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The cross-coupling of C-N bond directly from inert C-H bonds is an ideal approach to synthesize saturated azacycles due to its high efficiency and atom economy. In this article, a copper-catalyzed intramolecular amination via the cross coupling of C(sp3)-H and N-H bonds of secondary amine has been reported, which exhibit excellent chemo- and regioselectivity, extensive substrate scope, and functional group tolerance in good to excellent yield, offering an efficient pathway to build nitrogen-containing heterocycle skeletons.

A general and practical regioselective approach for the C-H amination of 2H-indazoles under transition-metal-free conditions was developed. A series of substrates were tested showing eminent functional group tolerance and affording the C-N functionalization products in good to excellent yields. Mechanism studies revealed that a radical process was involved in this transformation.

A strategy for one-pot synthesis of isoindoles is describedviaa catalytic multicomponent dehydrogenative annulation of diarylimines, vinyl ketones and simple amines. In the presence of a rhodium catalyst and Cu oxidant, four C-H and two N-H bonds are activated along with the formation of one new C-C and two new C-N bonds, leading to a series of isoindole derivatives in good to very high isolated yields.

Visible-light-induced one-pot, multistep, and chemoselectivity adjustable reactions highlight the economical, sustainable, and green process. Herein, we report Pt nanoparticles dispersed on S and N co-doped titanium dioxide/titanium carbide (MXene) (3%Pt/

Schiff bases that are generally formed from condensation reactions of aldehydes (or ketones) and amino groups could also be produced by a photodriven one-pot tandem reaction between alcohols and nitro compounds, in our case. Herein, TiO2-x porous cages derived from NH2-MIL-125 by a self-sacrificing template route are used to study the organic transformation and exhibit 100% conversion efficiency of nitrobenzene and 100% selectivity for Schiff bases in the system of benzyl alcohol (5 mL) and nitrobenzene (41 μL) upon light irradiation, but hydrogen by dehydrogenation of benzyl alcohol cannot be detected. Successful occurrence of the organic transformation is mainly attributed to Ti(III)-oxygen vacancy associates. Surface oxygen vacancy-related Ti(III) sites are responsible for binding with nitro groups, and low-coordinated Ti5c sites selectively adsorb hydroxyl groups of benzyl alcohol. The Ti(III) and oxygen vacancy associates capture photogenerated electrons for achievement of multielectron reduction of nitrobenzene and the subsequent Schiff base condensation reaction with the as-formed benzaldehyde.

The selective synthesis of imines from biomass-derived chemicals over heterogeneous non-noble metal catalysts is of great importance for organic transformation. Herein, non-noble heterogeneous nitrogen-doped carbon supported Ni catalysts (abbreviated as Ni/CN-MgO-T, whereTrepresents the pyrolysis temperature) have been facilely prepared from the simple pyrolysis of Ni precursors and biomass, and Ni/CN-MgO-600 with the smallest size of Ni nanoparticles demonstrated the highest catalytic activity. The reductive coupling of nitroarenes and carbonyl compounds could be performed under mild conditions (80 °C, and 10 bar H2), affording structurally-diverse imines with high to excellent yields (84.2-98.1%). Thanks to the mild reaction conditions, the developed method showed good tolerance to other functional groups such as nitriles, halogen and vinyl groups.

A straightforward and selective reduction of nitroarenes with various alcohols was efficiently developed using an iron catalyst via a hydrogen transfer methodology. This protocol led specifically to imines in 30-91% yields, with a good functional group tolerance. Noticeably, starting from o-nitroaniline derivatives, in the presence of alcohols, benzimidazoles can be obtained in 64-72% yields when the reaction was performed with an additional oxidant, DDQ, and quinoxalines were prepared from 1,2-diols in 28-96% yields. This methodology, unprecedented at iron for imines, also provides a sustainable alternative for the preparation of quinoxalines and benzimidazoles.

One-pot tandem synthesis of imines from alcohols and amines is regarded as an effective, economic and green approach under mild conditions. In this work, Au nanoparticles (NPs) dispersed on MIL-101 (Au/MIL-101) were demonstrated as highly active and selective bifunctional heterogeneous catalyst for production of various imine derivatives with excellent yields, via amine-alcohol cross-coupling reaction at 343 K in an open flask under an Ar atmosphere. Various physicochemical techniques, including inductively coupled plasma optical emission spectroscopy (ICP-OES), powder X-ray diffraction (P-XRD), X-ray photoelectron spectroscopy (XPS) transmission electron microscopy (TEM) and N2 adsorption-desorption, were used to characterize of the Au/MIL-101 catalyst. The obtained bifunctional catalyst is highly active and selective towards one-pot imine formation and exhibited the highest TOF (30.15-51.47 h?1) among all the ever-reported MOF-supported Au catalysts. The reaction mechanism of the imine formation from alcohol and amine over Au/MIL-101 catalyst was proposed. Mechanism experiment results demonstrate that Au NPs highly effective in activating oxidation of benzyl alcohol to benzaldehyde while the Lewis acid sites on MIL-101 catalyzed the second condensation step without interfering with the oxidation step. As a result, the excellent catalytic performance of Au/MIL-101 can be ascribed to the synergistic effect between Au NPs with Lewis acid sites in MIL-101.

