Reaction Of Amines Research Articles

Intermolecular Enantioselective Amination Reactions Mediated by Visible Light and a Chiral Iron Porphyrin Complex.

In the presence of 1 mol % of a chiral iron porphyrin catalyst, various 3-arylmethyl-substituted 2-quinolones and 2-pyridones underwent an enantioselective amination reaction (20 examples; 93-99 % ee). The substrates were used as the limiting reagents, and fluorinated aryl azides (1.5 equivalents) served as nitrene precursors. The reaction is triggered by visible light which allows a facile dediazotation at ambient temperature. The selectivity of the reaction is governed by a two-point hydrogen bond interaction between the ligand of the iron catalyst and the substrate. Hydrogen bonding directs the amination to a specific hydrogen atom within the substrate that is displaced by the nitrogen substituent either in a concerted fashion or by a rebound mechanism.

Intermolecular Enantioselective Amination Reactions Mediated by Visible Light and a Chiral Iron Porphyrin Complex

AbstractIn the presence of 1 mol % of a chiral iron porphyrin catalyst, various 3‐arylmethyl‐substituted 2‐quinolones and 2‐pyridones underwent an enantioselective amination reaction (20 examples; 93–99 % ee). The substrates were used as the limiting reagents, and fluorinated aryl azides (1.5 equivalents) served as nitrene precursors. The reaction is triggered by visible light which allows a facile dediazotation at ambient temperature. The selectivity of the reaction is governed by a two‐point hydrogen bond interaction between the ligand of the iron catalyst and the substrate. Hydrogen bonding directs the amination to a specific hydrogen atom within the substrate that is displaced by the nitrogen substituent either in a concerted fashion or by a rebound mechanism.

Thioxanthrone-based ionic liquid as efficient and recyclable photocatalyst for α-cyanidation reaction of aromatic tertiary amines

A stabile and recyclable photocatalyst IL-TX was designed and synthesized by introducing the dye photocatalyst thioxanthenone into ionic liquids and its excellent photocatalytic performance was demonstrated by photophysical and electronic performance tests. The IL-TX was applied as a recyclable photocatalyst for α-cyanidation reaction of aromatic tertiary amines in MeOH at room temperature under blue light irradiation, and a range of cyanide products were obtained in good to excellent yields. Furthermore, the practicality of this protocol was further demonstrated through the optimization of the synthesis of the drug praziquantel and the natural product 8-oxopseudopalmatine. This study provides a greener and sustainable solution for photocatalytic cyanation reaction.

Yolk-Shell Au NPs@Carbon Porous Nanoreactors Derived from ZIF-8: A High-Efficiency Catalyst for Three-Component Coupling Reaction.

A yolk-shell Au NPs@carbon porous nanoreactor with an active gold (Au) core and a porous carbon shell has been fabricated and demonstrates excellent high activity and cyclic stability as a heterogeneous catalyst for the three-component coupling reaction of aldehyde, amine, and alkyne. Remarkably, the unique yolk-shell nanostructure can protect gold nanoparticles (Au NPs) from aggregation, allow for efficient mass transport, and benefit substrate enrichment, giving rise to enhanced activity, stability, and recyclability.

Electrocatalytic methylation and amination reactions with CO2 and NOxy–

Electrocatalytic methylation and amination reactions with CO2 and NOxy–

Understanding the coupling of non-metallic heteroatoms to CO2 from a Conceptual DFT perspective

ContextA Conceptual DFT (CDFT) study has been carry out to analyse the coupling reactions of the simplest amine (CH3NH2), alcohol (CH3OH), and thiol (CH3SH) compounds with CO2 to form the corresponding adducts CH3NHCO2H, CH3OCO2H, and CH3SCO2H. The reaction mechanism takes place in a single step comprising two chemical events: nucleophilic attack of the non-metallic heteroatoms to CO2 followed by hydrogen atom transfer (HAT). According to our calculations, the participation of an additional nucleophilic molecule as HAT assistant entails important decreases in activation electronic energies. In such cases, the formation of a six-membered ring in the transition state (TS) reduces the angular stress with respect to the non-assisted paths, characterised by four-membered ring TSs. Through the analysis of the energy and reaction force profiles along the intrinsic reaction coordinate (IRC), the ratio of structural reorganisation and electronic rearrangement for both activation and relaxation energies has been computed. In addition, the analysis of the electronic chemical potential and reaction electronic flux profiles confirms that the highest electronic activity as well as their changes take place in the TS region. Finally, the distortion/interaction model using an energy decomposition scheme based on the electron density along the reaction coordinate has been carried out and the relative energy gradient (REG) method has been applied to identify the most important components associated to the barriers.MethodsThe theoretical calculation were performed with Gaussian-16 scientific program. The B3LYP-D3(BJ)/aug-cc-pVDZ level was used for optimization of the minima and TSs. IRC calculations has also been carried out connecting the TS with the associated minima. Conceptual-DFT (CDFT) calculations have been carried out with the Eyringpy program and in-house code. The distortion/interaction model along the reaction coordinate have used the decomposition scheme of Mandado et al. and the analysis of the importance of each components have been done with the relative energy gradient (REG) method.

