To quantify cTnI, participants used a homogeneous sandwich-based immunoassay with an enzymatic amplification step. The antibody format consisted of a single capture and single detection antibody (referred to as 1 + 1), both were supplied to study participants. In the previous P58 study, ELISA measurement results were compared between laboratories which all used common ELISA reagents (including 96-well plates), samples, a standard for the production of calibrants, and a detailed ELISA protocol, which were supplied by a single laboratory. The P58.1 study only utilized common samples, a standard of the production of calibrants, and a set of monoclonal antibodies (mAbs). Because much of the experimental procedure for the P58 study was essentially standardized across participating labs, the study primarily highlighted between-laboratory differences in plate sampling designs and in plate reader response. As the participants in the P58.1 study had to produce most of their own analytical reagents and develop their own measurement procedure, the study provides a better evaluation of the equivalence of ELISA measurements between the participating laboratories.Main text.To reach the main text of this paper, click on Final ReportThe final report has been peer-reviewed and approved for publication by CCQM.

SELECTIVE FLUORINATION METHODS OF ORGANIC MOLECULES

Presently, the world depends on a wide variety of new materials based on organofluorine compounds. These compounds can be used as surfactants, high resistance polymers, liquid crystals, agrochemicals, radiopharmaceuticals for positron emission tomography, and drugs. However, the selective formation of C–F bonds remains a challenge. This study reviews our knowledge of organofluorine compounds and describes conventional and modern selective fluorination methods for obtaining these compounds. Here, we highlight the most common fluorination reagents and describe the fluorination reactions. This review is organized by the type of fluorine transfer: nucleophilic, electrophilic, and enzymatic

Organic impurity profiling of 3,4-methylenedioxymethamphetamine (MDMA) synthesised from catechol

This work examines the organic impurity profile of 3,4-methylenedioxymethamphetamine (MDMA) that has been synthesised from catechol (1,2-dihydroxybenzene), a common chemical reagent available in industrial quantities. The synthesis of MDMA from catechol proceeded via the common MDMA precursor safrole. Methylenation of catechol yielded 1,3-benzodioxole, which was brominated and then reacted with magnesium allyl bromide to form safrole. Eight organic impurities were identified in the synthetic safrole. Safrole was then converted to 3,4-methylenedioxyphenyl-2-propanone (MDP2P) using two synthetic methods: Wacker oxidation (Route 1) and an isomerisation/peracid oxidation/acid dehydration method (Route 2). MDMA was then synthesised by reductive amination of MDP2P. Thirteen organic impurities were identified in MDMA synthesised via Route 1 and eleven organic impurities were identified in MDMA synthesised via Route 2.Overall, organic impurities in MDMA prepared from catechol indicated that synthetic safrole was used in the synthesis. The impurities also indicated which of the two synthetic routes was utilised.

Accessing Brominated Natural Product Motifs Using Phosphoramidite Catalysis

This article describes the application of a first-generation phosphoramidite catalyst to the construction of the most commonly encountered subunits of bromine-containing natural products. The process is compared with previous efforts, and is found to be complementary to existing methods. Application of the process enables bromocarbocyclisations, bromoetherifications, and bromoallene formation using the common laboratory reagent N-bromosuccinimide.

Direct Arylation of Benzo[b]furan and Other Benzo-Fused Heterocycles.

The direct arylation of benzo[b]furan, benzo[b]thiophene, and indole has been studied by using aromatic bromides as the aryl source. The protocol employing common reagents and a Pd catalyst has led to the regioselective arylation of these heterocycles at the 2-position. A range of functional groups were tolerated, providing quick access to a variety of arylated benzo-fused heterocycles that would be accessible more elaborately using classical synthetic strategies. This is the first systematic study of the direct arylation of benzo[b]furan.

Cationic lipid-mediated delivery of proteins enables efficient protein-based genome editing in vitro and in vivo.

