cas 2211-66-7, N-benzylidenecyclohexylamine

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Electrochemical dehydrogenation of 1,2,3,4-tetrahydroisoquinoline to 3,4-dihydroisoquinoline
Dehydrogenation of 1,2,3,4-tetrahydroisoquinoline to 3,4-dihydroisoquinoline was carried out using an electrochemical method in the presence of KI. In this method, the iodide ion presumably played an important role as an electron carrier.
Okimoto, Mitsuhiro,Takahashi, Yukio,Numata, Kaori,Sasaki, Gaku
p. 371 - 375
(2005)
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Visible Light-driven Dehydrogenation of Benzylamine under Liberation of H2
The visible light-driven transformation of chemical compounds in combination with the liberation of H2 is highly attractive. Herein, we report on a photocatalyst that allows the acceptorless dehydrogenation of benzylamine. Upon light absorption, free charge carriers are generated and used for the concerted imine formation and liberation of H2. Our photocatalyst consists of CdS as a light harvesting semiconductor supported on colloidal metal-organic framework crystallites. The decoration with co-catalytic nickel nanoparticles promotes hydrogen evolution and, in addition, stabilizes the CdS component under irradiation.
Klarner, Mara,Hammon, Sebastian,Feulner, Sebastian,Kümmel, Stephan,Kador, Lothar,Kempe, Rhett
p. 4593 - 4599
(2020)
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Transient imine as a directing group for the metal-free o-C-H borylation of benzaldehydes
Organoboron reagents are important synthetic intermediates and have wide applications in synthetic organic chemistry. The selective borylation strategies that are currently in use largely rely on the use of transition-metal catalysts. Hence, identifying much milder conditions for transition-metal-free borylation would be highly desirable. We herein present a unified strategy for the selective C-H borylation of electron-deficient benzaldehyde derivatives using a simple metal-free approach, utilizing an imine transient directing group. The strategy covers a wide spectrum of reactions and (i) even highly sterically hindered C-H bonds can be borylated smoothly, (ii) despite the presence of other potential directing groups, the reaction selectively occurs at the o-C-H bond of the benzaldehyde moiety, and (iii) natural products appended to benzaldehyde derivatives can also give the appropriate borylated products. Moreover, the efficacy of the protocol was confirmed by the fact that the reaction proceeds even in the presence of a series of external impurities.
Rej, Supriya,Chatani, Naoto
supporting information
p. 2920 - 2929
(2021/03/01)

Metal-free regioselective C-H amination for the synthesis of pyrazole-containing 2H-indazoles
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.
Wang, Kai,Wei, Tingting,Zhang, Yujia,Hou, Jiahao,Bai, Renren,Xie, Yuanyuan
p. 1787 - 1794
(2021/03/14)

Rhodium catalyzed multicomponent dehydrogenative annulation: one-step construction of isoindole derivatives
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.
Cheng, Biao,Lyu, Hairong,Quan, Yangjian,Xie, Zuowei
supporting information
p. 7930 - 7933
(2021/08/17)

Redox-Neutral Imination of Alcohol with Azide: A Sustainable Alternative to the Staudinger/Aza-Wittig Reaction
The traditional Staudinger/aza-Wittig reaction represents one of the most powerful tools for imine formation. However, for this multistep procedure, the sacrificial phosphine has to be used, resulting in difficulties in the purification process and waste disposal at the same time. Here, we report a redox-neutral azide-alcohol imination methodology enabled by a base-metal nickel PN3 pincer catalyst. The one-step, waste-free, and high atom-economical features highlight its advantages further. Moreover, mechanistic insight suggests a non-metal-ligand cooperation pathway based on the observation of an intermediate and density functional theory calculations.
Li, Huaifeng,Lupp, Daniel,Das, Pradip K.,Yang, Li,Gon?alves, Théo P.,Huang, Mei-Hui,El Hajoui, Marwa,Liang, Lan-Chang,Huang, Kuo-Wei
p. 4071 - 4076
(2021/04/12)

Manganese-Catalyzed Selective Hydrogenative Cross-Coupling of Nitriles and Amines to Form Secondary Imines
Manganese complexes with tridentate PNN ligands have been synthesized as catalysts for hydrogenative cross-coupling reaction of nitriles and amines to form secondary imines. This reaction afforded a variety of unsymmetrical secondary imines in good yields with excellent selectivity. Investigation of catalyst intermediates indicated that an amido manganese complex may be the active catalyst species for this reaction. (Figure presented.).
Li, Xiao-Gen,Zhou, Qi-Lin
supporting information
p. 3471 - 3475
(2021/04/29)

One-Pot Construction of Diverse β-Lactam Scaffolds via the Green Oxidation of Amines and Its Application to the Diastereoselective Synthesis of β-Amino Acids
In this study, a simple one-pot construction of β-lactam scaffolds was successfully achieved via 4,6-dihydroxysalicylic acid-catalyzed organocatalytic oxidation of amines to imines using molecular oxygen. Although some imines are highly unstable and difficult to isolate by conventional methods, the organocatalytic oxidation of amines described herein, followed by their direct reaction with acyl chlorides in the presence of a base, afforded a series of new β-lactam derivatives with excellent cis selectivity, which could not be synthesized and isolated by previously reported methods. Thus, this one-pot protocol will be one of the powerful methods applicable to the synthesis of various potential drug candidates and functional molecules. Furthermore, the subsequent hydrolysis of these β-lactams successfully afforded the corresponding β-amino acids as almost single diastereomers in up to 99% yields.
Yamamoto, Yuki,Kodama, Shintaro,Nishimura, Riku,Nomoto, Akihiro,Ueshima, Michio,Ogawa, Akiya
p. 11571 - 11582
(2021/08/20)

