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We report here a method to make a branched and partially ethoxylated polyethyleneimine derivative directly from ethanolamine. The polymerization reaction is catalysed by a pincer complex of Earth-abundant metal, manganese, and produces water as the only byproduct. Industrial processes to produce polyethyleneimines involve the transformation of ethanolamine to a highly toxic chemical, aziridine, by an energy-intensive/waste-generating process followed by the ring-opening polymerization of aziridine. The reported method bypasses the need to produce a highly toxic intermediate and presents advantages over the current state-of-the-art. We propose that the polymerization process follows a hydrogen borrowing pathway that involves (a) dehydrogenation of ethanolamine to form 2-aminoacetaldehyde, (b) dehydrative coupling of 2-aminoacetaldehyde with ethanolamine to form an imine derivative, and (c) subsequent hydrogenation of imine derivative to form alkylated amines. The industrial process for the synthesis of branched polyethylenimine (PEI) and polyethylenimine ethoxylated (PEIE) uses highly toxic and mutagenic chemicals. Here the authors report a method to make a branched and partially ethoxylated polyethyleneimine derivative directly from ethanolamine using a pincer complex of Earth-abundant manganese, and producing water as the only byproduct. [ABSTRACT FROM AUTHOR]

Developing highly active materials that efficiently utilize solar spectra is crucial for photocatalysis, but still remains a challenge. Here, we report a new donor-acceptor (D-A) covalent organic framework (COF) with a wide absorption range from 200 nm to 900 nm (ultraviolet-visible-near infrared light). We find that the thiophene functional group is accurately introduced into the electron acceptor units of TpDPP-Py (TpDPP: 5,5'-(2,5-bis(2-ethylhexyl)−3,6-dioxo-2,3,5,6-tetrahydropyrrolo [3,4-c]pyrrole-1,4-diyl)bis(thiophene-2-carbaldehyde), Py: 1,3,6,8-tetrakis(4-aminophenyl)pyrene) COFs not only significantly extends its spectral absorption capacity but also endows them with two-photon and three-photon absorption effects, greatly enhancing the utilization rate of sunlight. The selective coupling of benzylamine as the target reactant is used to assess the photocatalytic activity of TpDPP-Py COFs, showing high photocatalytic conversion of 99% and selectivity of 98% in 20 min. Additionally, the TpDPP-Py COFs also exhibit the universality of photocatalytic selective coupling of other imine derivatives with ~100% conversion efficiency. Overall, this work brings a significant strategy for developing COFs with a wide absorption range to enhance photocatalytic activity. Creating highly active materials that effectively harness solar spectra is essential for photocatalysis, though challenging. Here the authors introduce a novel donor-acceptor covalent organic framework with a broad absorption range of 200 nm to 900 nm, achieving efficient artificial photocatalytic amine coupling. [ABSTRACT FROM AUTHOR]

Umpolung is an old and important concept in organic chemistry, which significantly expands the chemical space and provides unique structures. While, previous research focused on carbonyls or imine derivatives, the umpolung reactivity of polarized C–C σ-bonds still needs to explore. Herein, we report an umpolung reaction of bicyclo[1.1.0]butanes (BCBs) with electron-deficient alkenes to construct the C(sp3)-C(sp3) bond at the electrophilic position of C–C σ-bonds in BCBs without any transition-metal catalysis. Specifically, this transformation relies on the strain-release driven bridging σ-bonds in bicyclo[1.1.0]butanes (BCBs), which are emerged as ene components, providing an efficient and straightforward synthesis route of various functionalized cyclobutenes and conjugated dienes, respectively. The synthetic utilities of this protocol are performed by several transformations. Preliminary mechanistic studies including density functional theory (DFT) calculation support the concerted Alder-ene type process of C–C σ-bond cleavage with hydrogen transfer. This work extends the umpolung reaction to C–C σ-bonds and provides high-value structural motifs. Umpolung reactions typically focus on carbonyls or imine derivatives. Here, the authors report the umpolung reaction of C–C σ-bonds in bicyclo[1.1.0]butanes (BCBs) with electrophilic alkenes, yielding various cyclobutenes or conjugated dienes. [ABSTRACT FROM AUTHOR]