Efficient intracellular delivery of proteins is needed to fully realize the potential of protein therapeutics. Current methods of protein delivery commonly suffer from low tolerance for serum, poor endosomal escape, and limited in vivo efficacy. Here we report that common cationic lipid nucleic acid transfection reagents can potently deliver proteins that are fused to negatively supercharged proteins, that contain natural anionic domains, or that natively bind to anionic nucleic acids. This approach mediates the potent delivery of nM concentrations of Cre recombinase, TALE- and Cas9-based transcriptional activators, and Cas9:sgRNA nuclease complexes into cultured human cells in media containing 10% serum. Delivery of Cas9:sgRNA complexes resulted in up to 80% genome modification with substantially higher specificity compared to DNA transfection. This approach also mediated efficient delivery of Cre recombinase and Cas9:sgRNA complexes into the mouse inner ear in vivo, achieving 90% Cre-mediated recombination and 20% Cas9-mediated genome modification in hair cells.

Solution Synthesis of Cu3PdN Nanocrystals as Ternary Metal Nitride Electrocatalysts for the Oxygen Reduction Reaction

The synthesis of transition metal nitride nanoparticles is challenging, in part because the unreactive nature of the most common nitrogen reagents necessitates high-temperature and/or high-pressure reaction conditions. Here we report the solution-phase synthesis and characterization of antiperovskite-type Cu3PdN nanocrystals that are multifaceted, uniform, and highly dispersible as colloidal solutions. Colloidal Cu3PdN nanocrystals were synthesized by reacting copper(II) nitrate and palladium(II) acetylacetonate in 1-octadecene with oleylamine at 240 °C. The Cu3PdN nanocrystals were evaluated as electrocatalysts for the oxygen reduction reaction (ORR) under alkaline conditions, where both Cu3N and Pd nanocrystals are known to be active. The ORR activity of the Cu3PdN nanocrystals appears to be superior to that of Cu3N and comparable to that of Pd synthesized using similar methods, but with significantly improved mass activity than Pd control samples. The Cu3PdN nanocrystals also show greater stability than comparably synthesized Pd nanocrystals during repeated cycling under alkaline conditions.

Toward complete miniaturisation of flow injection analysis systems: microfluidic enhancement of chemiluminescent detection.

Conventional flow injection systems for aquatic environmental analysis typically comprise large laboratory benchscale equipment, which place considerable constraints for portable field use. Here, we demonstrate the use of an integrated acoustically driven microfluidic mixing scheme to enhance detection of a chemiluminescent species tris(2,2'-bipyridyl)dichlororuthenium(II) hexahydrate-a common chemiluminescent reagent widely used for the analysis of a wide range of compounds such as illicit drugs, pharmaceuticals, and pesticides-such that rapid in-line quantification can be carried out with sufficient on-chip sensitivity. Specifically, we employ surface acoustic waves (SAWs) to drive intense chaotic streaming within a 100 μL chamber cast in polydimethoxylsiloxane (PDMS) atop a microfluidic chip consisting of a single crystal piezoelectric material. By optimizing the power, duration, and orientation of the SAW input, we show that the mixing intensity of the sample and reagent fed into the chamber can be increased by one to two orders of magnitude, leading to a similar enhancement in the detection sensitivity of the chemiluminescent species and thus achieving a theoretical limit of detection of 0.02 ppb (0.2 nM) of l-proline-a decade improvement over the industry gold-standard and two orders of magnitude more sensitive than that achievable with conventional systems-simply using a portable photodetector and without requiring sample preconcentration. This on-chip microfluidic mixing strategy, together with the integrated miniature photodetector and the possibility for chip-scale microfluidic actuation, then alludes to the attractive possibility of a completely miniaturized platform for portable field-use microanalytical systems.

A new dual-channel optical signal probe for Cu2+ detection based on morin and boric acid.

