C-N Bond Research Articles

An efficient triple cascade process for synthesis of novel disperse dyes from lawsone: A modification of natural colorant

This article describes the synthesis of novel dihydropyrimidone derivatives that have been paid attention in organic, medicinal, dyes and many other chemistry disciplines. Here we have developed an efficient triple cascade process to prepare novel disperses dyes with dihydropyrimidine-thiones scaffold. These 3, 4-dihydropyrimidin-2-(1H)-thione derivatives were prepared by simple triple cascade reaction via formal [1+2+3] cyclization among 2-hydroxy-1, 4-naphthoquinone, thiourea and various aromatic aldehyde. This process has varied substrate scope and shortened reaction duration with isolated yield up to 95% resulting in situ formation of one carbon–carbon as well as two carbon–nitrogen bonds. The structures of all the prepared molecules are confirmed with NMR, HRMS and IR spectroscopies. The color properties, UV visible spectral studies are also performed with all the prepared molecules.

An overview of the applications of chiral phosphoric acid organocatalysts in enantioselective additions to CO and CN bonds

Since 2004, chiral phosphoric acids (CPAs) have emerged as highyl efficient organocatalysts, providing excellent results in a wide reaction scope. In this review, the applications of CPA for enantioselective additions to CO and CN bonds are covered.

Recyclable and reusable ionic liquid-supported azo precursors in Mitsunobu reactions.

A new type of azo precursor, ionic liquid-supported hydrazidecarboxylate, was synthesized and applied in Mitsunobu reactions. The developed reagent is recyclable during the reaction and reusable after recovery by the ionic liquids. The ionic liquid-based azo precursor in conjugation with PhI(OAc)2 has been proved to be useful in the formation of carbon-oxygen, carbon-nitrogen, and carbon-sulfur bonds.

Decarboxylative cross-nucleophile coupling via ligand-to-metal charge transfer photoexcitation of Cu(II) carboxylates.

Reactions that enable carbon-nitrogen, carbon-oxygen and carbon-carbon bond formation lie at the heart of synthetic chemistry. However, substrate prefunctionalization is often needed to effect such transformations without forcing reaction conditions. The development of direct coupling methods for abundant feedstock chemicals is therefore highly desirable for the rapid construction of complex molecular scaffolds. Here we report a copper-mediated, net-oxidative decarboxylative coupling of carboxylic acids with diverse nucleophiles under visible-light irradiation. Preliminary mechanistic studies suggest that the relevant chromophore in this reaction is a Cu(II) carboxylate species assembled in situ. We propose that visible-light excitation to a ligand-to-metal charge transfer (LMCT) state results in a radical decarboxylation process that initiates the oxidative cross-coupling. The reaction is applicable to a wide variety of coupling partners, including complex drug molecules, suggesting that this strategy for cross-nucleophile coupling would facilitate rapid compound library synthesis for the discovery of new pharmaceutical agents.

Carbon-Nitrogen Bond Formation on Cu Electrodes During Co2 Reduction in No3- Solution

Carbon-Nitrogen Bond Formation on Cu Electrodes During Co2 Reduction in No3- Solution

Photocatalytic redox-neutral arylation of cyclopropanols with cyanoarenes via radical-mediated C–C and C–CN bond cleavage

This work describes a photocatalytic redox-neutral arylation of cyclopropanols with cyanoarenes via radical-mediated C–C and C–CN bond cleavage to afford various β-arylated ketones.

Reactions of an aluminium(I) diketiminate compound with arenes

The reactivity of an aluminium(I) diketiminate compound NacNacAl (NacNac is [ArNC(Me)CHC(Me)NAr]−, where Ar is 2,6-diisopropylphenyl) towards arenes has been systematically explored. Heating NacNacAl in benzene results in a fragmentation of the NacNac moiety due to cleavage of the CN bond, while anthracene adds to the main group carbenoid in a [4+1] fashion. Reactions with phenanthrene, triphenylene and fluoranthene demonstrate a reversible [4+1] addition process.

Accelerated and Scalable C(sp3)-H Amination via Decatungstate Photocatalysis Using a Flow Photoreactor Equipped with High-Intensity LEDs.

Carbon–nitrogen bonds are ubiquitous in biologically active compounds, prompting synthetic chemists to design various methodologies for their preparation. Arguably, the ideal synthetic approach is to be able to directly convert omnipresent C–H bonds in organic molecules, enabling even late-stage functionalization of complex organic scaffolds. While this approach has been thoroughly investigated for C(sp2)–H bonds, only few examples have been reported for the direct amination of aliphatic C(sp3)–H bonds. Herein, we report the use of a newly developed flow photoreactor equipped with high intensity chip-on-board LED technology (144 W optical power) to trigger the regioselective and scalable C(sp3)–H amination via decatungstate photocatalysis. This high-intensity reactor platform enables simultaneously fast results gathering and scalability in a single device, thus bridging the gap between academic discovery (mmol scale) and industrial production (>2 kg/day productivity). The photocatalytic transformation is amenable to the conversion of both activated and nonactivated hydrocarbons, leading to protected hydrazine products by reaction with azodicarboxylates. We further validated the robustness of our manifold by designing telescoped flow approaches for the synthesis of pyrazoles, phthalazinones and free amines.

