- Gold nanoparticles catalyst with redox-active poly(aniline sulfonic acid): Application in aerobic dehydrogenative oxidation of cyclic amines in aqueous solution
-
The catalysis of poly(2-methoxyaniline-5-sulfonic acid) (PMAS)/gold nanoparticles catalyst was demonstrated for the dehydrogenative oxidation reaction of 2-substituted indoline and dihydropyridine under molecular oxygen in aqueous solution. This catalyst was recyclable. Redox mediating function of PMAS was revealed by following the UV-vis spectra.
- Amaya, Toru,Ito, Tsubasa,Inada, Yuhi,Saio, Daisuke,Hirao, Toshikazu
-
-
Read Online
- Rhodium(III)-Catalyzed Synthesis of Indole Derivatives from Pyrimidyl-Substituted Anilines and Diazo Compounds
-
An efficient method for the synthesis of indole derivatives from readily available pyrimidyl-substituted anilines and diazo compounds via rhodium(III)-catalyzed C-H bond activation has been developed. This cyclization reaction displays excellent functional group compatibility and regioselectivity, which overcomes some drawbacks of the classical indole synthetic methods and provides a facile approach for the construction of multi-substituted indole derivatives. The redox-neutral intermolecular annulation procedure comprises tandem C-H bond activation, cyclization, and condensation steps, releasing water and nitrogen as by-products.
- Yu, Ke,Liang, Yujie,Li, Bin,Wang, Baiquan
-
-
Read Online
- Nickel-Catalyzed Asymmetric Reductive Heck Cyclization of Aryl Halides to Afford Indolines
-
A nickel-catalyzed asymmetric reductive Heck reaction of aryl chlorides has been developed that affords substituted indolines with high enantioselectivity. Manganese powder is used as the terminal reductant with water as a proton source. Mechanistically, it is distinct from the palladium-catalyzed process in that the nickel–carbon bond is converted into a C?H bond to release the product through protonation instead of hydride donation followed by C?H reductive elimination on Pd.
- Qin, Xurong,Lee, Marcus Wen Yao,Zhou, Jianrong Steve
-
-
Read Online
- Sterically Controlled Ru(II)-Catalyzed Divergent Synthesis of 2-Methylindoles and Indolines through a C-H Allylation/Cyclization Cascade
-
A ruthenium-catalyzed synthesis of 2-methylindole was accomplished via a C-H allylation/oxidative cyclization cascade. Strategically, β-hydride elimination from the σ-alkyl-Ru intermediate has been suppressed by steric hindrance from a remote position. Hence, 2-methylindolines from the corresponding ortho-substituted anilines were achieved via protodemetalation in lieu of β-hydride elimination under a modified reaction condition. This mild intermolecular annulation cascade proceeds smoothly by a redox-neutral ruthenium catalyst without stoichiometric metal oxidants, such as silver(I) or copper(II) salts, providing excellent functional group tolerance.
- Manna, Manash Kumar,Bairy, Gurupada,Jana, Ranjan
-
-
Read Online
- Homogeneously-catalysed hydrogen release/storage using the 2-methylindole/2-methylindoline LOHC system in molten salt-organic biphasic reaction systems
-
Ir-Complex catalysed hydrogen release/storage using a 2-methylindole/2-methylindoline Liquid Organic Hydrogen Carrier (LOHC) system is shown to be effective in a temperature range of 120 to 140 °C. In the form of a liquid-liquid biphasic reaction system with molten [PPh4][NTf2] as catalyst immobilisation phase, the applied cationic Ir-complex can be easily separated and recycled enabling a small amount of ionic catalyst solution to store/release a large amount of hydrogen.
- S?gaard, Alexander,Scheuermeyer, Marlene,B?smann, Andreas,Wasserscheid, Peter,Riisager, Anders
-
-
Read Online
- Asymmetric transfer hydrogenation of heterocycle-containing acetophenone derivatives using N-functionalised [(benzene)Ru(II)(TsDPEN)] complexes
-
The application of enantiomerically-pure ruthenium(II) catalysts containing N - functionalised TsDPEN ligand to the asymmetric transfer hydrogenation of 15 examples of α-heterocyclic acetophenone derivatives is reported. Products of up to 99% ee were formed.
- Barrios-Rivera, Jonathan,Xu, Yingjian,Clarkson, Guy J.,Wills, Martin
-
supporting information
(2021/12/02)
-
- Metal–Organic Layers Hierarchically Integrate Three Synergistic Active Sites for Tandem Catalysis
-
We report the design of a bifunctional metal–organic layer (MOL), Hf12-Ru-Co, composed of [Ru(DBB)(bpy)2]2+ [DBB-Ru, DBB=4,4′-di(4-benzoato)-2,2′-bipyridine; bpy=2,2′-bipyridine] connecting ligand as a photosensitizer and Co(dmgH)2(PPA)Cl (PPA-Co, dmgH=dimethylglyoxime; PPA=4-pyridinepropionic acid) on the Hf12 secondary building unit (SBU) as a hydrogen-transfer catalyst. Hf12-Ru-Co efficiently catalyzed acceptorless dehydrogenation of indolines and tetrahydroquinolines to afford indoles and quinolones. We extended this strategy to prepare Hf12-Ru-Co-OTf MOL with a [Ru(DBB)(bpy)2]2+ photosensitizer and Hf12 SBU capped with triflate as strong Lewis acids and PPA-Co as a hydrogen transfer catalyst. With three synergistic active sites, Hf12-Ru-Co-OTf competently catalyzed dehydrogenative tandem transformations of indolines with alkenes or aldehydes to afford 3-alkylindoles and bisindolylmethanes with turnover numbers of up to 500 and 460, respectively, illustrating the potential use of MOLs in constructing novel multifunctional heterogeneous catalysts.