In this work we utilized the common analytical reagent morin to develop a new a dual-channel, cost-effective, and sensitive method for determination of Cu(2+). It is found that morin is only weakly fluorescent by itself, but forms highly fluorescent complexes with boric acid. Moreover, the fluorescence of complexes of morin with boric acid is quenched linearly by Cu(2+) in a certain concentration range. Under optimum conditions, the fluorescence quenching efficiency was linearly proportional to the concentration of cupric ions in the range of 0.5-25 μM with high sensitivity, and the detection limit for Cu(2+) was 0.38 μM. The linear range was 1-25 μM determined by spectrophotometry, and the detection limit for cupric ions was 0.8 μM. Furthermore, the mechanism of sensitive fluorescence quenching response of morin to Cu(2+) is discussed.

Ultrasensitive proteome analysis using paramagnetic bead technology.

In order to obtain a systems-level understanding of a complex biological system, detailed proteome information is essential. Despite great progress in proteomics technologies, thorough interrogation of the proteome from quantity-limited biological samples is hampered by inefficiencies during processing. To address these challenges, here we introduce a novel protocol using paramagnetic beads, termed Single-Pot Solid-Phase-enhanced Sample Preparation (SP3). SP3 provides a rapid and unbiased means of proteomic sample preparation in a single tube that facilitates ultrasensitive analysis by outperforming existing protocols in terms of efficiency, scalability, speed, throughput, and flexibility. To illustrate these benefits, characterization of 1,000 HeLa cells and single Drosophila embryos is used to establish that SP3 provides an enhanced platform for profiling proteomes derived from sub-microgram amounts of material. These data present a first view of developmental stage-specific proteome dynamics in Drosophila at a single-embryo resolution, permitting characterization of inter-individual expression variation. Together, the findings of this work position SP3 as a superior protocol that facilitates exciting new directions in multiple areas of proteomics ranging from developmental biology to clinical applications.

Effects of the oral, direct factor Xa inhibitor apixaban on routine coagulation assays and anti‐FXa assays

Apixaban is an oral direct factorXa inhibitor developed for the prophylaxis and treatment of thromboembolic disorders. Laboratory monitoring is not necessary, but the effects on common coagulation reagents and assays constitute clinically valuable information. To investigate the effects of apixaban on commonly used coagulation methods, and to evaluate anti-FXa assays for specific determination of the drug concentration. Apixaban was added to plasma from healthy subjects in the concentration range 0-1000μgL(-1) , and analyses were performed with different reagents for activated partial thromboplastin time (APTT), prothrombin time (PT), antithrombin, proteinC, and proteinS. A lupus anticoagulant assay and an APTT assay with varying phospholipid concentrations were used to study the phospholipid dependence. In general, apixaban showed fewer effects invitro than have been shown for rivaroxaban, another direct FXa inhibitor. The concentration needed to double the APTT varied between 2200 and 4700μgL(-1) , and the concentration needed to double the PT varied between 700 and 3900μgL(-1) . The effects on antithrombin, proteinC and proteinS assays were dependent on the type of reagent. Apixaban did not cause false-positive lupus anticoagulant results. Chromogenic anti-FXa assays showed linear dose-response curves with apixaban. Therapeutic concentrations of apixaban variably affect different assay groups, and even different reagents within an assay group. The effects were much smaller than with rivaroxaban. The use of APTT and/or PT assays to screen the anticoagulant activity of apixaban cannot be recommended. A chromogenic anti-FXa assay can be used for reliable measurements of apixaban concentration.

Efficacy of Common Reagents for Killing Ticks in the Ear Canal

Objectives: Determine if widely available solutions can effectively kill ticks that may be found in the human ear canal. Methods: This study was prospective, controlled, and blinded. Lone star ticks ( Amblyomma americanum), both nymphal and adult, were submerged in 1 of 4 preparations in test tubes (20/group) for 20 minutes. Ticks were agitated by intermittent probing. Activity of adult ticks was video-recorded during the exposure period. A blinded investigator viewed the videos of adult ticks and directly observed the nymphal ticks during the exposure period to determine the time until death (ie, movement cessation). Mortality was assessed immediately after exposure, and confirmed 24 and 48 hours after exposure. Results: Acetone killed ticks most rapidly (nymph mean time, 185.1 s; adult mean, 562.9 s). Isopropanol 70% (nymphs, 328.9 s; adults, 1128.4 s) and ethanol 95% (nymphs, 294.0 s; adults, 1129.4 s) took longer to kill the ticks. All ticks treated with 4% lidocaine survived. These differences were significant (nymphs, P < .0001; adults, P < .0001). Conclusions: Acetone is the most effective of the tested, commonly available solutions to kill ticks in the ear canal.

