- Copper(i)-catalysed intramolecular hydroarylation-redox cross-dehydrogenative coupling ofN-propargylanilines with phosphites
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Intramolecular hydroarylation-redox cross-dehydrogenative coupling ofN-propargylanilines with phosphite diesters proceeded in the presence of Cu(i)-catalysts (20 mol%) to selectively give 2-phosphono-1,2,3,4-tetrahydroquinolines in good yields with 100% atomic utilization. P-H and two C-H bonds are activated at once and these hydrogen atoms are trapped by a propargylic triple bond in the molecule.
- Li, Guangzhe,Yu, Guo,Wang, Chengdong,Morita, Taiki,Zhang, Xuhai,Nakamura, Hiroyuki
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supporting information
p. 113 - 116
(2021/12/29)
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- Copper-Catalyzed Intramolecular Amination of C(sp3)-H Bond of Secondary Amines to Access Azacycles
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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.
- Jin, Ruo-Xing,Dai, Jing-Cheng,Li, Yan,Wang, Xi-Sheng
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supporting information
p. 421 - 426
(2021/01/26)
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- 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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- Sulfated polyborate: A dual catalyst for the reductive amination of aldehydes and ketones by NaBH4
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An efficient, quick, and environment-friendly one-pot reductive amination of aldehydes or ketones was developed. In ethanol at 70 °C, a imination catalyzed by sulfated polyborate and further reduced by sodium borohydride yields various amines. The present method has many significant benefits, including a shorter reaction time, excellent yields, and a hassle-free, straightforward experimental process. The reaction has a wide range of applications due to its flexibility, including secondary amine for reductive amination.
- Ganwir, Prerna,Chaturbhuj, Ganesh
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supporting information
(2021/05/19)
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- Rhodium catalyzed multicomponent dehydrogenative annulation: one-step construction of isoindole derivatives
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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
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supporting information
p. 7930 - 7933
(2021/08/17)
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- Rhodium-Catalyzed Dehydrogenative Annulation of N-Arylmethanimines with Vinylene Carbonate for Synthesizing Quinolines
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Here we report a novel Rh-catalyzed C-H/C-H alkenylation of N-arylmethanimines with vinylene carbonate acting as a vinylene unit. Forty examples of C3,C4-nonsubstituted quinolines were achieved from commercially available starting materials. This identified process features an exceedingly simple system, a lower loading of catalyst, and the capacity for postfunctionalization with bioactive molecules.
- Hu, Yan,Nan, Jiang,Yin, Jiacheng,Huang, Guanjie,Ren, Xin,Ma, Yangmin
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supporting information
p. 8527 - 8532
(2021/11/13)
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- Photocatalytic one-pot multidirectional N-alkylation over Pt/D-TiO2/Ti3C2: Ti3C2-based short-range directional charge transmission
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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/
- Jiang, Heyan,Sheng, Meilin,Li, Yue,Kong, Shuzhen,Bian, Fengxia
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- Redox-Neutral Imination of Alcohol with Azide: A Sustainable Alternative to the Staudinger/Aza-Wittig Reaction
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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
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p. 4071 - 4076
(2021/04/12)
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- Direct synthesis of imines from nitro compounds and biomass-derived carbonyl compounds over nitrogen-doped carbon material supported Ni nanoparticles
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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.
- Li, Bo,Wang, Yanxin,Chi, Quan,Yuan, Ziliang,Liu, Bing,Zhang, Zehui
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p. 4464 - 4471
(2021/03/15)
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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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- Ionic-Liquid-Catalyzed Synthesis of Imines, Benzimidazoles, Benzothiazoles, Quinoxalines and Quinolines through C?N, C?S, and C?C Bond Formation
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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
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p. 6705 - 6716
(2021/12/31)
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- Switchable Imine and Amine Synthesis Catalyzed by a Well-Defined Cobalt Complex
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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
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supporting information
p. 418 - 426
(2021/02/01)
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- Iron-Catalyzed Hydrogen Transfer Reduction of Nitroarenes with Alcohols: Synthesis of Imines and Aza Heterocycles
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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.
