Secondary Aromatic Amines Research Articles

In Situ Reversible and Robust Mechano-Responsive Ultralong Phosphorescence of Polyurethane Elastomer.

Though mechano-responsive luminescent materials obtained much attention, most of their responses are non-reversible, let alone in situ reversible. Here, the study presents a new strategy to push through this limitation for their applications, which relies on the reversible mechano-responsive (MR) hydrogen bonding interactions and polymer chain orientation among a doped polyurethane (PU) elastomer. The radiative and nonradiative transitions inside these phosphorescent triphenylene-based aromatic secondary amines (TpNP and TpNPO) doped in the PU matrix can be accordingly modulated by these MR variations, including the PU chains orientation and the interactions between emitters and PU, respectively. Surprisingly, the intensities, quantum yields, and even lifetimes of their ultralong phosphorescence correlate well with the stress of PU, showing triple mechano-enhancement with a small threshold value of 7.9MPa. Importantly, these in situ and rapidly reversible MR phosphorescences possess excellent repeatability, which is still displayed even after >500 cycles of loading/unloading. Based on such a robust and highly sensitive MR afterglow, these PU materials have been demonstrated applications with no interruption of background in several fields, including micro-crack detection, material damage prediction, limb movement monitoring, and information encryption. This work provides new insights for developing innovative ultralong phosphorescence materials with improved luminescence and reversible mechano-responsive behavior.

Preparation of chitosan-based macromolecular antioxidant with high-efficiency free radical scavenging ability to improve the antioxidative properties of styrene-butadiene rubber/silica composites

To address the disadvantages of traditional rubber antioxidants with low molecular weight such as easy migration, poor extraction resistance, low thermal stability and antioxidant efficiency, in this work, we first prepared an antioxidant containing primary and secondary antioxidant groups (MC-MPA) through thiol-ene click reaction between N-(4-aminophenyl)maleimide (MC) and 3-mercaptopropionic acid (MPA). Then, we synthesized a chitosan-based macromolecular antioxidant with long-chain alkene, aromatic secondary amine, and thioether groups (COS-UC-MC-MPA) by sequentially grafting functional compounds 10-undecanonyl chloride (UC) and antioxidant MC-MPA onto natural macromolecular polymer chitosan (COS). The free radical scavenging ability of COS-UC-MC-MPA was assessed by using 2,2-Diphenyl-1-picrylhydrazyl (DPPH), and the results demonstrated that COS-OC-MC-MPA has high scavenging rate of 76.5 % for DPPH free radicals after 1 min of contact with DPPH dimethyl sulfoxide solution, showing excellent free radical scavenging ability. In addition, the results of accelerated thermo-oxidative aging test, thermogravimetric (TG) test, kinetic analysis of thermal-oxidative degradation, extraction resistance test, and volatilization resistance test indicated that COS-UC-MC-MPA with superior migration resistance and volatilization resistance could effectively enhance the antioxidative properties, thermal stability and thermal-oxidative stability of rubber composites. Moreover, the results of rubber processibility analysis (RPA) test and scanning electron microscopy (SEM) implied that the addition of COS-UC-MC-MPA is also conductive to improving the dispersibility of silica in rubber matrix. This study supplies a new perspective for the preparation of environmentally friendly and highly efficient macromolecular antioxidants for rubber composites.

Ultraviolet absorbents and industrial antioxidants in seabirds, mammals, and fish from the Canadian Arctic

