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1,3-Dipolar cycloaddition reactions are one of the most important methods to obtain diverse heterocycles with novel skeletons. We herein report the Brønsted acid or Lewis acid catalyzed [3+3] cycloaddition of azomethine imines with nonstabilized azomethine ylide generated in situ from an N-benzyl precursor, providing a clean and facile access to diverse bicyclic N-heterocycles in moderate to good yields for further biological testing. Also, the protocol developed achieved the formation of C-C and C-N bonds simultaneously in a single step. [ABSTRACT FROM AUTHOR]

The synthesis, characterization, and ethylene polymerization properties of a series of xanthene-bridged dinuclear α-diimine NiII complexes are described. The dinucleating α-diimine ligands were prepared from the xanthene-bridged di-anilines, which were synthesized and isolated on the multigram scale without using column chromatography. The di-anilines could potentially be used to prepare various dinucleating imine-containing olefin polymerization ligands. In ethylene polymerization, the dinuclear α-diimine NiII complexes showed good thermal stability and high catalytic activity. In addition, the polyethylene generated by these dinuclear α-diimine NiII complexes showed high molecular weight, narrow polydispersity, and very low branching density. Metal-metal cooperativity effects was invoked to explain the slow β-hydride elimination process and the correspondingly slow chain-walking process. [ABSTRACT FROM AUTHOR]

The interaction of uranyl(VI) nitrate with a series of bis(2-hydroxyaryl)imine (H 2 L 1 –H 2 L 5 ) and bis(2-hydroxyaryl)amine (H 2 L 8 , H 2 L 9 ) derivatives incorporating 1,3-dimethylenebenzene or 1,3-dimethylenecyclohexane bridges between nitrogen sites is reported. Crystalline complexes of type [UO 2 (H 2 L)(NO 3 ) 2 ] (where H 2 L is H 2 L 1 –H 2 L 4 ) were isolated from methanol. X-ray structures of the complexes of H 2 L 1 , H 2 L 2 and H 2 L 4 show that each of these neutral ligands bind to their respective UO 2 2 + centres in a bidentate fashion in which coordination only occurs via each ligand’s hydroxy functions. Two bidentate nitrate anions complete the metal’s coordination sphere in each complex to yield hexagonal bipyramidal coordination geometries. A density functional theory (DFT) investigation of [UO 2 (H 2 L 1 )(NO 3 ) 2 ] in a simulated methanol environment is in accord with this complex maintaining its solid state conformation in solution. Solvent extraction experiments (water/chloroform) employing H 2 L 1 –H 2 L 7 in the organic phase and uranyl(VI) nitrate in the aqueous phase showed that both amine derivatives, H 2 L 8 and H 2 L 9 , yielded enhanced extraction of UO 2 2 + over the corresponding imine derivatives, H 2 L 1 and H 2 L 2 . These results were further compared with those obtained for the corresponding Schiff bases incorporating 1,2-phenylene and 1,2-cyclohexane bridged ligands, H 2 L 6 and H 2 L 7 ; these more rigid systems also yielded enhanced extraction of UO 2 2 + relative to the more flexible Schiff bases H 2 L 1 –H 2 L 5 . A very significant synergistic enhancement of the extraction of UO 2 2 + by H 2 L 1 –H 2 L 4 and H 2 L 7 was observed in the presence of a 10-fold excess of n -octanoic acid; the influence of pH on extraction efficiency was also investigated. A parallel set of experiments employing H 2 L 1 –H 2 L 9 as extractants for europium(III) nitrate indicated a clear uptake preference for UO 2 2 + over Eu 3+ in all cases; separation of the uranyl ion from the rare earths is an important objective in mineral processing. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis and theoretical investigation of a nonsymmetric bis(diisopropylamino)cyclopropenimine (DAC)-functionalized proton sponge derivative, coined the "Janus" sponge. The reported sponge was isolated as a monoprotonated salt, though no intramolecular hydrogen bond was observed. Homodesmotic equations supported the absence of a N-HN intramolecular hydrogen bond and a relatively low freebase strain, while DFT calculations and X-ray crystallography revealed the presence of a hydrogen bond to the Cl- counterion. Associated with this fact was the rare in-out geometry of the basic nitrogens, which represents the first such instance in a proton sponge not having an ortho-substituent and/or being in a protonated state. Furthermore, NLP donation into the cyclopropenium cation was found to stabilize this unprecedented in-out geometry. The measured pKa was determined to be 23.8, in good agreement with the computed value of 23.9. Lastly, the Janus sponge was found to have fluorescent properties both in the solid state and in solution, which notably represents the first example of a cyclopropenimine-based fluorescent organic compound. [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]