- Wu, Jiajun,Darcel, Christophe
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p. 1023 - 1036
(2021/01/09)
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- T3P-promoted synthesis of a series of novel 3-aryl-2-phenyl-2,3-dihydro-4H-1,3-benzothiazin-4-ones
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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.
- Silverberg, Lee J.,Pacheco, Carlos,Sahu, Debashish,Scholl, Peter,Sobhi, Hany F.,Bachert, Joshua T.,Bandholz, Kaitlyn,Bendinsky, Ryan V.,Bradley, Heather G.,Colburn, Baylee K.,Coyle, David J.,Dahl, Jonathon R.,Felty, Megan,Fox, Ryan F.,Gonzalez, Kyanna M.,Islam, Jasra M.,Koperna, Stacy E.,Moyer, Quentin J.,Noble, Duncan J.,Ramirez, Melissa E.,Yang, Ziwei
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p. 1797 - 1805
(2020/02/05)
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- Cross dehydrogenative coupling strategy for allylation of benzylanilines promoted by DDQ
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A cross dehydrogenative coupling strategy for allylation of benzylanilines promoted by DDQ is reported, which uses nonmetallic quinone DDQ as an oxidant in the allylation of N-benzylanilines under mild conditions. C–C bond with high selectivity and activity was constructed in this reaction and homoallylic amines were obtained with yields of up to 99%.
- Xiong, Ruimei,Hussain, Muhammad Ijaz,Liu, Qing,Xia, Wen,Xiong, Yan
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supporting information
(2019/12/11)
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- Tert-Butyl Hydroperoxide-Mediated Oxo-Sulfonylation of 2 H-Indazoles with Sulfinic Acid toward Indazol-3(2 H)-ones
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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.
- Ghosh, Payel,Mondal, Susmita,Hajra, Alakananda
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supporting information
p. 1086 - 1090
(2020/02/04)
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- Retraction: Harnessing Thiol as a Benzyl Reagent for Photocatalytic Reductive Benzylation of Imines (Organic Letters DOI: 10.1021/2Facs.orglett.0c00065)
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The authors retract this article after finding in subsequent studies that the quality of the purchased catalysts has a notable impact on the reproducibility of the results. Accordingly, the authors note that additional work is necessary to understand the
- Zhang, Jinghui,Zhang, Muliang
-
supporting information
p. 2112 - 2112
(2020/02/15)
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- Study on the interaction of triaryl-dihydro-1,2,4-oxadiazoles with α-glucosidase
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Purpose: One of the therapeutic approaches in the management of Type 2 diabetes is delaying the absorption of glucose through α-glucosidase enzymes inhibition, which can reduce the incidence of postprandial hyperglycemia. The existence of chronic postpran
- Khosravi, Arefeh,Vaezi, Gholamhassan,Hojati, Vida,Abdi, Khosrou
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p. 109 - 117
(2020/01/11)
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- Ni-Catalyzed asymmetric reduction of α-keto-β-lactams: via DKR enabled by proton shuttling
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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
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supporting information
p. 15557 - 15560
(2020/12/30)
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- Method for synthesizing imine by catalyzing alcohol-amine through NNN cobalt complex
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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.
- -
-
Paragraph 0046-0049
(2020/07/02)
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- Polyoxometalate catalyzed imine synthesis: Investigation of mechanistic pathways
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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
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supporting information
(2020/05/25)
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- Mild and efficient synthesis of secondary aromatic amines by one-pot stepwise reductive amination of arylaldehydes with nitroarenes promoted by reusable nickel nanoparticles
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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.
- Fiore, Ambra Maria,Romanazzi, Giuseppe,Dell'Anna, Maria Michela,Latronico, Mario,Leonelli, Cristina,Mali, Matilda,Rizzuti, Antonino,Mastrorilli, Piero
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- Visible light photocatalytic aerobic oxidative synthesis of imines from alcohols and amines on dye-sensitized TiO2
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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
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p. 128 - 135
(2019/01/04)
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- Visible-light-induced regioselective cross-dehydrogenative coupling of 2 H-indazoles with ethers
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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.