Vanadium-and chromium-catalyzed dehydrogenative synthesis of imines from alcohols and amines
Vanadium(IV) tetraphenylporphyrin dichloride and chromium(III) tetraphenylporphyrin chloride have been developed as catalysts for the acceptorless dehydrogenation of alcohols. The catalysts have been applied to the direct synthesis of imines in overall good yields from a variety of alcohols and amines. The transformations are proposed to proceed by metal?ligand bifunctional pathways with an outer-sphere transfer of two hydrogen atoms from the alcohol to the metal porphyrin complexes. The results show that vanadium and chromium catalysts can also be employed for the dehydrogenation of alcohols with the release of hydrogen gas, and they may represent valuable alternatives to other catalysts based on Earth-abundant metals.
Madsen, Robert,Miao, Yulong,Samuelsen, Simone V.
supporting information
p. 1328 - 1335
(2021/05/29)

Ionic-Liquid-Catalyzed Synthesis of Imines, Benzimidazoles, Benzothiazoles, Quinoxalines and Quinolines through C?N, C?S, and C?C Bond Formation
We report the tetramethyl ammonium hydroxide catalyzed oxidative coupling of amines and alcohols for the synthesis of imines under metal-free conditions by utilizing oxygen from air as the terminal oxidant. Under the same conditions, with ortho-phenylene diamines and 2-aminobenzenethiols the corresponding benzimidazoles and benzothiazoles were obtained. Quinoxalines were obtained from ortho-phenylene diamines and 1-phenylethane-1,2-diol, the conditions were then extended to the synthesis of quinoline building blocks by reaction of 2-amino benzyl alcohols either with 1-phenylethan-1-ol or acetophenone derivatives. The formation of C?N, C?S and C?C bonds was achieved under metal-free conditions. A broad range of amines (aromatic, aliphatic, cyclic and heteroaromatic) as well as benzylic alcohols including heteroaryl alcohols reacted smoothly and provided the desired products. The mild reaction conditions, commercially available catalyst, metal-free, good functional-group tolerance, broad range of products (imines, benzimidazoles, benzothiazoles, quinoxalines and quinolines) and applicability at gram scale reactions are the advantages of the present strategy.
Adimurthy, Subbarayappa,Badhani, Gaurav,Joshi, Abhisek
p. 6705 - 6716
(2021/12/31)

Efficient Imine Formation by Oxidative Coupling at Low Temperature Catalyzed by High-Surface-Area Mesoporous CeO2 with Exceptional Redox Property
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.
Wu, Shipeng,Wang, Yinghao,Cao, Qiue,Zhao, Qihua,Fang, Wenhao
supporting information
p. 3019 - 3028
(2020/12/11)

Switchable Imine and Amine Synthesis Catalyzed by a Well-Defined Cobalt Complex
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.
Paudel, Keshav,Xu, Shi,Hietsoi, Oleksandr,Pandey, Bedraj,Onuh, Chuka,Ding, Keying
supporting information
p. 418 - 426
(2021/02/01)

Efficient imine synthesisviaoxidative coupling of alcohols with amines in an air atmosphere using a mesoporous manganese-zirconium solid solution catalyst
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.
Wu, Shipeng,Zhang, Hao,Cao, Qiue,Zhao, Qihua,Fang, Wenhao
p. 810 - 822
(2021/02/26)

Ni-Catalyzed asymmetric reduction of α-keto-β-lactams: via DKR enabled by proton shuttling
Chiral α-hydroxy-β-lactams are key fragments of many bioactive compounds and antibiotics, and the development of efficient synthetic methods for these compounds is of great value. The highly enantioselective dynamic kinetic resolution (DKR) of α-keto-β-lactams was realized via a novel proton shuttling strategy. A wide range of α-keto-β-lactams were reduced efficiently and enantioselectively by Ni-catalyzed asymmetric hydrogenation, providing the corresponding α-hydroxy-β-lactam derivatives with high yields and enantioselectivities (up to 92% yield, up to 94% ee). Deuterium-labelling experiments indicate that phenylphosphinic acid plays a pivotal role in the DKR of α-keto-β-lactams by promoting the enolization process. The synthetic potential of this protocol was demonstrated by its application in the synthesis of a key intermediate of Taxol and (+)-epi-Cytoxazone. This journal is
Wang, Fangyuan,Tan, Xuefeng,Wu, Ting,Zheng, Long-Sheng,Chen, Gen-Qiang,Zhang, Xumu
supporting information
p. 15557 - 15560
(2020/12/30)

Silicon hydrogenation reaction method of organic boron and inorganic alkali catalysis amide (by machine translation)
The method is characterized in that organic boron and inorganic bases are used as catalysts, silane is used as a reducing agent, primary amide is reduced to primary amine or dehydration dinitrile, the secondary amide is reduced to a secondary amine or aldimine, and the tertiary amide is reduced to tertiary amine. The method has the advantages of simple operation, mild reaction conditions, wide substrate universality, good functional group compatibility and the like, and has the characteristics of good stability, cheap and accessible catalyst, simple and convenient operation, high practicality and the like. (by machine translation)
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Paragraph 0182-0188

(2020/08/18)

Bidentate geometry-constrained iminopyridyl nickel-catalyzed synthesis of amines or imines via borrowing hydrogen or dehydrogenative condensation
The efficient Ni-catalyzed N-alkylation of various anilines with alcohols via borrowing hydrogen is reported using a bidentate geometry-constrained iminopyridyl nickel complex as the catalyst. Substituted benzylic alcohols and short/long chain aliphatic alcohols could be applied as the alkylation sources to couple with aromatic and heteroaromatic amines to give a diverse set of N-alkylation outcomes in moderate to excellent yields. The nickel catalytic system was also suitable for aliphatic amines, selectively delivering the corresponding imines via an acceptorless dehydrogenative condensation strategy.
Jiang, Yong,Hu, Miao,Sun, Nan,Hu, Baoxiang,Shen, Zhenlu,Hu, Xinquan,Jin, Liqun
supporting information

(2020/11/27)

