Simple Reagents Research Articles

Highly diastereoselective preparation of chiral NHC-boranes stereogenic at the boron atom.

Stereogenic main group elements are clearly generating interest in the enantioselective catalysis field. Surprisingly, while chiral organoboron reagents are very useful in stereoselective transformations, few scaffolds stereogenic at boron and configurationally stable have been reported to date. Herein, we describe an original library of chiral NHC-boranes, stereogenic at the boron atom, that has been prepared in only a few steps and in good yields (up to 93%). Key steps involve a chlorination/arylation sequence in the presence of simple Grignard reagents from bicyclic NHC-boranes. The high and unprecedented diastereoselectivity observed during the second step (up to 99 : 1 dr) has been rationalized through a plausible SRN1 mechanism thanks to EPR observations and DFT calculations.

Conductometric Determination of Sulfur Dioxide in Wine Using a Multipumping System Coupled to a Gas-Diffusion cell

A conductometric system with a multipumping module and a gas-diffusion cell has been developed to determine free and total sulfur dioxide (SO2) in wine. The developed method has two protocols to determine both types of SO2 using the same system. For free SO2, sulfite is converted to H2SO4 by acidification and diffusion with H2O2 in an acceptor channel. The sample was previously hydrolyzed by mixing the sample with NaOH and heated at 70 °C prior making the determination of total SO2 in order to break the bonds of the combined SO2. Free and total SO2 were determined in the ranges of 2.5–25.4 and 10.2–76.2 mg L−1 with a sample throughput of 13 and 12 h−1, respectively. The calibration curves of free and total SO2 were in the range of ΔG (mS cm−1) = (–1.0242 ± 0.2871) + (0.6613 ± 0.0201) [SO2, mg L−1], r2 of 0.997 and ΔG (mS cm−1) = (–0.5850 ± 0.1678) + (0.1236 ± 0.0033) [SO2, mg L−1], r2 of 0.997. The proposed automated method is simple and easy to apply for the determination of SO2 in wine using simple reagents.

Silica-supported ceric ammonium nitrate (CAN): a simple, mild and solid-supported reagent for quickest oxidative aromatization of Hantzsch 1,4-dihydropyridines

An efficient and environmentally benign methodology for the oxidative aromatization of 1,4-dihydropyridines to their corresponding pyridine derivatives is developed. The oxidative aromatization of 1,4-dihydropyridines was explored using silica-supported ceric ammonium nitrate as catalyst in CH3CN with or without sonication at room temperature. This supported catalyst acts as a more efficient oxidising reagent and offers several advantages over other reported reagents in terms of reaction time and yields. The supported reagent is found to be more efficient and selective when compared with its unsupported form. The Belousov–Zhabotinskii reaction was not observed in present reaction. The dealkylation observed in case of 4-n-alkyl/n-alkenyl with other oxidising agents is also not observed in the present case.

Automated detection of anomalies in cervix cells using image analysis and machine learning

Usage machine-based learning image cytometry to establish the diagnosis of cervix cancer using cellular morphology classification in comparison to the conventional cytological test. The study was divided into two phases consisting of 15 samples of cervix cells. In phase1, with previous diagnosis, the samples were divided into three groups of five samples each: normal (NC), low-grade squamous intraepithelial lesion (LGSIL or LSIL), and high-grade squamous intraepithelial lesion (HGSIL or HSIL). Images of cells were analyzed to create a training set of cells with known diagnosis for machine learning purposes. With the numerical data created, the software was trained to automatically classify the three types of cells. In phase 2, 885 cells were classified without previous diagnosis. In a last step, the classification of CPA was compared to cytopathology. NC and HSIL were identified with a high sensitivity and specificity (99%, 99%) and (98%, 97%) respectively. While the sensitivity and specificity of LSIL cells were lower (78%, 79%). It is possible to extract features of cervical cells by automatically generating numerical data that allowed the program to identify and classify different cell classes, using simple and low-cost reagents and free, reproducible softwires.

Urolithin B as a Simple, Selective, Fluorescent Probe for Sensing Iron(III) in Semi-Aqueous Solution.