- Quan, Yangjian,Lan, Guangxu,Shi, Wenjie,Xu, Ziwan,Fan, Yingjie,You, Eric,Jiang, Xiaomin,Wang, Cheng,Lin, Wenbin
-
supporting information
p. 3115 - 3120
(2020/12/09)
-
- Highly Ordered Mesoporous Cobalt Oxide as Heterogeneous Catalyst for Aerobic Oxidative Aromatization of N-Heterocycles
-
N-heterocycles are key structures for many pharmaceutical intermediates. The synthesis of such units normally is conducted under homogeneous catalytic conditions. Among all methods, aerobic oxidative aromatization is one of the most effective. However, in homogeneous conditions, catalysts are difficult to be recycled. Herein, we report a heterogeneous catalytic strategy with a mesoporous cobalt oxide as catalyst. The developed protocol shows a broad applicability for the synthesis of N-heterocycles (32 examples, up to 99 % yield), and the catalyst presents high turnover numbers (7.41) in the absence of any additives. Such a heterogenous approach can be easily scaled up. Furthermore, the catalyst can be recycled by simply filtration and be reused for at least six times without obvious deactivation. Comparative studies reveal that the high surface area of mesoporous cobalt oxide plays an important role on the catalytic reactivity. The outstanding recycling capacity makes the catalyst industrially practical and sustainable for the synthesis of diverse N-heterocycles.
- Cao, Yue,Wu, Yong,Zhang, Yuanteng,Zhou, Jing,Xiao, Wei,Gu, Dong
-
p. 3679 - 3686
(2021/06/18)
-
- Ruthenium-Catalyzed Dehydrogenation Through an Intermolecular Hydrogen Atom Transfer Mechanism
-
The direct dehydrogenation of alkanes is among the most efficient ways to access valuable alkene products. Although several catalysts have been designed to promote this transformation, they have unfortunately found limited applications in fine chemical synthesis. Here, we report a conceptually novel strategy for the catalytic, intermolecular dehydrogenation of alkanes using a ruthenium catalyst. The combination of a redox-active ligand and a sterically hindered aryl radical intermediate has unleashed this novel strategy. Importantly, mechanistic investigations have been performed to provide a conceptual framework for the further development of this new catalytic dehydrogenation system.
- Huang, Lin,Bismuto, Alessandro,Rath, Simon A.,Trapp, Nils,Morandi, Bill
-
supporting information
p. 7290 - 7296
(2021/03/01)
-
- Iron-Catalyzed ?±,?-Dehydrogenation of Carbonyl Compounds
-
An iron-catalyzed α,β-dehydrogenation of carbonyl compounds was developed. A broad spectrum of carbonyls or analogues, such as aldehyde, ketone, lactone, lactam, amine, and alcohol, could be converted to their α,β-unsaturated counterparts in a simple one-step reaction with high yields.
- Zhang, Xiao-Wei,Jiang, Guo-Qing,Lei, Shu-Hui,Shan, Xiang-Huan,Qu, Jian-Ping,Kang, Yan-Biao
-
supporting information
p. 1611 - 1615
(2021/03/03)
-
- Zwitterion-induced organic-metal hybrid catalysis in aerobic oxidation
-
In many metal catalyses, the traditional strategy of removing chloride ions is to add silver salts via anion exchange to obtain highly active catalysts. Herein, we reported an alternative strategy of removing chloride anions from ruthenium trichloride using an organic [P+-N-] zwitterionic compound via multiple hydrogen bond interactions. The resultant organic-metal hybrid catalytic system has successfully been applied to the aerobic oxidation of alcohols, tetrahydroquinolines, and indolines under mild conditions. The performance of zwitterion is far superior to that of many other common Lewis bases or Br?nsted bases. Mechanistic studies revealed that the zwitterion triggers the dissociation of chloride from ruthenium trichloride via nonclassical hydrogen bond interaction. Preliminary studies show that the zwitterion is applicable to catalytic transfer semi-hydrogenation.
- Hu, Rong-Bin,Lam, Ying-Pong,Ng, Wing-Hin,Wong, Chun-Yuen,Yeung, Ying-Yeung
-
p. 3498 - 3506
(2021/04/07)
-
- Iron(II)-Catalyzed Aerobic Biomimetic Oxidation of N-Heterocycles
-
Herein, an iron(II)-catalyzed biomimetic oxidation of N-heterocycles under aerobic conditions is described. The dehydrogenation process, involving several electron-transfer steps, is inspired by oxidations occurring in the respiratory chain. An environmentally friendly and inexpensive iron catalyst together with a hydroquinone/cobalt Schiff base hybrid catalyst as electron-transfer mediator were used for the substrate-selective dehydrogenation reaction of various N-heterocycles. The method shows a broad substrate scope and delivers important heterocycles in good-to-excellent yields.
- Manna, Srimanta,Kong, Wei-Jun,B?ckvall, Jan-E.