Biodegradable films of chitosan and tea polyphenols catalyzed by laccase and their physical and antioxidant activities

The effects of laccase crosslinking chitosan (CS) and tea polyphenols (TP) on the structure, physical and antioxidant properties of CS-based biodegradable films were investigated in this study. Laccase crosslinking significantly increased the particle size and zeta-potential of CS + TP particles. A simple blending of CS and TP decreased the elongation at break significantly, while the elongation at break of biodegradable films significantly increased after laccase crosslinking. Furthermore, TP addition increased the tensile strength (TS) of CS based films, while laccase crosslinking promoted the increase, making it more suitable for application. The addition of TP significantly changed the CS-based films from white and transparent to light brown. NMR spectra showed that no CN bond was observed in CS + TP particles, which could result from the inhibition of Schiff base reaction due to the big steric hindrance of TP. Right shift of amide I peak to lower wavelength in laccase catalyzed films indicated the conversion of some primary amines into secondary amines caused by Michael addition reaction. It was proposed that laccase oxidized polyphenol to o-quinones, which reacted with nucleophilic groups of chitosan, leading to the increase of secondary amines. Furthermore, the antioxidant capacity of CS + TP films crosslinked by laccase increased significantly compared with CS and CS + TP blended films. In summary, laccase catalysis could be applied to manufacture biodegradable films with improved mechanical property and antioxidant activity.

Five-coordination aluminum complexes: Synthesis, crystal structures and utilization for the construction of substituted guanidines

Insertion of 2,6-iPr2C6H3N(Li)SiMe3 or PhN(Li)SiMe3 to the CN bond of Me2NCN or PhCN afforded the lithium complexes [Li(2,6-iPr2C6H3)NC(NMe2)NC(NMe2)N(SiMe3)]2 (1a) and [Li(PhNC(Ph)NSiMe3)]2 (1b). Complexes 1a and 1b were used as precursors to react with AlCl3 affording [(2,6-iPr2C6H3)NC(NMe2)NC(NMe2)N(SiMe3)]2AlCl (2) and [(PhNC(Ph)NSiMe3)]2AlCl (3), respectively. The structures of 2 and 3 were presented. Both 2 and 3 exhibit good activity to catalyze the addition reaction of arylamines to N,N'-diisopropylcarbodiimide.

Phosphazene base-catalyzed hydroamination of aminoalkenes for the construction of isoindoline scaffolds: Application to the total synthesis of aristocularine

A method for isoindoline synthesis via phosphazene base-catalyzed intramolecular hydroamination of aminoalkenes was developed. The reaction has a broad functional group tolerance, including for halide, cyano, and methoxy groups, and could also be used to synthesize tetrahydroisoquinoline, pyrrolidine, and piperidine. The method was used as a key step in the total synthesis of aristocularine in six steps in 35% overall yield. The strategy involved the construction of an isoindoline core through controlling the formation of the desired CN bond, with the relatively labile methoxymethyl group and arylbromide remaining intact.

Suspect screening of antimicrobial agents transformation products in environmental samples development of LC-QTrap method running in pseudo MRM transitions

The aim of the work was to develop a new HPLC-MS/MS method that allows for the simultaneous detection of antimicrobials agents (targeted analysis) and their transformation products (non-targeted analysis), which enabled the elucidation of their transformation pathways in the environment. Targeted analysis was performed for 16 selected antimicrobials agents (AMs) in wastewater collected at different stages of the treatment process and river water from sections before and after wastewater discharge. The samples were collected in the Łyna sewage treatment plant (Olsztyn, Poland) in three measuring periods at different seasons. Analytes were selected from tetracyclines, fluoroquinolones, β-lactams, macrolides, glycopeptides, lincosamides and synthetic antibiotics.As a part of the targeted analysis, 13 AMs were detected in wastewater samples, and 7 of them in river water samples. However, their presence and concentrations were closely related to the type of the sample and the season in which the sample was taken. The highest concentrations of AMs were detected in samples collected in September (max. 1643.7 ng L−1 TRI), while the lowest AMs concentrations were found in samples collected in June (max. 136.1 ng L−1 CLR). The total content of AMs in untreated wastewater was in the range of 1.42–1644 ng L−1, while in the river water was for upstream 1.22–48.73 ng L−1 and for downstream 2.24–149 ng L−1. In the non-target analysis, 33 degradation products of the selected AMs were identified, and the transformation pathways of their degradation were speculated. In the course of the research, it was found that as a result of the processes taking place in wastewater treatment plant, the parent substances are transformed into a number of stable transformation products. Transformation products resulted from hydroxylation, ring opening, oxidation, methylation or demethylation, carboxylation, or cleavage of the CN bond of the parent AMs.