High-surface-area mesoporous CeO2 (hsmCeO2) was prepared by a facile organic-template-induced homogeneous precipitation process and showed excellent catalytic activity in imine synthesis in the absence of base from primary alcohols and amines in air atmosphere at low temperature. For comparison, ordinary CeO2 and hsmCeO2 after different thermal treatments were also investigated. XRD, N2 physisorption, UV-Raman, H2 temperature-programmed reduction, O2 temperature-programmed desorption, EPR spectroscopy, and X-ray photoelectron spectroscopy were used to unravel the structural and redox properties. The hsmCeO2 calcined at 400 °C shows the highest specific surface area (158 m2 g?1), the highest fraction of surface coordinatively unsaturated Ce3+ ions (18.2 %), and the highest concentration of reactive oxygen vacancies (2.4×1015 spins g?1). In the model reaction of oxidative coupling of benzyl alcohol and aniline, such an exceptional redox property of the hsmCeO2 catalyst can boost benzylideneaniline formation (2.75 and 5.55 mmol (Formula presented.) h?1 based on >99 % yield at 60 and 80 °C, respectively) in air with no base additives. It can also work effectively at a temperature of 30 °C and in gram-scale synthesis. These are among the best results for all benchmark ceria catalysts in the literature. Moreover, the hsmCeO2 catalyst shows a wide scope towards primary alcohols and amines with good to excellent yield of imines. The influence of reaction parameters, the reusability of the catalyst, and the reaction mechanism were investigated.

Switchable imine and amine synthesis catalyzed by a tripodal ligand-supported well-defined cobalt complex is presented herein. A large variety of primary alcohols and amines were selectively converted to imines or amines in good to excellent yields. It is discovered that the base plays a crucial role on the selectivity. A catalytic amount of base leads to the imine formation, while an excess loading of base results in the amine product. This strategy on product selectivity also strongly depends on the organometallic catalysts in use. We expect that the present study could provide useful insights toward selective organic synthesis and catalyst design.

Direct oxidative coupling of alcohols with amines using a non-precious metal oxide catalyst under mild conditions is highly desirable for imine synthesis. In this work, a mesoporous Mn1ZrxOysolid solution catalyst prepared by a co-precipitation method showed excellent catalytic performance in imine synthesis from primary alcohols and amines without base additives in an air atmosphere. XRD, N2physisorption, H2-TPR, O2-TPD, EPR and XPS were comprehensively used to unravel its structural, redox and amphoteric properties that closely depended on the interaction between MnOyand ZrO2with a variable Zr ratio. The Mn1Zr0.5Oycatalyst presented the highest fractions of Mn3+ions and reactive oxygen species on the surface, and the highest concentrations of acidic-basic sites, which were disclosed to play important roles in activating alcohols and molecular O2in the rate-determining step. In the model reaction of oxidative coupling of benzyl alcohol with aniline, such enhanced features of the Mn1Zr0.5Oycatalyst can promote the intrinsic catalytic activity (iTOF of 1.87 h?1) and boost benzylideneaniline formation (5.56 mmol gcat.?1h?1) based on a >99% yield at 80 °C respectively at a fast response. It can also work effectively at a room temperature of 30 °C, as well as for the gram-grade synthesis. This is one of the best results among all the MnOy-based catalysts in the literature. Moreover, this catalyst showed good stability and a wide substrate scope with good to excellent yields of imines.

Four air-stable cyclometalated half-sandwich iridium complexes 1-4 with C,N-donor Schiff base ligands were prepared through C-H activation in moderate-to-good yields. These complexes have been well characterized, and their exact structure was elaborated on by single-crystal X-ray analysis. The iridium(III) complexes 1-4 showed good catalytic activity in the imine synthesis under open-flask conditions (air as the oxidant) from primary amine oxidative homocoupling, secondary amine dehydrogenation, and the cross-coupling reaction of amine and alcohol. Substituents bonded on the ligands of the iridium complexes displayed little effect on the catalytic efficiency. The stability and good catalytic efficiency of the iridium catalysts, mild reaction conditions, and substrate universality showed their potential application in industrial production.