Ultraviolet (UV) absorbents and industrial antioxidants are two groups of plastic-derived contaminants of emerging environmental concern. However, their distribution and fate are poorly understood in Arctic wildlife. In the present study, 16 UV absorbents (10 benzotriazole UV stabilizers (BZT-UVs) and 6 organic UV filters (UVFs)) and 7 industrial antioxidants (6 aromatic secondary amines (Ar-SAs) and 2,6-di-tert-butylphenol (26DTBP)) were analyzed in the livers of thick-billed murre (Uria lomvia; n = 28), northern fulmar (Fulmarus glacialis; n = 4), black guillemot (Cepphus grylle; n = 11), polar bear (Ursus maritimus; n = 18), beluga whale (Delphinapterus leucas; n = 10), landlocked (n = 25) and sea-run (n = 10) Arctic char (Salvelinus alpinus) from the Canadian Arctic collected between 2017 and 2021. Compared to industrial antioxidants (median range: ΣAr-SAs: not calculated due to detection frequency < 30 % (NA)-4.06 ng/g, wet weight (ww); 26DTBP: NA-1.91 ng/g ww), UV absorbents (median range: ΣBZT-UVs: NA-8.71 ng/g ww; ΣUVFs: NA-48.3 ng/g ww) generally showed greater concentrations in the liver of these species. Seabirds accumulated higher levels of these contaminants (median range: ΣBZT-UVs: 3.38–8.71 ng/g ww; ΣUVFs: NA-48.3 ng/g ww; ΣAr-SAs: 0.07–4.06 ng/g ww; 26DTBP: NA-1.14 ng/g ww)) than the other groups (median range: ΣBZT-UVs: NA-1.31 ng/g ww; ΣUVFs: NA-4.22 ng/g ww; ΣAr-SAs: NA; 26DTBP: NA-1.91 ng/g ww), suggesting that seabirds may be useful indicator species for future long-term monitoring. The livers of Arctic char in the Canadian Arctic generally contain lower levels of these contaminants than those of freshwater fish in temperate regions. Spatial variations were found in the liver of black guillemots, Hudson Bay polar bears, and landlocked char for some target contaminants, indicating differences in the levels of these contaminants in their surrounding environment or diet. Consumption of liver tissues from these species may expose humans to varying levels of UV absorbents and industrial antioxidants. This study establishes a baseline for future research of the spatial and temporal trends of these contaminants in Arctic species. It provides the basis for elucidating the fate of these contaminants and assessing their adverse effects at environmental-relevant concentrations in the Arctic. Factors influencing the accumulation patterns of these contaminants in Arctic biota and their potential health risks require further investigation.

Exploring Catalytic Intermediates in Pd-Catalyzed Aerobic Oxidative Amination of 1,3-Dienes: Multiple Metal Interactions of the Palladium Nanoclusters.

Metal nanoclusters (NCs) have unique properties because of their small size, which makes them useful as catalysts in reactions like cross-coupling. Pd-catalyzed oxidative amination, which involves dehydrogenative C-N bond formation, uses Pd complexes as the active species. It is known that the catalytic conditions involve the formation of Pd(0) species from Pd NCs, but the precise role of Pd NCs in the transformations has not been established. In this study, we investigated the characteristic properties of Pd NCs in oxidative amination of 1,3-dienes. The reaction achieved direct amination of commercially accessible 1,3-dienes with secondary aromatic amines, providing a variety of nitrogen containing 1,3-dienes. The compound was applicable to radical polymerization to provide the nitrogen-fabricated 1,3-diene-based polymer, which exhibited a different thermal stability compared to aliphatic nitrogen-fabricated diene polymers. In addition to the synthetic utility, by combining X-ray absorption fine structure and small-angle X-ray scattering analysis, we revealed amines and 1,3-dienes affected metal leaching from the Pd nanoparticles and stabilization of Pd NCs in the catalytic reaction. Additionally, DFT calculation suggested that the catalytic intermediate contained multiple adjacent Pd atoms and was responsible for formation of an σ-allylic intermediate that is difficult to form with the use of Pd complexes. These results could be used to understand the underlying phenomenon in the oxidative coupling reaction and develop Pd NCs-based dehydrogenation.

Iron(II)-Catalyzed 1,2-Diamination of Styrenes Installing a Terminal NH2 Group Alongside Unprotected Amines.