Microwave Induced Green Chemistry Approach Towards the Synthesis of Heterocyclic Compounds via C-N Bond Forming Reactions

: The synthesis of heterocyclic compounds via carbon-nitrogen (C-N) bond formation reaction is considered an emerging and efficient protocol in the field of synthetic chemistry. The C– N bond-forming reactions can proceed through condensation, coupling, ring-opening, cyclization, or ring closure process, etc. The reactivity pattern of these reactions mainly depends upon the reaction conditions, as well as the type of catalysts and reacting substances that are associated with the synthesis of heterocyclic compounds containing the C-N system, including pyrazole, imidazole, pyridine, pyrimidine, thiazole, tetrazole, isoxazole, benzothiazine, and benzimidazole, etc. Further, the technique of microwave-induced synthesis becomes an alternative strategy for the sustainable production of structurally diverse organic compounds. This method provides a cleaner reaction, faster reaction rate, atom economy, and energy-efficiency. Therefore, the utilization of microwave radiation in organic synthesis becomes resource-friendly and eco-friendly proces. It follows the green chemistry approach by using safer solvents, renewable starting materials, and green catalysts. The unique feature of this method is to generate various types of bioactive or medicinal agents.

Metal-catalyzed reactions for the C(sp2)–N bond formation: achievements of recent years

The review deals with the main catalytic methods for the C(sp2)–N bond formation, including Buchwald–Hartwig palladium-catalyzed amination of aryl and heteroaryl halides, renaissance of the Ullmann chemistry, i.e., the application of catalysis by copper complexes to form the carbon–nitrogen bond, and Chan–Lam reactions of (hetero)arylboronic acids with amines. Also, oxidative amination with C–H activation, which has been booming during the last decade, is addressed. Particular attention is paid to achievements in the application of heterogenized catalysts.The bibliography includes 350 references.

SINTESIS NANOPARTIKEL PERAK (NPAg) DENGAN BIOREDUKTOR EKSTRAK BIJI JARAK PAGAR DAN KAJIAN AKTIVITAS ANTIBAKTERINYA

The redox analysis as indicated by a change in color from yellow to reddish-brown was measured at the optimum wavelength of 405 nm with the highest redox result of 480 nm obtained in the NPAg-S sample. The optimal absorption wavelength changes according to the characteristics of the NPAg produced, but is generally in the range of 400-500 nm. Analysis of the active groups with the FTIR instrument showed active groups (OH, CH aldehyde, vibrations of CN bonds in the amine group, amide I groups from proteins, and CO double bonds in the 4000-1500 cm-1) zone. Additionally, in the identification zone 1500-600 cm-1 the formation of CN bond vibrations and the presence of an amide I group from the protein was found. Photographs at 10.000 and 15.000x magnification showed that the morphology of the distribution of NPAg in the jatropha seed extract solution was polydisperse and in the form of fibrous balls with non-uniform particles and tended to agglomerate. The distribution and size of the particles measured using the Particle Size Analyzer (PSA) instrument showed that the particle size ranged from 33-116 nm. NPAg-S samples at two concentrations (1 and 2%) showed inhibitory activity for all types of Gram positive and Gram negative bacteria. Analysis of the particle size distribution using PSA showed that the particle size of the NPAg-S sample was 33.8 nm, which was smaller than the NPAg-K sample of 44.8 nm. Antibacterial activity is strongly influenced by the particle size of a sample. Small size silver nanoparticles have a large surface area to interact with bacteria as compared to large silver nanoparticles, thus they can provide a greater antibacterial effect.

Study on heterogeneous catalytic wet air oxidation process of high concentration MDEA-containing wastewater

High concentration N-methyldiethanolamine (MDEA)-containing wastewater with strong alkaline, high chemical oxygen demand (COD), and toxic organics, cannot be directly treated by biochemical process. In this paper, effect of operation parameters (temperature, reaction pressure and residence time) on removal ratio of COD and MDEA was investigated by catalytic wet air oxidation (CWAO) over commercial activated carbon (AC). The degradation pathway of MDEA in the CWAO was proposed. The results showed that the concentration of MDEA, COD, total organic carbon (TOC), and total nitrogen (TN) were 18.92, 61.2, 21.34 and 5.65 g·L−1, respectively. The contribution rate of MDEA concentration to COD in the wastewater reached up to 89.8%. The removal ratio of MDEA and COD exceeded 98% and ∼90% at temperature of 230 °C, reaction pressure of 5.0 MPa and residence time of 90 min for 168 h continuous running, respectively. The surface carboxylic acid groups of AC played a key role in the formation of hydroxyl radicals (·OH), due to the O2 was adsorbed by the carboxyl groups on the surface of AC to form ·OH, and the ·OH then attacked the CN bond of the MDEA to generate other intermediate products, and then these intermediate products was further oxidized to NH4+, CO2 and H2O. This work provides a promising pretreatment technology of high concentration MDEA-containing wastewater.