Selective Extraction of Metal Ions from Aqueous Phase to Ionic Liquids: A Novel Thermodynamic Approach to Separations

The selective extraction of metals from aqueous mixtures has generally relied on the use of selective ionophores. We present an alternative strategy that exploits a recently developed approach to extraction into an ionic liquid phase, and show that a high degree of control over selectivity can be obtained by tuning the relative concentrations of extraction agents. A thermodynamic model for the approach is presented, and an experimental separation of strontium and potassium ions is performed. It is shown that tuning the concentrations of the species involved can shift the ratio of potassium to strontium in the ionic liquid phase from 4:1 to 3:4. This extraction is performed under mild conditions with relatively common reagents. The result is a proof-of-concept for a novel separations scheme that could have great importance in a wide range of technological applications.

Kinetic Assembly of a Thermally Stable Porous Coordination Network

The advantage of porous coordination network synthesis is designability by changing metal sources and ligands.[1] Therefore, not only many commercially available ligands but also newly synthesized ones were used for networking. On the other hand, most of metal sources are common reagents or stable metal moieties because they can be more predictable as a metal connector. So far, there is no report focusing on usage of labile metal sources for selective network formation. One of the promising methods to produce unique networks with such labile metal sources is kinetic control[2] because labile metal sources produce various species in solution. In this talk, we will introduce selective syntheses of thermally stable porous coordination networks using a labile Cu4I4 cubane cluster [Cu4I4(PPh3)4] (1) and a rigid tetradentate Td-symmetry ligand tetra-(4-(4-pyridyl)phenyl)methane (2) by kinetic and thermodynamic control.[3] On heating the mixture of 1 and 2 in DMSO at 453 K, a homogenous colorless solution was obtained. Rapid cooling (~20 Kmin-1) of the solution produced yellow needle crystals, {[(CuI)2(2)]·solvent}n (3a) that shows novel CuI helical chain unit, in 99% yield (Fig. A). On the other hand, slow cooling (~3 Kmin-1) produced orange block crystals, {[(Cu2I2)(2)]·solvent}n (3b) that shows rhombic Cu2I2 dimer unit, in 95% yield. Both the network crystals can keep the crystallinity up to 673 K under N2 atmosphere. In kinetic product 3a, due to the unique structure, iodides of the CuI chains facing to 1D channel, the network crystal shows chemisorption of I2 by making a covalent bond with an iodide of part of the CuI chains to form an I3– group (Fig. B). On the other hand, in thermodynamic product 3b, Cu2I2 dimer units are hindered by bridging ligand 2. That is why network crystal 3b shows only physisorption of I2, even though network has 1D channel similar to 3a.

Resolving acetylated and phosphorylated proteins by neutral urea Triton-polyacrylamide gel electrophoresis: NUT-PAGE.

Protein acetylation and phosphorylation are key modifications that regulate both normal and pathological protein functions. The gel systems currently used for analyzing modified proteins require either expensive reagents or time-consuming second dimension electrophoresis. Here we present a neutral pH gel system that allows the analysis of acetylated and phosphorylated proteins. The neutral pH urea Triton-polyacrylamide gel electrophoresis (NUT-PAGE) system separates proteins based on their charge at pH 7.0 and generates discrete bands from each acetylated and/or phosphorylated species. In addition, the gel is composed of common and inexpensive laboratory reagents and requires only a single dimension of electrophoresis. We demonstrate the effectiveness of this system by analyzing the phosphorylated species of an acidic protein, α-synuclein, and both acetylated and phosphorylated species of a basic protein, histone H3. NUT-PAGE thus provides a cost-effective alternative for resolving acetylated and phosphorylated proteins, and potentially proteins with other post-translational modifications that alter net charge.