-
supporting information
p. 13725 - 13729
(2021/09/08)
-
- Efficient acceptorless dehydrogenation of hydrogen-rich N-heterocycles photocatalyzed by Ni(OH)2@CdSe/CdS quantum dots
-
Hydrogen storage using liquid organic hydrogen carriers (LOHCs) is a promising hydrogen storage technology; however, the hydrogen release process typically requires a high temperature. Developing dehydrogenation technology under mild conditions is highly desirable. Herein, a new approach for photocatalytic acceptorless dehydrogenation of hydrogen-rich LOHCs using Ni(OH)2@CdSe/CdS QDs as the photocatalyst was demonstrated. 1,2,3,4-Tetrahydroquinoline (THQ), iso-THQ, indoline, and their derivatives were selected as hydrogen-rich substrates, which exhibit excellent dehydrogenation efficiency with the release of hydrogen photocatalyzed by Ni(OH)2@CdSe/CdS QDs. Up to 100% yields of hydrogen and over 90% yields of complete dehydrogenation products were obtained at ambient temperature. Isotope tracer studies indicate a stepwise pathway, beginning with the photocatalytic oxidation of the substrate to release a proton and followed by proton exchange with heavy water. This work provides a promising alternative strategy to develop highly efficient, low cost and earth-abundant photocatalysts for acceptorless dehydrogenation of hydrogen-rich LOHCs.
- Liu, Yanpeng,Yu, Tianjun,Zeng, Yi,Chen, Jinping,Yang, Guoqiang,Li, Yi
-
p. 3810 - 3817
(2021/06/18)
-
- An iron(iii)-catalyzed dehydrogenative cross-coupling reaction of indoles with benzylamines to prepare 3-aminoindole derivatives
-
We report a green cascade approach to prepare a variety of 3-aminoindole derivatives in good to excellent yields through an iron(iii)-catalyzed dehydrogenative cross-coupling reaction of 2-arylindoles and primary benzylamines under mild reaction conditions. Mechanistic studies show that a cascade reaction involves a tert-butyl nitrite (TBN)-mediated nitrosation of 2-substituted indoles and a 1,5-hydrogen shift to afford indolenine oximes, sequential iron(iii)-catalyzed condensation and a 1,5-hydrogen shift over four steps in a one-pot reaction. The reaction shows a broad substrate scope of indoles and benzylamines and tolerates a wide range of functional groups. Moreover, the reaction is easily performed at the gram scale without producing waste after the reaction is completed. The 3-aminoindole product is purified by simple extraction, washing, and recrystallization without flash column chromatography. A double imine ligand containing the 3-aminoindole unit is facile to obtain in a 52% yield in one step. The present method highlights readily available starting materials, a simple purification procedure, and the usage of cheap, nontoxic, and environmentally benign iron(iii) catalysts. This journal is
- Chen, Wei-Li,Li, Kun,Liang, Cui,Liang, Wang-Fu,Liao, Wei-Cong,Mo, Dong-Liang,Qiu, Pei-Wen,Su, Gui-Fa
-
supporting information
p. 9610 - 9616
(2021/12/09)
-
- Cobalt-Catalyzed Dearomatization of Indoles via Transfer Hydrogenation to Afford Polycyclic Indolines
-
A cobalt-catalyzed dearomatization of indoles via transfer hydrogenation with HBpin and H2O has been developed. This reaction offered a straightforward platform to access hexahydropyrido[1,2-a]indoles in high regio- and chemoselectivity. A preliminary reaction mechanism was proposed on the basis of deuterium-labeling experiments, and a cobalt hydride species was involved in the reaction.
- Chen, Siwei,Cai, Min,Huang, Junru,Yao, Hequan,Lin, Aijun
-
supporting information
p. 2212 - 2216
(2021/04/05)
-
- Method for synthesizing 2-substituted indole derivative under catalysis of copper
-
The invention relates to a method for synthesizing a 2-substituted indole derivative under the catalysis of copper, which comprises the following step of: reacting by taking copper acetylacetonate (Cu (acac) 2) as a catalyst and taking indole and halogenated hydrocarbon as raw materials to obtain the 2-substituted indole derivative. Compared with the prior art, the method has the advantages that the copper acetylacetonate Cu (acac) 2 which is low in price, easy to obtain and stable in property is used as the catalyst, the method is green and economical, the catalyst is used for catalyzing the indole and halogenated hydrocarbon to react to synthesize the 2-substituted indole derivative, the reaction condition is mild, and the selectivity and yield of the product are high; and the synthesis method is simple and green, the 2-substituted indole derivative is directly constructed by using cheap and easily available raw materials indole and halogenated hydrocarbon, and the 2-substituted indole derivative has good substrate universality and has wide application value in the fields of pharmaceutical chemistry, fine chemical industry and the like.
- -
-
Paragraph 0023-0026
(2021/09/11)
-
- Facile C-S Bond Cleavage of Aryl Sulfoxides Promoted by Bronsted Acid
-
A method for the Bronsted acid promoted desulfination of aryl sulfoxides is presented. In the presence of a thiol, electron-rich sulfoxides undergo C-S bond cleavage to give the corresponding protodesulfinated arenes and disulfides.
