One-pot Synthesis of MoO_(3)/PI Composite with Enhanced Photocatalytic Performance for Oxidative Coupling of Amines to Imines

Organic-inorganic MoO_(3)/PI(MoPI)composites were prepared using a simple one-pot thermal copolymerization method.The resulting composites exhibited enhanced photocatalytic activity for the selective oxidation of benzylamine to N-benzylidene benzylamine(N-BDBA)in ambient air under simulated solar light irradiation compared to pristine MoO_(3) or polyimide(PI).In particular,the MoPI composite with a 0.3:1 molar ratio of Mo to melamine,referred to as MoPI-0.3,demonstrated the best performance in the photo-oxidation of benzylamine,achieving a benzylamine conversion of 95%with a N-BDBA selectivity exceeding 99%after 3 h irradiation.The enhanced photocatalytic activity of the MoPI-0.3 catalyst was attributed to the formation of a direct Z-scheme heterojunction between MoO_(3) and PI,facilitating more efficient separation of the photoinduced electrons and holes.Additionally,the MoPI-0.3 composite maintained considerably high activity over four consecutive cycles,highlighting its good stability and recyclability.Furthermore,the MoPI-0.3 composite could photo-oxidize benzylamine derivatives and heterocyclic amines to their corresponding imines,demonstrating the universal applicability of this composite catalyst.

A Metal-free Polyimide Photocatalyst for the Oxidation of Amines to Imines

Polyimide(PI) is an organic polymer material with good stability and diverse sources that has attracted widespread attention in the field of photocatalysis. In this study, a series of PI photocatalysts were synthesized by a thermal polymerization approach using pyromellitic dianhydride(PMDA) and various diamine monomers(melamine(MA), 4,4′-oxydianiline, and melem) as the precursors as well as different heating rates. The effects of the diamine precursor and heating rate on the structure, composition, morphology, and optical properties of the as-prepared PI materials were systematically investigated by various characterization techniques. The selective photo-oxidation of benzylamine was used as a model reaction to evaluate the photocatalytic activities of the resulting PI samples for the oxidation of amines to imines. The results revealed that the PI sample prepared using MA and PMDA as the precursors and a heating rate of 7 ℃/min(MA-PI-7) exhibited the best catalytic performance, with 98% benzylamine conversion and 98% selectivity for N-benzylidene benzylamine after 4 h of irradiation. Several benzylamine derivatives and heterocyclic amines also underwent the photo-oxidation reaction over the MA-PI-7 catalyst to afford the corresponding imines with good activity. In addition, MA-PI-7 exhibited good stability over four successive photocatalytic cycles.

Crystal Structure of 1-Phenyl-1,3-butandione Benzidine Diketoimine

1-Phenyl-1,3-butandione benzidine diketoimine 2a （C32H28N2O2, Mr = 472.56） was synthesized in high yield by the reaction of 1-phenyl-1,3-butandione with benzidine in absolute ethanol, and determined by X-ray structure analysis. It crystallizes in the orthorhombic system, space group P21/c with a = 7.9839（16）, b = 12.910（3）, c = 12.358（3）A, α = 90.00, β= 93.71（3）,γ = 90.00°, V = 1271.1（4） A3, Z = 2, Dc = 1.235 g/cm^3,/1 = 0.077 mm^-1, F（000） = 500, the final R = 0.0717 and wR = 0.1187. It presents a linear centrosymmetric framework constituted by a linkage of benzidine as a bridge and two terminal 1-phenyl-1,3-butanedione moieties.

Synthesis and plant-growth regulatory activities of novel imine derivatives containing 1H-1,2,4-triazole and thiazole rings

Eleven new imine derivatives 6 containing 1H-1,2,4-triazole and thiazole rings were synthesized by the condensation of 5-((1H- 1,2,4-triazol-1-yl)methyl)-4-tert-butylthiazol-2-amine with various substituted benzaldehydes.The structures of the title compounds were characterized by ~1H NMR,MS and elemental analysis.The plant-growth regulatory activities of these compounds were evaluated.The primary bioassay results indicated that these target compounds exhibited promising plant-growth regulatory activities.

Addition of Allyltrimethylsilane to tert-Butanesulfinyl Imines Triggered by Tetra-n-butylammonium Fluoride

The addition of allyltrimethylsilane to tert-butanesulfinyl imines triggered by tetra-n-butylammonium fluoride （TBAF） in the presence of 4A molecular sieves has been studied, and homoallylsulfinamides were obtained in good yields with moderate to high diastereoselectivities.