Ruthenium Complexes with NNN-Pincer Ligands for N-Methylation of Amines Using Methanol.

A series of ruthenium complexes (Ru1-Ru4) bearing new NNN-pincer ligands were synthesized in 58-78% yields. All of the complexes are air and moisture stable and were characterized by IR, NMR, and high-resolution mass spectra (HRMS). In addition, the structures of Ru1-Ru3 were confirmed by X-ray crystallographic analysis. These Ru(II) complexes exhibited high catalytic efficiency and broad functional group tolerance in the N-methylation reaction of amines using CH3OH as both the C1 source and solvent. Experimental results indicated that the electronic effect of the substituents on the ligands considerably affects the catalytic reactivity of the complexes in which Ru3 bearing an electron-donating OMe group showed the highest activity. Deuterium labeling and control experiments suggested that the dehydrogenation of methanol to generate ruthenium hydride species was the rate-determining step in the reaction. Furthermore, this protocol also provided a ready approach to versatile trideuterated N-methylamines under mild conditions using CD3OD as a deuterated methylating agent.

Antimicrobial, anti‐inflammatory, and antioxidant evaluations of ammonium and phosphonium salts based on poly(vinylbenzyl chloride‐co‐acrylonitrile)

AbstractPolymers with ammonium or phosphonium salts have been known to possess antimicrobial activity. Herein, synthesis of poly(vinylbenzyl chloride‐co‐acrylonitrile) (P(VBC‐co‐AN)) is reported via a free radical polymerization by employing AIBN as initiator. The copolymer was then quaternized using triethylamine, triphenylphosphine, and tributylphosphine. The triphenylphosphonium salt was selected for further modification, on which the polyacrylonitrile chains were reacted with two different amines: tris (2‐aminoethylamine) and diethylenetriamine. The copolymerization, quaternization, and amination reactions were confirmed by spectroscopic and morphologic analysis besides the thermal features. The water uptake of modified polymers was investigated, where tributylphosphonium salt (KH4) showed the highest water uptake capacity (41 g/g). The antimicrobial assay findings demonstrated that all the evaluated copolymers displayed a wide range of antimicrobial activity against different multidrug resistant human pathogens, for example polymer coded KH4 containing tributylphosphonium salt showed the highest growth inhibition rates against Staphylococcus aureus and Staphylococcus epidermidis populations, recorded 87% and 72%; respectively. The anti‐inflammatory activity revealed that all the quaternized copolymers have a protection effect of human erythrocyte membrane against lysis. Antioxidant results revealed that all quaternized copolymers displayed 1,1‐diphenyl‐2‐picryl hydrazyl scavenging activities. Among the studied copolymers, aminated copolymer coded (KH6) exhibited the highest scavenging activity, with IC50 ~ 120 μg/mL.

Introducing Bis(5-(Trifluoromethyl)pyridin-2-yl)amine Chelating Unit via Pd-Catalyzed Amination

We report a one-step synthesis of trifluoromethyl-substituted di(pyridin-2-yl)amine-based ligands. N-(hetero)aryl-substituted bis(5-(trifluoromethyl)pyridin-2-yl)amines were obtained from 2-bromo-5-(trifluoromethyl)pyridine and corresponding aromatic amines via Pd-catalyzed amination reaction in the presence of a Pd(dba)2/BINAP catalytic system. Four new ligands were prepared in good to high yields and characterized by NMR, IR spectroscopies and mass spectrometry. The structure of one of the products was additionally supported by X-ray analysis.