- Brutiu, Bogdan R.,Klose, Immo,Maulide, Nuno
-
supporting information
p. 488 - 490
(2021/03/09)
-
- Synthesis of Substituted Anilines from Cyclohexanones Using Pd/C-Ethylene System and Its Application to Indole Synthesis
-
The synthesis of anilines and indoles from cyclohexanones using a Pd/C-ethylene system is reported. A simple combination of NH4OAc and K2CO3 under nonaerobic conditions was found to be the most suitable to perform this reaction. Hydrogen transfer between cyclohexanone and ethylene generates the desired products. The reaction tolerates a variety of substitutions on the starting cyclohexanones.
- Maeda, Katsumi,Matsubara, Ryosuke,Hayashi, Masahiko
-
p. 1530 - 1534
(2021/03/08)
-
- Synthesis of indoles through acceptorless dehydrogenative coupling catalyzed by nickel on silica-alumina
-
The high atom-economical formation of indoles from anilines and diols was described with affordable and easy to handle Ni/SiO2-Al2O3. After optimization, 2,3-dimethylindole was isolated with an excellent 98% yield in neat conditions. The scope of the reaction was studied and 13 indoles were isolated in 16–80% yields.
- Charvieux, Aubin,Hammoud, Abdul Aziz,Duclos, Marie-Christine,Duguet, Nicolas,Métay, Estelle
-
supporting information
(2021/07/25)
-
- Synthesis of Indoles by Reductive Cyclization of Nitro Compounds Using Formate Esters as CO Surrogates
-
Alkyl and aryl formate esters were evaluated as CO sources in the Pd- and Pd/Ru-catalyzed reductive cyclization of 2-nitrostyrenes to give indoles. Whereas the use of alkyl formates requires the presence of a ruthenium catalyst such as Ru3(CO)12, the reaction with phenyl formate can be performed by using a Pd/phenanthroline complex alone. Phenyl formate was found to be the most effective CO source and the desired products were obtained in excellent yields, often higher than those previously reported using pressurized CO. The reaction tolerates many functional groups, including sensitive ones like a free aldehydic group or a pendant pyrrole. Detailed experiments and kinetic studies allow to conclude that the activation of phenyl formate is base-catalyzed and that the metal doesn't play a role in the decarbonylation step. The reactions can be performed in a single thick-walled glass tube with as little as 0.2 mol-% palladium catalyst and even on a 2 g scale. The same protocol can be extended to other nitro compounds, affording different heterocycles.
- Ahmed Fouad, Manar,Ferretti, Francesco,Formenti, Dario,Milani, Fabio,Ragaini, Fabio
-
supporting information
p. 4876 - 4894
(2021/09/20)
-
- Catalytic C(sp2)?H amination reactions using dinickel imides
-
C?H amination reactions are valuable transformations for the construction of C?N bonds. Due to their relatively high bond dissociation energies, C(sp2)?H bonds are generally not susceptible toward direct nitrene insertion, necessitating alternative mechanisms for C?H activation. Here, we report that cationic dinuclear (NDI)Ni2 (NDI = naphthyridine?diimine) complexes catalyze intramolecular nitrene insertions into aryl and vinyl C(sp2)? H bonds. Mechanistic studies suggest that a bridging imido ligand supported at a Ni2 site induces C?H activation by a 1,2-addition pathway to generate an azametallacyclic intermediate. This organometallic mechanism contrasts with the electrocyclization/1,2-shift mechanism proposed for analogous transformations using Rh2 catalysts. The implications of these mechanistic differences for the stereoselectivity and chemoselectivity of C?H amination are described.
- Andjaba, John M.,Powers, Ian G.,Uyeda, Christopher,Zeller, Matthias
-
supporting information
p. 3794 - 3801
(2020/11/23)
-
- Ir-Catalyzed Reversible Acceptorless Dehydrogenation/Hydrogenation of N-Substituted and Unsubstituted Heterocycles Enabled by a Polymer-Cross-Linking Bisphosphine
-
The polystyrene-cross-linking bisphosphine ligand PS-DPPBz was effective for the Ir-catalyzed reversible acceptorless dehydrogenation/hydrogenation of N-heterocycles. Notably, this protocol is applicable to the dehydrogenation of N-substituted indoline derivatives with various N-substituents with different electronic and steric natures. A reaction pathway involving oxidative addition of an N-adjacent C(sp3)-H bond to a bisphosphine-coordinated Ir(I) center is proposed for the dehydrogenation of N-substituted substrates.
- Zhang, Deliang,Iwai, Tomohiro,Sawamura, Masaya
-
supporting information
p. 5240 - 5245
(2020/07/03)
-
- NCP-Type Pincer Iridium Complexes Catalyzed Transfer-Dehydrogenation of Alkanes and Heterocycles?
-
A series of NCP-type pincer iridium complexes, (RNCCP)IrHCl (2a—2c) and (BQ-NCOP)IrHCl 3, have been studied for catalytic transfer alkane dehydrogenation. Complex 3 containing a rigid benzoquinoline backbone exhibits high activity and robustness in dehydrogenation of alkanes to form alkenes. Even more importantly, this catalyst system was also highly effective in the dehydrogenation of a wide range of heterocycles to furnish heteroarenes.
