- Metal-free regioselective C-H amination for the synthesis of pyrazole-containing 2H-indazoles
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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
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p. 1787 - 1794
(2021/03/14)
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- Arene diruthenium(II)-mediated synthesis of imines from alcohols and amines under aerobic condition
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The utility and selectivity of the newly synthesized dinuclear arene Ru(II) complex were demonstrated towards the synthesis of imines from coupling of alcohols and amines in the aerobic condition. Analytical and various spectral methods have been used to establish the unprecedented formation of the new thiolato-bridged dinuclear ruthenium complex. The molecular structure of the titled complex was evidenced with aid of X-ray crystallographic technique. A wide range of imines were obtained in good-to-excellent yields up to 98% and water as the by-product through an acceptorless dehydrogenative coupling of alcohols with amines. The catalytic reaction operated a concise atom economical without any oxidant with 1 mol% of the catalyst load. Further, the role of base, solvent and catalyst loading of the coupling reaction has been investigated. A plausible mechanism has been described and was found to proceed via the formation of an aldehyde intermediate. Short synthesis of antibacterial drug N-(salicylidene)-2-hydroxyaniline illustrated the utility of the present protocol.
- Tamilthendral, Veerappan,Ramesh, Rengan,Malecki, Jan Grzegorz
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- Highly chemoselective synthesis of imine over Co/Zn bimetallic MOFs derived Co3ZnC-ZnO embed in carbon nanosheet catalyst
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One-pot direct synthesis of imines via reductive amination of nitroarenes with aromatic aldehydes remains a great challenge due in part to its over-hydrogenation of imines to secondary amines. Herein, a novel Co3ZnC and ZnO supported on N-doped carbon nanosheet catalyst with the thickness of ca. 5.0 nm was fabricated through the direct pyrolysis of a Co/Zn bimetallic MOFs at 500 °C (named as Co3ZnC-ZnO/NC-500). Surprisingly, the developed Co3ZnC-ZnO/NC-500 catalyst delivers 99.9 % conversion of nitrobenzene and 98.5 % selectivity to N-benzylideneaniline in one-pot reductive amination of nitrobenzene with benzaldehyde. Various characterizations (including as SEM, XRD, TEM, AFM, XPS, Raman and N2 adsorption–desorption) have revealed that the generated small size of Co3ZnC alloy, abundant structural defects, larger specific surface area (105.5 m2·g?1) as well as more basic sites are responsible for the outstanding catalytic activity of Co3ZnC-ZnO/NC-500 catalyst for tandem reaction. Moreover, the Co3ZnC-ZnO/NC-500 catalyst exhibits high stability during the recycling experiments without the loss of its catalytic activity. Notably, the results of contrast experiments have demonstrated that the intentional introduction of ZnO in Co3ZnC-ZnO/NC-500 catalyst plays a key role in the selectivity to N-benzylideneaniline in the tandem reaction. This study provides a new guideline for designing tandem catalysts with high selectivity.
- Li, Guangming,Li, Jingfang,Li, Weizuo,Li, Xuewei,Mao, Guijie,She, Wei,Wang, Jing
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- Oxygen-vacancies-engaged efficient carrier utilization for the photocatalytic coupling reaction
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Defects can greatly optimize the solar light harvesting capability and electronic structure of oxide materials. However, it remains challenging to achieve a defect engineering strategy under mild conditions. Meanwhile, the simultaneous exploitation of photogenerated holes (h+) and electrons (e?) to promote both photooxidation and photoreduction in a coupled system has rarely been reported. For the first time, we reveal an oxygen-vacancies-mediated photocatalytic strategy in which the electrons and holes are fully utilized for nitrobenzene reduction coupled with benzyl alcohol oxidation. The oxygen vacancies (OVs) generated in situ on the surface of TiO2 greatly extend light absorption into the visible region and promote the photogenerated electron transport for efficient photocatalysis. The experimental and theoretical results together indicate that chemisorption on the TiO2 surface decreases the oxidation potential of benzyl alcohol and causes an upward shift in its HOMO, which facilitates the oxidation reaction of benzyl alcohol to benzaldehyde. The in situ generated surface OVs also act as a bridge to enable the trapping and transferring of the photoinduced electrons to the nitrobenzene. This work provides a new perspective of utilizing the chemisorption between the reactant and catalyst to achieve a defect engineering strategy for synergetic photocatalysis.