A new protocol for the direct formation of amides from imines derived from aromatic aldehydes via metal-free aerobic oxidation in the presence of cyanide is described. This protocol was applicable to various aldimines, and the desired amides were obtained in moderate to good yields. Mechanistic studies suggested that this aerobic oxidative amidation might proceed via the addition of cyanide to imines followed by proton transfer from carbon to nitrogen in the original imines, leading to carbanions of a-amino nitriles, which undergo subsequent oxidation with molecular oxygen in air to provide the desired amide compounds. [ABSTRACT FROM AUTHOR]

Waterborne epoxy coatings were modified by adding mesoporous-TiO 2 nanoparticles (meso-TiO 2 ). In order to achieve proper dispersion of meso-TiO 2 in the epoxy-based coating and make possible chemical interactions between meso-TiO 2 and polymeric coating, meso-TiO 2 was treated with polyethylenimine (PEI) of various molecular weights. Corrosion performance of mild steel coated specimens was investigated employing electrochemical impedance spectroscopy (EIS) and salt spray test. Coatings with meso-TiO 2 /PEI (600 molecular weight) possessed the best corrosion performance among the coating specimens. The EIS results showed that the resistance value of coating with meso-TiO 2 /PEI (600 molecular weight) was above 9.87 × 10 7 Ω cm 2 which was higher than neat epoxy coating. Possible chemical interactions between polymeric matrix and treated nanoparticles caused high barrier properties and high degree of cross-linking. [ABSTRACT FROM AUTHOR]

A highly efficient gram-scale method for the C(4)-functionalization of sydnone imine hydrochloride derivatives was developed. This new approach was realized through consecutive reactions including the preparation of a C(3)-substituted N 6 - tert -butoxycarbonyl sydnone imine derivative, deprotonation with n -BuLi and reaction of the lithiated-intermediate with an electrophilic agent, and removal of the Boc protecting group. [ABSTRACT FROM AUTHOR]

A new class of compounds featuring a camphor moiety has been discovered that exhibits potent inhibitory activity against influenza A(H1N1)pdm09 and A(H5N1) viruses. The synthesized compounds were characterized by spectroscopic analysis; in addition the structures of compound 2 and 14 were elucidated by the X-ray diffraction technique. Structure–activity relationship studies have been conducted to identify the 1,7,7-trimethylbicyclo[2.2.1]heptanes2-ylidene group as the key functional group responsible for the observed antiviral activity. The most potent antiviral compound is imine 2 with therapeutic index more than 500. [ABSTRACT FROM AUTHOR]

Optically pure α-ketoimines were obtained under solvent-free conditions starting from 2,2′-pyridil and (S)-(−)-1-phenylethylamine and (S)-(−)-1-(4-methylphenyl)ethylamine, respectively. These new chiral ketoimines were then complexed with palladium yielding new optically pure mono-Pd complexes3A–B. The compounds have been characterized by IR,1H NMR, and13C NMR spectroscopies along with MS-FAB+spectrometry. The crystal and molecular structure of3Ahas been fully confirmed by single-crystal X-ray studies.In vitrostudies of3A–Bdisplay growth inhibition against leukemia (K-562 CML), colon cancer (HCT-15), breast cancer (MCF-7), central nervous system (U-251 Glio), and prostate cancer (PC-3) cancer cell lines. [ABSTRACT FROM PUBLISHER]