- Wang, Yulei,Qian, Lu,Huang, Zhidao,Liu, Guixia,Huang, Zheng
-
supporting information
p. 837 - 841
(2020/05/18)
-
- Monoamine Oxidase (MAO-N) Biocatalyzed Synthesis of Indoles from Indolines Prepared via Photocatalytic Cyclization/Arylative Dearomatization
-
The biocatalytic aromatization of indolines into indole derivatives exploiting monoamine oxidase (MAO-N) enzymes is presented. Indoline substrates were prepared via photocatalytic cyclization of arylaniline precursors or via arylative dearomatization of unsubstituted indoles and in turn chemoselectively aromatized by the MAO-N D11 whole cell biocatalyst. Computational docking studies of the indoline substrates in the MAO-N D11 catalytic site allowed for the rationalization of the biocatalytic mechanism and experimental results of the biotransformation. This methodology represents an efficient example of biocatalytic synthesis of indole derivatives and offers a facile approach to access these aromatic heterocycles under mild reaction conditions.
- Black, Gary W.,Brancale, Andrea,Castagnolo, Daniele,Colonna, Serena,Ferla, Salvatore,Masci, Domiziana,Turner, Nicholas J.,Varricchio, Carmine,Zhao, Fei
-
p. 6414 - 6421
(2020/07/09)
-
- Acceptorless dehydrogenation of amines and alcohols using simple ruthenium chloride
-
A highly efficient, economic and environmental friendly catalyst system has been developed for the dehydrogenation of alcohols and amines using simple RuCl3·nH2O and N-benzylhexamethylenetetramine. The in situ catalyst system efficiently oxidized the primary and secondary amines and secondary alcohols into nitrile, imine and ketone products, respectively in moderate to excellent yields. The developed catalyst system was also found to be efficient for the dehydrogenation of N-heterocyles. A detailed mechanism study revealed the first example of N-benzylhexamethylenetetramine (HMTA-Bz) being simultaneously acting as base, reducing agent and hydride source to generate the [Ru(II)(H)2] species as the active catalyst. The mechanism studies also revealed both the alcohol and amine oxidation involves dehydrogenative pathway with the evolution of hydrogen as the only by-product. The developed catalyst system also provides possible platform for the release of hydrogen from liquid organic hydrogen carriers (LOHCs).
- Barteja, Parul,Devi, Preeti,Kannan, Muthukumar,Muthaiah, Senthilkumar
-
-
- Reusable, homogeneous water soluble photoredox catalyzed oxidative dehydrogenation of N-heterocycles in a biphasic system: Application to the synthesis of biologically active natural products
-
Herein, a simple and efficient method for the oxidative dehydrogenation (ODH) of tetrahydro-β-carbolines, indolines and tetrahydro-(iso)quinolines is described using a reusable, homogeneous cobalt-phthalocyanine photoredox catalyst in a biphasic medium. A biphasic system offers an advantage of easy separation of the product and an efficient reusability of the homogeneous photoredox catalyst. Also, the current system significantly helps to overcome the solubility issue of the substrate and catalyst at room temperature. Its potential applications to organic transformations are demonstrated by the synthesis of various biologically active N-heterocycles such as indoles, (iso)quinolines and β-carbolines and natural products such as eudistomin U, norharmane, and harmane and precursors to perlolyrine and flazin. Without isolation and purification, the catalyst solution can be reused up to 5 times with almost comparable reactivity. Furthermore, the efficiency of the reaction was demonstrated on a gram scale. To the best of our knowledge, this is the first report on ODH reactions using a non noble, reusable and homogeneous cobalt photoredox catalyst under environmentally friendly conditions.
- Abinaya, R.,Baskar, B.,Mariappan, M.,Prasanth, Arun,Sridhar, R.,Srinath, S.
-
p. 2575 - 2587
(2020/05/13)
-
- Visible-Light-Promoted Efficient Aerobic Dehydrogenation of N-Heterocycles by a Tiny Organic Semiconductor Under Ambient Conditions
-
An efficient reusable catalytic system has been developed based on perylene diimide (PDI) organic semiconductor for the aerobic dehydrogenation of N-heterocycles with visible light. This practical catalytic system without any additives proceeds under ambient conditions. The minute aggregates of PDI molecules on the surface of SiO2 nanospheres form tiny organic semiconductors, resulting in high-efficiency photo-oxidative activity. Notably, the robustness of this method is demonstrated by the synthesis of a wide range of N-heteroarenes, gram-scale experiments as well as reusability tests.
- Su, Chenliang,Yu, Kunyi,Zhang, Hanjie,Zhu, Yongfa
-
supporting information
p. 1956 - 1960
(2020/04/10)
-
- Aerobic Dehydrogenation of N-Heterocycles with Grubbs Catalyst: Its Application to Assisted-Tandem Catalysis to Construct N-Containing Fused Heteroarenes
-
An aerobic dehydrogenation of nitrogen-containing heterocycles catalyzed by Grubbs catalyst is developed. The reaction is applicable to various nitrogen-containing heterocycles. The exceptionally high functional group compatibility of this method was confirmed by the oxidation of an unprotected dihydroindolactam V to indolactam V. Furthermore, by taking advantage of the oxygen-mediated structural change of the Grubbs catalyst, we integrated ring-closing metathesis and subsequent aerobic dehydrogenation to develop the novel assisted-tandem catalysis using molecular oxygen as a chemical trigger. The utility of the assisted-tandem catalysis was demonstrated by the concise synthesis of N-containing fused heteroarenes including a natural antibiotic, pyocyanine.