Probing the limits of tetraalkylthiuram disulfide synthesis by direct reaction of secondary amines with CS2: The structures of Cy2NC(S)SSC(S)NCy2 and Cy2NC(S)SSSSC(S)NCy2

Reaction of Cy2NH with CS2 in NaOH/H2O, followed by oxidation with I2, yields a complex mixture that includes the tetracyclohexylthiuram disulfide, Cy2NC(S)SSC(S)NCy2, in mixture with S8 and the tetrasulfide Cy2NC(S)SSSSC(S)NCy2. Direct reaction of 2 eq of Cy2NH with CS2 in EtOH, followed by I2 oxidation, does not yield isolable Cy2NC(S)SSC(S)NCy2, even though other tetraalkylthiuram disulfides are effectively produced by this protocol. Deprotonation of Cy2NH with t BuLi, followed by treatment with CS2 and then oxidative coupling with I2 yields Cy2NC(S)SSC(S)NCy2 in ∼74% yield, suggesting secondary amines that are branched at the α carbon may generally require this lattermost approach to the corresponding tetraalkylthiuram disulfide. Evaporation of an Et2O solution of the crude product mixture obtained from the CS2/NaOH/H2O reaction yielded a triclinic form of Cy2NC(S)SSC(S)NCy2, which contained two independent molecules in its asymmetric unit with opposite C 2 handedness. This same product mixture contained Cy2NC(S)SSSSC(S)NCy2, which was identified crystallographically in monoclinic C2/c and is the first such tetrasulfide to be characterized by X-ray diffraction. A second polymorph of Cy2NC(S)SSC(S)NCy2, obtained by evaporation of an acetone solution, is disordered across a mirror plane in monoclinic P21/m. This monoclinic polymorph of Cy2NC(S)SSC(S)NCy2 is the only tetraalkylthiuram disulfide found to crystallize on a mirror plane.

An Efficient Propylphosphonic Anhydride (T3P®)-Mediated MW-induced Solvent-free Rapid Synthesis of Enamino Esters and Ketones including 5, 5-Dimethyl-3-aminocyclohex-2-enones

Abstract: This work presents a clean and convenient synthesis of various β-enaminones including 5,5- dimethyl-3-aminocyclohex-2-enones, in satisfactory to excellent yields from the condensation reaction of primary amines with β -dicarbonyls by employing T3P® as a catalyst and performing the reaction under microwave irradiation and solvent-free conditions. These rapid reactions launched readily and stood a diversity of organic functional groups. A mixture of 1,3-dicarbonyl compound, primary amine and T3P® (50% in AcOEt) was irradiated for an appropriate time under microwave at 80°C. After completing the reaction (TLC) and cooling to r.t., ethyl acetate and saturated aqueous NaHCO3 solution were added. The aqueous phase was extracted ethyl acetate. The combined organic layer was washed with brine, dried over Na2SO4, and filtered, and the solvent was removed under reduced pressure to afford the product, which was recrystallized from diisopropyl ether. The presented results exhibit a better catalytic activity of T3P in the synthesis of enaminones. It could be concluded that T3P is the best catalyst as it took only a few minutes for the completion of the reaction with an excellent yield of product, which indicates T3P is more efficient, compared to other catalysts. A comparison of the efficiency of the present procedure with some heterogeneous solid catalysts was evaluated as well. Clearly, a higher yield was established in this procedure compared to other catalysts. Furthermore, the reaction of amines with dimedone was investigated as well, delivering excellent yields. The reaction catalyzed by T3P under microwave irradiation supplies a comprehensive method for the synthesis of enaminones. In this work, T3P is an effective, efficient and green catalyst, which forms the procedure economic, suitable, and safe with widespread application in the synthesis of enaminones. background: This work presents a clean and convenient synthesis of various β-enaminones incuding 5,5-dimethyl-3-aminocyclohex-2-enones in good to excellent yields from the reaction of different primary amines with 1,3-dicarbonyl compounds by employing T3P® as a catalyst and performing the reaction under microwave irradiation and solvent-free conditions. This one-pot rapid reaction proceeded readily and tolerated a variety of functional groups.

Differences in mechanisms between divalent and univalent copper complexes-catalyzed hydroacylation of terminal alkyne with aldehyde and amine

DFT calculations are carried out to investigate the hydroacylation mechanism based on copper-catalyzed A3-coupling tandem reaction of terminal alkynes, aldehydes and amines. The study reveals significant mechanistic differences between copper(I) and copper(II) catalysts. In the Cu(II)-catalyzed system, incorporation of a ligand is deemed necessary for facilitating reactivity, whereas no ancillary ligand is required in Cu(I) system. The ligand, through coordination with the Cu(II) center, stabilizes the key transition states and intermediates, resulting in a substantial reduction in the activation barrier. The ligand exhibits varying effect, with the order of activity being piperidine > pyridine > DMSO, correlating positively with the interaction energy between ligand and Cu complex. Additionally, the study sheds light on the pivotal roles played by the catalyst, ligand, base, and solvent DMSO in the reaction.

