Iodine-catalyzed ultrasound-assisted construction of pyridines and their glutamine synthetase molecular docking

Iodine-promoted facile protocol is designed for the production of pyridines at room temperature under ultrasound irradiation. Eleven pyridine derivatives in excellent yields (91–97%) are synthesized with 2 hr reaction time. Additional advantage of the proposed ultrasound-assisted eco-friendly, cost-effective protocol is easy separation of product, and our in silico studies show good binding affinity toward binding and made strong hydrogen interactions.     

Cascade reaction involving intramolecular oxygen-migration:Efficient synthesis of 3-allylidene-indolin-2-one compounds under metal-free conditions

An efficient synthesis of 3-(diarylallylidene)oxindoles from 3-(1 H-indol-3-yl)-1,1-diarylpropan-1-ol under metal-free conditions is described.NBS serves as a critical medium leading to a facile oxygenmigration in the transformation.The protocol has advantages of high efficiency,simple opreation,mild reaction conditions,good atom-economy,wide substrate scope and good yields of products.A detailed mechanism is proposed after careful investigation.     

Domino Reaction for the Synthesis of Highly Functionalized Triazatricyclo[6.2.2.01,6]dodecane

A simple and highly efficient protocol has been developed for the synthesis of triazatricyclo[6.2.2.0^1,6]dodecane-9,12-dione (TATCD) derivatives. Use of metal hydroxide catalyst in the presence of protic solvent plays a key role in these reaction transformations. Mechanistic studies specify that the proposed mechanism proceeds only via aldol reaction, condensation, cyclization, and dehydration to form the desired product. This current protocol provides several advantages such as use of a readily available precursor, consumption of less energy, short reaction time, moderate to good yields, and convenient workup.     

Use of gel permeation chromatography for automatic and rapid extract clean-up for the determination of diarrhetic shellfish toxins (DSP) by liquid chromatography-mass spectrometry

Summary A new analytical technique was established to improve the performance of DSP toxin determination in different sample matrices. High performance size exclusion chromatography (gel permeation chromatography, SEC) was applied for the clean-up of raw extracts from algal cells and mussel tissue prior to the determination of DSP toxins by LC/MS. The proposed protocol can be performed totally automatically and enables fast and sensitive analysis of large sample numbers. The recovery of the entire method protocol (consisting of extraction, clean-up and LC/MS determination) was approximately 70% with good repeatability (standard deviation ranging from 1.9% to 5.0% in the concentration range analyzed).     

Inexpensive and nonconventional fabrication of microfluidic devices in PMMA based on a soft-embossing protocol

This study describes an inexpensive and nonconventional soft-embossing protocol to produce microfluidic devices in poly(methyl methacrylate) (PMMA). The desirable microfluidic structure was photo-patterned in a poly(vinyl acetate) (PVAc) film deposited on glass substrate to produce a low-relief master. Then, this template was used to generate a high-relief pattern in stiffened PDMS by increasing of curing agent /monomer ratio (1:5) followed by thermal aging in a laboratory oven (200°C for 24 h). The stiffened PDMS masters were used to replicate microfluidic devices in PMMA based on soft embossing at 220–230°C and thermal sealing at 140°C. Both embossing and sealing stages were performed by using binder clips. The proposed protocol has ensured the replication of microfluidic devices in PMMA with great fidelity (>94%). Examples of MCE devices, droplet generator devices and spot test array were successfully demonstrated. For testing MCE devices, a mixture containing inorganic cations was selected as model and the achieved analytical performance did not reveal significant difference from commercial PMMA devices. Water droplets were successfully generated in an oil phase at rate of ca. 60 droplets/min (fixing the continuous phase flow rate at 100 μL/h) with size of ca. 322 ± 6 μm. Glucose colorimetric assay was performed on spot test devices and good detectability level (5 μmol/L) was achieved. The obtained results for two artificial serum samples revealed good agreement with the certified concentrations. Based on the fabrication simplicity and great analytical performance, the proposed soft-embossing protocol may emerge as promising approach for manufacturing PMMA devices.     

ZnO Nanoparticles as an Efficient,Heterogeneous, Reusable,and Ecofriendly Catalyst for One-Pot,Three-Component Synthesis of 3,4-Dihydropyrimidin-2(1H)-(thio)one Derivatives in Water

An extremely efficient heterogeneous protocol is reported for the one-pot, three-component synthesis of a series of dihydropyrimidinones (DHPMs) in the presence of ZnO nanoparticles in water as a green solvent. The ZnO nanoparticles exhibited excellent catalytic activity and the proposed methodology is capable of providing the desired products in good yields (65–94%) within short reaction times. After the reaction course, ZnO nanoparticles can be recycled and reused without any apparent loss of activity, which makes this ecofriendly process cost-effective.     