Modification of Norditerpenoid Alkaloids:Ⅱ.A Simple andConvenient Preparation of the Imine Derivatives of Norditerpenoid Alkaloids

Treatment of 3-acetylpseudaconie 6 and 3. 13-diacetylyunnaconitine 9 withNBS/acetone-H2O(2:1) at room temperature produced corresponding imine derivatives & and 10.respectively. in good yields. This is a novel simple and convenient method for preparation of theimine compounds.

Controllable synthesis of novel nanoporous manganese oxide catalysts for the direct synthesis of imines from alcohols and amines

A novel template-free oxalate route was applied to synthesize different mesoporous manganese oxides(amorphous manganese oxide(AMO),Mn5 O8,Mn3 O4,Mn O2)in the narrow temperature range from 350°C to 400°C by controlling the calcination conditions,which were employed as the efficient catalysts for the oxidative coupling of alcohols with amines to imines.The chemical and structural properties of the manganese oxides were characterized by the methods of thermogravimetry analysis and heat flow(TG-DSC),X-ray diffraction(XRD),nitrogen sorption,scanning electron microscope(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),H2 temperature-programmed reduction(H2-TPR),and inductively coupled plasma optical emission spectrometry(ICP-OES)techniques.The structures of different manganese oxides were confirmed by characterization.The M-350(AMO)presented the maximum surface area,amorphous nature,the lowest reduction temperature,the higher(Mn3++Mn4+)/Mn2+ratio,and the higher adsorbed oxygen species compared to other samples.Among the catalysts,M-350 showed the best catalytic performance using air as an oxidant,and the conversion of benzyl alcohol(BA)and the selectivity of N-benzylideneaniline(NBA)reached as high as 100%and 97.1%respectively at the lower reaction temperature(80°C)for 1 h.M-350 had also the highest TOF value(0.0100 mmol·mg-1·h-1)compared to the other manganese oxide catalysts.The catalyst was reusable and gave 95.8%conversion after 5 reuse tests,the XRD pattern of the reactivated M-350 did not show any obvious change.Lattice oxygen mobility and(Mn3++Mn4+)/Mn2+ratio were found to play the important roles in the catalytic activity of aerobic reactions.

Relative Stability of the Key Enamine,Oxazolidinone,and Imine Intermediates in Some Proline-catalyzed Asymmetric Reactions

Many proline-catalyzed asymmetric addition reactions with ketones as substrates were assumed to involve a key intermediate, an enamine, produced by the condensation of proline and ketone. In this paper, the key intermediate enamines derived from L-proline and cyclohexanone （or acetone） as well as the corresponding oxazolidinone and imine tautomers have been investigated by means of density functional calculations at the B3LYP/6-311＋G^＊＊ level. The predicted order of stability for these tautomers is oxazolidinones 〉 enamines 〉 imines in gas phase and oxazolidinones 〉 imines 〉 enamines in aprotic THF solvent. This prediction explains why enamine intermediate can not be observed experimentally. The predicted energy/enthalpy difference between the formal oxazolidinone structure and the zwitterionic imine structures is very small in THF solvent, suggesting the oxazolidinone-to-imine tautomerization can be readily induced in solvent. ^13C NMR chemical shifts of the oxazolidinone and imine structures have been computed and used to explain the experimental NMR spectra observed in oxazolidinone-to-imine tautomerization induced by protic solvent.

The synthesis of boronic-imine structured compounds and identification of their anticancer, antimicrobial and antioxidant activities