- Yang, Xue,Tao, Huilin,Leow, Wan Ru,Li, Jingjun,Tan, Yanxi,Zhang, Yongfan,Zhang, Teng,Chen, Xiaodong,Gao, Shuiying,Cao, Rong
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p. 116 - 125
(2019/04/08)
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- Manganese catalyzed reductive amination of aldehydes using hydrogen as a reductant
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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
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supporting information
p. 4302 - 4305
(2018/05/03)
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- Activated Carbon Supported Ruthenium Nanoparticles Catalyzed Synthesis of Imines from Aerobic Oxidation of Alcohols with Amines
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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.]
- Zhang, Yuecheng,Lu, Fei,Zhang, Hong-Yu,Zhao, Jiquan
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- Synthesis and spectroscopic properties of a series of novel 2-aryl-3-phenyl-2,3-dihydro-4H-1,3-benzothiazin-4-ones
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A series of thirteen novel 2-aryl-3-phenyl-2,3-dihydro-4H-1,3-benzothiazin-4-ones was prepared at room temperature by T3P-mediated cyclization of N-phenyl-C-aryl imines with thiosalicylic acid. The spectroscopic and physical properties are reported and discussed. 1H-19F and 13C-19F couplings were observed in the NMR spectra of fluorinated compounds. Through-space interactions were observed in the 1H and 13C NMR spectra of the ortho-nitro compound. Trends were observed in the IR and UV absorptions of the ortho/meta/para-nitro series.
- Silverberg, Lee J.,Pacheco, Carlos,Lagalante, Anthony,Tierney, John,Bachert, Joshua T.,Bayliff, J. Austin,Bendinsky, Ryan V.,Cali, Aaron S.,Chen, Liuxi,Cooper, Avril D.,Minehan, Michael J.,Mroz, Caitlin R.,Noble, Duncan J.,Weisbeck, Alexander K.,Xie, Yiwen,Yang, Ziwei
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p. 122 - 143
(2018/05/09)
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- A Route to Polysubstituted Aziridines from Carbenes and Imines through a Nondiazo Approach
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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.
- Luo, Hejiang,Chen, Kai,Jiang, Huanfeng,Zhu, Shifa
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supporting information
p. 5208 - 5211
(2016/11/02)
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- Ruthenium-catalyzed reductive methylation of imines using carbon dioxide and molecular hydrogen
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The use of the well-defined [Ru(triphos)(tmm)] catalyst, CO2 as C1 source, and H2 as reducing agent enabled the reductive methylation of isolated imines, as well as the direct coupling of amines with aldehydes and the subsequent reductive methylation of the insitu formed imines. The method, which afforded the corresponding N-methyl amines in very good to excellent yields, was also used for the preparation of the antifungal agent butenafine in one step with no apparent waste, thus increasing the atom efficiency of its synthesis.
- Beydoun, Kassem,Ghattas, Ghazi,Thenert, Katharina,Klankermayer, Jürgen,Leitner, Walter
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supporting information
p. 11010 - 11014
(2015/03/30)
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- N-Alkylation of amines through hydrogen borrowing over a heterogeneous Cu catalyst
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Substitution of alkylhalides for the synthesis of amines is a relevant target for synthetic chemists. Secondary amines can be obtained in a one pot-one step reaction from secondary and benzylic alcohols and aniline over a heterogeneous copper catalyst. The process does not require any additive, is intrinsically safe and produces no waste.
- Santoro, Federica,Psaro, Rinaldo,Ravasio, Nicoletta,Zaccheria, Federica
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p. 2596 - 2600
(2014/01/06)
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- Highly active and selective synthesis of imines from alcohols and amines or nitroarenes catalyzed by Pd/DNA in water with dehydrogenation
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A direct imination was developed from alcohols and amines under catalysis of Pd/DNA by dehydrogenation without additional oxidant, affording the corresponding imines in moderate to good yields with excellent chemoselectivity. By virtue of the liberated molecular hydrogen, the nitroarenes could also be deoxidized in situ into amines and a one-pot tandem synthesis of imines was achieved from nitroarenes. This heterogeneous catalyst can be recovered and reused at least five times by taking advantage of its water-soluble reversibility. All these conformations were performed smoothly in water under mild conditions, and an atom economical and environmentally benign synthesis was embodied in this imination.