Polyoxometalate catalyzed imine synthesis: Investigation of mechanistic pathways
The syntheses of imines by oxidative coupling of primary alcohols and amines were achieved by using 2 molpercent polyoxometalate (POM) Na12[WZn3(H2O)2(ZnW9O34)2] (Zn–WZn3) catalyst in the presence of t-BuOK and di-oxygen with excellent conversion (up to 100percent) and selectivity (up to 100percent). Non-noble metal-based POM catalyst in the presence of base represents a new reaction protocol for the selective synthesis of imine from both aromatic and aliphatic primary amines with functional group tolerance. Control experiment shows the formation of di-oxygen bind Zn–WZn3 activated species. The electron-density of POM is mostly situated on the surface oxygen atoms of W–O–W bonds which can engage the alcoholic OH group and helps for the imine selectivity in the second step of imine synthesis.
Adhikary, Subhasis D.,Mandal, Debaprasad
supporting information

(2020/05/25)

H2 Activation by Non-Transition-Metal Systems: Hydrogenation of Aldimines and Ketimines with LiN(SiMe3)2
In recent years, H2 activation at non-transition-metal centers has met with increasing attention. Here, a system in which H2 is activated and transferred to aldimines and ketimines using substoichiometric amounts of lithium bis(trimethylsilyl)amide is reported. Notably, the reaction tolerates the presence of acidic protons in the α-position. Mechanistic investigations indicated that the reaction proceeds via a lithium hydride intermediate as the actual reductant.
Elliott, Daniel C.,Marti, Alex,Mauleón, Pablo,Pfaltz, Andreas
supporting information
p. 1918 - 1922
(2019/01/16)

Visible light photocatalytic aerobic oxidative synthesis of imines from alcohols and amines on dye-sensitized TiO2
A general visible light photocatalytic protocol for the synthesis of imines via a two-step one-pot route on alizarin red S (ARS)-sensitized TiO2 was uncovered. This efficient synthesis protocol involves one step of the highly selective formation of aldehydes from the oxidation of alcohols with O2 on ARS-sensitized TiO2 photocatalyst, and a subsequent step of condensation of newly formed aldehydes with various amines on TiO2 to afford imines in one pot. Anatase TiO2 provides a versatile platform for catalytic amounts of ARS (0.67 mol%) to facilitate the electron transfer from dye traversing its conduction band to O2 under green LED irradiation. Moreover, the Lewis acid sites of TiO2 can promote the formation of imines from aldehydes and amines in very high isolated yields. We took advantage of both the photocatalytic and catalytic properties of TiO2 to significantly expand the scope of imines. Our work suggests that the synthetic applications of TiO2 photocatalysis can be achievable under mild conditions by exploring the excellent functionalities of TiO2.
Xu, Hui,Shi, Ji-Long,Hao, Huimin,Li, Xia,Lang, Xianjun
p. 128 - 135
(2019/01/04)

Synthesis of Secondary Aldimines from the Hydrogenative Cross-Coupling of Nitriles and Amines over Al2O3-Supported Ni Catalysts
A heterogeneous Ni catalyst was discovered to be active in the synthesis of secondary cross-imines via hydrogenative coupling of nitriles and amines. The mesoporous Al2O3-supported Ni nanoparticles (abbreviated as Ni/m-Al2O3-600, where 600 represents the reduction temperature) were active in hydrogenative coupling of nitriles and amines reaction at 80 °C and 1 bar H2, affording corresponding cross-imines with yields in the range 64.1-98.1%. Density functional theory calculations reveal the hydrogenation of benzonitrile (PhCN) to benzylamine (PhCH2NH2) has higher activation energy than that for hydrogenative cross-coupling of PhCN and RNH2 on the Ni/m-Al2O3-600 catalyst, suggesting the latter reaction is more favorable. The theoretical calculations are in good agreement with our experimental results.
Zhou, Peng,Jiang, Liang,Wang, Shuguo,Hu, Xun,Wang, Hongming,Yuan, Ziliang,Zhang, Zehui
p. 8413 - 8423
(2019/09/07)

Metal-free nitrogen -doped carbon nanosheets: A catalyst for the direct synthesis of imines under mild conditions
Herein, a highly stable, porous, multifunctional and metal-free catalyst was developed, which exhibited significant catalytic performance in the oxidation of amines and transfer hydrogenation of nitriles under mild conditions; this could be attributed to the presence of numerous active sites and their outstanding BET surface area. The obtained results showed that most of the yields of imines exceeded 90%, and the cycling performance of the catalyst could be at least seven runs without any decay in the reaction activity, which could be comparable to those of metal catalysts. Subsequently, a kinetic study has demonstrated that the apparent activation energy for the direct synthesis of imines from amines is 67.39 kJ mol-1, which has been performed to testify that the catalytic performances are rational. Via catalyst characterizations and experimental data, graphitic-N has been proven to be the active site of the catalyst. Hence, this study is beneficial to comprehend the mechanism of action of a metal-free N-doped carbon catalyst in the formation of imines.
Wang, Kaizhi,Jiang, Pengbo,Yang, Ming,Ma, Ping,Qin, Jiaheng,Huang, Xiaokang,Ma, Lei,Li, Rong
p. 2448 - 2461
(2019/05/17)

Readily Available Primary Aminoboranes as Powerful Reagents for Aldimine Synthesis
Primary aminoboranes (RNHBR2), which are readily available by spontaneous dehydrocoupling of amines and boranes cleanly react at room temperature with aldehydes to give aldimines. The overall transformation from amines to aldimines can be conveniently performed by a sequential one-pot reaction. This synthetic strategy is especially useful for electron poor and bulky amines which are reluctant to react with aldehydes under dehydration conditions. Using a Glorius robustness screen, we show that this methodology is chemoselective, and functional group tolerant. Computational and experimental data support the irreversible formation of the aldimine product in marked contrast with traditional methods.
Junor, Glen P.,Romero, Erik A.,Chen, Xi,Jazzar, Rodolphe,Bertrand, Guy
supporting information
p. 2875 - 2878
(2019/02/13)