1,2-Diamination of alkenes represents an attractive way to generate differentiated vicinal diamines, which are prevalent motifs in biologically active compounds and catalysts. However, existing methods are usually limited in scope and produce diamines where one or both nitrogens are protected, adding synthetic steps for deprotection and further N-functionalization to reach a desired target. Furthermore, the range of amino groups that can be introduced at the internal position is fairly limited. Here we describe a 1,2-diamination of styrenes that directly installs a free amino group at the terminal position and a wide variety of unprotected nitrogen nucleophiles (primary or secondary alkyl or aromatic amines, sulfoximines, N-heterocycles, and ammonia surrogate) at the internal position. Two complementary sets of conditions encompass electronically activated and deactivated styrenes with diverse substitution patterns and functional groups. Moreover, this strategy can be extended to the 1,2-aminothiolation of styrenes.

Iron(II)‐Catalyzed 1,2‐Diamination of Styrenes Installing a Terminal NH2 Group Alongside Unprotected Amines

1,2‐Diamination of alkenes represents an attractive way to generate differentiated vicinal diamines, which are prevalent motifs in biologically active compounds and catalysts. However, existing methods are usually limited in scope and produce diamines where one or both nitrogens are protected, adding synthetic steps for deprotection and further N‐functionalization to reach a desired target. Furthermore, the range of amino groups that can be introduced at the internal position is fairly limited. Here we describe a 1,2‐diamination of styrenes that directly installs a free amino group at the terminal position and a wide variety of unprotected nitrogen nucleophiles (primary or secondary alkyl or aromatic amines, sulfoximines, N‐heterocycles, and ammonia surrogate) at the internal position. Two complementary sets of conditions encompass electronically activated and deactivated styrenes with diverse substitution patterns and functional groups. Moreover, this strategy can be extended to the 1,2‐aminothiolation of styrenes.

Preparation of chitosan‐based macromolecular synergistic antioxidants containing hindered phenolic and secondary amine structures and its effects on thermo‐oxidative aging of styrene‐butadiene rubber/silica composites

AbstractIn this study, chitosan (CS)‐based macromolecular synergistic antioxidant CS‐UC‐TDAA containing carbon–carbon double bond, hindered phenol, and aromatic secondary amine was prepared by using CS,10‐undecenoyl chloride (UC), p‐aminobenzoic acid (AA), 3,5‐di‐tert‐butyl‐2‐hydroxybenzaldehyde (TD) via esterification, Schiff base reaction, and acylation reaction. The molecular structure of CS‐UC‐TDAA was characterized by fourier transform infrared, 1H NMR, and elemental analysis. The effects of macromolecular synergistic antioxidant CS‐UC‐TDAA, small molecular antioxidant TDAA, commercial antioxidant 4020, and butylated hydroxytoluene (BHT) on the antiaging properties of styrene‐butadiene rubber (SBR)/SiO2 composites were systematically studied by accelerated thermo‐oxidative aging test, thermogravimetric (TG) analysis, and methanol Soxhlet extraction experiment. The experimental results show that CS‐UC‐TDAA has more outstanding thermo‐oxidative aging resistance, thermal stability, and solvent extraction resistance in SBR/SiO2 composites than TDAA, 4020, and BHT. The macromolecular synergistic antioxidant CS‐UC‐TDAA endows SBR/SiO2 composites with more durable antiaging performance, which is attributed to the synergistic antioxidant effect of its hindered phenol and aromatic secondary amine groups. Additionally, its resistance to migration and extraction is facilitated by the crosslinking of the carbon–carbon double bond with the rubber and its substantial molecular weight.

Selected Electrosynthesis of 3-Aminopyrazoles from α,β-Alkynic Hydrazones and Secondary Amines.

An available and simple electromediated cyclization method for 3-amino-substituted pyrazoles by using α,β-alkynic hydrazone and secondary amine is described. The strategy utilizes KI as an electrolyte in an undivided cell with a constant current, generating the desired products in moderate-to-good yield. The method features selective amination at the 3-position of the pyrazole skeleton. The results indicate that α,β-alkynic hydrazones functionalized with aromatic groups and secondary amines functionalized with electron-rich groups were better tolerated in this transformation.