A series of 11 novel 3-aryl-2-phenyl-2,3-dihydro-4H-1,3-benzothiazin-4-ones was prepared at room temperature by T3P-mediated cyclization of N-aryl-C-phenyl imines with thiosalicylic acid. This provides simple and ready access to N-aryl compounds in this family, which have been generally difficult to prepare.

A new and efficient oxo-sulfonylation protocol has been established for the synthesis of N-sulfonylated indazolones employing sulfinic acid as a sulfonylating agent using tert-butyl hydroperoxide (TBHP) under ambient air. A series of structurally diverse 1-sulfonylindazol-3(2H)-one derivatives were obtained in good yields. A radical reaction mechanism has been proposed for this transformation.

Developing high-performance heterogeneous catalysts for one-pot reductive amination reactions is critically important for pharmaceutical and agrochemical synthetic industries. In this work, N-doped carbon nanotubes supported CoPt alloy decorated Co nanoparticles (NPs) are successfully fabricated. As a consequence, the resultant catalyst exhibits desirable activity, selectivity and stability toward the one-pot synthesis of imines. More importantly, the extensive experimental studies and density function theory (DFT) calculations results reveal that the high catalytic activity of the catalyst is mainly due to the co-existence of CoPt alloy NPs and Co NPs with Co?Nx active sites. The high selectivity of imines could be ascribed to the following aspects: (1) competitively preferred adsorption of nitroarenes to avoid side-hydrogenation of aldehydes; (2) weakened adsorption of imines to minimize its over-hydrogenation. This work may provide a promising direction and strategy to design high-performance reductive amination catalysts for industrial applications.

The invention discloses a method for synthesizing imine by catalyzing alcohol-amine through an NNN cobalt complex. The method comprises the following steps: in a nitrogen atmosphere and at the temperature of 75-85 DEG C, taking an organic solvent as a solvent, taking an NNN cobalt complex (LCoCl2) as a catalyst under an alkaline condition, and reacting arylamine with aryl methanol for 40-55 hoursto obtain imine. The preparation method has the characteristics of high yield, few by-products, environmental friendliness and the like and has a wide application prospect.

The invention discloses a method for catalyzing synthesis of an imine by using an aluminum phosphate molecular sieve, and belongs to the technical field of catalytic synthesis of imines. Under the action of an HP-MeAlPO-5 molecular sieve, air or oxygen is used as an oxidant, and an amine and an alcohol which contain different substituents are directly subjected to oxidative coupling to synthesizethe imine under mild conditions. According to the method provided by the invention, the reaction conditions of the adopted catalytic system are mild, and the TOF is high; a reaction can efficiently catalyze the synthesis of the imine at room temperature under air; and the method can adopt transition metals, which are cheap and easy to obtain, such as iron, cobalt and nickel as a molecular sieve dopant, and the availability of the molecular sieve is improved.

Several N,O-coordinate half-sandwich iridium complexes, 1-5, containing constrained bulky β-enaminoketonato ligands were prepared and clearly characterized. Single-crystal X-ray diffraction characterization of these complexes indicates that the iridium center adopts a distorted octahedral geometry. Complexes 1-5 showed good catalytic efficiency in the oxidative homocoupling of primary amines, dehydrogenation of secondary amines, and the oxidative cross-coupling of amines and alcohols, which furnished various types of imines in good yields and high selectivities using O2 as an oxidant under mild conditions. No distinctive substituent effects of the iridium catalysts were observed in these reactions. The diverse catalytic activity, broad substrate scope, mild reaction conditions, and high yields of the products made this catalytic system attractive in industrial processes.

A facile and scaled-up synthesis route to efficient and environment-friendly metal oxide catalysts with desirable properties is of great practical importance, owing to their excellent performance as heterogeneous catalysts in organic synthesis. Herein, a novel amorphous Fe2O3 modified Mn3O4 catalyst (Fe5Mn5-100) has been prepared by adopting a simple co-precipitation method following low temperature baking. Fe5Mn5-100 showed exceptionally high catalytic activity for the atom-economic production of imine from benzyl alcohol with aniline, giving a 98% imine yield at 60 °C in only 3 h, which is higher than all of the reported non-noble and noble metal catalysts. Importantly, Fe5Mn5-100 could still exhibit extraordinary catalytic performance on a large-scale reaction without any solvent, including the frequently used toxic mesitylene, xylene or toluene. Interestingly, the amorphous Fe2O3-100 provided no catalytic activity, and pure Mn3O4-100 showed very inferior catalytic activity towards this reaction. Further detailed characterizations and experimental results revealed that amorphous Fe2O3 plays an important role in expediting the [O] transfer cycle of Mn3+/Mn2+ in Mn3O4, and enhances the oxidation ability and acidity of Fe5Mn5-100. This discovery would provide a new avenue for the atom-economic and environment-friendly industrial synthesis of imine. This journal is