Boronic acid compounds with different substituted groups were handled to synthesize various ligands encoded as B1, B2, B3, B4, BS, B6, B7 and BS. B5 and B7 were tested for the cytotoxic activity against the prostate cancer cells and it was found that the cell viability of cancer cells was decreased while most of the healthy cells could still be viable. 5 μM solutions of B5 and B7 decreased the cell viability to 33% and 44%; whereas healthy cells were 71% and 95%, respectively, after treatment. Antimicrobial properties were explored against the bacterial and fungal microorganisms with B1, B5 and BZ The inhibition zones were evaluated for all boronic structures, and the growth inhibition zones were determined in a range of 7-13 mm diameter for different microorganism species. Staphylococcus aureus was the common micro- organism that three boronic compounds with imine ligands showed the activity. Antioxidant features of B2, B3, B4, B5, B6, B7 and B8 were investigated by different processes such as Beta-carotene bleaching （BCB）, 2,2-diphenyl picryl hydrazyl （DPPH）, 2,2″-azino-bis（ 3-ethylbenzothiazoline-6-sulphonic acid） （ABTS） and CUPric reducing antioxidant capacity （CLIPRAC） methods. Significant antioxidant activity was achieved by the phenyl boronic based ligands and these compounds demonstrated as much activity as standards （α-Toc and BHT）. In addition, all structures were applied properly without any decomposition during the experiments. They were rather stable both in aqueous media and solid state.

Photochemical Reduction of Aromatic Imines by 2-Phenyl-N, N-dimethylbenzimidazoline

A series of aromatic imines were reduced to corresponding amines in excellent yields by 2-phenyl-N. N-dimethylbenzimidazoline (PDMBI) photochemically in the presence of magnesium perchloride (Mg(ClO4)(2)). A Mg2+ mediated photoinduced electron transfer mechanism was proposed.

Study on Unexpected Cycloaddition Reactions of Imines with THF

An unexpected tricyclic compound 2,3,3a,4,5,9b-hexahydrophenylfuro[3.2-c] quinoline 4 and its aromatized product 6 were obtained when the cycloaddtion of imine 1 and substituted norbornene 2 was carried out in THF with a catalytic amount of boron trifluoride. The structures of the products were determined by spectral data and the mechanism of reaction was substantiated by the imitation reaction.

Synthesis and Crystal Structure of a Degraded Dehydroabietylamine Thiophene Imine

A degraded dehydroabietylamine thiophene imine （C24H30NS, Mr = 364.55） has been synthesized from dehydroabietic acid, and its structure was characterized by IR, IH NMR spectroscopy and single-crystal X-ray diffraction. White crystals of the title compound crystallize in the monoclinic system, space group P21 with a = 5.9490（12）, b = 16.337（3）, c = 10.780（2）A, β = 92.21（3）°, V = 1046.9（3）A^3, Z = 2, Dc = 1.156 g/cm^3, λ= 0.71073A,μ = 0.162 mm^-1, F（000） = 394, the final R = 0.0443 and wR = 0.0805 for 1325 observed reflections with I 〉 2σ（I）. The imine group was directly attached to the chiral carbon atom of tricyclo hydrophenthenrane structure with a trans configuration. The dihedral angle between two aromatic rings is 88.3°.

Perfect Solvent- and Catalyst-Free Syntheses of Imine Derivatives Using the Pressure Reduction Technique

In the field of organic syntheses, the development of environmentally friendly methods based on the concept of green chemistry has been always required. In response to this requirement, we reported solvent- and catalyst-free syntheses of imines using the pressure reduction technique as a key technology. We found that this reaction proceeded very rapidly in the initial stage, but its rate decreased with the passage of time. It was also found that the reaction of benzaldehyde with aniline had a specificity that the phase transition occurred. In this method, the desired imines could be obtained in good to excellent yields, but target compounds had to be given by purifications using organic solvents. Therefore, we tried to develop the perfect synthetic method of imine derivatives without organic or inorganic solvents. We selected two methods and took them into this investigation. One was exactly mixing (1:1, substance ratio) aldehydes and amines and the other was employing lower pressure (>0.1 mmHg, previous method: 1.0 mmHg) at the pressure reducing technique. When this improved synthetic method was performed, it was revealed that pure target imines were obtained in excellent yields without any purification.

SYNTHESIS AND CHARACTERIZATION OF PALLADIUM COORDINATING IMINE SIDE CHAIN LIQUID CRYSTALLINE POLYSILOXANES

New thermotropic chloro-bridged dinuclear palladium coordinating imine side chain liquid crystalline polysiloxanes have been synthesized. Their mesomorphic properties have been investigated by DSC, X-ray diffraction and polarizing microscopy. The polymeric complexes show nematicdiscotic (Nd) mesophase. It is found that the temperature range of liquid crystalline state of chloro- bridged polymeric complexes is much wider than that of acetato- bridged ones and imine side chain polysiloxane. This indicates that the disc-like chloro-bridged palladium complexing units play a role as mesogen in mesophase.