- Singsardar, Mukta,Laru, Sudip,Mondal, Susmita,Hajra, Alakananda
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p. 4543 - 4550
(2019/04/30)
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- Metal-Free Ring Opening Cyclization of Cyclopropane Carbaldehydes and N-Benzyl Anilines: An Eco-Friendly Access to Functionalized Benzo[b]azepine Derivatives
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Herein, we report a p-toluenesulfonic acid (PTSA) initiated mild and user-friendly ring opening/domino ring opening cyclization reaction (depends on substituent present in N-benzyl aniline) of cyclopropane carbaldehyde and N-benzyl aniline towards the formation of substituted 4-amino butanal/2,3-dihydro-1H-benzo[b]azepine. The product dihydro-1H-benzo[b]azepine was also converted into the corresponding tetrahydro-1H-benzo[b]azepine. (Figure presented.).
- Dey, Raghunath,Banerjee, Prabal
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supporting information
p. 2849 - 2854
(2019/04/26)
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- Chemoselective Reduction of Imines Catalyzed by Ruthenium(II) Half-Sandwich Complexes: A Mechanistic Study
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Ruthenium half-sandwich complexes ligated to chiral 2-oxazolidinethiones or 2-thiozolidinethiones in the reduction of N-benzylideneaniline using silyl hydrides as reductants has been examined. The chemoselective reduction of imines takes place under mild conditions to afford the corresponding amines in nearly quantitative yield. Mechanistic studies indicate that dissociation of the ancillary ligands generate the active catalyst in all the complexes studied, which is the same species generated by [Ru(p-cymene)(Cl)2]2 under the reaction conditions. This results in the formation of a single catalytic species irrespective of the starting half-sandwich complex. Detailed mechanistic studies involving trapping of intermediates, in situ studies using mass spectrometry and NMR spectroscopy were carried out using the active catalyst generated by [Ru(p-cymene)(Cl)2]2. The mechanism of the reaction is dependent on the number of the hydrogen atoms in the reducing silane. The reaction proceeds via Gade-Hoffman pathway or Zheng-Chan pathway when a dihydro or trihydrosilane is the reductant. However, the use of a monohydrosilane, leads to longer reaction times presumably due to a change in the reaction pathway.
- Reshi, Noor U. Din,Kathuria, Lakshay,Samuelson, Ashoka G.
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p. 2947 - 2955
(2019/06/27)
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- Iron-Catalyzed Nitrene Transfer Reaction of 4-Hydroxystilbenes with Aryl Azides: Synthesis of Imines via C=C Bond Cleavage
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C=C bond breaking to access the C=N bond remains an underdeveloped area. A new protocol for C=C bond cleavage of alkenes under nonoxidative conditions to produce imines via an iron-catalyzed nitrene transfer reaction of 4-hydroxystilbenes with aryl azides is reported. The success of various sequential one-pot reactions reveals that the good compatibility of this method makes it very attractive for synthetic applications. On the basis of experimental observations, a plausible reaction mechanism is also proposed.
- Peng, Yi,Fan, Yan-Hui,Li, Si-Yuan,Li, Bin,Xue, Jing,Deng, Qing-Hai
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p. 8389 - 8394
(2019/10/16)
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- Direct reductive coupling of nitroarenes and alcohols catalysed by Co-N-C/CNT@AC
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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.
- Liu, Di,Yang, Ping,Zhang, Hao,Liu, Minjie,Zhang, Wenfei,Xu, Dongmei,Gao, Jun
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p. 2129 - 2137
(2019/04/27)
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- Carbonylation Access to Phthalimides Using Self-Sufficient Directing Group and Nucleophile
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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
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p. 104 - 112
(2018/02/19)
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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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- Dynamic Covalent Metathesis in the C=C/C=N Exchange between Knoevenagel Compounds and Imines
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Fast and reversible dynamic covalent C=C/C=N exchange takes place without catalyst in nonpolar solvents between barbiturate-derived Knoevenagel (Kn) compounds and imines. A detailed study of the reaction indicates that it proceeds by an associative organo-metathesis mechanism involving the formation of a four-membered ring azetidine intermediate by addition of the imine C=N group to the C=C bond of the Kn compound. This intermediate could be generated cleanly and stabilized at low temperature by condensation of the o,p-dinitrophenyl Kn derivative with the cyclic imine 1-azacyclohexene. It was characterized by extensive NMR and mass spectrometric studies. The process described represents a genuine dynamic covalent organo-metathesis through a four-membered ring adduct as intermediate. It paves the way for the exploration of a wide set of dynamic systems involving (strongly) polarized C=C bonds and various imines, extending also into covalent dynamic polymers and polymolecular assemblies.