The development of simple, environmental friendly, and cheap reagents with metal binding properties are quite important not only for the treatment of environmental pollution but also for their application in medicine. Within this study, for the first time, we displayed a natural chromen analogue, Urolithin B, as a simple, selective, fluorescent iron (III) sensing probe. Following the synthesis and structure identification studies, the selective metal binding property of the compound was displayed employing fluorescence techniques. Accordingly, urolithin B has the capacity to coordinate selectively to iron (III) with a 3:2 stoichiometry.

Two classes of heterocycles—6,8‐dioxabicyclo[3.2.1]octanes and cyclopentenols from the same reagents: A quantum‐chemical comparison of mechanism

AbstractMost of the strategies for the synthesis of 6,8‐dioxabicyclo[3.2.1]octanes (BCO) and cyclopentenols (CP), which show high biological and pharmaceutical activity, are multistage and/or require hardly accessible starting materials and catalysts. The general method for BCO and CP preparation in a single preparative stage from two simple reagents, ketones and acetylene, under the action of an available super‐basic catalytic system KOH/DMSO becomes promising for the development of general approaches to the design of these classes of biologically active compounds. The mechanism of competing reactions yielding both 7‐methylene‐6.8‐dioxabicyclo[3.2.1]‐octanes and functionalized cyclopentenoles from their common intermediate 1,5‐diketones and acetylene in the KOH/DMSO superbasic media is investigated using the B2PLYP/6‐311++G**//B3LYP/6‐31+G* calculations with particular attention to the diastereoselectivity aspects of individual stages.

Hydrogen Sulfide: A Reagent for pH-Driven Bioinspired 1,2-Diol Mono-deoxygenation and Carbonyl Reduction in Water.

Hydrogen sulfide (H2S) was evaluated for its peculiar sulfur radical species generated at different pHs and was used under photolytical conditions in aqueous medium for the reduction of 1,2-diols to alcohols. The conversion steps of 1,2-cyclopentanediol to cyclopentanol via cyclopentanone were analyzed, and it was proven that the reaction proceeds via a dual catalytic/radical chainmechanism. This approach was successfully adapted to the reduction of a variety of carbonyl compounds using H2S at pH 9 in water. This work opens up the field of environmental friendly synthetic processes using the pH-driven modulation of reactivity of this simple reagent in water.

ANALISIS KUALITATIF DAN KUANTITATIF CEMARAN LOGAM BERAT TIMBAL (Pb) DAN KADMIUM (Cd) PADA PRODUK KOSMETIK PENSIL ALIS MENGGUNAKANSPEKTROFOTOMETER SERAPAN ATOM (SSA)

The aim of this study was to identify and determine the heavy metal content of lead (Pb) and cadmium (Cd) towards eyebrow pencil registered and not registered by the Food and Drug Supervisory Agency (BPOM). This research was conducted in several markets in Surabaya. Twelve eyebrow pencil items were investigated for lead (Pb)and cadmium (Cd). Simple reagents, included HCl, NaOH, KI, Na2S2O3 and NH4OH were used to identify the presence of these heavy metal first. The study results showed that samples of eyebrow pencil registered and unregistered by BPOM RI after being tested turned out to contain lead and cadmium in a range of 1.092-5,834 mg/kg and 0,054-0.243 mg/kg, respectively. The content is still within what is required based on the regulations of BPOM RI, < 20 mg/kg for lead content and < 5 mg/kg for cadmium content. In short, all the sample of eyebrow pencil contained lead (Pb) and cadmium(Cd)within what is required based on the regulations of BPOM RI.

Convenient new synthesis of umeclidinium bromide

ABSTRACTUmeclidinium bromide, a drug used for chronic obstructive pulmonary disease, is synthesized through a new intermediate of phenyl(quinuclidin-4-yl)methanone. This novel method with simple operation flow and cheap reagents, makes it suitable for scale up. The overall four-step process provides umeclidinium bromide in 29% yield and the purity up to 99.83%. The X-ray crystal structure of the drug molecule was first reported.

An oxygen plasma treated poly(dimethylsiloxane) bioscaffold coated with polydopamine for stem cell therapy.