Iron-catalyzed deoxygenation and 2-sulfonylation of quinoline N-oxides by sodium sulfinates towards 2-sulfonyl quinolines

An iron(III)-catalyzed protocol towards 2-sulfonyl quinolines from quinoline N-oxides and sodium sulfinates was herein illustrated. The general and direct option featured for high efficiency (up to 91% yields) and good functional compatibilities (27 examples) in the Fe(III)-catalysis. Moreover, free radical mechanism was proposed for the one-pot deoxygenation and sulfonylation reaction based on the results of the control reactions.     

Base-promoted O-deprotonation/alkylation reaction of P(O)–OH compounds with alkyl halides

A novel base-promoted O-deprotonation/alkylation reaction of P(O)–OH compounds with alkyl halides has been developed. The protocol is practical, representing a simple way to produce a broad spectrum of functionalized phosphinates, phosphonates, and phosphates from basic starting materials with good to excellent yields. A plausible mechanism was proposed for this reaction.     

Nonadiabatic Absorption Spectra and Ultrafast Dynamics of DNA and RNA Photoexcited Nucleobases

We have recently proposed a protocol for Quantum Dynamics (QD) calculations, which is based on a parameterisation of Linear Vibronic Coupling (LVC) Hamiltonians with Time Dependent (TD) Density Functional Theory (TD-DFT), and exploits the latest developments in multiconfigurational TD-Hartree methods for an effective wave packet propagation. In this contribution we explore the potentialities of this approach to compute nonadiabatic vibronic spectra and ultrafast dynamics, by applying it to the five nucleobases present in DNA and RNA. For all of them we computed the absorption spectra and the dynamics of ultrafast internal conversion (100 fs timescale), fully coupling the first 2–3 bright states and all the close by dark states, for a total of 6–9 states, and including all the normal coordinates. We adopted two different functionals, CAM-B3LYP and PBE0, and tested the effect of the basis set. Computed spectra are in good agreement with the available experimental data, remarkably improving over pure electronic computations, but also with respect to vibronic spectra obtained neglecting inter-state couplings. Our QD simulations indicate an effective population transfer from the lowest energy bright excited states to the close-lying dark excited states for uracil, thymine and adenine. Dynamics from higher-energy states show an ultrafast depopulation toward the more stable ones. The proposed protocol is sufficiently general and automatic to promise to become useful for widespread applications.     

Novel deoxygenation reaction of epoxides by indium

[reaction: see text] A novel, mild, ecofriendly protocol for the deoxygenation of epoxides to alkenes using indium metal and indium(I) chloride or ammonium chloride in alcohol has been developed. It was necessary for the presence of good radical-stabilizing groups adjacent to the oxirane ring for the deoxygenation reaction to occur. It is proposed that this reaction occurs through an SET process with indium as an electron donor.     

Substrate-promoted ligand-free CuI catalyzed S-arylation of 2-mercaptobenzothiazoles with aryl iodides in water

A green and efficient method has been developed for the cross-coupling of 2-mercaptobenzothiazoles with aryl iodides in water. The reactions proceeded smoothly under ligand-free conditions in the presence of TBAB to give the corresponding products in good yields. The protocol showed good tolerance toward a variety of functional groups. A substrate-promoted mechanism for this catalytic reaction has been proposed.     

Protocol for high-resolution electrophoresis separation of myosin heavy chain isoforms in bovine skeletal muscle

In this short communication we describe a specific protocol for SDS-PAGE separation of adult bovine myosin heavy-chain (MyHC) isoforms. The conditions defined in this protocol allow a good separation with a good reproducibility of the four MyHC isoforms (MyHC I, IIa, IIx, IIb) identified in adult skeletal muscle of this species. This procedure uses mini-gel electrophoresis system and does not involve preparation of gradient separating gels. In addition, this protocol can also be applied to the electrophoretic separation of ovine and camel MyHC isoforms.     

Tris(4-anisyl)phosphine as an Efficient and Practical Reagent for the Synthesis of (E)-2-Benzylidenesuccinates

Condensation of maleic anhydride or dimethyl maleate with benzylaldehydes controlled by tris(4‐anisyl)‐phosphine to synthesize dimethyl (E)‐2‐benzylidenesuccinates has been systematically investigated. The protocol gives the product with high stereoselectivity in moderate to good yields under mild conditions. A plausible mechanism has been proposed.     