A visible-light-promoted regioselective C(sp2)-H/C(sp3)-H cross-dehydrogenative coupling between 2H-indazoles and ethers has been achieved using a catalytic amount of rose bengal as an organophotoredox-catalyst and tert-butyl hydroperoxide (TBHP) as an oxidant at ambient temperature under aerobic conditions. A variety of C-3 oxyalkylated 2H-indazoles have been synthesized in moderate to good yields. Mechanistic studies suggest a radical pathway of the present reaction.

Mn–Co-decorated reduced graphene oxide (Mn–Co–rGO) was prepared by modified condensation method and characterized through XRD, SEM, EDX, FTIR and BET surface area analysis. The prepared sample was explored for its activity in the synthesis of N-benzylideneaniline (N-BA) using benzyl alcohol and PhNH2 as precursors. The catalyst has been used efficiently with high activity and selectivity for oxidation of benzyl alcohol to benzaldehyde in the presence of molecular oxygen, which further react with aniline to produced N-BA with sustainable catalytic activity up to five cycles. Furthermore, the effect of the nature and position of the substituent on aniline on the chemical reactivity of the nucleophile was studied theoretically using density functional calculations.

The organocatalytic synthesis of densely substituted mono- and bis-?-lactams involving the Mukaiyama Mannich addition of 2,5-bis(trimethylsilyloxy)furan to imines is described. Use of a ditoluenesulfonylimide catalyst produces ?-lactams from monoaddition, whereas a more acidic catalyst (triflic acid) produces fused bis-lactams from double addition. Optimized organocatalytic conditions allow for the selective synthesis of either desired core as well as the one-pot, multicomponent assembly of the trisubstituted monolactams from aldehydes, amines, and bis-trimethylsilyloxyfuran. An examination of chiral acids found these organocatalysts to be highly active and diastereoselective in the monoaddition reaction, albeit with no enantioselectivity.

The one-pot stepwise reductive amination of arylaldehydes with nitroarenes is described, using reusable nickel nanoparticles (Ni-pol) as catalyst and NaBH4 as mild, inexpensive, and safe reducing agent. The proposed catalytic system holds several advantages such as the use of a non-precious and earth-abundant metal, the facile separation of the catalyst from the reaction mixture by centrifugation, excellent stability towards air and moisture, very mild reaction conditions, good recyclability, broad substrate scope with good to excellent yields, and easy scalability (up to 1.0 g). FESEM analyses indicate that the active species are cubic nanocrystals of Ni in the average cross section value of 35 nm with a quite narrow (25–45 nm) and monomodal distribution, which becomes bimodal with the recycling reactions but without agglomeration.

The selective N-alkylation of anilines with benzylic alcohols can be switched in favor of the dehydrogenative condensation process using the nitrile-ligated Kn?lker's complex by conducting the reaction either in a closed system under inert conditions, or in an open system in air. The selective formation of imines, containing reactive C=N bonds, provides an opportunity towards further functionalization. Indeed, a one-pot three-component condensation of alcohols, amines and phosphites, promoted by an iron-based Kn?lker-type complex in combination with a chiral BINOL-based phosphoric acid, provides access to enantioenriched α-N-alkylaminophosphonates.

A non-noble heterogeneous catalyst-a Co, N and C composite encapsulated carbon nanotube grown in situ on the surface of activated carbon (Co-N-C/CNT@AC)-was fabricated via the pyrolysis-reduction process. Co-N-C/CNT@AC catalyzed the reductive coupling of structurally diverse nitroarenes and alcohols to imines and secondary amines under exogenous base- and solvent-free conditions. BET, TEM, SEM, XRD and XPS characterization showed that the exceptional catalytic property of Co-N-C/CNT@AC could be explained by its nanostructure, Co-N and basic N species. Our protocol had advantages of low cost, environment-friendliness, and good applicability. Furthermore, a reaction route of nitroarenes, amines and alcohols as the starting materials was proposed to improve the atom economy of the reductive coupling of nitroarenes with alcohols.