A simple imine derivative based sensor (IDP) has been synthesized and characterized by 1 H NMR, 13 C NMR and mass spectral techniques. IDP is more capable of detecting perfluorooctanoic acid (PFOA) in a selective and sensitive manner. The PFOA as a biomarker interacts with IDP and shows "TURN-ON" response by colorimetric and fluorimetric method. Under optimized experimental observations, the selective determination of PFOA using IDP among other competitors as biomolecules has been noticed. The detection limit is 0.31 × 10− 8 mol/L. The practical applications of the IDP is effectively evaluated in human biofluids and water samples. [ABSTRACT FROM AUTHOR]

New macrocyclic Schiff bases, lower rim disubstituted imine derivatives of thia- and calix[4]arenes 7 and 8 adopted in a cone stereoisomeric conformation, bearing two tert-butyl substituents grafted to iminophenol coordinating sites, and containing a spacer composed of two methylene bridges were synthesized. The prepared compounds were characterized by a complex of physicochemical methods in solution (1H/13C NMR spectroscopy, MALDI TOF mass spectrometry) and in the crystalline phase (IR spectroscopy, single-crystal X-ray diffraction (XRD)). In crystals calix[4]arene 7 forms a solvate in which acetonitrile or methanol molecules are included into the macrocycle cavity, whereas the crystals of thiacalix[4]arene 8 contain no solvent molecules. The difference in the conformational behavior of the macrocyclic platform was evidenced when comparing the crystal structures of calix[4]arene 7 and thiacalix[4]arene 8. The stoichiometry and the logarithm and stability constant values of the corresponding complexes of the synthesized macrocyclic Schiff bases with 3d-metal cations (CoII, NiII) in solution were determined using spectrophotometry titration. When interacting with CoII cations, compound 7 forms complexes with stoichiometry Lig: M = 1: 1 and 1: 2 (Lig is ligand, and M is metal). In the case of compound 8, complexes with the stoichiometry Lig: M = 1: 4, as well as 1: 2, are observed, which presumably indicates the involvement of "soft" sulfur atoms in the interaction with the metal cations. The replacement of CoII cations by NiII resulted in the formation in the solution of complexes with the stoichiometry Lig: M = 2: 1, 1: 1 and Lig: M = 1: 1, 1: 2 for compounds 7 and 8, respectively. [ABSTRACT FROM AUTHOR]

Series of new derivatives of ninhydrin, isatin, and 4-hydroxy-1,3-thiazine-2,6-dione were synthesized. Their antimicrobial activity against opportunistic microflora of Staphylococcus aureus and Pseudomonas aeruginosa isolated from neurotrophic ulcers of leprosy patients was studied. Antibacterial activity against S. aureus was observed for derivatives of chalcone (MIC 2.31 ± 0.99 and 8.0 ± 2.83 μg/mL), benzofuran (MIC 3.5 ± 1.66 μg/mL), imines (MIC 0.56 ± 0.16 and 3.01 ± 1.68 μg/mL), and indene (MIC 1.38 ± 0.38 μg/mL). Derivatives of imine (MIC 0.25 ± 0.05 and 0.63 ± 0.26 μg/mL) and indene also exhibited pronounced inhibitory effects against P. aeruginosa. Bactericidal effects on both cultures were observed for 5-{(1E)-1-[2-(1-benzothiophen-2-yl)hydrazinylidene]-ethyl}-4-hydroxy-2H-1,3-thiazine-2,6(3H)-dione. An indene derivative with a morpholine fragment showed a pronounced bactericidal effect (MBC 2.3 ± 0.58 μg/mL) on the growth of P. aeruginosa culture. [ABSTRACT FROM AUTHOR]