- Gu, Ruirui,Flidrova, Karolina,Lehn, Jean-Marie
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supporting information
p. 5560 - 5568
(2018/05/01)
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- The Divergent Cascade Reactions of Arylalkynols with Homopropargylic Amines or Electron-Deficient Olefins: Access to the Spiro-Isobenzofuran- b-pyrroloquinolines or Bridged-Isobenzofuran Polycycles
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Two divergent cascade reactions of arylalkynols with homopropargylic amines or electron-deficient olefins were developed to synthesize the spiro-isobenzofuran-b-pyrroloquinolines or bridged-isobenzofuran heterocycles in good yields, respectively. One reaction actually involved intramolecular 5-endo-dig hydroamination cyclization-protonation of homopropargylic amines to give cycloiminium ions and intramolecular 5-exo-dig hydroalkoxylation cyclization of arylalkynols to generate isobenzofuran with exocyclic double bond, followed by the nontypical Povarov-type reaction in the presence of PtCl2/FeCl3 cocatalysts. The other underwent intramolecular hydroalkoxylation cycloisomerization of alkynols with the subsequent normal [4 + 2] cycoaddition with dienophiles. Herein, the arylalkynols acted as both "masked" electron-rich olefins and "masked" electron-rich dienes.
- Wang, Lun,Liu, Lingyan,Chang, Weixing,Li, Jing
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supporting information
p. 7799 - 7813
(2018/06/18)
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- Visible-Light Photocatalytic Synthesis of Amines from Imines via Transfer Hydrogenation Using Quantum Dots as Catalysts
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CdSe/CdS core/shell quantum dots (QDs) can be used as stable and highly active photoredox catalysts for efficient transfer hydrogenation of imines to amines with thiophenol as a hydrogen atom donor. This reaction proceeds via a proton-coupled electron transfer (PCET) from the QDs conduction band to the protonated imine followed by hydrogen atom transfer from the thiophenol to the α-aminoalkyl radical. This precious metal free transformation is easy to scale up and can be carried out by a one-pot protocol directly from aldehyde, amine, and thiophenol. Additional advantageous features of this protocol include a wide substrate scope, high yield of the amine products, extremely low catalyst loading (0.001 mol %), high turnover number (105), and the mild reaction conditions of using visible light or sun light at room temperature in neutral media.
- Xi, Zi-Wei,Yang, Lei,Wang, Dan-Yan,Pu, Chao-Dan,Shen, Yong-Miao,Wu, Chuan-De,Peng, Xiao-Gang
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p. 11886 - 11895
(2018/09/25)
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- Cross-dehydrogenative coupling strategy for phosphonation and cyanation of secondary N-alkyl anilines by employing 2,3-dichloro-5,6-dicyanobenzoquinone
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The cross-dehydrogenative coupling strategy for metal-free phosphonation and cyanation of secondary N-alkyl anilines has been developed firstly under mild reaction conditions. Based on detailed optimization of reaction conditions, the substrate generality of N-alkyl anilines and various hydrogen phosphonates has been investigated, and a series of versatile α-aminophosphonates and α-aminonitriles were therefore furnished in good to excellent yields. A plausible collective reaction mechanism through dehydrogenation to imine formation, then to respective α-aminophosphonates and α-aminonitriles was proposed.
- Liu, Qing,Yu, Shuchen,Hu, Liangzhen,Hussain, Muhamad Ijaz,Zhang, Xiaohui,Xiong, Yan
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p. 7209 - 7217
(2018/11/10)
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- Conversion of aldimines to secondary amines using iron-catalysed hydrosilylation
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Iron-catalyzed hydrosilylation of imines to amines using a well-defined iron complex is reported. This method employs relatively mild conditions, by reaction of imine, (EtO)3SiH in a 1 : 2 ratio in the presence of 1 mol% precatalyst ([BIAN]Fe(η6-toluene), 3, BIAN = bis(2,6-diisopropylaniline)acenaphthene) at 70 °C. A broad scope of imines was readily converted into the corresponding secondary amines without the need for precatalyst activators.