Direct oxidative coupling of alcohols and amines is regarded as an effective and green approach for imine synthesis under mild conditions. In this work, Zn-doped γ-Al2O3 supported Au nanoparticles was demonstrated as highly active and selective heterogeneous catalyst for a series of imine productions with good to excellent yields, from alcohols and amines via direct oxidative coupling under air atmosphere without extra base additives. Various physicochemical techniques, including ICP-MS, XRD, N2 physisorption, TEM, XPS and CO2-/NH3-TPD, were used to study the properties of the catalysts. Well-dispersed Au0 nanoparticles with a mean size of ca. 2.9 nm were found highly effective in activating alcohols in the presence of reactive amines. The amount of Zn2+ dopant and the calcination temperature of support during catalyst preparation showed crucial impact on tuning the intrinsic activity for oxidation of benzyl alcohol to benzaldehyde (i.e., the rate-determining step for the model reaction), which was disclosed to be related with the active surface oxygen species and the acidic-basic property of support. The 0.4% Au/Zn0.02Al2O3 catalyst calcined at 400 °C exhibited the highest TOF (39.1 h?1) at 60 °C based on a >99% yield to benzylideneaniline among all the ever-reported Au-based catalysts. Moreover, this catalyst could afford 98% yield to benzylideneaniline at only 30 °C and work effectively for the gram-scale synthesis. It also showed considerable stability after five consecutive recycling.

The efficient and stable catalyst applied to the transformation of amines into the corresponding imines and hydrogenation of nitroarenes under mild reaction conditions is reported. The catalytic performance of porous N-doped carbon with FeCu (FeCu@NPC) catalyst are tested by aromatic alcohol-based N-alkylated of amines with solvent-free and hydrogenation of nitroarenes via N2H4·H2O. The results proved that the yield of these two reactions are all over 99.9% under optimum condition. Moreover, the synergistic effect of the catalyst for N-alkylated reaction was investigated through the kinetic study. The catalyst can be easily separated from reaction system by an external magnetism, and can be recycled and reutilized for at least 4 runs with conversions are all over 75%. The study of the catalyst indicated that it was suitable for the reactions in industry. Hence, the catalysis process by the inexpensive metals-based catalyst is green and sustainable.

Ce-Ni mixed oxides with different Ni/Ce molar ratios, promoted by a rather low amount of Pd (0.2 wt%), were prepared by a simple one-pot precipitation method. The thus-synthesized CeNiXOY and Pd-CeNiXOY catalysts were applied respectively to the direct N-alkylation of amine and alcohol via oxidative coupling, under O2 in the absence of basic additives. The CeNiXOY catalyst could provide a >99% yield of imine in the model alkylation reaction of aniline with benzyl alcohol at 100 °C. The Pd-promoted Pd-CeNiXOY catalyst surprisingly showed an enhanced imine yield (>99%) at a mild temperature of 60 °C. This catalyst exhibited good reusability, and moreover, demonstrated high performance towards imine synthesis from various amines with alcohols. The presence of Pd species and the Ni/Ce molar ratio showed a synergistic impact on the conversion of aniline, as well as on the product selectivity, which was believed to be related to the improvement on the intrinsic activity of the oxidation of benzyl alcohol to benzaldehyde. Various physicochemical techniques, including ICP-MS, XRD, N2 adsorption-desorption, UV-Raman, H2-TPR, TEM, EPMA and XPS, were employed to study mainly the composition, structure and redox properties of the catalysts. The proportion of Ce3+ species and oxygen vacancies, which can be manipulated by the Ce-Ni redox system and the interaction between Ce and Ni, was crucial to the selective activation of alcohols in the presence of reactive amines. The activation of alcohol on the highly reactive Pd0 species was the other crucial factor.

CeO2 based catalysts have been investigated in various catalytic reactions due to its unique reversible Ce3+/Ce4+ redox pair and physicochemical property, but its poor cycle efficiency and low reservoir limit its wide application in the fine chemicals industry. In this work, a novel amorphous Fe2O3 modified CeO2 catalytic system was developed by a facile co-precipitation method. The as-prepared samples were characterized in detail, and were employed for catalyzing the one-pot synthesis of imine from benzyl alcohol and aniline under air atmosphere at low temperature. The as-prepared sample with molar ratio of Fe:Ce = 8:2 dried at 100 °C (named Fe8Ce2-100) exhibited superhigh activity for atom economy synthesis of imine, which was much higher than the reported CeO2 catalyst, even higher than some noble metal catalysts. It is worth noting that pure amorphous Fe2O3-100 could not catalyze this reaction at all, and both pure CeO2-100 and the mechanical mixed sample with the same molar ratio of Fe:Ce exhibited much more inferior catalytic activity than Fe8Ce2-100. Combining characterization results and the catalytic activities of different catalysts at various reaction conditions, the enhanced catalytic activity of Fe8Ce2-100 could be ascribed to the novel synergistic effect between CeO2 and amorphous Fe2O3. Amorphous Fe2O3 plays the role of engine to greatly improve the [O] transfer cycle of Ce4+/Ce3+, as well as enhances the redox and amphoteric properties of the catalysts. This work firstly determines amorphous Fe2O3 can participate and facilitate the catalytic cycle for organic reaction, and may provide a significant strategy for designing polymetallic oxide catalyst towards organic aerobic transformation.