In this research, the cotton fabrics grafted with two generations of the poly(propylene imine) dendrimers were applied to adsorb textile dyes from aqueous solutions. Direct Red 80 (anionic dye), Disperse Yellow 42 (nonionic dye) and Basic Blue 9 (cationic dye) were selected as model dyes. The effect of various experimental parameters such as initial concentration of dyes, charge of dyes molecule, salt and pH was investigated on the adsorption process. Furthermore, kinetics and equilibrium of the adsorption process on the grafted samples were studied. It was found that maximum adsorption of anionic and disperse dyes took place at around pH 3, while cationic dye could be adsorbed at around pH 11. The Langmuir equation was able to describe the mechanism of dyes adsorption. In addition, the second-order equation was found to be fit with the kinetics data. Interestingly, it seems that the dye adsorption of the grafted fabrics is strongly pH dependent. [ABSTRACT FROM AUTHOR]

The convenient methods for the synthesis of new trimethylsilyl esters of aminomethylenediphosphonic acids are elaborated. The new substituted N-formylaminomethylenediphosphonates are obtained via the interaction of trimethylsilyl esters of methylenediphosphonic acids with a mixture of triethyl orthoformate and ethanol. Also boron trifluoride-diethyl etherate as an effective catalyst is used for the interaction of hydrochlorides of ethoxymethylene imines with diethyl trimethylsilyl phosphite. The corresponding aminomethylenediphosphonic acids are presented. [ABSTRACT FROM AUTHOR]

CF3-Substituted ketimines synthesized from trifluoroacetone, hexafluoroacetone, and trifluoroacetophenones were studied in aza-Henry reactions with nitroalkanes. We found that nitromethane and nitropropane react with CF3-substituted ketimines to form the target β-nitroamines in high yield. The aza-Henry reaction proceeded under mild conditions in the presence of an appropriate base. A new simple method for the synthesis of β-nitroamines bearing CF3 group was developed. α-CF3-β-nitroamines can easily be converted into trifluoromethylated 1,2-diamines, α-aminooximes, and imidazolidinones. [ABSTRACT FROM AUTHOR]

Infrared spectra of [Re(X)(CO)3(α-diimine)](α-diimine = 2,2′-bipyridine, X = Cl, NCS, or pyridylimidazo[1,5-a]pyridine, X = Cl) in the ground and the lowest tripletelectronic states were calculated by a global hybrid density functionalgoing beyond the harmonic level by means of second-order vibrationalperturbation theory (VPT2) and including bulk solvent effects by thepolarizable continuum model (PCM). The full-dimensionality (FD) VPT2is compared with the reduced-dimensionality (RD) model, where onlyselected vibrational modes are calculated anharmonically. The simulateddifference IR spectra (excited state minus ground state) in the ν(CO)region closely match experimental time-resolved infrared (TRIR) spectra.Very good agreement was also obtained for ground-state spectra inthe fingerprint region. In comparison with the harmonic simulatedspectra, the calculated anharmonic frequencies are closer to experimentalvalues and do not require scaling when the B3LYP functional is used.Several spectral features due to combination bands have been identifiedby VPT2 simulations in the ν(CO) spectral region, which areof importance for a correct interpretation of TRIR experiments. [ABSTRACT FROM AUTHOR]

Four new series of salicylaldazines 1 and salicylaldimines 2 – 4 were prepared, characterized and their mesomorphic properties were studied. The structures of all compounds were identified and confirmed by spectroscopic techniques such as 1 H, 13 C NMR, MS and elemental analysis. Three single crystallographic structures of compounds 1a ( n =3, 6) and 2 ( n =3) were determined by X-ray analysis in order to correlate the molecular structures with the formation of mesophases. Crystallographic data indicated that the better mesomorphic properties might be controlled by CH–π, π–π or/and H-bonds in such system. Except for crystalline compounds 4 , all other compounds 1 – 3 showed mesomorphic behavior of nematic, smectic A or/and smectic C phases, which were characterized by differential scanning calorimetry, optical polarizing microscope and X-ray diffraction experiments. All compounds 1 – 4 showed yellow–green photoluminescence in THF occurred at 519–521 nm. [ABSTRACT FROM AUTHOR]