- Saini, Anu,Smith, Cecilia R.,Wekesa, Francis S.,Helms, Amanda K.,Findlater, Michael
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supporting information
p. 9368 - 9372
(2019/01/03)
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- CO2-Catalyzed Efficient Dehydrogenation of Amines with Detailed Mechanistic and Kinetic Studies
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CO2-catalyzed dehydrogenation of amines has been achieved under photocatalytic conditions. With this concept, various amines have been selectively dehydrogenated to the corresponding imines in the presence of different functional groups such as nitrile, nitro, ester, halogen, ether, thioether, and carbonyl or carboxylic acid moieties. At the end, the CO2-catalyzed synthesis of pharmaceutical drugs has been achieved. The CO2 radical has been detected by EPR spectroscopy using DMPO, and the mechanism of this reaction is proposed on the basis of DFT calculations and experimental evidence.
- Riemer, Daniel,Schilling, Waldemar,Goetz, Anne,Zhang, Yu,Gehrke, Sascha,Tkach, Igor,Hollóczki, Oldamur,Das, Shoubhik
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p. 11679 - 11687
(2018/11/23)
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- Selective aerobic oxidation of halides and amines with an inorganic-ligand supported zinc catalyst
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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
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p. 13323 - 13327
(2018/10/15)
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- Mechanistic investigation of imine formation in ruthenium-catalyzed N-alkylation of amines with alcohols
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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
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- Direct synthesis of imines by 9-azabicyclo-[3,3,1]nonan-N-oxyl/KOH-catalyzed aerobic oxidative coupling of alcohols and amines
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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.
- Wan, Yan,Ma, Jia-Qi,Hong, Chao,Li, Mei-Chao,Jin, Li-Qun,Hu, Xin-Quan,Hu, Bao-Xiang,Mo, Wei-Min,Sun, Nan,Shen, Zhen-Lu
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p. 1269 - 1272
(2017/10/26)
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- Unsymmetrical indazolyl-pyridinyl-triazole ligand-promoted highly active iridium complexes supported on hydrotalcite and its catalytic application in water
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Herein, an indazolyl-pyridinyl-triazole ligand was synthesized and its iridium complex supported on hydrotalcite was characterized via X-ray power diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray (EDX) spectroscopy and transmission electron microscopy (TEM). This new heterogeneous catalyst bearing the unsymmetrical indazolyl-pyridinyl-triazole ligand exhibits high catalytic activity in water. Both functionalized amines and imines were obtained from the challenging selective reaction of benzylamines with arylamines through transfer hydrogenation and dehydrogenation under clean conditions. In particular, it was observed that this catalyst system showed good recovery performance in water. Mechanistic studies showed that this transformation occurs via amine dehydrogenation, hydrolysis and condensation processes. The direct capture of the reaction intermediate provides sufficient proof for this process.
- Ge, Chenyang,Sang, Xinxin,Yao, Wei,Zhang, Liang,Wang, Dawei
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supporting information
p. 1805 - 1812
(2018/04/30)
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- Method of synthesizing imine and amine compounds by means of borrowing-hydrogen reduction coupling
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The invention belongs to energy and chemical industry and particularly relates to a method of synthesizing imine and amine compounds by means of borrowing-hydrogen reduction coupling by using a nitrogen-doped hierarchical-porous biomass-based carbon material supported catalyst. The method includes the steps of: under a seal reaction condition, adding a nitro-aromatic hydrocarbon compound, benzyl alcohol compounds with different substituent groups, the supported catalyst, methylbenzene and potassium tert-butoxide; performing a reaction at 50-150 DEG C for 4-24 h, cooling the product to room temperature and filtering a reaction liquid to obtain the imine compound represented in the formula (1) or the amine compound represented in the formula (2). The raw materials of the catalyst are regenerable resources, are widely distributed, are green and environment-friendly, are easy to prepare and abundant in sources, and are low in cost; the catalyst can be recycled without deactivation and is stable to air, water and heat. By means of the supported metal catalyst, the conversion rate of the borrowing-hydrogen reduction coupling reaction on the nitro-compound and alcohol to prepare the iminecompounds is higher than 99%, and yield can reach 90-60%; the conversion rate of same to prepare the amine compounds is higher than 99%, and yield can reach 90-60%.