In this study, 3D macroporous bioscaffolds were developed from poly(dimethylsiloxane) (PDMS) which is inert, biocompatible, non-biodegradable, retrievable and easily manufactured at low cost. PDMS bioscaffolds were synthesized using a solvent casting and particulate leaching (SCPL) technique and exhibited a macroporous interconnected architecture with 86 ± 3% porosity and 300 ± 100 µm pore size. As PDMS intrinsically has a hydrophobic surface, mainly due to the existence of methyl groups, its surface was modified by oxygen plasma treatment which, in turn, enabled us to apply a novel polydopamine coating onto the surface of the bioscaffold. The addition of a polydopamine coating to bioscaffolds was confirmed using composition analysis. Characterization of oxygen plasma treated-PDMS bioscaffolds coated with polydopamine (polydopamine coated-PDMS bioscaffolds) showed the presence of hydroxyl and secondary amines on their surface which resulted in a significant decrease in water contact angle when compared to uncoated-PDMS bioscaffolds (35 ± 3%, P < 0.05). Seeding adipose tissue-derived mesenchymal stem cells (AD-MSCs) into polydopamine coated-PDMS bioscaffolds resulted in cells demonstrating a 70 ± 6% increase in viability and 40 ± 5% increase in proliferation when compared to AD-MSCs seeded into uncoated-PDMS bioscaffolds (P < 0.05). In summary, this two-step method of oxygen plasma treatment followed by polydopamine coating improves the biocompatibility of PDMS bioscaffolds and only requires the use of simple reagents and mild reaction conditions. Hence, our novel polydopamine coated-PDMS bioscaffolds can represent an efficient and low-cost bioscaffold platform to support MSC therapies.

Remote radical halogenation of aminoquinolines with aqueous hydrogen halide (HX) and oxone

Simple and halide-atom economical HX reagents (X = Cl, Br and I) were applied to the remote CH bond halogenation reaction of 8-aminoquinoline amides. This strategy features a broad substrate scope and good functional group tolerance. A series of C5-halogenated 8-aminoquinolines were obtained in moderate to good yields under mild conditions.

Synthesis, Structure, and Biological Activity of 2,6-Disubstituted 2,3a,4a,6,7a,8a-Hexaazaperhydrocyclopenta[def]fluorene-4-thioxo­-8-ones

A two-step one-pot condensation for the synthesis of previously inaccessible 2,6-disubstituted 2,3a,4a,6,7a,8a-hexaazaperhydrocyclopenta[def]fluorene-4-thioxo-8-ones from simple reagents [5-thioxohexahydroimidazo[4,5-d]imidazol-2(1H)-one, paraformaldehyde and amines] was developed. The structure, antimicrobial, and anticancer activity of a number of synthesized compounds were studied.

Oxidized Carbon Black: Preparation, Characterization and Application in Antibody Delivery across Cell Membrane

Modulating biomolecular networks in cells with peptides and proteins has become a promising therapeutic strategy and effective biological tools. A simple and effective reagent that can bring functional proteins into cells can increase efficacy and allow more investigations. Here we show that the relatively non-toxic and non-immunogenic oxidized carbon black particles (OCBs) prepared from commercially available carbon black can deliver a 300 kDa protein directly into cells, without an involvement of a cellular endocytosis. Experiments with cell-sized liposomes indicate that OCBs directly interact with phospholipids and induce membrane leakages. Delivery of human monoclonal antibodies (HuMAbs, 150 kDa) with specific affinity towards dengue viruses (DENV) into DENV-infected Vero cells by OCBs results in HuMAbs distribution all over cells’ interior and effective viral neutralization. An ability of OCBs to deliver big functional/therapeutic proteins into cells should open doors for more protein drug investigations and new levels of antibody therapies and biological studies.

Access to 3-Prenylated Oxindoles by α-Regioselective Prenylation: Application to the Synthesis of (±)-Debromoflustramine E.