2,4,6-Trihydroxybenzoic Acid-Catalyzed Oxidative Ugi Reactions with Molecular Oxygen via Homo- And Cross-Coupling of Amines
Metal-free, oxidative four-component Ugi reactions (U-4CRs) were conducted to synthesize dipeptides from two different amines, isocyanides, and carboxylic acids using 2,4,6-trihydroxybenzoic acid catalyst in O2 atmosphere. The organocatalytic U-4CRs proceed via oxidative cross-coupling of benzylamines with other aliphatic or aromatic amines to form imines, followed by condensation with isocyanides and carboxylic acids. The U-4CRs via cross-coupling of amines are rare, and the simple, metal-free procedures are advantageous for further applications in drug and heterocycle syntheses.
Dong, Chun-Ping,Uematsu, Akinori,Kumazawa, Shun,Yamamoto, Yuki,Kodama, Shintaro,Nomoto, Akihiro,Ueshima, Michio,Ogawa, Akiya
p. 11562 - 11571
(2019/10/03)

Cobalt-Catalyzed Dehydrogenative Coupling of Amines into Imines
Primary amines have been subjected to an acceptorless dehydrogenative homo- and heterocoupling into imines with a cobalt catalyst. The catalytically active species are composed of cobalt nanoparticles, which are generated in situ by heating Co2(CO)8 in the presence of trioctylphosphine oxide as a surfactant. The nanoparticles have been characterized by transmission electron microscopy where the image showed spherical and small particles with a narrow size distribution. The catalyst can be recovered and used again with essentially no effect on the yield. The catalyst can also be used for the dehydrogenative coupling of alcohols and amines into imines.
Bottaro, Fabrizio,Takallou, Ahmad,Chehaiber, Ahmad,Madsen, Robert
supporting information
p. 7164 - 7168
(2019/11/16)

In Situ Generated Cobalt Catalyst for the Dehydrogenative Coupling of Alcohols and Amines into Imines
An in situ formed cobalt catalyst is developed from cobalt(II)bromide, bis[2-(diisopropylphosphino)-4-methylphenyl]amine and zinc metal. The catalyst mediates the acceptorless dehydrogenative coupling of alcohols and amines into imines with the release of hydrogen gas and the transformation is applied to the synthesis of a variety of imines from different alcohols and amines. The mechanism is investigated with labelled substrates and based on the results a cobalt(I) PNP complex is believed to be the catalytically active species which abstracts hydrogen gas from the alcohol through a metal ligand bifunctional pathway.
Bottaro, Fabrizio,Madsen, Robert
p. 2707 - 2712
(2019/05/15)

Development and mechanistic investigation of the manganese(iii) salen-catalyzed dehydrogenation of alcohols
The first example of a manganese(iii) catalyst for the acceptorless dehydrogenation of alcohols is presented. N,N′-Bis(salicylidene)-1,2-cyclohexanediaminomanganese(iii) chloride (2) has been shown to catalyze the direct synthesis of imines from a variety of alcohols and amines with the liberation of hydrogen gas. The mechanism has been investigated experimentally with labelled substrates and theoretically with DFT calculations. The results indicate a metal-ligand bifunctional pathway in which both imine groups in the salen ligand are first reduced to form a manganese(iii) amido complex as the catalytically active species. Dehydrogenation of the alcohol then takes place by a stepwise outer-sphere hydrogen transfer generating a manganese(iii) salan hydride from which hydrogen gas is released.
Samuelsen, Simone V.,Santilli, Carola,Ahlquist, M?rten S. G.,Madsen, Robert
p. 1150 - 1157
(2019/02/03)

Manganese(III) Porphyrin-Catalyzed Dehydrogenation of Alcohols to form Imines, Tertiary Amines and Quinolines
Manganese(III) porphyrin chloride complexes have been developed for the first time as catalysts for the acceptorless dehydrogenative coupling of alcohols and amines. The reaction has been applied to the direct synthesis of imines, tertiary amines and quinolines where only hydrogen gas and/or water are formed as the by-product(s). The mechanism is believed to involve the formation of a manganese(III) alkoxide complex which degrades into the aldehyde and a manganese(III) hydride species. The latter reacts with the alcohol to form hydrogen gas and thereby regenerates the alkoxide complex.
Azizi, Kobra,Akrami, Sedigheh,Madsen, Robert
p. 6439 - 6446
(2019/04/26)

Efficient imine synthesis from oxidative coupling of alcohols and amines under air atmosphere catalysed by Zn-doped Al2O3 supported Au nanoparticles
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.
Wu, Shipeng,Sun, Weixiao,Chen, Junjie,Zhao, Jinghan,Cao, Qiue,Fang, Wenhao,Zhao
p. 110 - 121
(2019/08/01)

Bi-functional catalyst of porous N-doped carbon with bimetallic FeCu for solvent-free resultant imines and hydrogenation of nitroarenes
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.
Wang, Kaizhi,Gao, Wenbing,Jiang, Pengbo,Lan, Kai,Yang, Ming,Huang, Xiaokang,Ma, Lei,Niu, Fang,Li, Rong
p. 43 - 53
(2019/01/08)

One-pot synthesis of Pd-promoted Ce-Ni mixed oxides as efficient catalysts for imine production from the direct: N -alkylation of amine with alcohol
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.
Zhang, Mengyuan,Wu, Shipeng,Bian, Longchun,Cao, Qiue,Fang, Wenhao
p. 286 - 301
(2019/01/28)

Method for preparing imine by utilizing copper catalyst to catalyze cross coupling of amine and alcohol
The invention discloses a method for preparing imine by utilizing a copper catalyst to catalyze cross coupling of amine and alcohol. The method comprises the following steps: under the condition of nooxidant, adopting Cu/Al2O3 as a catalyst to catalyze the cross coupling of the amine and the alcohol so as to prepare the imine. The method disclosed by the invention has beneficial effects that thereaction system is simple, cocatalysts such as organic ligand, alkaline, and free radical of nitroxide do not need to be added, and simultaneously under the condition of no oxidant, the method utilizes Cu/Al2O3 to catalyze cross coupling of the amine and the alcohol so as to prepare the imine; the problem that the imine is easily peroxidated can be effectively solved; in addition, the catalyst Cu/Al2O3 used by the method is simple in preparation, is highly-effective and stable and is low in price.
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Paragraph 0036; 0037; 0039

(2019/02/04)