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Paragraph 0043; 0044; 0045; 0046; 0048
(2018/11/04)
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- Preparation method for imine compounds
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The invention relates to a preparation method for imine compounds. The preparation method comprises the following concrete steps: with toluene or derivatives thereof and aminated compounds as reaction substrates, adding an oxygen source under the action of a catalyst; putting the above-mentioned substances into a pressure container, enclosing the pressure container and carrying out a stirring reaction at 50 to 150 DEG C for 6 to 24 h; and carrying out oxidative condensation so as to prepare the imine compounds. The method is characterized in that a metal oxide is used as the catalyst. According to the method, raw materials are cheap and easily available; the prepared imine compounds are easily separable from the catalyst; the catalyst can be cyclically used; reaction process is simple, controllable and easy to operate; and the yield of the imine compounds is as high as 90%.
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Paragraph 0072; 0073
(2017/10/25)
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- C–H Bond Functionalization of 1,4-Benzoquinone by Silver-Mediated Regioselective Phosphination and Amination Reactions
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The one-pot synthesis of 2,5-bis(diarylphosphoryl)-3,6-bis(arylamino)cyclohexa-2,5-diene-1,4-diones has been achieved by AgI-mediated full C–H functionalization of 1,4-benzoquinone (BQ) through regioselective dual phosphination and amination reactions. BQ, diarylphosphine oxides [SPOs, Ar2PH(=O)], and imines reacted to give the products under mild conditions. 1,4-Naphthoquinone (NQ) could also be used instead of BQ. When aniline was used instead of the corresponding imine, a lower yield of the desired product was obtained. In the absence of Ag2CO3, hydrophosphinylation of the imine by the SPO occurred as a competitive side-reaction. AgI plays versatile roles in this reaction, as a mediator for facilitating the consecutive additions of Ar2P(=O)– and aniline to the related β-carbon atoms of BQ, as an oxidant of hydroquinone (HQ) intermediates to form the substituted BQ counterpart, and as an inhibitor of the hydrophosphinylation side-reaction of the imine by the SPO. The X-ray crystal structures of several new products have been determined. A reaction mechanism is also proposed based on the experimental results.
- Chang, Yu-Chang,Yuan, Pin-Ting,Hong, Fung-E
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p. 2441 - 2450
(2017/05/12)
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- Reactivity of 3-Oxo-β-lactams with Respect to Primary Amines—An Experimental and Computational Approach
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The reactivity of 3-oxo-β-lactams with respect to primary amines was investigated in depth. Depending on the specific azetidin-2-one C4 substituent, this reaction was shown to selectively produce 3-imino-β-lactams (through dehydration), α-aminoamides (thr
- Piens, Nicola,Goossens, Hannelore,Hertsen, Dietmar,Deketelaere, Sari,Crul, Lieselotte,Demeurisse, Lotte,De Moor, Jelle,Van den Broeck, Elias,Mollet, Karen,Van Hecke, Kristof,Van Speybroeck, Veronique,D'hooghe, Matthias
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p. 18002 - 18009
(2017/12/13)
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- Transition metal free catalytic hydroboration of aldehydes and aldimines by amidinato silane
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The transition metal free catalytic hydroboration of aldehydes and ketones is very limited and has not been reported with a well-defined silicon(iv) compound. Therefore, we chose to evaluate the previously reported silicon(iv) hydride [PhC(NtBu)2SiHCl2], (1) as a single component catalyst and found that it catalyzes the reductive hydroboration of a range of aldehydes with pinacolborane (HBpin) under ambient conditions. In addition, compound 1 can catalyze imine hydroboration. DFT calculation was carried out to understand the mechanism.
- Bisai, Milan Kumar,Pahar, Sanjukta,Das, Tamal,Vanka, Kumar,Sen, Sakya S.