The development of a rapid, highly efficient, and one-pot synthesis of C3-α-prenylated oxindoles with simple reagents is described. The process is based on zinc-mediated α-regioselective prenylation of 3-acylidene-oxindole with commercially available prenyl bromide using inexpensive CeCl3 as the catalyst. The new transformation tolerates a wide range of 3-acylidene-oxindoles, providing easy access to a variety of functionalized 3-prenylated oxindoles. The synthetic utility of the approach is verified by formal synthesis of the flustramine family alkaloid (±)-debromoflustramine E.

Metal-free C(sp2)-H functionalization of azoles: K2CO3/I2-mediated oxidation, imination, and amination.

The direct C2-H oxidation and imination of a wide variety of azoles was achieved by using a commercially available simple K2CO3/I2 reagent combination. The iodinated azole adduct, produced via the in situ generation of N-heterocyclic carbene, is the key intermediate for C2-H oxidation, imination, and amination of azoles. Significantly, these reactions proceed under mild conditions with high to excellent yields, are scalable to large quantity and exhibit a broad substrate scope. Interestingly, this direct C2-H imination method allowed us to access various pharmacologically active N6-alkyl or N6-aryl substituted benzimidazoquinazolinone scaffolds through intramolecular C-H imination in a sequential one-pot reaction.

Multinuclear iron-phenyl species in reactions of simple iron salts with PhMgBr: identification of Fe4(μ-Ph)6(THF)4 as a key reactive species for cross-coupling catalysis.

The first direct syntheses, structural characterizations, and reactivity studies of iron-phenyl species formed upon reaction of Fe(acac)3 and PhMgBr in THF are presented. Reaction of Fe(acac)3 with 4 equiv. PhMgBr in THF leads to the formation of [FePh2(μ-Ph)]2 2- at -80 °C, which can be stabilized through the addition of N-methylpyrrolidone. Alternatively, at -30 °C this reaction leads to the formation of the tetranuclear iron-phenyl cluster, Fe4(μ-Ph)6(THF)4. Further synthetic studies demonstrate that analogous tetranuclear iron clusters can be formed with both 4-F-PhMgBr and p-tolylMgBr, illustrating the generality of this structural motif for reactions of simple ferric salts and aryl Grignard reagents in THF. Additional studies isolate and define key iron species involved in the synthetic pathway leading to the formation of the tetranuclear iron-aryl species. While reaction studies demonstrate that [FePh2(μ-Ph)]2 2- is unreactive towards electrophile, Fe4(μ-Ph)6(THF)4 is found to rapidly react with bromocyclohexane to selectively form phenylcyclohexane. Based on this reactivity, a new catalytic reaction protocol has been developed that enables efficient cross-couplings using Fe4(μ-Ph)6(THF)4, circumventing the current need for additives such as TMEDA or supporting ligands to achieve effective cross-coupling of PhMgBr and a secondary alkyl halide.

A new scalable synthesis of entecavir

A new synthesis of entecavir from d-glucose in an average total yield of 3.5% was achieved via an intramolecular nitrile oxide cycloaddition (INOC) reaction and a Peterson olefination as key-steps. The present process was designed for industrial application, using widely available raw materials, simple and cheap reagents and avoiding low reaction temperatures, which are very common in the synthetic approaches towards similarly complex structures.

Rapid reagent-less on-line H2O2 quantification in alkaline semiconductor etching solution, Part 2: Nephelometry application

A simple and rapid reagent less nephelometric method for on-line H2O2 quantification in semiconductors etching solutions was developed, optimized, characterized and validated. The intensity of the light scattered by the oxygen gas suspension resulted from H2O2 catalytic decomposition by immobilized MnO2 was registered as analytical response. The influences of the light wave length, the agitation rate, the temperature and the catalyst surface area on the response amplitude were studied and optimization was done. The achieved linear concentration range from 10 to 150mmolL−1 at 0.9835 calibration curve correlation coefficient, precision from 3.65% to 0.95% and response time from 35 to 20s respectively, at sensitivity of 8.01µAmmol−1 L and LOD of 2.9mmolL −1 completely satisfy the semiconductor industry requirements.