Transition Metal-free α-C-H Functionalization of Tertiary Amines Catalysed/ Promoted by Acids: A Brief Review

Abstract: C-H Functionalization of α-carbon of tertiary amines has been of great importance for the past two decades as N-heterocycles can be synthesized by this approach and these heterocycles are highly useful as drugs or drug precursors in the pharmaceutical industry. In this review article, we have summarized only the α-C-H functionalization reactions of tertiary amines that are catalysed or promoted by acids. These C-H functionalization reactions are usually catalysed by transition metal salts, although metal-free catalysts are also used. However, several such reactions have been reported that are efficiently catalysed by acids. They are cost-effective, have a simple purification process, less sensitive to air/moisture, and are relatively environmentally benign. However, this area has not received enough focus due to the lack of review articles, which encouraged us to write this review.

Synthesis, Characterization and Antioxidant Evaluation of New N-Α-Chloroacetylsalicyloyl-N-Antipyrine Benzamide

The new compound N-α-chloroacetylsalicyloyl-N-antipyrine benzamide was synthesized by a reaction of N-benzylidene antipyrine amine and O-acetyl salicyloyl chloride. On the other hand, N-benzylidene antipyrine amine was obtained by a coupling reaction between benzaldehyde and 4-aminoantipyrine, while O-acetyl salicyloyl chloride resulted from acylation reaction of aspirin starting from salicylic acid. All synthesized compounds were characterized by using m.ps., UV-Vis., FTIR, MS, and 1HNMR spectroscopic methods. The method of DPPH was also used as testing to measure the radical scavenging of the new compound. It showed very powerful antioxidant activity with IC50value of 29 ppm. Moreover, its antibacterial activity was tested against three types of bacteria.

Crystalline Olefin-Linked Chiral Covalent Organic Frameworks as a Platform for Asymmetric Catalysis.

The construction of olefin-linked chiral covalent organic frameworks (COFs) with high crystallinity is highly desirable while remains great challenge due to the poor reversibility of the formation reaction for the olefin linkages during the in situ structural self-healing process. Herein, we successfully synthesized two sets of enantiomeric olefin-linked COFs. The chiral catalytic groups are uniformly distributed on the pore walls of COFs, resulting in the full exposure of catalytic sites to the reactants in asymmetric catalysis. The as-prepared (R)/(S)-CCOF8 exhibits excellent catalytic performance with exceeding 99 % enantiomeric excess in the enantioselective electrophilic amination reaction. Moreover, the heterogeneous chiral catalysts are conveniently recycled and could maintain the performance after ten catalytic cycles. Our findings expand the scope to construct stable and crystalline chiral COFs for the asymmetric catalysis.

Crystalline Olefin‐Linked Chiral Covalent Organic Frameworks as a Platform for Asymmetric Catalysis

AbstractThe construction of olefin‐linked chiral covalent organic frameworks (COFs) with high crystallinity is highly desirable while remains great challenge due to the poor reversibility of the formation reaction for the olefin linkages during the in situ structural self‐healing process. Herein, we successfully synthesized two sets of enantiomeric olefin‐linked COFs. The chiral catalytic groups are uniformly distributed on the pore walls of COFs, resulting in the full exposure of catalytic sites to the reactants in asymmetric catalysis. The as‐prepared (R)/(S)‐CCOF8 exhibits excellent catalytic performance with exceeding 99 % enantiomeric excess in the enantioselective electrophilic amination reaction. Moreover, the heterogeneous chiral catalysts are conveniently recycled and could maintain the performance after ten catalytic cycles. Our findings expand the scope to construct stable and crystalline chiral COFs for the asymmetric catalysis.