Simple,rapid and sensitive method for the determination of mefenamic acid in pharmaceutical preparations

Two simple and fast automated methods for the direct determination of mefenamic acid (MEF) in pharmaceutical samples are described. Continuous flow and stopped-flow systems with spectrophotometric detection of mefenamic acid with sodium nitroprusside and hydroxylamine hydrochloride were developed. Both methods show a good reproducibility (RSD < 1.5 and 1.8%, respectively) and a wide range of linearity (between 10–500 and 3–300 μg/mL). The stopped-flow protocol has a lower detection limit (1.2 μg/mL) with a sensitivity of about two times greater than the continuous flow technique. The proposed procedures are rapid, reliable and can be applied successfully to the estimation of mefenamic acid in different commercial forms.     

S(N)Ar-based, facile synthesis of a library of benzothiaoxazepine-1,1'-dioxides

The construction of a library of benzothiaoxazepine-1,1'-dioxides utilizing a one-pot, S(N)Ar diversification-ODCT(50) scavenging protocol is reported. This protocol combines microwave irradiation to facilitate the reaction, in conjunction with a soluble ROMP-derived scavenger (ODCT) to afford the desired products in good overall purity. Utilizing this protocol, a 78-member library was successfully synthesized and submitted for biological evaluation.     

A Solvent‐Based Strategy for Tuning the Internal Structure of Metallo‐Folded Single‐Chain Nanoparticles

Controlling the spatial distribution of catalytic sites in metallo‐folded single‐chain nanoparticles (SCNPs) is a first step toward the rational design of improved catalytic soft nano‐objects. Here an unexplored pathway is reported for tuning the internal structure of metallo‐folded SCNPs. Unlike the conventional SCNP synthesis in good solvent (protocol I), the proposed new route (protocol II) is based on the use of amphiphilic random copolymers and transfer, after SCNP formation, from selective to good (nonselective) solvent conditions. The size and morphology of the SCNPs obtained by the two protocols, and the corresponding spatial distribution of the catalytic sites, have been determined by combining results from size exclusion chromatography with triple detection, small‐angle X‐ray scattering and molecular dynamics (MD) simulations. Remarkably, the use of these protocols allows the tuning of the internal structure of the metallo‐folded SCNPs, as supported by MD simulations results. While the conventional protocol I yields a homogeneous distribution of the catalytic sites in the SCNP, these are arranged into clusters in the case of protocol II.

     

Performance tests and internal quality control activities for the routine analytical use of composite electrodes

The use of a solid electrode in routine analytical work is proposed as a good alternative for electroanalytical detection. The performance of the electrode for oxidative voltammetry was studied for the model compound, catechol. Some theoretical aspects of the preparation and features of the PVC-graphite composite electrode are shown. A protocol has been described for its construction and general advice for the appropriate use. Quality control activities were designed to check the performance of the electrode. Received: 7 October 2000 Accepted: 19 July 2001     

Combined protocol for the analysis of polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBx) from sediments using focussed microwave assisted (FMW) extraction at atmospheric pressure

A microwave-assisted protocol has been developed using focussed microwaves at atmospheric pressure for the extraction of PAHs and PCBs from sediments. It combines extraction and purification assisted by microwaves. This protocol has been applied to the quantification of 12 individual PAHs, 8 individual PCBs and 8 PCB coeluted mixtures from two Standard Reference Materials and one natural sediment. The results for both classes of compounds (PAHs and PCBs) are good in terms of recoveries, which are always greater than 70% and in most cases around 100%. The reproducibility is also good with coefficients of variation below 10% in most cases. This protocol has the great advantage of saving time, the time dedicated to the preparation / extraction assisted by microwaves being reduced to less than half an hour.     

Combined protocol for the analysis of polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs) from sediments using focussed microwave assisted (FMW) extraction at atmospheric pressure

A microwave-assisted protocol has been developed using focussed microwaves at atmospheric pressure for the extraction of PAHs and PCBs from sediments. It combines extraction and purification assisted by microwaves. This protocol has been applied to the quantification of 12 individual PAHs, 8 individual PCBs and 8 PCB coeluted mixtures from two Standard Reference Materials and one natural sediment. The results for both classes of compounds (PAHs and PCBs) are good in terms of recoveries, which are always greater than 70% and in most cases around 100%. The reproducibility is also good with coefficients of variation below 10% in most cases. This protocol has the great advantage of saving time, the time dedicated to the preparation / extraction assisted by microwaves being reduced to less than half an hour.     

Access to thiomorpholin-3-one derivatives: [3 + 3]-cycloadditions of α-chlorohydroxamates and 1,4-dithiane-2,5-diol

A protocol of [3 + 3]-cycloaddition was proposed for the synthesis of 2H-1,4-thiazin-3(4H)-ones and thiomorpholine-3,5-diones from α-chlorohydroxamates and 1,4-dithiane-2,5-diol. This direct and practical method provides a novel and rapid approach for the synthesis of thiomorpholin-3-one derivatives under mild condition with moderate to good yield and wide functional group tolerance.