Microbiota and other detrimental metabolites in colorectal cancer.

Increasing scientific evidence demonstrates that gut microbiota plays an essential role in the onset and development of Colorectal cancer (CRC). However, the mechanisms by which these microorganisms contribute to cancer development are complex and far from completely clarified. Specifically, the impact of gut microbiota-derived metabolites on CRC is undeniable, exerting both protective and detrimental effects. This paper examines the effects and mechanisms by which important bacterial metabolites exert detrimental effects associated with increased risk of CRC. Metabolites considered include heterocyclic amines and polycyclic aromatic hydrocarbons, heme iron, secondary bile acids, ethanol, and aromatic amines. It is necessary to delve deeper into the mechanisms of action of these metabolites in CRC and identify the microbiota members involved in their production. Furthermore, since diet is the main factor capable of modifying the intestinal microbiota, conducting studies that include detailed descriptions of dietary interventions is crucial. All this knowledge is essential for developing precision nutrition strategies to optimise a protective intestinal microbiota against CRC.

Exploring the reductive CO2 fixation with amines and hydrosilanes using readily available Cu(II) NHC-phenolate catalyst precursors.

N-Methylation of amines is of great interest in the synthesis of pharmaceuticals and valuable compounds, and the possibility to perform this reaction with an inexpensive and non-toxic substrate like CO2 and its derivatives is quite appealing. Herein, the synthesis of four novel homoleptic Cu(II) complexes with hybrid NHC-phenolate (NHC = N-Heterocyclic Carbene) ligands is reported, and their use in the catalytic N-methylation of amines with CO2 in the presence of hydrosilanes is explored. Both bidentate or tetradentate ligands can be used in the preparation of the complexes provided that the structural requirement that the two NHC and the two phenolate donors in the metal coordination sphere are mutually in trans is fulfilled. A new reaction protocol to perform the N-methylation of secondary aromatic amines and dibenzylamine in high yield under mild reaction conditions is developed, using the ionic liquid [BMMIM][NTf2] (1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide) as solvent and the catalyst precursor [Cu(L2)2]. Reactivity studies indicate that the reaction follows two different pathways with different hydrosilanes, and that the starting Cu(II) complexes are reduced under the catalytic conditions.

Molecular Docking, Synthesis and Antimicrobial Evaluation of 4-[(3 hydroxybenzalidene)amino]antipyrine and its Copper Complex

The synthesis and characterization of Schiff base-containing transition metal complexes have gained increasing importance due to their catalytic roles in various reactions and their biological activities. These metal complexes have become crucial in drug design, leading to a growing interest in metal-based drugs. The study aimed to synthesize copper metal complex with a new Schiff base ligand 4-[(3-hydroxybenzalidene)amino]antipyrine derived from 4-aminoantipyrine and 3-hydroxybenzaldehyde, as well as evaluate their antimicrobial activity against gram positive and gram-negative bacterial strains. The ligand and its copper complex were assessed for antimicrobial activity against gram-positive and gram-negative strains utilizing disc diffusion and broth dilution methods. Spectroscopic techniques (UV-Vis, FT-IR, XRD, and EDXRF), solubility tests, and elemental analysis were employed to investigate the ligand and copper complex. The ligand displayed high insolubility in various solvents but had limited solubility in chloroform and methyl chloride. The FTIR spectrum of the Schiff base reveals the presence of aromatic hydrocarbons, imine (C=N), hydroxyl (-OH), secondary amine (C-N), carbonyl (C=O), and vibrations associated with C-O and C-C bonds, reflecting its molecular structure. In the EDXRF analysis, a prominent peak at 7.80 keV corresponding to copper was detected, indicating that copper is the most abundant element found in the ligand. XRD analysis demonstrated distinct crystal structures for both the ligand and its copper complex. The UV-Vis spectra of the ligand exhibited an absorption peak at a UV lambda max of 220 nm, indicating a π→π* transition. In contrast, the absorption peaks observed in the copper complex indicated different transitions compared to the Schiff base. The MIC results indicated the copper complex's stronger antimicrobial activity than the Schiff base against tested bacteria. Molecular docking studies showed that the interaction energies of the synthesized compounds, particularly the ligand and copper complex, surpassed that of the well-known anti-diabetic drug, metformin.