A simple and efficient method for preparation of imines by the oxidative coupling of benzyl alcohols with aromatic amines or aliphatic amines was developed. The reaction was catalyzed by 9-azabicyclo[3.3.1]nonan-N-oxyl (ABNO)/KOH with air as the economic and green oxidant. Under the optimal reaction conditions, a variety of imines were obtained in 80%-96% isolated yields.

The invention discloses a method for preparing an imine compound from alcohol and amine through catalytic oxidation. According to the method, an alcohol compound and an amine compound are used as reaction substrates, and a feeding mol ratio of the alcohol compound to the amine compound is 100: 100-60; 9-azabicyclo[3.3.1]nonane N-oxyl free radical is used as a catalyst, potassium hydroxide is used as an auxiliary agent, and a feeding mol ratio of the amine compound to the 9-azabicyclo[3.3.1]nonane N-oxyl free radical to potassium hydroxide is 100: 1-6: 10-50; air is used as an oxidizing agent, the reaction substrates are added into an organic solvent, and the mass of the used organic solvent is 2.5 to 5 times of the reaction substrate the amine compound; and a reaction is carried out at normal pressure at a temperature of 70 to 110 DEG C for 2 to 12 h, and aftertreatment is carried out after completion of the reaction so as to obtain the imine compound. The method provided by the invention is simple and safe to operate, reduces environmental cost due to usage of clean oxygen as the oxidizing agent and prevents the problem of transition-metal pollution by discarding usage of any transition-metal catalyst.

Abstract: Imines were synthesized from the cross-coupling of alcohols with amines catalyzed by activated carbon (AC) supported ruthenium nanoparticles under atmospheric molecular oxygen without aid of any additives. The readily prepared catalyst 5%Ru/AC showed good to excellent (yield > 90%) performances in the reaction of aromatic and heterocyclic alcohols with various amines, such as aromatic, aliphatic and heterocyclic amines. This protocol is simple, efficient, and environmentally friendly, and the catalyst can be easily recovered without major ruthenium loss. Graphical Abstract: Imines were synthesized from the cross-coupling of alcohols with amines catalyzed by activated carbon (AC) supported ruthenium nanoparticles under atmospheric molecular oxygen without aid of any additives. This protocol is simple, efficient, and environment friendly, and the readily prepared catalyst 5%Ru/AC showed good to excellent performances in the reaction of aromatic and heterocyclic alcohols with various amines, such as aromatic, and aliphatic amines. [Figure not available: see fulltext.]

A green and efficient catalytic approach for the selective synthesis of imines in air at room temperature was achieved with the aid of newly synthesised diruthenium(II) complexes [(η6-p-cymene)2Ru2Cl2(μ-L)] containing substituted 1,2-diacylhydrazine ligands. All the new complexes were fully characterised by analytical and spectroscopic techniques. The solid-state structure of a representative complex was solved by single-crystal X-ray diffraction analysis. The diruthenium(II) complexes also enable the selective aerobic oxidation of alcohols to aldehydes. The catalytic reaction operates in the presence of air as a green and cheap oxidant, and releases water as the only by-product. A plausible mechanism is proposed for the imine formation, which is believed to proceed via an aldehyde intermediate.

A silver-catalyzed formation of C-C bond for the construction of a series of polysubstituted quinolines from arylamines, aldehydes, and ketones or arylamines and 1,3-diketones has been developed. The transformation is effective for a broad range of substrates, thus enabling the expansion of constituent architectures on the heterocyclic framework. This use of a single catalytic system to mediate chemical transformations in a synthetic operation is important for the development of new atom-economic strategies and this strategy is efficient in building complex structures from simple starting materials in an environmentally benign fashion.

A silver-catalyzed sequential formation of two C-C bonds for the construction of a series of polysubstituted quinolines from anilines, aldehydes, and alcohols under mild conditions has been developed. The transformation is effective for a broad range of substrates, including aliphatic alcohols, arylalkanols, cycloalkanols, and ethylene glycol, thereby permitting the expansion of the constituent architectures of the heterocyclic framework.