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supporting information
p. 2420 - 2424
(2017/03/08)
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- P-N Cooperative Borane Activation and Catalytic Hydroboration by a Distorted Phosphorous Triamide Platform
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Studies of the stoichiometric and catalytic reactivity of a geometrically constrained phosphorous triamide 1 with pinacolborane (HBpin) are reported. The addition of HBpin to phosphorous triamide 1 results in cleavage of the B-H bond of pinacolborane through addition across the electrophilic phosphorus and nucleophilic N-methylanilide sites in a cooperative fashion. The kinetics of this process of were investigated by NMR spectroscopy, with the determined overall second-order empirical rate law given by ν = -k[1][HBpin], where k = 4.76 × 10-5 M-1 s-1 at 25 °C. The B-H bond activation process produces P-hydrido-1,3,2-diazaphospholene intermediate 2, which exhibits hydridic reactivity capable of reacting with imines to give phosphorous triamide intermediates, as confirmed by independent synthesis. These phosphorous triamide intermediates are typically short lived, evolving with elimination of the N-borylamine product of imine hydroboration with regeneration of the deformed phosphorous triamide 1. The kinetics of this latter process are shown to be first-order, indicative of a unimolecular mechanism. Consequently, catalytic hydroboration of a variety of imine substrates can be realized with 1 as the catalyst and HBpin as the terminal reagent. A mechanistic proposal implicating a P-N cooperative mechanism for catalysis that incorporates the various independently verified stoichiometric steps is presented, and a comparison to related phosphorus-based systems is offered.
- Lin, Yi-Chun,Hatzakis, Emmanuel,McCarthy, Sean M.,Reichl, Kyle D.,Lai, Ting-Yi,Yennawar, Hemant P.,Radosevich, Alexander T.
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supporting information
p. 6008 - 6016
(2017/05/04)
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- Development of a General Protocol to Prepare 2H-1,3-Benzoxazine Derivatives
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A practical synthesis and detailed development process of 2H-1,3-benzoxazine derivatives catalyzed by aldimine and trifluoromethanesulfonic acid is described. A broad range of substrates with diverse steric and electronic properties were explored. Aliphatic/aromatic/heteroaromatic substrates all proceed well under conditions which have been optimized into a robust, scalable process.
- Qi, Ji,Oliver, Steven F.,Xiao, Wensong,Song, Licheng,Brands, Karel M. J.
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p. 1547 - 1556
(2017/10/25)
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- Well-Defined Silica Grafted Molybdenum Bis(imido) Catalysts for Imine Metathesis Reactions
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Novel site-isolated tetracoordinated molybdenum complexes possessing bis(imido) ligands, [( - Si-O)2Mo( - NR)2] (R = t-Bu, 2,6-C6H3-i-Pr2), were immobilized on partially dehydroxylated silica (SiO2-200) by a rigorous surface organometallic chemistry protocol. The newly developed materials adorned with bis(imido) functional units, which were previously exploited mainly as spectator ligands on silica-supported olefin metathesis molybdenum catalysts, are found to be efficient heterogeneous catalytic systems for imine cross metathesis under mild conditions.
- Barman, Samir,Merle, Nicolas,Minenkov, Yury,De Mallmann, Aimery,Samantaray, Manoja K.,Le Quéméner, Frédéric,Szeto, Kai C.,Abou-Hamad, Edy,Cavallo, Luigi,Taoufik, Mostafa,Basset, Jean-Marie
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supporting information
p. 1550 - 1556
(2017/04/28)
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- Silica functionalized Cu(II) acetylacetonate Schiff base complex: An efficient catalyst for the oxidative condensation reaction of benzyl alcohol with amines
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Silica functionalized Cu(II) acetylacetonate Schiff base complex via the one pot reaction of silica functionalized 3-aminopropyltriethoxysilane with acetyl acetone and copper acetate has been reported. The synthesized material was well characterized by analytical techniques such as FT-IR, UV-DRS, XRD, SEM-EDX, HR-TEM, EPR, ICP-AES and BET analysis. The characterization results confirmed the grafting of Cu(II) Schiff base complex on the silica surface. The catalytic activity of synthesized silica functionalized Cu(II) acetylacetonate Schiff base complex was evaluated through the oxidative condensation reaction of benzyl alcohol to imine.
- Anbarasu,Malathy,Karthikeyan,Rajavel
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p. 305 - 312
(2017/06/27)
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- Method for preparing imine compound from alcohol and amine through catalytic oxidation
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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.
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Paragraph 0039
(2017/08/31)
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