- Kawauchi, Daichi,Noda, Kenta,Komatsu, Yoshiyuki,Yoshida, Kei,Ueda, Hirofumi,Tokuyama, Hidetoshi
-
supporting information
p. 15793 - 15798
(2020/10/12)
-
- MnOx/catechol/H2O: A cooperative catalytic system for aerobic oxidative dehydrogenation of N-heterocycles at room temperature
-
Amorphous manganese oxide doped by Na+ ion (Na-AMO) was successfully prepared and found to be an efficient heterogeneous catalyst in aerobic oxidative dehydrogenation of N-heterocycles, cooperate with catechol. Na-AMO was fully characterized by XRD, XPS BET H2-TPR, CO2-TPD FT-IR, TEM, SEM and had rich amounts of surface absorbed active oxygen species which are responsible for superior catalytic performance. The synergistic interaction between Na-AMO and catechol makes catalytic system efficient and tolerant, which offers various N-heterocycles in good to excellent yields under mild conditions.
- Tang, Tao,Bi, Xiuru,Meng, Xu,Chen, Gexin,Gou, Mingxia,Liu, Xiang,Zhao, Peiqing
-
-
- Rh/TiO2-Photocatalyzed Acceptorless Dehydrogenation of N-Heterocycles upon Visible-Light Illumination
-
TiO2 is an effective and extensively employed photocatalyst, but its practical use in visible-light-mediated organic synthesis is mainly hindered by its wide band gap energy. Herein, we have discovered that Rh-photodeposited TiO2 nanoparticles selectively dehydrogenate N-heterocyclic amines with the concomitant generation of molecular hydrogen gas in an inert atmosphere under visible light (λmax = 453 nm) illumination at room temperature. Initially, a visible-light-sensitive surface complex is formed between the N-heterocycle and TiO2. The acceptorless dehydrogenation of N-heterocycles is initiated by direct electron transfer from the HOMO energy level of the amine via the conduction band of TiO2 to the Rh nanoparticle. The reaction condition was optimized by examining different photodeposited noble metals on the surface of TiO2 and solvents, finding that Rh0 is the most efficient cocatalyst, and 2-propanol is the optimal solvent. Structurally diverse N-heterocycles such as tetrahydroquinolines, tetrahydroisoquinolines, indolines, and others bearing electron-deficient as well as electron-rich substituents underwent the dehydrogenation in good to excellent yields. The amount of released hydrogen gas evinces that only the N-heterocyclic amines are oxidized rather than the dispersant. This developed method demonstrates how UV-active TiO2 can be employed in visible-light-induced synthetic dehydrogenation of amines and simultaneous hydrogen storage applications.
- Bahnemann, Detlef W.,Balayeva, Narmina O.,Dillert, Ralf,Mamiyev, Zamin,Zheng, Nan
-
p. 5542 - 5553
(2020/08/25)
-
- DMSO/t-BuONa/O2-Mediated Aerobic Dehydrogenation of Saturated N-Heterocycles
-
Aromatic N-heterocycles such as quinolines, isoquinolines, and indolines are synthesized via sodium tert-butoxide-promoted oxidative dehydrogenation of the saturated heterocycles in DMSO solution. This reaction proceeds under mild reaction conditions and has a good functional group tolerance. Mechanistic studies suggest a radical pathway involving hydrogen abstraction of dimsyl radicals from the N-H bond or α-C-H of the substrates and subsequent oxidation of the nitrogen or α-aminoalkyl radicals.
- Cai, Hu,Tan, Wei,Xie, Yongfa,Yang, Ruchun,Yue, Shusheng
-
p. 7501 - 7509
(2020/07/07)
-
- Aerobic oxidative dehydrogenation of N-heterocycles over OMS-2-based nanocomposite catalysts: Preparation, characterization and kinetic study
-
OMS-2-based nanocomposites doped with tungsten were prepared for the first time and their remarkably enhanced catalytic activity and recyclability in aerobic oxidative dehydrogenation of N-heterocycles were examined in detail. Many tetrahydroquinoline derivatives and a broad range of other N-heterocycles could be tolerated by the catalytic system using a biomass-derived solvent as a reaction medium. Newly generated mixed crystal phases, noticeably enhanced surface areas and labile lattice oxygen of the OMS-2-based nanocomposite catalysts might contribute to their excellent catalytic performance. Moreover, a kinetic study was extensively performed which concluded that the dehydrogenation of 1,2,3,4-tetrahydroquinoline is a first-order reaction, and the apparent activation energy is 29.66 kJ mol-1
- Bi, Xiuru,Tang, Tao,Meng, Xu,Gou, Mingxia,Liu, Xiang,Zhao, Peiqing
-
p. 360 - 371
(2020/02/04)
-
- Nanocatalosomes as Plasmonic Bilayer Shells with Interlayer Catalytic Nanospaces for Solar-Light-Induced Reactions
-
Interest and challenges remain in designing and synthesizing catalysts with nature-like complexity at few-nm scale to harness unprecedented functionalities by using sustainable solar light. We introduce “nanocatalosomes”—a bio-inspired bilayer-vesicular design of nanoreactor with metallic bilayer shell-in-shell structure, having numerous controllable confined cavities within few-nm interlayer space, customizable with different noble metals. The intershell-confined plasmonically coupled hot-nanospaces within the few-nm cavities play a pivotal role in harnessing catalytic effects for various organic transformations, as demonstrated by “acceptorless dehydrogenation”, “Suzuki–Miyaura cross-coupling” and “alkynyl annulation” affording clean conversions and turnover frequencies (TOFs) at least one order of magnitude higher than state-of-the-art Au-nanorod-based plasmonic catalysts. This work paves the way towards next-generation nanoreactors for chemical transformations with solar energy.