Synthesis of macromolecular antioxidants containing thioether and aromatic secondary amine to improve the anti-oxidation properties of EPDM

A macromolecular antioxidant PM containing thioether and aromatic secondary amine was synthesized by the thiol-ene click reaction between the antioxidant N-(4-aminophenyl)maleimide (MC) and pentaerythritol tetra(3-mercapto propionate) (PETPM). Then, the curing properties and anti-oxidation properties of PM in EPDM were investigated. The results showed that PM reduced the negative effect of the coexisted of PETPM and MC (PETPM+MC) on rubber curing and improved the crosslinking density of the rubber. PM also exhibited high anti-volatility and anti-migration properties due to its high molecular mass. Moreover, the aromatic secondary amine group in PM was able to capture aging radicals and inhibit the occurrence of oxidation reactions, while the thioether group effectively decomposed hydroperoxides and inhibited the occurrence of autocatalytic oxidation reactions. The combination of these two groups improved the anti-oxidation properties of EPDM. As a result, PM/EPDM demonstrated the lowest crosslinking density change rate and carbonyl index, as well as the largest aging coefficient K when compared to the EPDM containing low molecular weight antioxidants (PETPM/EPDM, MC/EPDM, MC+PETPM/EPDM).

Pyridine–SO3H]ZnCl3: A Multipurpose Catalyst for A3 Coupling Synthesis of Propargylamines under Mild Conditions

Abstract N-Sulfopyridin-1-ium monozinc(II) trichloride ([NSPy]ZnCl3) was prepared and used as a multipurpose catalyst for the synthesis of propargylamines by the A3 coupling reaction of aromatic aldehydes, alkynes, and secondary amines under mild conditions. In this reaction, the carbonyl group in the aldehyde was activated by the acidic part in the catalyst, and the C–H activation of phenylacetylene was carried out by zinc.

A novel nanomagnetic palladium (II) complex of bisimidazolium-based N[sbnd]heterocyclic carbene; An efficient heterogeneous catalyst for A3 coupling reactions

Herein, a novel nanomagnetic NHC-Palladium complex was successfully prepared applying post-synthetic modification (PSM) condensation between Fe3O4-support imidazole and a synthetic bisamide moiety, carrying the alkyl halide functionalities at the end of its chain, followed by chelation of Pd ions to generate the corresponding complex. The [Fe3O4@bisimidazolium-Pd]2Cl− complex gave the best catalytic performance in synthesizing propargylamines through A3 coupling of various substituted aromatic and cycloaliphatic aldehydes and secondary amines with aromatic and liner alkynes in PEG-400. Primary amines are inefficient to produce unknown byproducts; whereas, secondary amines react quickly. Significantly, alkynes having a high electron density reduce the conversion rate. Moreover, aromatic and aliphatic aldehydes are active, but the electron-drawing substituent on benzaldehyde decreases the rate of conversion. Furthermore, the [Fe3O4@bisimidazolium-Pd]2Cl− catalyst can be reused seven times without metal leaching or losing its ability, which shows how stable it is when used in a reaction.