H2-Generation from Alcohols by the MOF-Based Noble Metal-Free Photocatalyst Ni/CdS/TiO2@MIL-101
The synthesis of important classes of chemical compounds from alcohols helps to conserve Earth's fossil carbon resources, since alcohols can be obtained from indigestible and abundantly available biomass. The utilisation of visible light for the activation of alcohols permits alcohol-based C-N and C-C bond formation under mild conditions inaccessible with thermally operating hydrogen liberation catalysts. Herein, we report on a noble metal-free photocatalyst able to split alcohols into hydrogen and carbonyl compounds under inert gas atmosphere without the requirement of electron donors, additives, or aqueous reaction media. The reusable photocatalyst mediates C-N multiple bond formation using the oxidation of alcohols and subsequent coupling with amines. The photocatalyst consists of a CdS/TiO2 heterojunction decorated with co-catalytic Ni nanoparticles and is prepared on size-optimised colloidal metal-organic framework (MOF) crystallites.
Tilgner, Dominic,Klarner, Mara,Hammon, Sebastian,Friedrich, Martin,Verch, Andreas,De Jonge, Niels,Kümmel, Stephan,Kempe, Rhett
p. 842 - 847
(2019/08/26)

Catalytic Assessment of Copper(I) Complexes and a Polymer Analog towards the One-Pot Synthesis of Imines and Quinoxalines
Three copper(I) complexes, [CuCl(L)(PPh3)2] [L = FL (1), BL (2) or TL (3)] were prepared from [(PPh3)2Cu(μ-Cl)2Cu(PPh3)] and N-carbamothioylfuran-2-carboxamide (FL), N-carbamothioylbenzamide (BL) or N-carbamothioylthiophene-2-carboxamide (TL) ligands in benzene and four-coordinated tetrahedral copper complexes were well characterized by various spectroscopic techniques (UV/Vis, FT-IR, 1H NMR, 13C NMR and 31P NMR). The molecular structure of the ligands (FL and BL) and complexes was established from single-crystal X-ray diffraction studies. Copper complexes have been shown to catalyse the one-pot synthesis of imines and quinoxalines. Heterogenized catalyst (4) was prepared by reacting more active complex 3 with polystyrene supported triphenylphosphane, and characterized by elemental analyses, and DRS-UV, FT-IR, ICP-OES, and solid-state NMR techniques. Catalytic activity of the complexes (3 and 4) was tested in the formation of imines from alcohols and amines, and quinoxalines from hydroxy ketones and diamines. Heterogeneity and reusability of catalyst 4 were evaluated, and the catalyst can be reused for four runs without any loss in activity.
Sindhuja, Dharmalingam,Vasanthakumar, Punitharaj,Bhuvanesh, Nattamai,Karvembu, Ramasamy
p. 3588 - 3596
(2019/08/20)

N–Alkylation of Amines Catalyzed by a Ruthenium–Pincer Complex in the Presence of in situ Generated Sodium Alkoxide
We report the use of ruthenium–NNN-pincer complexes of the type (R2NNN)RuCl2(PPh3) (R = tBu, iPr, Cy and Ph) for the catalytic N-alkylation of primary amines under solvent-free conditions. For the first time, the base that is required to promote these reactions is generated in situ from the alcohol by the use of sodium. The resulting sodium alkoxide regenerates the alcohol substrate while acting as the water scavenger thus mitigating the need of an additional base. Among the catalysts screened, (tBu2NNN)RuCl2(PPh3) (0.02 mol-%) gives very high turnovers and good yields at 140 °C. The (tBu2NNN)RuCl2(PPh3) catalyzed N-alkylation tolerates a variety of amine and alcohol substrates. While excellent turnover (29000) was obtained for the (tBu2NNN)RuCl2(PPh3) (0.002 mol-%) catalyzed alkylation of aniline with cyclohexyl methanol, the turnovers obtained in the corresponding catalytic methylation of p-anisidine was also very high (12000). The (tBu2NNN)RuCl2(PPh3) catalyzed reactions have also been accomplished under open-vessel conditions resulting in a net dehydrogenative coupling reaction. This protocol has been used to transform benzene-1,2-diamines to benzimidazoles with high productivity (12000 turnovers). DFT studies indicate that while β-hydride elimination is rate-determining (RDTS: 24.31 kcal/mol) for the alcohol dehydrogenation segment which is endothermic, insertion of the imine is rate-determining (RDTS: 11.26 kcal/mol) for its hydrogenation that is exothermic.
Das, Kanu,Nandi, Pran Gobinda,Islam, Khadimul,Srivastava, Hemant Kumar,Kumar, Akshai
p. 6855 - 6866
(2019/11/03)

Crystal phase effect of iron oxides on the aerobic oxidative coupling of alcohols and amines under mild conditions: A combined experimental and theoretical study
Selective catalytic oxidation using air as the terminal oxidant is an ecofriendly route for the synthesis of fine and commodity chemicals. However, the catalyst generally faces the challenges of the inertness of molecular oxygen, limited substrate scope, poor selectivity, and high cost. Moreover, the toxicity of the catalyst should also be considered when the products are used in pharmaceutical or biotechnological areas. Here, upon investigating the dependence of catalytic oxidation on the crystal phases of iron oxides, we find that naked γ-Fe2O3 particles exhibit excellent catalytic activity, selectivity, and stability in a series of imine synthetic reactions. The performance of γ-Fe2O3 particles is significantly better than that of α-Fe2O3 and Fe3O4 under mild reaction conditions, and the γ-Fe2O3 catalyst can be separated from the reaction mixture magnetically. Both experimental and theoretical calculation results show that γ-Fe2O3 possesses supercapability for oxygen activation. The inverse spinel structure of γ-Fe2O3 has abundant cation vacancies, which confers unique electronic properties on surface Fe species. These Fe species tend to transfer electrons to molecular oxygen to form O2? or O22? species. These oxygen species are favorable for the dehydrogenation of alcohols, which is responsible for the high activity of γ-Fe2O3 in this coupling reaction.
Geng, Longlong,Jian, Wei,Jing, Pei,Zhang, Wenxiang,Yan,Bai, Fu-Quan,Liu, Gang
p. 145 - 152
(2019/08/01)