An efficient method for the synthesis of polysubstituted aziridines utilizing enynones and imines is described. This transformation is achieved through the reaction of imines with donor/donor carbene intermediates, which were generated in situ from the cyclization of enynones. Furthermore, the resulted aziridines were good 1,3-dipoles, which could be efficiently trapped by dipolarophiles to give five-membered heterocycles. The obvious advantages of wide substrate scopes, mild reaction conditions, and high atom efficiency make this system highly appealing for construction of polysubstituted aziridines, 2,5-dihydropyroles, and 1,2,4-triazolidines.

CeO2 nanorods anchored on mesoporous carbon exhibit high activity and stability in aerobic oxidative coupling of alcohols and amines to imines. The abundant surface Ce3+ and the suitable interaction between CeO2 nanorods and the carbon support should be responsible for the excellent catalytic behaviors.

The invention belongs to the technical fields of chemistry and chemical engineering, and concretely relates to a method for one step synthesis of imine through catalyzing alcohol and amine by supported manganese oxide. A reaction of alcohol and amine is carried out in a solvent or solvent-free state at 60-90DEG C for 6-48h with the supported manganese oxide as a catalyst and molecular oxygen or air as an antioxidant to realize one step synthesis of a corresponding imine compound. The valence of manganese in the catalyst is +2, +3 or +4, the general formula of the catalyst is MnOx, and a carrier is hydroxyapatite (Ca10(PO4)6(OH)2). The catalyst still has very good activity and selectivity after the catalyst is reused at least 9 times. The catalyst used in the method has the characteristics of simple preparation, cheapness, high reaction selectivity and environmental protection.

Herein, a new and efficient approach towards the oxidative cross-coupling of benzylalcohol and various aromatic amines to form corresponding imines with high degree conversion (>80 %) and chemo-selectivity using lanthanide salts as pre-catalysts is presented. The catalyzed oxidative cross-coupling reaction using La(NO3)3·6H2O as pre-catalyst displayed a broad substrate scope. The reaction afforded various substituted imines from the reaction of benzylalcohol with ample variety of amines in good yields.

The invention relates to an imine compound preparation method. The preparation method comprises that benzyl alcohol or its derivative and an amine compound as reaction substrates undergo an oxidative condensation reaction in the presence of a catalyst to produce the imine compound. The imine compound preparation method utilizes a metal oxide as a catalyst and comprises that benzyl alcohol or its derivative, an amine compound and the metal oxide are mixed, the mixture is put into a pressure container, the pressure container is sealed, the mixture undergoes a stirring reaction at a temperature of 30-150 DEG C for 1-24h and the reaction product is separated so that the imine compound is obtained. The preparation method has the advantages of easy separation of the product and the catalyst, recycle of the catalyst, simple and easy reaction processes and the highest imine compound yield of 99%.

The kinetics of oxidation of aromatic anils in aniline moiety by meta-chloroperbenzoic acid (m-CPBA) has been studied in aqueous acitic medium. The order of reaction was found to be second order with respect to aromatic anil and first order with respect to m-chloroperbenzoic acid. The increase of [H+] in this oxidation retards the rate of reaction. The effects of substituents on the oxidation rate were studied with 3 meta- and 5 para-substituted anils at five different temperatures. Thermodynamic parameters for the oxidation have been determined and discussed. meta-Chloroperbenzoic acid oxidation with substituted anils fulfills the isokinetic relationship and Exner relationship but not to any of the linear free energy relationships. The deviation of Hammett plot was noted and a concave downward curve was obtained for the anils with substituents in aniline moiety.

In the present work, uniform litchi shaped cuprous oxide (Cu2O) nanoaggregates were synthesized via a facile method by employing copper(ii) chloride, sodium hydroxide, ethylene glycol and ascorbic acid in the absence of surfactants at room temperature. With further increase of the reaction temperature, broken hollow copper nanoaggregates were obtained. The structure of a Cu2O nanoaggregate was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Transmission Electron Microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis and High Resolution Transmission Electron Microscopy (HRTEM). The as-obtained Cu2O nanoaggregates showed efficient catalytic activities in the aerobic oxidative synthesis of imines.

We herein report the effects of CeO2 crystal planes on the oxidative coupling of alcohols and amines to form imines. CeO2 exhibits significant catalytic activity under mild reaction conditions (60 °C) during the synthesis of 13 different imines, giving >89% conversions and >90% selectivities. The crystal planes of CeO2 greatly affect the catalytic performance. Among the crystal planes investigated (the (110), (100) and (111) planes), the (110) plane shows the strongest redox ability and thus the best catalytic activity, generating a 97% yield of the imine at 60 °C in 2 h, because it contains the highest concentration of oxygen vacancies.