In silico screening, synthesis, and antimalarial evaluation of PABA substituted 1,3,5-triazine derivatives as Pf-DHFR inhibitors

ObjectivesDrug resistance in malaria parasites necessitates the development of new antimalarial drugs with unique mechanisms of action. In the present research work, the PABA conjugated 1,3,5-triazine derivatives were designed as an antimalarial agent. MethodsIn this present work, a library of two hundred-seven compounds was prepared in twelve different series such as [4A (1-23), 4B(1-22), 4C(1-21), 4D(1-20), 4E(1-19), 4F(1-18), 4G(1-17), 4H(1-16), 4I(1-15), 4J(1-13), 4K(1-12) and 4L(1-11) ] respectively using different primary and secondary aliphatic and aromatic amines. Ten compounds were ultimately selected through in silico screening. They were synthesized by conventional and microwave-assisted methods followed by in vitro antimalarial evaluations performed in chloroquine-sensitive (3D7) and resistant (DD2) strains of P. falciparum. ResultsThe docking results showed that compound 4C(11) had good binding interaction with Phe116, Met55 (−464.70 kcal/mol) and Phe116, Ser111 (−432.60 kcal/mol) against wild (1J3I) and quadruple mutant (1J3K) type of Pf-DHFR. Furthermore, in vitro, antimalarial activity results indicated that compound 4C(11) showed potent antimalarial activity against chloroquine-sensitive (3D7) and chloroquine-resistant (Dd2) strain of P. falciparum along with IC50 (14.90 μg mL−1) and (8.30 μg mL−1). ConclusionThese PABA-substituted 1,3,5-triazine compounds could be exploited to develop a new class of Pf-DHFR inhibitors as a lead candidate.

Development of magnetic Fe3O4-chitosan immobilized Cu(II) Schiff base catalyst: An efficient and reusable catalyst for microwave assisted one-pot synthesis of propargylamines via A3 coupling

A novel heterogeneous catalyst (Fe3O4@CS@Schiffbase@Cu) is developed by generating the Cu(II) Schiff base complex on the Fe3O4-chitosan surface. The structural and morphological characteristics of the catalyst is confirmed by all physicochemical techniques. A low catalyst loading (1.1 mol% Cu) of the immobilized Cu(II) Schiff base complex shows its catalytic activity for A3 coupling reaction of Aldehyde, Alkyne, and Amines under microwave irradiation. The catalyst was proven very active for a wide variety of propargylamines syntheses using different substituted aromatic aldehydes, secondary amines, and phenylacetylene under optimized conditions. The recyclability of the catalyst was efficient even after six cycles with a 95% efficiency.

Hemilabile Amine-Functionalized Efficient Azo-Aromatic Cu-Catalysts Inspired by Galactose Oxidase: Impact of Amine Sidearm on Catalytic Aerobic Oxidation of Alcohols.

A series of azo-aromatic copper(II) complexes, [1a-g] and a Cu(I) complex, [1h], with varying amine-functionalized hemilabile pincer-like [HL1-3] and [L1,2], methyl-substituted azo [L3], and imine [L4] ligands, were synthesized and characterized. These complexes were investigated for aerobic oxidation of a variety of aromatic alcohols in the presence of 2.0 mol % precatalysts [1a-g], cobaltocene (2.0 mol %), N-methyl imidazole (NMI) (8.0 mol %), and TEMPOH (2.0 mol %) at room temperature. The Cu(I) complex (1h) acted as a catalyst in the absence of cobaltocene. To understand the mechanism, detailed experimental and theoretical studies have been performed with the representative complex [1a], which has suggested a new kind of mechanism involving a Cu(II)/Cu(I) redox couple. Cobaltocene acts as a reductant to [1a] to generate a Cu(I) complex, which activates dioxygen in the presence of NMI. TEMPOH transfers a hydrogen atom to the activated dioxygen with the generation of TEMPO•, which further participates in α-C-H bond activation in the Cu(II)-alkoxide intermediate in an intermolecular fashion in the catalytic cycle. The amine sidearm in the ligand backbone of the complexes has a significant role in catalytic activity. Complexes with amine sidearms are more effective than complexes without them. Moreover, the aliphatic secondary amine sidearm is more efficient among the amine sidearm than the aromatic secondary amine and tertiary amines. The amine sidearm that remained coordinated to the Cu(II) center is hemilabile, and it facilitates alcohol coordination in the catalytic process. Alcohol coordination was the rate-limiting step, and it was supported by the isotope effect study on benzyl alcohol, substitution effect on the amine moiety of the ligands, and DFT calculation. The hemilabile amine sidearm of the coordinated ligand also acted as a base in deprotonating the alcoholic O-H proton and acted as an acid in releasing H2O2 during the catalysis.