An Alternative Approach for Preparing and Standardizing Some Common Aqueous Reagents Used in an Undergraduate Laboratory

A guide for instructors and laboratory assistants to prepare some common aqueous reagents used in an undergraduate laboratory is presented. Dilute reagents consisting of H+(aq), I3–(aq), Ce4+(aq), and Ag+(aq) were prepared by electrolytic oxidation of respective precursors. Electrolysis was promptly stopped when potassium hydrogen phthalate (KHP) was completely neutralized by OH–(aq) resulting from an electrolytic reduction of water in the cathode compartment. The neutralization of KHP was monitored by a visual color change of an indicator. The amount of reagent produced in the anode compartment was directly determined from the mass of KHP added to the cathode compartment. The concentrations of reagents determined from the mass of KHP and from an independent volumetric titration were in agreement. The electrolysis cell, powered by an 18 V dc power supply, eliminated the requirement of a coulometer. Setup of an electrolysis cell and experimental details for preparing reagents are presented.

Nivulian-II a new milk clotting cysteine protease of Euphorbia nivulia latex

Nivulian-II, new milk clotting cysteine protease has been purified from the latex of Euphorbia nivulia Buch.-Ham. Nivulian-II is a monomeric protein with an apparent molecular mass 43670.846Da. It presents its optimum activity at pH 6.3 and temperature of 50°C. The enzyme was strongly inhibited by common thiol-blocking reagents thereby indicating that it belongs to cysteine protease family. Nivulian-II is a type of glycoprotein and its pI is 3.4. The N-terminal amino acid sequence of Nivulian-II is DFPPNTCCCICC. This sequence showed relatively low homology with several other proteases of Euphorbian plants, suggesting that the isolated enzyme is a new cysteine protease.

Single source precursor-based solvothermal synthesis of heteroatom-doped graphene and its energy storage and conversion applications.

Solvothermal processes are considered efficient approaches for the gram-scale production of graphene. Further modification of graphene by chemical doping is an important approach to tailor its properties. In this work, we successfully synthesized sulfur-doped graphene by using a solvothermal method with dimethyl sulfoxide as a precursor, which is a common laboratory reagent. Nitrogen-doped graphene was produced to demonstrate the generality of this process. These heteroatom-doped graphene materials exhibited high surface areas and high contents of heteroatoms. Furthermore, the lithium-ion storage properties and oxygen reduction reaction catalytic activity of these materials were also investigated. The success of this approach might facilitate the development of other advanced graphene-based materials with relative simplicity, scalability, and cost effectiveness for use in various potential applications.

A new and efficient synthetic method for the herbicide carfentrazone-ethyl based on the Heck reaction

The herbicide carfentrazone-ethyl (1) was prepared by a new and improved synthetic method. The common and inexpensive reagent ethyl acrylate was employed to replace commercially unavailable ethyl 3-hydroxy-2-methylenebutanoate, which was used in the synthetic route reported previously. Starting from iodination of 1-(4-chloro-2-fluorophenyl)-4-difluoromethyl-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazole (2), an intermediate 1-(4-chloro-2-fluoro-5-iodophenyl)-4-difluoromethyl-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazole (3) was afforded in an excellent yield. Then, an intermediate ethyl 3-[2-chloro-5-(4-difluoromethyl-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl)-4-fluorophenyl]-2-propenoate (4) was synthesized by Heck coupling of 3 with ethyl acrylate. Next, oxidative addition–elimination of 4 with OXONE®/HCl-Et3N in one pot produced ethyl 2-chloro-3-[2-chloro-5-(4-difluoromethyl-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl)-4-fluorophenyl]-2-propenoate (5). Finally, the target product 1 was obtained via reduction of 5 by H2. This new synthetic method exhibits the advantages of mild conditions, atom economy, low-cost, and efficiency.