The kinetics of oxidation of 9 meta- and 15 para- substituted aromatic anils by sodium perborate were investigated in aqueous acetic acid medium. The reaction was second order with respect to aromatic anil and first order with respect to the sodium perborate. The increase of [H+] in this oxidation retards the rate of the reaction. The observed rate constant for the substituents were plotted against the Hammett constant, δ and a non-linear concave downward curve was obtained for the anils with substituents in the aniline moiety. The observed break in the log kobs versus δwas attributed to the transition state whereas the non-linear concave upward curve was observed for the substituents in the benzaldehyde moiety and a non-linear concave upward curve was observed for the substituents in the combination of aniline and benzaldehyde moiety. The electron withdrawing substituents fall on one side of the curve, having a negative ρvalue and the electron releasing substituents fall on the other side, with a positive ρvalue and a suitable mechanism was proposed.

Using a supported palladium catalytic system, the reaction of nitroarenes with benzyl alcohols occurred smoothly via hydrogen transfer to produce imines in an atom-economical manner. The palladium species were dispersed well on hydrotalcite (HT) support and palladium nanoparticles with size of about 3.5 nm were formed during reaction. Both of the small size of palladium nanoparticles and the rich hydroxyl groups on HT surface enhanced the catalytic performance of Pd/HT. The catalytic system is recyclable and amenable to a variety of aromatic alcohols and nitro compounds.

An Au/HT catalyst was found to be an efficient heterogeneous catalyst for the coupling reaction of aromatic alcohols and amines. The amides and imines can be selectively synthesized with up to 99% yield with or without the addition of NaF as the cocatalyst. This journal is the Partner Organisations 2014.

Manganese oxides loaded on various supports have been prepared and studied for the direct imine formation by oxidative coupling of alcohols and amines. Among the catalysts, hydroxyapatite supported manganese oxides (MnO x/HAP) show the best activity and selectivity for this reaction in the absence of an additional base using air as the environmentally benign terminal oxidant. NH3-/CO2-TPD results show that the amphoteric properties of MnOx/HAP are crucial for this reaction to obtain a satisfactory yield. Various aromatic alcohols and amines are smoothly transformed into the corresponding imines in good to excellent yields. The catalyst is reusable and gives 98% yield of the product in all 9 reuse tests. Compared with the fresh catalyst, the XRD and SEM of the reactivated MnO x/HAP after nine reactions do not show any obvious change. This journal is the Partner Organisations 2014.

The catalytic dehydrogenation and tandem transformation of aromatic alcohols, including oxidative coupling of alcohols and amines, were achieved successfully using a catalytic amount of organosilicon-supported titania (TiO2@PMHSIPN), which enables the efficient synthesis of aromatic aldehydes, imines, and benzimidazoles in good to excellent yields. This journal is the Partner Organisations 2014.

The kinetics of oxidation of aromatic anils to benzaldehyde and azobenzene by potassium peroxymonosulfate has been studied in aqueous acetic acid medium. The low dielectric constant of the medium facilitates the reactivity. It has been found that the variation in the ionic strength of the reaction has a negligible effect on the rate. Similarly, polymerization was not observed when acrylonitrile was added to the reaction mixture. This observation rules out the formation of any free radical in the reaction. The added Mn(II) increases the rate of the reaction, which indicates the involvement of two-electron transfer. Highly negative ΔS# values indicate a structured transition state. The deviation of the Hammett plot was noted, and a concave downward curve was obtained for the anils with substituents in the aniline moiety. The observed break in the log kobs versus σ is attributed to the transition state whereas the concave upward curve was observed for the substituents in the benzaldehyde moiety and in the combination of aniline and benzaldehyde moieties, and a suitable mechanism was proposed.

A convenient preparative approach for synthesis of various 1,5-diaryl-3-(arylamino)-1H-pyrrol-2(5H)-ones promoted by 1-butyl-1- methylpyrrolidinium hydrogen sulfate is developed which involves cyclocondensation of aldehydes with amines and ethyl pyruvate under ambient conditions. Graphical abstract: A convenient preparative approach for synthesis of various 1,5-diaryl-3-(arylamino)-1H-pyrrol-2(5H)-ones promoted by 1-butyl-1-methylpyrrolidinium hydrogen sulfate is developed which involves cyclocondensation of aldehydes with amines and ethyl pyruvate under ambient conditions.[Figure not available: see fulltext.]