Recent Developments in Hydrodecyanation and Decyanative Functionalization Reactions

AbstractNitrile is one of the ubiquitous functional groups in natural products and polymer industry. It is often used as a versatile building block in synthetic chemistry. Classically, nitrile group is used for alpha functionalization, ortho−C−H activation and as a precursor for amine or carbonyl functionalities. With the development of various transition metal catalyzed methods, in the last two decades, nitrile group has emerged as a source of carbon synthons through C−CN bond activation despite of its high bond energy. In this review we have summarized all recent developments involving the carbon synthons arising from the cleavage of C−CN bonds. Depending on the fate of the carbon center after cleavage, all the reactions are classified in two major categories for the ease of discussion: 1) decyanation (removal of the nitrile group) and 2) decyanative functionalization (replacement of the nitrile group). Finally, current limitations in C−CN bond activation strategies and future prospects are discussed.

Comparative Studies on Thermal Decompositions of Dinitropyrazole-Based Energetic Materials.

Dinitropyrazole is an important structure for the design and synthesis of energetic materials. In this work, we reported the first comparative thermal studies of two representative dinitropyrazole-based energetic materials, 4-amino-3,5-dinitropyrazole (LLM-116) and its novel trimer derivative (LLM-226). Both the experimental and theoretical results proved the active aromatic N-H moiety would cause incredible variations in the physicochemical characteristics of the obtained energetic materials. Thermal behaviors and kinetic studies of the two related dinitropyrazole-based energetic structures showed that impressive thermal stabilization could be achieved after the trimerization, but also would result in a less concentrated heat-release process. Detailed analysis of condensed-phase systems and the gaseous products during the thermal decomposition processes, and simulation studies based on ReaxFF force field, indicated that the ring opening of LLM-116 was triggered by hydrogen transfer of the active aromatic N-H moiety. In contrast, the initial decomposition of LLM-226 was caused by the rupture of carbon-nitrogen bonds at the diazo moiety.

Design and supramolecular architecture of stepped molecular aggregation in monochloroacetate salt of 2-aminopyridine: Its bacterial and cancer inhibitory properties

A hydrogen bonded compound namely, 2-aminopyridinium monochloroacetate monochloroacetic acid (2APMCA) has been synthesized and crystallized by solvent slow evaporation process. Single crystal X-ray diffraction (SCXRD) study has been employed to determine the 3-D structure and hydrogen bonds of the compound. Protonation on the N-site of the 2-aminopyridine has been confirmed from elongated CN bond distances [1.325(5) to 1.328 (5) Å] and CN-C bond angle [122.5(4)°]. The cations and anions of adjacent units are interconnected by one bifurcated and one unbifurcated NH…O hydrogens bonds leading to ring R12(4) and R21(6) motifs. Computational quantum chemical studies such as frontier molecular orbitals (FMOs) and atomic charge distributions have been performed by using density functional theory (DFT) with the standard 6–311++G(d,p) basis set. The plot of FMOs has been found to be localized to the highest occupied molecular orbital (HOMO) region on the cation and the lowest unoccupied molecular orbital (LUMO) region has surrounded by anion. The antibacterial activity of the synthesised compound has been assessed by using the well diffusion method. In addition, molecular docking studies of the breast cancer proteins investigate to determine the binding efficiency of the title compound.

Creating triazine units to bridge carbon nitride with titania for enhanced hydrogen evolution performance

In this work, a wealth of triazine units was created in carbon nitride through a facile molten salt method to bridge titania and carbon nitride for accelerating charge transportation and enhancing hydrogen production performance. The doping of triazine ring into C3N4 framework results in more exposure of − CN − and − CN bond and forms a homojunction (MCN), which favors photocatalysis by acting as photoresponse and active centers, respectively. Moreover, the triazine units can bridge the hybridized C3N4 and TiO2, forming a stable MCN/TiO2 homo-heterojunction. Attributed to the matched band energy structure of MCN and TiO2 and the structural characteristics of triazine/heptazine heterocyclic, the light response, charge separation and transfer as well as the lifetime of carriers on MCN/TiO2 hybrid are improved significantly. As a result, the MCN/TiO2 homo-heterojunction exhibits excellent activity and stability for photocatalytic hydrogen production performance, up to 2594 μmol∙g−1∙h−1 under simulated solar irradiation, which is 5.5 times higher than that of the bare g-C3N4.