THE ASYMMETRIC ALKYLATIONS OF CHIRAL TRANSITION METAL COMPLEXES OF(+)—CAMPHOR IMINE

The asymmetric alkylations of chiral transition metal complexes derived from (+)-camphor and 2-aminomethyl-6-methylpyridine were examined under mild conditions.The formation of the complexes 2 is conductive to the enhancement of di- astereoselectivity in the alkylations at room temperature.

Efficient Solvent- and Catalyst-Free Syntheses of Imine Derivatives Applying the Pressure Reduction Technique: Remarkable Change of the Reaction Rate with the Phase Transition

Because imines could be used as convenient starting materials in various fields, the development of an easy synthetic method of imine was strongly desired. In response to this demand, we thought that it would be an effective synthesis method if an aldehyde and an amine could be reacted to give an imine in good yield under solvent- and catalyst-free conditions. In fact, we tried the reaction of benzaldehyde with various amines under solvent- and catalyst-free conditions followed by removal of water that was produced in the reaction system by a vacuum pump, and desired imines could be obtained in good yields. Observation of this reaction using a nuclear magnetic resonance spectrometer revealed that the reaction rate was extremely fast at the initial stage but slowed over time. However, the reaction of benzaldehyde with aniline differed greatly, and the reaction rate dramatically improved in 47 - 48 minutes after the start of the reaction. At this time, we found that the reaction system underwent a phase transition from the liquid phase to the solid phase.

Environmentally Friendly Syntheses of Imines Applying the Pressure Reduction Technique: Reaction Cases of Less Reactive Amines and Studies by Computational Chemistry

Recently, the development of environmentally friendly syntheses of imine derivatives, which were attracting great attention for their reactivity and structure in various fields, progressed rapidly because the concept of green chemistry had deeply penetrated into society. In our previous work, we had reported new synthetic methods of imine derivatives using some active amines under solvent- and catalyst-free reaction conditions. This synthetic reaction proceeded smoothly and target compounds were obtained in excellent yields. In this system, when less reactive amines were used as substrates, the synthetic reaction was not finished in the short reaction time, and the corresponding compounds were given in moderate yields. In order to solve this point, we tried to improve the reaction conditions of this method. Through this improvement, it was found that pure target compounds could be obtained in excellent yields by using 1.1 equivalents of less reactive amines to aldehydes and extending the reaction time compared with our previous work. In this paper, we will introduce the detail of this study, and also report the result of the investigation of the reaction property by computational chemistry.

Mannich-Type Reaction of Aldimines with 2-Silyloxydienes Catalyzed by Ammonium Chloride

Reaction of imines with 2-silyloxydiene catalyzed by ammonium chloride has been perfectly proceeded under environmentally friendly conditions to give Mannich-type product selectively. The reaction would proceed via Mannich-type mechanism, not cyclization/ring-opening process. Cyclopropanation of the corresponding Mannich-type product gave the precursor of prasugrel skeleton in high yield.

New Strategy for Chemically Attachment of Imine Group on Multi-Walled Carbon Nanotubes Surfaces: Synthesis, Characterization and Study of DC Electrical Conductivity

This paper used a new approach of preparing poly-composites by covalent linkage between the MWCNT’s by imine group. The Poly (Imine)/MWCNT Composite was synthesized by the solution blending method from reacted amino multi-walled carbon nanotubes (MWCNT-NH2) with Terephthalaldehyde (TPAL). The obtained poly-composite was characterized by FT-IR, UV-Vis, XRD, TEM, SEM, TGA, DSC and DC electrical conductivity. The formation of Poly (Imine)/MWCNT composite was confirmed. The DC electrical conductivity of poly-composites was within the range 2.3 × 10–4 - 5.3 × 10–4 S/cm due to the interaction between the nanotubes.

Carbohydrate-Derived Organocatalysts for the Reduction of Imines with Trichlorosilane

The backbone of D-glucosamine hydrochloride was fine-tuned and modified by protecting the hydroxyl groups. In order to reduce imines with trichlorosilane, the carbohydrate-derived organocatalysts were prepared and screened. Methyl-4,6-O-benzylidene-2-amino-2-deoxy-α-D-glucopyr anoside was found as the best catalyst. The reduction was proceeded under CHCl3 as solvent at 40?C, affording 68% - 94% yield.