Carbonylation Access to Phthalimides Using Self-Sufficient Directing Group and Nucleophile
Herein we report a novel palladium-catalyzed oxidative carbonylation reaction for the synthesis of phthalimides with high atom- and step-economy. In our strategy, the imine and H2O, which are generated in situ from the condensation of aldehyde and amine, serve as self-sufficient directing group and nucleophile, respectively. This method provides rapid access to phthalimides starting from readily available materials in a one-pot manner. Various phthalimide derivatives are constructed efficiently, including medicinally and biologically active phthalimide-containing compounds.
Ji, Fanghua,Li, Jianxiao,Li, Xianwei,Guo, Wei,Wu, Wanqing,Jiang, Huanfeng
p. 104 - 112
(2018/02/19)

Manganese catalyzed reductive amination of aldehydes using hydrogen as a reductant
A one-pot two-step procedure was developed for the alkylation of amines via reductive amination of aldehydes using molecular dihydrogen as a reductant in the presence of a manganese pyridinyl-phosphine complex as a pre-catalyst. After the initial condensation step, the reduction of imines formed in situ is performed under mild conditions (50-100 °C) with 2 mol% of catalyst and 5 mol% of tBuOK under 50 bar of hydrogen. Excellent yields (>90%) were obtained for a large combination of aldehydes and amines (40 examples), including aliphatic aldehydes and amino-alcohols.
Wei, Duo,Bruneau-Voisine, Antoine,Valyaev, Dmitry A.,Lugan, No?l,Sortais, Jean-Baptiste
supporting information
p. 4302 - 4305
(2018/05/03)

Selective aerobic oxidation of halides and amines with an inorganic-ligand supported zinc catalyst
A practical, efficient and environmentally benign catalytic protocol for the oxidative cross-coupling reaction of halides with amines, oxidative self-coupling of amines and oxidation of halides was developed with inorganic-ligand supported ZnPOM (NH4)4[ZnMo6O18(OH)6] using molecular oxygen. This method mainly utilizes an inorganic polymolybdate ligand to support the Zn2+ ion, avoiding the use of complicated organic ligands.
Wang, Jingjing,Zhai, Yongyan,Wang, Ying,Yu, Han,Zhao, Wenshu,Wei, Yongge
p. 13323 - 13327
(2018/10/15)

Visible-Light-Driven Photocatalytic Oxidation of Organic Chlorides Using Air and an Inorganic-Ligand Supported Nickel-Catalyst Without Photosensitizers
Engineering photoredox-triggered chemical transformation via visible light has been an emerging area in organic synthesis. However, most of the well-established photocatalysts are based upon either transition metal complexes involved with noble metals and organic ligands or photosensitive organic dyes, the development of pure inorganic molecular photocatalysts that could provide better stability and durability is greatly retarded. Herein we discover that the Anderson polyoxometalate (POM) Na4[NiMo6O18(OH)6] (1), which consists of pure inorganic framework built from a central NiII core supported by six MoVIO6 inorganic scaffold/ligands, can be used as a powerful photocatalyst. Upon irradiation with visible light (>400 nm), the compound can catalyze, in high efficiency, a wide range of reactions, including the oxidative cross-coupling reaction of chlorides with amines, as well as oxidation of chlorides using molecular oxygen, affording various imines, aldehydes, and ketones, respectively in high selectivity and good yields. Owing to the robust inorganic framework, this catalyst exhibits excellent stability during the catalysis and reusability with little loss of the catalytic activity, thus providing an alternative without use of complicated organic ligands and expensive noble metal-based photosensitizers.
Yu, Han,Wang, Jingjing,Zhai, Yongyan,Zhang, Mengqi,Ru, Shi,Han, Sheng,Wei, Yongge
p. 4274 - 4279
(2018/09/10)

PdAu@MIL-100(Fe) cooperatively catalyze tandem reactions between amines and alcohols for efficient N-alkyl amines syntheses under visible light
PdAu@MIL-100(Fe), with PdAu alloy nanoparticles of ca. 1.7 nm encapsulated inside MIL-100(Fe) cavities, were prepared via a double-solvent impregnation followed by photoreduction. As compared with bare Pd@MIL-100(Fe), bimetallic PdAu@MIL-100(Fe) showed superior activities for the tandem reactions between amines and alcohols to produce N-alkyl amines under visible-light irradiation, ascribed to the promoting effect of metallic Au in the photocatalytic alcohol-to-aldehyde dehydrogenation. A Pd/Au ratio dependent N-alkylation activity was observed over PdAu@MIL-100(Fe), implying the possibility of synchronizing the reaction rates of two consecutive steps in the N-alkylation reaction, i.e., photocatalytic alcohol-to-aldehyde dehydrogenation and imines hydrogenation, to optimize the whole reaction. This study provides a highly efficient and stable catalytic system for the realization of alkylation of amines via a successful coupling of MOF-based photocatalysis and metal nanoparticle-based hydrogenation. This work also demonstrates that the reaction rates of different catalytic steps in a cascade/tandem reaction can be synchronized for an efficient overall reaction via a rational design of the multifunctional catalysts.
Wang, Dengke,Pan, Yating,Xu, Lizhi,Li, Zhaohui
p. 248 - 254
(2018/04/02)

Switching the Selectivity of Cobalt-Catalyzed Hydrogenation of Nitriles
Previous studies of base metals for catalytic hydrogenation of nitriles to primary amines or secondary aldimines focus on designing complexes with elaborate structures. Herein, we report "twin" catalytic systems where the selectivity of nitrile hydrogenation can be tuned by including or omitting the ligand HN(CH2CH2PiPr2)2 (iPrPNHP). Simply treating CoBr2 with NaHBEt3 generates cobalt particles, which can catalyze the hydrogenation of nitriles to primary amines with high selectivity and broad functional group tolerance. Ligating CoBr2 with iPrPNHP followed by the addition of NaHBEt3, however, forms a homogeneous catalyst favoring secondary aldimines for both hydrogenation and hydrogenative coupling of benzonitrile.
Dai, Huiguang,Guan, Hairong
p. 9125 - 9130
(2018/09/21)