Spectrophotometric and theoretical studies on the determination of etilefrine hydrochloride in pharmaceutical formulations and biological samples

Purpose: To develop a simple and cost effective spectrophotometric method for the determination of etilefrine hydrochloride (ET) in pharmaceutical formulations and human plasma.Methods: The method is based on extraction of ET into chloroform as ion-pair complexes with bromocresol green (BCG) and methyl orange (MO) in acidic medium. The interaction of ET with BCG and MO reagents were investigated using B3LYP/6-31G(d) level of theory. The geometrical parameters of the interacting species and the ion pairs formed were characterized based on their frontier molecular orbitals, atomic charges, electrostatic potential map, as well as NBO analysis.Results: The colored species exhibited absorption maxima at 410 and 479 nm for the two systems in universal buffer of pH range (3.0 - 3.5), with molar absorptivity of 2.4 × 104 and 1.7 × 104 Lmol-1cm-1, for BCG and MO methods, respectively. The methods demonstrated good linearity with correlation coefficient ranging from 0.9987 – 0.9991 in the concentration ranges 0.5 – 16 and 2.0 – 18 μgmL-1 for BCG and MO methods, respectively. The composition ratio of the ion-association complexes was 1:1 in all cases as established by Job’s method. Sandell,s sensitivity, correlation coefficient, detection and quantification limits were also calculated. Molecular descriptors were obtained based on optimized structures of the molecules under investigation, by applying the B3LYP/6-31G(d) method, and used to interpret the mode of interaction between these molecules to form the investigated ion pairs.Conclusion: The proposed methods make use of simple reagents, which a basic analytical laboratory can afford. No interference was observed from common pharmaceutical excipients and additives. ETMO ion pair has a larger interaction energy (higher stability) than ET-BCG ion pair as inferred from their interaction energies.Keywords: Density functional theory, Etilefrine hydrochloride, Ion pair complex, Spectrophotometry, Bromocresol green, Methyl orange, Geometric analysis

Maternal urogenital schistosomiasis; monitoring disease morbidity by simple reagent strips.

BackgroundUrine analysis is one of the recommended antenatal guidelines for early diagnosis of pregnancy-associated complications. While in practice, urine analysis by dipstick had been used to provide useful information on other urinary tract infections, its applications for early detection of urogenital schistosomiasis in pregnant women is often times not given due attention in most endemic areas. Our study therefore assessed the performance of some common urinalysis parameters in the diagnosis of maternal urogenital schistosomiasis in endemic rural communities of Nigeria.Methodology/Principal findingsThe cross-sectional epidemiologic survey of urogenital schistosomiasis was conducted among pregnant women in Yewa North Local Government, Ogun State, Nigeria. The women were microscopically examined for infection with Schistosoma haematobium, visually observed for macrohematuria, and screened for microhematuria and proteinuria using standard urine chemical reagent strips. Of 261 volunteered participants, 19.9% tested positive for S. haematobium infection. The proportion of microhematuria (23.8%) was significantly higher than that of macrohematuria (3.8%) and proteinuria (16.8%) (P<0.05). Microhematuria with sensitivity (82.7%) and specificity (89.0%) was the best diagnostic indicator of urogenital schistosomiasis. Macrohematuria with the least sensitivity (11.8%) was however the most specific (98.1%) for diagnosing urogenital schistosomiasis in pregnant women. Maximum microhematuria sensitivity (100.0%) was observed in women between 15–19 years but sensitivity was consistently low in older age groups. Maximum sensitivity, specificity and predictive values (100.0%) were recorded for microhematuria in first trimester women. Diagnostic efficiency of proteinuria and macrohematuria was also better in the first trimester women except the 25.0% specificity recorded for proteinuria. The overall diagnostic performance of microhematuria and proteinuria was better in secundigravidae.Conclusions/SignificanceMicrohematuria can be used for early detection of urogenital schistosomiasis in endemic areas especially in younger women. However because microhematuria is a condition that occurs during pregnancy and in several other diseases, it is necessary to compliment the diagnosis with other diagnostic tools such as microscopy and serology. Treatment with praziquantel is recommended for the women in their late trimesters after follow up test in order to avert associated adverse pregnancy outcomes.