The reactions between o-vanillin and three isomeric aminopyridines lead to imines of diverse spatial conformation and reactivity. The direct products of these simple reactions carried out in methanol are either imine compounds formed in the reactions of 2-amino- and 3-aminopyridine with o-vanillin or the α-aminoether formed in the reaction of o-vanillin with 4-aminopyridine. The Schiff-type derivative of 4-aminopyridine and o-vanillin, which is described in this paper for the first time, is very reactive and can only be obtained indirectly from the α-aminoether in anhydrous conditions. All compounds are characterized by X-ray diffraction and FT-IR and NMR spectroscopies. The DFT calculations at all-electron BLYP/Q4ZP level of theory are utilized to explain the differences between the reactivity of isomeric aminopyridines and their imine derivatives. [ABSTRACT FROM AUTHOR]

Six imines including four new ones were synthesized via the reaction of monoterpenoid aldehydes with aminoadamantanes. The inhibitory activities of the synthesized compounds against purified human recombinant DNA repair enzyme tyrosyl-DNA phosphodiesterase 1 (Tdp1) fell in the range IC50 = 5.5-7.1 μM. [ABSTRACT FROM AUTHOR]

2-Amino-4-R-6 H-1,3-thiazine-6-thiones and 2-amino-4-phenyl-6 H-1,3-thiazin-6-one react with highly electrophilic N-arylsulfonylimines of chloral and phenyldichloroacetic aldehyde at the exocyclic amino group affording in good yields products of nucleophilic addition to the azomethine group of imines: N-[2-polychloro-1-(6-thioxo-4-R-6 H-1,3-thiazin-2-ylamino)ethyl]- or -[2-polychloro-1-(6-oxo-4-phenyl-6 H-1,3-thiazin-2-ylamino)ethyl]arenesulfonamides. [ABSTRACT FROM AUTHOR]

Reaction direction of N-sulfonyl derivatives of 1,4-benzoquinone monoimine with substituted hydrazines depends on the redox potential of the quinone imine and on the basicity of the hydrazine. Aryl (alkyl)hydrazines of high basicity favor the reduction of quinone monoimine. In reactions with less basic aroylhydrazones N'-(4-oxocyclohexa-2,5-dienylidene)aroylhydrazides were obtained only from the alkylsubstituted in the quinoid ring N-sulfonyl derivatives possessing a lower redox potential. [ABSTRACT FROM AUTHOR]

Sulfamic acid supported on FeO@SiO superpara magnetic nanoparticles was successfully applied as a recyclable solid acid catalyst with a large density of sulfamic acid groups for the synthesis of pyrazole derivatives, an important class of potentially bioactive compounds. The products are obtained in high yield from the one-pot reaction procedure involving dicarbonyl compounds and hydrazines/hydrazides. This new method totally avoids the use of toxic or expensive solvents and organic acids in this reaction. [ABSTRACT FROM AUTHOR]

The ability of N,N'-disubstituted 9,10-phenanthrenediimines in neutral, monoand direduced states to act as bidentate ligands in main-group-metal and transition-metal complexes has been demonstrated for the first time. The formation of metal complexes with the radical anion form of phenanthrenediimines stabilized through the formation of contact pairs (for Li) or chelate complexes (for Rh) has been detected. [ABSTRACT FROM AUTHOR]

Anew antimigraine drug - Tropoxin (3-(3,4,5-trimethoxybenzoyloxyimino)-8-methyl-8-azabicyclo[-]octane hydrochloride) - was developed and was found to prevent or significantly weaken the constrictor reactions of cerebral arteries evoked by serotonin (5-HT) or the 5-HT receptor agonist meta-chlorophenylpiperazine (m-CPP) in intact animals and in animals with ischemic brain damage. Tropoxin showed affinity for5-HT receptors in the brain and had antiaggregatory actions. It had no marked neurotropic properties and did not alter blood pressure responses to noradrenaline, acetylcholine, or histamine. Pilot clinical trials of Tropoxin provided evidence that it has high efficacy in the interictal treatment of frequent and severe migraine attacks. [ABSTRACT FROM AUTHOR]

Depending on the conditions and the order of addition of the reactants, reactions of N-sulfonyl-1,4-benzoquinone imines with sodium azide afforded N-(3-azido-4-hydroxyphenyl)alkane(arene)sulfonamides, N-(3-azido-4-oxocyclohexa-2,5-dienylidene)alkane(arene)sulfonamides, and N-(3,5-diazido-4-hydroxyphenyl)-alkanesulfonamides. Quantum chemical calculations showed that the reactions begin with addition of azide ion to the quinone imine. [ABSTRACT FROM AUTHOR]