A simple and efficient one-pot synthesis of 2,3-disubstituted isoindolinones via the reaction of o -lithiated aromatic imines with carbon monoxide under one atmospheric pressure has been developed. Preliminary in vitro tests for fungicidal activity of these isoindolinone derivatives have been carried out, indicating that most of them exhibit good fungicidal activities. [ABSTRACT FROM AUTHOR]

Two imine compounds, 4-[(E)-(2-methoxybenzylidene)amino]phenol (L 1 ) and 4-[(E)-(3,4-dimethoxybenzylidene)amino]phenol (L 2 ) were synthesized and characterized by the analytical and spectroscopic methods. The electrochemical and photoluminescence properties of the imine compounds L 1 and L 2 were investigated in different solvents. The compounds L 1 and L 2 show different redox processes at some potentials. The molecular structures of two Schiff base compounds are broadly similar, differing principally in the position, the number of methoxy ( OCH 3 ) groups and dihedral angles between aromatic rings. While the compound L 1 has only one methoxy group located on the o -position with respect to the imine bond (C N), the L 2 contains two methoxy groups on the p – m -positions with respect to the imine bond. The imine compounds show two or three emission bands in the 619–832 nm range in organic solvents. In the 1.0 × 10 −3 M concentration, the compounds have the highest excitation and emission bands. The imine compounds L 1 and L 2 were screened for their in vitro cytotoxicity on HeLa cell lines using the xCELLigence system (Real Time Cell Analyzer). [ABSTRACT FROM AUTHOR]

In this work, we show that the sensing performance of graphene based humidity sensors can be largely improved through polymer functionalization. Chemical vapor deposited graphene is functionalized with amine rich polymer, leading to electron transfer from amine groups in the polymer to graphene. The functionalized graphene humidity sensor has demonstrated good sensitivity, recovery, and repeatability. Charge transfer between the functionalized graphene and water molecules and the sensing mechanism are studied systemically using field effect transistor geometry and scanning Kelvin probe microscopy. [ABSTRACT FROM AUTHOR]

An unusually strong affinity of unsupported nanoporous gold (AuNPore) towards aldimines and ketimines has been demonstrated. By using PhMe 2 SiH and water as a hydrogen source and AuNPore as a catalyst, ketimines and aldimines can be reduced to the corresponding amines in high chemical yields under mild conditions. This system was also applied to the reductive amination of aldehydes and ketones. [ABSTRACT FROM AUTHOR]

While N-acetyl-p-benzoquinoneimine(NAPQI), an electrophilic metabolite of acetaminophen (APAP), hasbeen found to undergo GSH conjugation associated with its detoxification,interaction of NAPQI with nucleophilic per- and polysulfides producedby cystathionine γ-lyase (CSE), cystathionine β-synthase,and/or other enzymes is not known. In the present study, we foundthat sulfur adducts such as the NAPQIH2–SSSCys adductand the NAPQIH2–SSG adduct are produced in biologicalsamples of mice upon APAP exposure. Our in vitro experiments indicatedthat the formation of these novel APAP metabolites is, at least inpart, attributable to the interaction of CysSSnSH producedby CSE and GSH persulfide with APAP-derived NAPQI. [ABSTRACT FROM AUTHOR]

A simple and efficient protocol for preparing benzimidazoles via Fe(NO3)3 · 9H2O-catalyzed aerobic oxidation reaction of imine derivatives witho-phenylenediamine. This process uses air as an economical and green oxidant, tolerates a wide range of substrates, and affords the targeted benzimidazoles in moderate to excellent yields. [ABSTRACT FROM PUBLISHER]