- Cho, Yoon-Kyoung,Dubbu, Sateesh,Kim, Inki,Koo, Jung Hun,Kumar, Amit,Kumar, Sumit,Kumari, Nitee,Kwon, Taewan,Lee, In Su,Lim, Jongwon,Rho, Junsuk
-
supporting information
p. 9460 - 9469
(2020/05/04)
-
- Catalytically Active Co?Nx Species Stabilized on Nitrogen-doped Porous Carbon for Efficient Hydrogenation and Dehydrogenation of N-heteroarenes
-
The development of bifunctional, highly active and stable non-noble-metal catalysts is important for synthetic chemistry. In this study, a highly dispersed Co catalyst stabilized on the mesoporous N-doped carbon layers was prepared by adsorption and pyrolysis of cobalt complex on dendritic fibrous silica nanospheres (KCC-1@Co?N?C?T). The characterizations of HAADF-STEM, XRD and XPS together with the KSCN poisoning tests determine the absence of Co0 or CoOx nanoparticles and suggest that the Co?Nx species are the active sites. The formation of Co?Nx species results from the properties of N-rich cobalt-phenanthroline complex and dendritic fibrous silica supports, increasing the original spatial distance between Co atoms and thus preventing them from aggregation. The KCC-1@Co?N?C-800 catalyst showed excellent activity and selectivity for the oxidative dehydrogenation (ODH) of saturated N-heterocycles and base-free catalytic transfer hydrogenation (CTH) of unsaturated N-heterocycles.
- Xu, Dan,Zhao, Hong,Dong, Zhengping,Ma, Jiantai
-
p. 4406 - 4415
(2020/07/06)
-
- A Visible-Light Promoted Amine Oxidation Catalyzed by a Cp*Ir Complex
-
Through a rapid screening of Cp*Ir complexes based on a turn-on type fluorescence readout, a [Cp*Ir(dipyrido[3,2-a : 2’,3’-c]phenazine)Cl]+ complex was found to catalyze the blue-light promoted dehydrogenation of N-heterocycles under physiological conditions. In the dehydrogenation of tetrahydroisoquinolines, the catalyst preferentially yielded the monodehydrogenated product, accompanying H2O2 generation. We surmise that this mechanism may be reminiscent of flavin-dependent oxidases.
- Davis, Holly Jane,H?ussinger, Daniel,Ward, Thomas R.,Okamoto, Yasunori
-
p. 4512 - 4516
(2020/07/27)
-
- Reversible aerobic oxidative dehydrogenation/hydrogenation of N-heterocycles over AlN supported redox cobalt catalysts
-
N-heterocycles with quinoline and tetrahydroquinoline structures are highly important in pharmaceutical and chemical industries, and their highly efficient mutual transformations are vital but still challenging. In the present work, AlN supported redox cobalt catalysts (Co3O4/AlN and Co/AlN) were prepared, which could achieve the reversible aerobic oxidative dehydrogenation/hydrogenation of N-heterocycles with good performances. The catalytic performances were stem from the strong interaction between Co species with AlN support, which were confirmed by the characterizations of Raman, XPS, UV–vis DRS, and H2-TPR etc. Both of the catalysts showed good stabilities and reusabilities for the titled reactions. Besides, the gram-scale experiments achieved with good yields to corresponding products, revealing the present protocol possesses great potential applications in industry. The strategy of using redox Co-based catalyst not only provides a potential catalyst for the reversible hydrogenation/oxidative dehydrogenation reactions but also replenishes methods for constructing of other redox catalyst, especially with AlN as a carrier.
- He, Zhen-Hong,Sun, Yong-Chang,Wang, Kuan,Wang, Zhong-Yu,Guo, Pan-Pan,Jiang, Chong-Shan,Yao, Man-Qing,Li, Zhu-Hui,Liu, Zhao-Tie
-
-
- Decarboxylation of indole-3-carboxylic acids under metal-free conditions
-
Two reaction systems have been developed for the decarboxylation of indole-3-carboxylic acids. The decarboxylation can be achieved smoothly under K2CO3-catalyzed or acetonitrile-promoted basic conditions. It provided an efficient and simple method for the transformation of indole-3-carboxylic acids and the corresponding indoles were isolated with good to excellent yields. From the experimental facts, we put forward the possible reaction mechanism.
- Chen, Xia,Zhou, Xiao-Yu
-
supporting information
p. 805 - 812
(2020/02/20)
-
- Synthesis of N-Heterocycles by Reductive Cyclization of Nitroalkenes Using Molybdenum Hexacarbonyl as Carbon Monoxide Surrogate
-
The development of a method that uses molybdenum hexacarbonyl [Mo(CO)6] as carbon monoxide (CO) surrogate for the palladium-catalyzed reductive cyclization of nitroalkenes into indoles or thienopyrroles is reported. Several types of nitroalkenes could be transformed into the desired products in excellent yields and in most cases with complete regioselectivities and higher yields than those previously reported with palladium/CO system.