The focus of the present work is on the design, synthesis, characterization, DNA-interaction, photo-cleavage, radical scavenging, in-vitro cytotoxicity, antimicrobial, docking and kinetic studies of Cu (II), Cd (II), Ce (IV) and Zr (IV) metal complexes of an imine derivative, 3 - (1 - (6 - methoxybenzo [d] thiazol - 2 - ylimino) ethyl) - 6 - methyl - 3H - pyran - 2, 4 - dione. The investigation of metal ligand interactions for the determination of composition of metal complexes, corresponding kinetic studies and antioxidant activity in solution was carried out by spectrophotometric methods. The synthesized metal complexes were characterized by EDX analysis, Mass, IR, H-NMR, C-NMR and UV-Visible spectra. DNA binding studies of metal complexes with Calf thymus (CT) DNA were carried out at room temperature by employing UV-Vis electron absorption, fluorescence emission and viscosity measurement techniques. The results revealed that these complexes interact with DNA through intercalation. The results of in vitro antibacterial studies showed the enhanced activity of chelating agent in metal chelated form and thus inferring scope for further development of new therapeutic drugs. Cell viability experiments indicated that all complexes showed significant dose dependent cytotoxicity in selected cell lines. The molecular modeling and docking studies were carried out with energy minimized structures of metal complexes to identify the receptor to metal interactions. [ABSTRACT FROM AUTHOR]

We studied the kinetics of the reaction between N, N′-diphenyl-1,4-benzoquinone diimine and thiophenol in n-propanol at 343 K and compared the results with the same data for the chlorobenzene medium. The replacement of chlorobenzene with n-propyl alcohol increases the reaction rate by one order of magnitude. The order of the reaction with respect to thiophenol was determined to be 1.0 in both solvents, and the order of the reaction with respect to quinone diimine decreases from 1.5 to 1.2 on passing from chlorobenzene to n-propanol. In contrast to the reaction in chlorobenzene, where the radical chain mechanism is realized, the reaction in n-propanol simultaneously proceeds via a radical chain channel and a heterolytic channel. In the absence of an initiator and at equal reactant concentrations of ∼10 mol/L, the reaction rates in both pathways are commensurable. The chain reaction is characterized by short chains whose length is a few units. Chain generation in the absence of an initiator occurs by the direct bimolecular reaction between the reactants, whose rate constant in n-propanol is one order of magnitude higher than that in chlorobenzene, which is explained by the high polarity of the transition state in this endothermic homolytic reaction. The reaction mechanism was proposed, and, for this mechanism, the rate constants of elementary steps were determined. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented which discusses the synthesis of 6-monoaldehyde found in β-cyclodextrin and its imino derivatives.

N-Arylsulfonyl, N-aroyl, and N-[arylsulfonylimino(phenyl)methyl] derivatives of 1,4-benzoquinone imine reacted with sodium arenesulfinates to give 1,4-, 1,6-, and 6,1-addition products which were formed according to two concurrent paths: direct nucleophilic addition of arenesulfinate anion to neutral quinone imine molecule and radical ion addition of arenesulfinate radical to radical anion derived from quinone imine. [ABSTRACT FROM AUTHOR]