Elucidating the Impact of Polyol Functional Moieties on Exothermic Poly(urethane-urea) Polymerization: A Thermo-Kinetic Simulation Approach

The pursuit of sustainable polyurethane (PU) product development necessitates a profound understanding of precursor materials. Particularly, polyol plays a crucial role, since PU properties are heavily influenced by the type of polyol employed during production. While traditional PUs are solely derived from hydroxyl functionalized polyols, the emergence of amine-hydroxyl hybrid polyols has garnered significant attention due to their potential for enhancing PU product properties. These hybrid polyols are characterized by the presence of both amine and hydroxyl functional groups. However, characterizing these polyols remains a daunting challenge due to the lack of established experimental testing standards for properties, such as fractional hydroxyl and amine moieties and thermo-kinetic parameters for amine reactions with isocyanates. Additionally, characterization methods demand extensive time and resources and pose risks to health and the environment. To bridge these gaps, this study employed computational simulation via MATLAB to determine the moieties’ fractions and thermo-kinetic parameters for hybrid polyols. The computational method integrated energy balance and reaction kinetics analysis for various polyols to elucidate the influence of functional moieties on the thermo-kinetic behavior of PU formations. Validation of the simulated results was conducted by comparing their experimental and simulated prepolymer and foam temperature profiles, highlighting the direct influence of fractional moieties on PU formations. The comparisons revealed an average relative error of less than 5%, indicating the accuracy and credibility of the simulation. Thus, this study represents a pivotal opportunity for advancing knowledge and driving sustainable developments in bio-based polyol characterization for PU production streamlining and formulation optimization.

Unlocking Biomolecular Activity through Pd‐Catalyzed Azides Reduction†

Comprehensive SummaryPd‐mediated bioorthogonal cleavage reactions have been extensively utilized in the activation of prodrug molecules, precise regulation of protein function, and cellular engineering. However, the availability of cleavable "caging" groups is quite limited, and their application in nucleic acid modification has seldom been reported. Herein, we introduce a method based on Pd‐catalyzed reduction amination of azides as a decaging strategy to activate the activity of biomolecules. We designed modifications on the bioactive sites with azides or their derivatives to mask the related biological function, followed by the release of biological activity through Pd‐catalyzed NaBH4 reduction amination reaction. This study has demonstrated that the strategy can effectively be used to activate bioactive molecules such as fluorescent probes, prodrugs, and to regulate the biological function of RNA, including reverse transcription extension, binding to ligands, and cleavage activity of the CRISPR‐Cas system. All results confirm that this strategy provides an efficient and controllable "OFF to ON" biological switch, capable of achieving significant regulatory effects substoichiometrically, and is expected to be extended to other biological applications.

Multi-element analysis of metals in human pathological and unchanged thyroid glands - pilot study.

Disturbances in the homeostasis of the elemental composition of thyroid tissue may have serious metabolic and health consequences. It is believed that the accumulation of some metals or the deficiency of others may even cause lethal tumours. Due to the fact that metallomics most often uses human serum to analyse macro and microelements as well as trace elements, it was decided to use material that is more difficult to obtain, but also adds credibility to the research - thyroid tissue samples biopsy. The experiments were conducted on 17 patients diagnosed with: nodular (10) and colloidal goitre (2), chronic thyroiditis (2), follicular adenoma (2) and papillary carcinoma (1). They were recruited by collecting a tumour fragment, control fragment and serum from each of them. The content of Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Zn was examined using ICP-OES (Inductively Coupled Plasma - Optical Emission Spectrometers). Simultaneously, biochemical methods were used to determine the markers of inflammation, glycation and peroxidation: malondialdehyde, pentosidine, reactive free amine content, compounds with thiol groups and galectin 3 in the sera of the examined patients. Three statistically significant correlations were identified: Ca-Mg and Cu-Zn in control tissues (p < 0.05) and Cr-Mn in pathological tissues (p < 0.05). A comparison of individual groups of patients shows that there are some potentail tendencies to increase or decrease in the concentration of certain elements or markers of inflammation and glycation, therefore we discuss potential relationships between a given parameter and a thyroid disorder. The pilot study is an introduction to a deeper analysis aimed at tracing the pathomechanism of the development of thyroid diseases, so that the risk of developing these diseases can be effectively minimized.

Photocatalyst/metal-free sequential C–N/C–S bond formation: Synthesis of S-arylisothioureas via photoinduced EDA complex activation

A photocatalyst-free visible-light-promoted three-component reaction of thianthrenium salts, isothiocyanates, and amines is presented, which affords a rapid and efficient approach to S-arylisothioureas under mild conditions. This developed method exhibits the advantages of readily available raw materials, broad substrate scope, good functional tolerance, and operational simplicity. It is worth mentioning that the byproduct thianthrene can be recycled in quantity, ultimately maximizing the atomic economy of the reaction and avoiding chemical waste. Mechanism investigations support the strategy involving a photoinduced EDA complex.