Comblike polyethylenimines with varyingdegrees of polymerizationof both the main and side chains as well as different grafting densitieswere evaluated as gene delivery vectors. They were able to condenselinear and plasmid DNA into nanosized polyplex particles with dimensionsand surface potentials in the 130–330 nm and −30 to+15 mV ranges, respectively, depending on the amine/phosphate (N/P)ratio. The polyplexes remained stable in aqueous and buffer solutionsfrom several hours up to several days. The moderate colloidal stabilitywas also manifested in a relatively broad size distribution (PDI typicallyabove 0.2) and structural polymorphism observed by transmission electronmicroscopy. Both the neat polymers and polyplexes displayed low cytotoxicityin WISH cells as the relative cell viability was more than 60%. Experimentswith lysosomal fluorescence staining revealed that the internalizationpathways and, in turn, transfection efficiency of the polyplex nanoparticlesdepended on the polymer chain topology. The vector systems based onthe polymers of denser structure can be considered to be promisingsystems for gene transfection in eukaryotic cells. [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]

Hydrogen production from the dehydrogenation of formic acid (FA) is promising. Most of the current catalysts for FA dehydrogenation are effective only in the presence of bases or additives. We report here newly developed iridium complexes containing conjugated N, N′-diimine ligands for FA dehydrogenation in water without the addition of bases or additives. A turnover frequency (TOF) of 487 500 h−1 with [Cp*Ir( L1)Cl]Cl ( L1=2,2′-bi-2-imidazoline) at 90 °C and a turnover number (TON) of 2 400 000 with in situ prepared catalyst from [IrCp*Cl2]2 and 2,2′-bi-1,4,5,6-tetrahydropyrimidine ( L2) at 80 °C were obtained, the highest values reported for FA dehydrogenation to date. A mechanistic study reveals that the formation of [Ir-H] intermediate species is the rate-determining step in the catalytic cycle. [ABSTRACT FROM AUTHOR]

A brief overview of the synthesis of 1,2-diamines using hydroamination reaction of alkenes is presented herein. In addition, the most recent breakthrough in this field showcasing the intermolecular hydroamination of N-allyl imines is discussed. [ABSTRACT FROM AUTHOR]

A simple, cheap, efficient, and metal-free method for one-step synthesis of a library of 1,3-diheteroatom five-membered heterocycles with exocyclic C N and C C double bonds was presented. The convenient reactions proceed via the direct three-component halocyclization of propargylamines, heterocumulenes and I 2 (NBS). [ABSTRACT FROM AUTHOR]

Five copper(II) complexes, [Cu(sal-Gly)(bipy)]( 1 ), [Cu(sal-Gly)(phen)] ( 2 ), [Cu(sal- l -Ala)(phen)] ( 3 ), [Cu(sal-D-Ala)(phen)] ( 4 ), [Cu(sal- l -Phe)(phen)] ( 5 ) and five oxidovanadium(IV) complexes, [V IV O(sal-Gly)(bipy)] ( 6 ), [V IV O(sal-Gly)(phen)] ( 7 ), [V IV O(sal- l -Phe)(H 2 O)] ( 8 ), [V IV O(sal- l -Phe)(bipy)] ( 9 ), [V IV O(sal- l -Phe)(phen)] ( 10 ) (sal = salicylaldehyde, bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline) were synthesized and characterized, and their interaction with DNA was evaluated by different techniques: gel electrophoresis, fluorescence, UV–visible and circular dichroism spectroscopy. The complexes interact with calf-thymus DNA and efficiently cleave plasmid DNA in the absence (only 2 and 5 ) and/or presence of additives. The cleavage ability is concentration-dependent as well as metal and ligand-dependent. Moreover, DNA binding experiments show that the phen-containing Cu II and V IV O compounds display stronger DNA interaction ability than the corresponding bipy analogues. The complexes present cytotoxic activity against human ovarian (A2780) and breast (MCF7) carcinoma cells. Cell-growth inhibition (IC 50 ) of compounds 1 , 2 and 5 in human promyelocytic leukemia (HL60) and human cervical cancer (HeLa) cells were also determined. The copper complexes show much higher cytotoxic activity than the corresponding vanadium complexes and the reference drug cisplatin (except for the sal-Gly complexes); namely, the phenanthroline copper complexes 2 – 5 are ca. 10-fold more cytotoxic than cisplatin and more cytotoxic than their bipyridine analogues. [ABSTRACT FROM AUTHOR]