Molybdenum Nitride Nanocatalyst Derived from Melamine and Polyoxometalate-based Hybrid for Oxidative Coupling of Amines to Imines with Air
Molybdenum nitride (Mo2N) is one of the most promising alternative catalysts for a wide range of Pt-catalyzed catalytic applications but is seldom investigated in oxidative coupling of amines to imines. A Mo2N-based nanocatalyst is successfully achieved by the hybridization of PMo12O403? (PMo)-paired ionic pyridine-4-carboxylic acid (PC) and melamine (Mel), followed by calcination in N2. Melamine acts as an outstanding carburization and nitridation reagent that can convert into carbon nitride, and meanwhile the released N element react with Mo species in PMo to form Mo2N. The obtained catalyst PC-PMo-Mel-800 exhibits high activity and remarkable stability for the oxidative coupling of amines to imines under solvent-free and atmospheric conditions. This is the first case of Mo2N-catalyzed oxidative coupling reaction catalyst. The strategy reported herein for fabricating Mo2N may provide a significant and interesting approach to design more transition metal nitrides for wide catalytic applications.
Li, Yue,Xiao, Kang,Li, Jingjing,Jiang, Pingping,Jiang, Yuchen,Du, Shengyu,Leng, Yan
p. 4317 - 4323
(2018/09/06)

Grouping Effect of Single Nickel?N4 Sites in Nitrogen-Doped Carbon Boosts Hydrogen Transfer Coupling of Alcohols and Amines
As a new type of heterogeneous catalyst with “homogeneous-like” activity, single-site transition-metal materials are usually treated as integrated but separate active centers. A novel grouping effect is reported for single Ni?N4 sites in nitrogen-doped carbon (Ni/NC), where an effective ligand-stabilized polycondensation method endows Ni/NC nanocatalysts with a high content of single-site Ni up to 9.5 wt %. The enhanced electron density at each single Ni?N4 site promotes a highly efficient hydrogen transfer, which is exemplified by the coupling of benzyl alcohol and aniline into N-benzylaniline with a turnover frequency (TOF) value of 7.0 molN-benzylaniline molmetal?1 h?1; this TOF outpaces that of reported stable non-noble-metal-based catalysts by a factor of 2.
Su, Hui,Gao, Peng,Wang, Meng-Ying,Zhai, Guang-Yao,Zhang, Jun-Jun,Zhao, Tian-Jian,Su, Juan,Antonietti, Markus,Li, Xin-Hao,Chen, Jie-Sheng
supporting information
p. 15194 - 15198
(2018/10/31)

Molybdenum-Catalyzed Dehydrogenative Synthesis of Imines from Alcohols and Amines
A molybdenum N-heterocyclic carbene catalyst has been developed for the synthesis of imines from primary alcohols and amines with the liberation of dihydrogen. The catalyst is generated in situ from molybdenum hexacarbonyl, 1,3-dicyclohexylimidazolium chloride and potassium tert-butoxide and is further stabilized by the phosphine ligand dppe. Imines are formed in moderate to good isolated yields and a variety of alcohols and amines can be employed in the reaction including anilines. The transformation constitutes the first example of a homogeneous molybdenum-catalyzed acceptorless dehydrogenative coupling with alcohols and is believed to proceed by formation of a cis-coordinated molybdenum bis-N-heterocyclic carbene complex, which performs an oxidative addition to the alcohol, β-hydride elimination and reductive elimination of dihydrogen.
Azizi, Kobra,Madsen, Robert
p. 3703 - 3708
(2018/07/31)

Synthesis of Ruthenium Complexes Bearing PCP-Type Pincer Ligands and Their Application to Direct Synthesis of Imines from Amines and Benzyl Alcohol
Ruthenium complexes bearing N-heterocyclic carbene- and phosphine-based PCP-type pincer ligands are synthesized and characterized by X-ray crystallography. The ruthenium-PCP complexes have catalytic activity toward direct synthesis of imines from reactions of amines and benzyl alcohol. The lifetime of the ruthenium complex bearing the PCP pincer ligand is longer than that of the ruthenium complex bearing a pyridine-based PNP-type pincer ligand.
Eizawa, Aya,Nishimura, Shunsuke,Arashiba, Kazuya,Nakajima, Kazunari,Nishibayashi, Yoshiaki
p. 3086 - 3092
(2018/09/17)

Mechanistic investigation of imine formation in ruthenium-catalyzed N-alkylation of amines with alcohols
Imines are observed frequently in ruthenium-catalyzed N-alkylation of amines with alcohols. Herein, nitrogen–phosphine functionalized carbene ligands were developed and used in ruthenium-catalyzed N-alkylation to explore the mechanism of imine formation. The results showed that strongly electron-donating ligands were beneficial for imine formation and alcohol dehydrogenation to generate acid. In addition, with an increase of electron density of nitrogen atom in substituted amines, the yield of imines in N-alkylation was improved. At the same time, with electron-rich imines as substrates, the transfer hydrogenation of imines became difficult. It is suggested that strongly electron-donating ligands and substrates caused an increase of electron density on the ruthenium center, which resulted in the elimination of hydrogen atoms in active species [LRuH2] as hydrogen gas rather than transfer onto the imine coordinated with the ruthenium center.
Yu, Xiaojun,Li, Yaqiu,Fu, Haiyan,Zheng, Xueli,Chen, Hua,Li, Ruixiang
(2018/02/09)

The synthesis of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides by the microwave-assisted Pudovik reaction
A family of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides was synthesized by the microwave-assisted solvent-free addition of dialkyl phosphites and diphenylphosphine oxide, respectively, to imines formed from benzaldehyde derivatives and primary amines. After optimization, the reactivity was mapped, and the fine mechanism was evaluated by DFT calculations. Two α-aminophosphonates were subjected to an X-ray study revealing a racemic dimer formation made through a N-H?O=P intermolecular hydrogen bridges pair.
Bálint, Erika,Tajti, ádám,ádám, Anna,Csontos, István,Karaghiosoff, Konstantin,Czugler, Mátyás,ábrányi-Balogh, Péter,Keglevich, Gy?rgy
supporting information
p. 76 - 86
(2017/02/15)