- Tang, Lin,Sun, Huayin,Li, Yunfeng,Zha, Zhenggen,Wang, Zhiyong
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p. 3423 - 3428
(2013/01/16)
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- Stereoselective synthesis of pyrano[3,2-c]- and furano[3,2-c]quinolines: Gadolinium chloride catalyzed one-pot aza-Diels-Alder reactions
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A simple and efficient method for the cis-selective synthesis of pyrano- and furano[3,2-c]quinolines via gadolinium chloride catalyzed onepot aza-Diels-Alder reaction is described. Solvent conditions played amajor role in affecting the diastereoselectivity of the products.
- Yu, Yong,Zhou, Jun,Yao, Zhigang,Xu, Fan,Shen, Qi
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experimental part
p. 351 - 354
(2011/04/22)
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- Proline triflate catalysed Diels-Alder reaction in the synthesis of tetrahydroquinoline derivatives
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Proline triflate was found to catalyse efficiently the one-pot synthesis of 2H-pyranotetrahydroquinolines from aryl imines, and 3,4-dihydro-2H-pyran with high stereoselectivity. The aryl imines were formed in situ from aromatic amines and arylaldehydes.
- Li, Jianjun,Li, Jia,Su, Weike
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experimental part
p. 499 - 504
(2010/01/16)
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- Electrochemical carboxylation of fluorocontaining imines with preparation of fluorinated N-phenylphenylglycines
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A possibility of obtaining fluorine-containing N-phenylphenylglycine derivatives at yields of up to 85% via the electrochemical carboxylation of corresponding benzalanilines was shown. The influence of imine's electron structure, the nature of supporting
- Koshechko,Titov,Bondarenko,Pokhodenko
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p. 701 - 706
(2008/12/22)
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- Separation of Ring Polar and Resonance Effects on the Rate and Equilibrium Constants for Methoxide Ion-Promoted Addition of Methanol to N-Benzylideneanilines Substituted at the Benzylidene Moiety
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Rate and equilibrium constants for the title reaction (α-amino ether formation) at 25 deg C in methanol are reported for 16 N-benzylideneanilines (BAs) substituted at the benzaldehyde moiety.In contrast to a previous report dealing with BAs substituted at the aniline residue, it is shown that an uncatalyzed pathway competes with the methoxide ion-catalyzed reaction, these two processes corresponding to rate-limiting attachment of the lyate ion to the C=N bond of iminium ion and free imine, respectively.For the latter reaction pathway, the lifetimes of the amide-ion intermediates are long enough to allow a stepwise mechanism.The equilibrium constants for the overall reaction are correlated by the two-parameter Young-Jencks (YJ) equation n?n + ρr(?+ - ?n) + C> allowing separation of the overall polar effect of the substituted ring (ρn = 0.87), including resonance-induced polar (RP) effects, from the direct resonance (DR) effect due to conjugation with the C=N group (ρr = 0.54).For the forward methoxide ion-catalyzed process, the polar and DR contributions to the substituent effects on the second-order rate constant have the same sign (ρn = 1.79 and ρr = 0.28, respectively), but these have opposite signs (ρn = 0.92 and ρr = -0.25) for the reverse reaction.The contribution of the DR effects for the reverse rate constants, which make the points lie above the log k-?n line, stems from gain in resonance at the negatively charged transition state.The validity and significance of the YJ treatment are discussed.
- Toullec, Jean,Bennour, Sadjia
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p. 2831 - 2839
(2007/10/02)
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- SYNTHESE VON FLUORIERTEN N-ARYLAMINO-ARYLMETHANPHOSPHONSAEUREDIALKYLESTERN
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Fluorinated α-C- and N-arylsubstituted aminomethanephosphonic acid diethylesters 5 are prepared in high yields by a "two-step" procedure: mixing equimolar amounts of fluorinated benzaldehydes 1 and anilines 2 to benzaldehyde-(N-aryl-)imines 3.Subsequently
- Gruss, Ulrike,Haegele, Gerhard
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p. 209 - 222
(2007/10/02)
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