Phenolic compounds are known as antioxidant and/or radical scavengers via H-atom transfer or single electron transfer pathway. Density functional theory (DFT) calculations have been performed on some phenolic aldehydes and some of their designed diimine derivatives with different spacer lengths. Both H-atom transfer and single electron transfer pathways have been investigated by calculating the phenolic O–H bond dissociation energy (BDE) and vertical ionization potentials (IP V ). Moreover, the polarity of the solvent medium has been included in calculating BDE and IP V . The radical scavenging activity of these derivatives has been compared with 1,1-diphenyl-2-picrylhydrazyl (DPPH ) free radical. [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]

In this study, we developed 3-/4-aminoacetophenones and their structure-based 3-/4-aminophenylethylidenethiosemicarbazide derivatives, respectively, as novel tyrosinase activators and inhibitors. Notably, all the obtained thiosemicarbazones displayed more potent tyrosinase inhibitory activities than kojic acid. Especially, compound 7k was found to be the most active tyrosinase inhibitor with IC 50 value of 0.291 μM. The structure-activity relationships (SARs) analysis showed that: (1) the amine group was absolutely necessarily for determining the tyrosinase activation activity; (2) the introduction of thiosemicarbazide group played a very vital role in transforming tyrosinase activators into tyrosinase inhibitors; (3) the phenylethylenethiosemicarbazide moiety was crucial for determining the tyrosinase inhibitory activity; (4) the type of acyl group had no obvious effect on the inhibitory activity; (5) the position of amide substituent on the phenyl ring influenced the tyrosinase inhibitory potency. Moreover, the inhibition mechanism and inhibition kinetics study revealed that compound 7k was reversible and non-competitive inhibitor, and compound 8h was reversible and competitive-uncompetitive mixed-II type inhibitor. [ABSTRACT FROM AUTHOR]

Harmful Algal Blooms (HAB) are complex to manage due to their intermittent nature and their severe impact on the economy and human health. The conditions which promote HAB have not yet been fully explained, though climate change and anthropogenic intervention are pointed as significant factors. The rise of water temperature, the opening of new sea canals and the introduction of ship ballast waters all contribute to the dispersion and establishment of toxin-producing invasive species that promote the settling of emergent toxins in the food-chain. Tetrodotoxin, ciguatoxin, palytoxin and cyclic imines are commonly reported in warm waters but have also caused poisoning incidents in temperate zones. There is evidence that monitoring for these toxins exclusively in bivalves is simplistic and underestimates the risk to public health, since new vectors have been reported for these toxins and as well for regulated toxins such as PSTs and DSTs. In order to avoid public health impacts, there is a need for adequate monitoring programs, a need for establishing appropriate legislation, and a need for optimizing effective methods of analysis. In this review, we will compile evidence concerning emergent marine toxins and provide data that may indicate the need to restructure the current monitoring programs of HAB. [ABSTRACT FROM AUTHOR]

Starting from 2-aminobenzyl alcohols and 1,2-amino alcohols, 2,3,4,5-tetrahydro-1 H-1,4-benzodiazepines (TH-BDZ) can be prepared through a one-pot ruthenium-catalyzed reaction encompassing two consecutive borrowing hydrogen cycles. First, benzyl alcohol oxidation, condensation with the amino alcohol, and imine reduction occurs. This is followed by oxidation of the other alcohol functionality and reductive cyclocondensation to give the TH-BDZ derivatives. A single catalyst does the entire job, with two molecules of water being the only waste product. Many new substituted 2,3,4,5-tetrahydro-1 H-1,4-benzodiazepines have been prepared to demonstrate the versatility of this method, which can be used for the preparation of privileged scaffolds for drug discovery. [ABSTRACT FROM AUTHOR]