44-Year Retrospective Analysis of Ultraviolet Absorbents and Industrial Antioxidants in Seabird Eggs from the Canadian Arctic (1975 to 2019).

Ultraviolet (UV) absorbents and industrial antioxidants are contaminants of emerging concern (CECs), but little is known about their distribution in Arctic wildlife, as well as how these contaminants vary over time, across regions, and between species. We used archived egg samples to examine the temporal patterns of 26 UV absorbents and industrial antioxidants in three seabird species (black-legged kittiwakes Rissa tridactyla, thick-billed murres Uria lomvia, northern fulmars Fulmarus glacialis) sampled in Arctic Canada between 1975 and 2019. Various synthetic phenolic antioxidants, aromatic secondary amines, benzotriazole UV stabilizers, and organic UV filters were detected in the seabird eggs. Overall, kittiwakes had higher levels of several UV absorbents and industrial antioxidants. Most target contaminants reached their peak concentrations at different points during the 44-year study period or did not vary significantly over time. None of these contaminant concentrations have increased in recent years. The antioxidant 2-6-di-tert-butyl-4-methylphenol (BHT) was the most frequently detected contaminant in seabird eggs, and its level significantly declined over the course of the study period in kittiwake eggs but did not change in the eggs of murres and fulmars. Future research should examine the effects of these CECs on the health of avian species, the sources, and exposure pathways of these contaminants.

YfeX - A New Platform for Carbene Transferase Development with High Intrinsic Reactivity.

Carbene transfer biocatalysis has evolved from basic science to an area with vast potential for the development of new industrial processes. In this study, we show that YfeX, naturally a peroxidase, has great potential for the development of new carbene transferases, due to its high intrinsic reactivity, especially for the N-H insertion reaction of aromatic and aliphatic primary and secondary amines. YfeX shows high stability against organic solvents (methanol and DMSO), greatly improving turnover of hydrophobic substrates. Interestingly, in styrene cyclopropanation, WT YfeX naturally shows high enantioselectivity, generating the trans product with 87 % selectivity for the (R,R) enantiomer. WT YfeX also catalyzes the Si-H insertion efficiently. Steric effects in the active site were further explored using the R232A variant. Quantum Mechanics/Molecular Mechanics (QM/MM) calculations reveal details on the mechanism of Si-H insertion. YfeX, and potentially other peroxidases, are exciting new targets for the development of improved carbene transferases.

A novel 2‐D accordion like Al‐BPED MOF as reusable and selective catalyst for N‐alkylation of amines with dialkylcarbonates

A novel 2‐D flakes like Al‐BPED ((N1,N2‐bis [pyridine‐2‐yl]methyl)ethane‐1,2‐diamine) metal–organic framework (MOF) have been explored for its catalytic potential in the N‐alkylation of amines with dialkyl carbonates. The Al‐BPED MOF catalyst has been synthesized by hydrothermal route. The X‐ray diffraction, Fourier Transform Infrared Spectroscope (FTIR), and High Resolution Transmission Electron Microscopy (HRTEM) images were used to analyze the morphology of the synthesized Al‐BPED MOF samples. With the use of Al‐BPED MOF, the primary and secondary aromatic amines were selectively and efficiently methylated with dimethyl carbonate. The effect of process conditions has been investigated toward N‐methylation, N‐ethylation, and N‐benzylation of aromatic amines. Under the optimal conditions with 10 mol% of the MOF catalyst, a maximum aniline conversion of 88% and a selectivity &gt;90% toward N‐alkylation was achieved. The kinetic studies revealed the N‐alkylation reaction in presence of Al‐BPED MOF followed pseudo‐first order rate kinetics.