In this work, quantum chemistry and kinetics calculations have been performed on the retro-cheletropic ene reactions of N-phenyl-1-methyl-6-methylenecyclohexa-2,4-dienylmethanimine (R1) and N-phenyl-2,2-dimethylbut-3-en (R2). Two major possible mechanisms have been considered and rate constants have been calculated using the transition state theory. The simple Wigner, Eckart zero-curvature tunneling and small-curvature tunneling (SCT) methods were evaluated. The best agreement with experimental rate coefficients was found when SCT correction was applied. A mean deviation of a factor 3 on the rate coefficients is found for the studied reactions at the temperatures of 417 and 773 K. Calculated rate coefficients showed that the tunneling corrections played a critical role in obtaining accurate rate coefficients, especially at lower temperature (417 K). Calculated rate coefficients are in good agreement with the reported experimental data and similar compounds in the case of R1 and R2, respectively. These results support the concerted and stepwise paths for the gas phase reactions of R1 and R2, respectively. Computed kinetic parameters confirmed that R1 had greater reactivity than R2. This trend explains the effects of an extra phenyl-like system on the stability of the transition state and hence increases the R1 rate constant. Calculated rate constants especially at the M06 level are in better agreement with the experimental values than the B3LYP ones. Natural bond orbital (NBO) studies of the reactants and their transition states reveal that their electron delocalization change is an important factor in the determination of the reactivity order for these compounds. Finally, the nature of bond making and breaking during the reactions has been investigated using the concepts of electron charge density and Laplacian in atom in the molecule method. [ABSTRACT FROM AUTHOR]

The imine intermediates of tazobactam and sulbactam bound to SHV-1 β-lactamase were investigated by molecular dynamics (MD) simulation respectively. Hydrogen bond networks around active site were found different between tazobactam and sulbactam acyl-enzymes. In tazobactam imine intermediate, it was observed that the triazolyl ring formed stable hydrogen bonds with Asn170 and Thr167. The results suggest that conformation of imine determined the population of intermediates. In imine intermediate of tazobactam, the triazolyl ring is trapped in Thr_Asn pocket, and it restricts the rotation of C5-C6 bond so that tazobactam can only generate trans enamine intermediate. Further, conformational cluster analyses are performed to substantiate the results. These findings provide an explanation for the corresponding experimental results, and will be potentially useful in the development of new inhibitors. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The chirality-organized quinonediimine derivatives bearing amino acid moieties were demonstrated to react with 2 molar equiv. of Pd(OAc), resulting in the formation of the chiral homobimetallic palladium(II) complexes. The crystal structures of the chiral conjugated complexes revealed the coordination of the quinonediimine nitrogen to a palladium center and a chiral propeller twist conformation of the π-conjugated backbone. The mirror image relationship of the CD signals around the quinonediimine moieties in acetonitrile was observed between l- and d-derivatives, indicating the preservation of the chirality-organized structures even in a solution. [ABSTRACT FROM AUTHOR]

Copper-based asymmetric photocatalysis has great potential in the development of green synthetic approaches to chiral molecules. However, there are several formidable challenges associated with such a conception. These include the relatively weak visible light absorption, short excited-state lifetimes, incompatibility of different catalytic cycles, and the difficulty of the stereocontrol. We report here an effective strategy by means of single-electron-transfer (SET) initiated formation of radicals and photoactive intermediates to address the long-standing problems. Through elaborate selection of well-matched reaction partners, the chiral bisoxazoline copper catalyst is engaged in the SET process, photoredox catalysis, Lewis acid activation and asymmetric induction. Accordingly, a highly enantioselective photocatalytic α-aminoalkylation of acyclic imine derivatives has been accessed. This strategy sheds light on how to make use of diverse functions of a single transition metal catalyst in one reaction, and offers an economic and simplified approach to construction of highly valuable chiral vicinal diamines. Copper-based asymmetric photocatalysis has great synthetic potential, however it has been rarely exploited due to challenges inherent to such systems. Here, a chiral bisoxazoline copper catalyst is involved in a SET process, photoredox catalysis, Lewis acid activation and asymmetric induction to construct chiral vicinal diamines. [ABSTRACT FROM AUTHOR]

A variety of imine derivatives have been synthesized via Suzuki cross coupling of N-(4-bromophenyl)-1-(3-bromothiophen-2-yl)methanimine with various arylboronic acids in moderate to good yields (58-72%). A wide range of electron donating and withdrawing functional groups were well tolerated in reaction conditions. To explore the structural properties, Density functional theory (DFT) investigations on all synthesized molecules (3a-3i) were performed. Conceptual DFT reactivity descriptors and molecular electrostatic potential analyses were performed by using B3LYP/6-31G(d,p) method to explore the reactivity and reacting sites of all derivatives (3a-3i). [ABSTRACT FROM AUTHOR]