Organomagnesium reagents enable swift and versatile derivatisation of diarylimines to the corresponding a-substituted diarylmethylamines in excellent yields, through fast and clean reactions. Where it occurs, 1,2-reduction can be circumvented using readily accessible dialkylmagnesium reagents. [ABSTRACT FROM AUTHOR]

A highly enantioselective Mannich reaction of silyl ketene imines with isatin-derived ketimines has been realized by using a chiral N, N′-dioxide/ZnII catalyst. A variety of β-amino nitriles containing congested vicinal tetrasubstituted stereocenters were obtained with excellent outcomes (up to 98 % yield, >19:1 d.r. and 99 % ee). Based on the experimental investigations, a possible transition state has been proposed to explain the origin of the asymmetric induction. [ABSTRACT FROM AUTHOR]

Air-stable P-chiral dihydrobenzooxaphosphole oxazoline ligands were designed and synthesized. When they were used in the iridium-catalyzed asymmetric hydrogenation of unfunctionalized 1-aryl-3,4-dihydronaphthalenes under one atmosphere pressure of H2, up to 99:1 e.r. was obtained. High enantioselectivities were also observed in the reduction of the exocyclic imine derivatives of 1-tetralones. [ABSTRACT FROM AUTHOR]

Highly linear selective, imine-directed hydroarylation of styrene has been achieved with cobalt-based catalytic systems featuring bis(2,4-dimethoxyphenyl)(phenyl)phosphine and either 2-methoxypyridine or DBU as a ligand and a Lewis base additive, respectively, thus affording a variety of 1,2-diarylethanes (bibenzyls) in good yields under mild reaction conditions. The triarylphosphine controls the regioselectivity, while the Lewis base significantly accelerates the reaction. Ligand screening and deuterium-labeling studies provide implications about the roles of the ligand and the Lewis base in the crucial CC reductive elimination step. [ABSTRACT FROM AUTHOR]

ONIOM method was used to investigate the mechanism of chiral phosphoric acid-catalyzed Friedel–Crafts reactions of pyrrole derivatives and imines. In the reaction of imine with pyrrole, regarding to the step of the regeneration of the chiral phosphoric acid catalyst has not been discussed in details. We are interested in how the chiral phosphoric acid regains the proton in this reaction. Through our results, the catalyst gets back a proton from the C H bond of pyrrole, not from the N H bond of pyrrole. In the real system of imine and N-methylpyrrole reaction, the most stable structure of TS2 is the ( R )-product with its Si face, which is formed by N-methylpyrrole with E - s - cis imine with the high ee value 90%. [ABSTRACT FROM AUTHOR]

Calixarene–iminosugar derivatives bearing four 1-deoxynojirimycin units at the upper or lower rim of calix[4]arenes in a fixed cone conformation were synthesized by copper-catalyzed azide-alkyne cycloaddition (CuAAC) and their inhibitory activity was evaluated against five glycosidases. Modest but significant affinity enhancements of up to seven per 1-deoxynojirimycin unit over the monovalent iminosugar derivative were observed for the inhibition of Jack bean ( Canavalia ensiformis ) α-mannosidase. It was also demonstrated that the residual copper ions did not contribute to the inhibitory properties of the newly prepared calixarene-based multivalent iminosugars. [ABSTRACT FROM AUTHOR]