Making Copper(0) Nanoparticles in Glycerol: A Straightforward Synthesis for a Multipurpose Catalyst
Small zero-valent copper nanoparticles (CuNPs) have been straightforwardly prepared from Cu(I) and Cu(II) precursors in glycerol and in the presence of polyvinylpyrrolidone as stabilizer. Thanks to the negligible vapor pressure of the solvent, these original nano-systems could be directly characterized in glycerol as well as in the solid state, exhibiting relevantly homogeneous colloidal dispersions, also even after catalysis. CuNPs coming from the well-defined coordination complex di-μ-hydroxobis[(N,N,N′,N′-tetramethylethylenediamine)copper(II)] chloride {[Cu(κ2-N,N-TMEDA)(μ-OH)]2Cl2} have been highly efficient in C–C and C–heteroatom bond formation processes. This new catalytic system has proved its performance in C–N couplings and in the synthesis of differently substituted propargylic amines through cross-dehydrogenative couplings, multi-component reactions such as A3 (aldehyde-alkyne-amine) and KA2 (ketone-alkyne-amine) couplings, as well as in the formation of heterocycles such as benzofurans, indolizines, and quinolines under smooth conditions. No significant copper amount was detected in the extracted organic compounds from the catalytic phase by inductively coupled plasma-atomic emission spectroscopic (ICP-AES) analyses, proving a highly efficient immobilization of copper nanoparticles in glycerol. From a mechanistic point of view, spectroscopic data (infrared and ultraviolet-visible spectra) agree with a surface-like catalytic reactivity. (Figure presented.).
Dang-Bao, Trung,Pradel, Christian,Favier, Isabelle,Gómez, Montserrat
supporting information
p. 2832 - 2846
(2017/08/23)

Co-N-C supported on SiO2: A facile, efficient catalyst for aerobic oxidation of amines to imines
We developed a novel, facile preparation method of Co-N-C/SiO2, which was the pyrolysis of silicone gel containing metal ion and triethanolamine (TEA) prepared by sol-gel process. N2 adsorption-desorption characterization displayed the sample had high specific surface area and pore volume (220.9 m2 g-1, 0.67 mL g-1). The active Co appeared to be small particles with size of about 5 nm and was well dispersed on SiO2. And the highly dispersed cobalt and nitrogen-doped carbon in Co-N-C/SiO2 served as active phase for the oxidation of amines to imines, thus Co-N-C/SiO2 could efficiently catalyze the oxidation of amines to imines in solvent-free, air atmospheric conditions, avoiding the use of large excesses of additives, specialized oxidant and solvent.
Zhang, Chenghui,Zhao, Pengshan,Zhang, Zongliang,Zhang, Jingwei,Yang, Ping,Gao, Peng,Gao, Jun,Liu, Di
p. 47366 - 47372
(2017/10/19)

MANGANESE BASED COMPLEXES AND USES THEREOF FOR HOMOGENEOUS CATALYSIS
The present invention relates to novel manganese complexes and their use, inter alia, for homogeneous catalysis in (1) the preparation of imine by dehydrogenative coupling of an alcohol and amine; (2) C-C coupling in Michael addition reaction using nitriles as Michael donors; (3) dehydrogenative coupling of alcohols to give esters and hydrogen gas (4) hydrogenation of esters to form alcohols (including hydrogenation of cyclic esters (lactones) or cyclic di-esters (di- lactones), or polyesters); (5) hydrogenation of amides (including cyclic dipeptides, lactams, diamide, polypeptides and polyamides) to alcohols and amines (or diamine); (6) hydrogenation of organic carbonates (including polycarbonates) to alcohols or hydrogenation of carbamates (including polycarbamates) or urea derivatives to alcohols and amines; (7) dehydrogenation of secondary alcohols to ketones; (8) amidation of esters (i.e., synthesis of amides from esters and amines); (9) acylation of alcohols using esters; (10) coupling of alcohols with water and a base to form carboxylic acids; and (11) preparation of amino acids or their salts by coupling of amino alcohols with water and a base. (12) preparation of amides (including formamides, cyclic dipeptides, diamide, lactams, polypeptides and polyamides) by dehydrogenative coupling of alcohols and amines; (13) preparation of imides from diols.
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(2017/09/05)

Tunable Ligand Effects on Ruthenium Catalyst Activity for Selectively Preparing Imines or Amides by Dehydrogenative Coupling Reactions of Alcohols and Amines
Selective dehydrogenative synthesis of imines from a variety of alcohols and amines was developed by using the ruthenium complex [RuCl2(dppea)2] (6 a: dppea=2-diphenylphosphino-ethylamine) in the presence of catalytic amounts of Zn(OCOCF3)2 and KOtBu, whereas the selective dehydrogenative formation of amides from the same sources was achieved by using another ruthenium complex, [RuCl2{(S)-dppmp}2] [6 d: (S)-dppmp=(S)-2-((diphenylphosphenyl)methyl)pyrrolidine], in the presence of catalytic amounts of Zn(OCOCF3)2 and potassium bis(trimethylsilyl)amide (KHMDS). Our previously reported ruthenium complex, [Ru(OCOCF3)2(dppea)2] (8 a), was the catalyst precursor for the imine synthesis, whereas [Ru(OCOCF3)2{(S)-dppmp}2] (8 d), which was derived from the treatment of 6 d with Zn(OCOCF3)2 and characterized by single-crystal X-ray analysis, was the pre-catalyst for the amide formation. Control experiments revealed that the zinc salt functioned as a reagent for replacing chloride anions with trifluoroacetate anions. Plausible mechanisms for both selective dehydrogenative coupling reactions are proposed based on a time-course study, Hammett plot, and deuterium-labeling experiments.
Higuchi, Takafumi,Tagawa, Risa,Iimuro, Atsuhiro,Akiyama, Shoko,Nagae, Haruki,Mashima, Kazushi
p. 12795 - 12804
(2017/09/06)