Two imine derivatives of chitosan (i -CTs), namely 2FCT and 5MCT, were synthesized by reacting chitosan (CT) with 2-(3-formyl-1 H -indol-1 yl)acetonitrile (2F), and 5-methoxyindole-3-carbaldehyde (5M), respectively. The antimicrobial evaluation of i -CTs exhibited stronger inhibition effect against Staphylococcus aureus , Escherichia coli and Candida albicans. The antioxidant activity of 2FCT and 5MCT showed strong scavenging ability with IC 50 2.31 and 6.92 μg/mL, respectively. The results of in vitro cytotoxicity of 2FCT and 5MCT examined using human monocyte leukemia (THP-1) cells indicate no cytotoxic effect on host cells and the value of cell viability was found to be 87.08 and 84.47%, respectively. Measurement of intracellular Reactive Oxygen Species (ROS) production by flow cytometry analysis revealed that the 2FCT and 5MCT reduced the ROS generation by 83 and 43%, respectively. In summary, these findings show that i -CTs synthesized to be promising biomaterial for biomedical applications such as wound healing. [Display omitted] [ABSTRACT FROM AUTHOR]

C20H20Cl2N2O5Ru, monoclinic, P1̅ (no. 2), a = 8.7921(2) Å, b = 11.2515(3) Å, c = 11.7014(3) Å, α = 103.752(1)°, β = 107.296(1)°, γ = 98.562(1)°, V = 1043.01(5) Å3, Z = 2, Rgt( F) = 0.0198, wRref( F2) = 0.0553, T = 173 K. [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.

The direct electrophilic trifluoromethylation of silyl ketene imines (SKIs) with hypervalent iodine reagents leads to the formation of quaternary α-trifluoromethyl nitriles in good yields. This new reaction has been carried out with a variety of substituted SKIs under solvent-free conditions using a vanadium(IV) catalyst (5 mol %). The corresponding products may be transformed into useful organofluorine building blocks. [ABSTRACT FROM AUTHOR]

Highly enantioselective [3+2] coupling of 3-substituted indoles with quinone monoimines promoted by a chiral phosphoric acid has been reported. A large variety of benzofuroindolines were prepared in moderate to good yields (up to 98%) with generally excellent enantioselectivities (up to 99% ee). [ABSTRACT FROM AUTHOR]

An unprecedented [3+2] cycloaddition between N-tert-butanesulfinyl imines and arynes provides a stereoselective method for the synthesis of cyclic sulfoximines. Not only does the difluoro(phenylsulfonyl)methyl group play an important role in facilitating the cycloaddition reaction, it can also be removed or substituted through the transformation of the difluorinated cyclic sulfoximines to cyclic sulfinamides. [ABSTRACT FROM AUTHOR]

The Pd(II)-catalyzed oxidative [3+2] cycloaddition of N-(2-pyridyl) ketoimines with internal alkynes has been developed. The transformation is tolerant of extensive substitution on halogen, alkene, alkyne, hydroxyl, aryl and acyl groups, and allows facile assembly of multisubstituted pyrroles. [ABSTRACT FROM AUTHOR]

An electron-transfer series of octahedral a-diimine complexes [HLCy3Cr]n+(BARF)n (n =2,1,0 ) has been synthesized and crystal-lographically characterized. Cyclic voltammetry indicated additional formation of [(H LCy)3Cr]3+. The molecular structures suggested that all redox processes were ligand-based. Magnetic moments were consistent with spin ground states of S =0 for [HLCy3Cr]0, S =½n for [HLCy3Cr]+1, and S =1 for [H LCy3 Cr]+2. The experimental data is consistent with chromium maintaining the +III oxidation state throughout, while being coordinated by varying numbers of neutral diimines (HLCy) and diimine radical anions (HLCy•-). [ABSTRACT FROM AUTHOR]

The gas-phase behavior of 12 quinolon-4( 1H)-imine derivatives with antiplasmodial activity was investigated using electrospray ionization tandem mass spectrometry together with collision induced dissociation and density functional theory (DFT) calculations. The most probable protonation site was predicted by calculating the proton affinity (PA) values for each possible protonation site and it was found to be the imine nitrogen for all compounds under study. Fragmentation pathways of the protonated molecules were proposed and the assignment of product ion structures was performed taking into account theoretical calculations. The nature of the quinoline substituent was found to influence the gas-phase behavior of the compounds under study. The data acquired allowed to bracket the proton affinity of the quinolin-4-imine scaffold, which can be a useful starting point to choose appropriate references for determining PA values of this scaffold. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]