- Su, Zhiyou,Liu, Bo,Liao, Hongze,Lin, Hou-Wen
-
supporting information
p. 4059 - 4066
(2020/06/21)
-
- Superhydrophobic nickel/carbon core-shell nanocomposites for the hydrogen transfer reactions of nitrobenzene and N-heterocycles
-
In this work, catalytic hydrogen transfer as an effective, green, convenient and economical strategy is for the first time used to synthesize anilines and N-heterocyclic aromatic compounds from nitrobenzene and N-heterocycles in one step. Nevertheless, how to effectively reduce the possible effects of water on the catalyst by removal of the by-product water, and to further introduce water as the solvent based on green chemistry are still challenges. Since the structures and properties of carbon nanocomposites are easily modified by controllable construction, a one step pyrolysis process is used for controllable construction of micro/nano hierarchical carbon nanocomposites with core-shell structures and magnetic separation performance. Using various characterization methods and model reactions the relationship between the structure of Ni?NCFs (nickel-nitrogen-doped carbon frameworks) and catalytic performance was investigated, and the results show that there is a positive correlation between the catalytic performance and hydrophobicity of catalysts. Besides, the possible catalytically active sites, which are formed by the interaction of pyridinic N and graphitic N in the structure of nitrogen-doped graphene with the surfaces of Ni nanoparticles, should be pivotal to achieving the relatively high catalytic performance of materials. Due to its unique structure, the obtained Ni?NCF-700 catalyst with superhydrophobicity shows extraordinary performances toward the hydrogen transfer reaction of nitrobenzene and N-heterocycles in the aqueous state; meanwhile, it was also found that Ni?NCF-700 still retained its excellent catalytic activity and structural integrity after three cycles. Compared with traditional catalytic systems, our catalytic systems offer a highly effective, green and economical alternative for nitrobenzene and N-heterocycle transformation, and may open up a new avenue for simple construction of structure and activity defined carbon nanocomposite heterogeneous catalysts with superhydrophobicity.
- Duan, Zhiying,Liu, Fangfang,Pang, Shaofeng,Su, Qiong,Wang, Yanbin,Xie, Xin,Zhang, Ping,Zhang, Yujing,Zhou, Feng
-
p. 1996 - 2010
(2020/04/07)
-
- Recyclable Pd/C catalyzed one-step reduction of carbonyls to hydrocarbons under simple conditions without extra base
-
The reductions of carbonyls for the synthesis of hydrocarbons were developed with hydrazine hydrate, hydrogen gas and ammonium formate respectively. The simple, mild and efficient conditions were provided by employing recyclable Pd/C as catalyst in normal solvents at 100 °C and the reactions proceeded smoothly to produce the corresponding products with good to excellent yields. And gram-scale reactions and recycling of the catalyst were also demonstrated. Furtherly, the mechanism has been proposed.
- Zhou, Xiao-Yu,Chen, Xia
-
supporting information
(2019/12/06)
-
- Efficient acceptorless photo-dehydrogenation of alcohols and: N -heterocycles with binuclear platinum(ii) diphosphite complexes
-
Although photoredox catalysis employing Ru(ii) and Ir(iii) complexes as photocatalysts has emerged as a versatile tool for oxidative C-H functionalization under mild conditions, the need for additional reagents acting as electron donor/scavenger for completing the catalytic cycle undermines the practicability of this approach. Herein we demonstrate that photo-induced oxidative C-H functionalization can be catalysed with high product yields under oxygen-free and acceptorless conditions via inner-sphere atom abstraction by binuclear platinum(ii) diphosphite complexes. Both alcohols (51 examples), particularly the aliphatic ones, and saturated N-heterocycles (24 examples) can be efficiently dehydrogenated under light irradiation at room temperature. Regeneration of the photocatalyst by means of reductive elimination of dihydrogen from the in situ formed platinum(iii)-hydride species represents an alternative paradigm to the current approach in photoredox catalysis.
- Zhong, Jian-Ji,To, Wai-Pong,Liu, Yungen,Lu, Wei,Che, Chi-Ming
-
p. 4883 - 4889
(2019/05/16)
-
- Room temperature catalytic dehydrogenation of cyclic amines with the liberation of H2 using water as a solvent
-
Catalytic dehydrogenation of cyclic amines, in particular partially saturated N-heterocycles to N-heterocyclic arenes, with the removal of molecular hydrogen as the sole byproduct in water is reported. This dehydrogenation reaction proceeds smoothly under very mild and benign conditions and operates at room temperature. This distinctive reactivity has been achieved under dual catalytic conditions by merging the visible-light active [Ru(bpy)3]2+ as the photoredox catalyst and a newly synthesized cobalt complex as the proton-reduction catalyst. A detailed mechanistic study (control experiments, electrochemical studies, UV-visible experiments) is presented for the present dual catalysis.
- Sahoo, Manoj K.,Balaraman, Ekambaram
-
supporting information
p. 2119 - 2128
(2019/04/26)
-
- A Reusable Cobalt Catalyst for Reversible Acceptorless Dehydrogenation and Hydrogenation of N-Heterocycles
-
The development of robust catalytic systems based on base-metals for reversible acceptorless dehydrogenation (ADH) and hydrogenation of feedstock chemicals is very important in the context of ‘hydrogen storage’. Herein, we report a highly efficient reusable cobalt-based heterogeneous catalyst for reversible dehydrogenation and hydrogenation of N-heterocycles. Both the ADH and the hydrogenation processes operate under mild, benign conditions.
- Jaiswal, Garima,Subaramanian, Murugan,Sahoo, Manoj K.,Balaraman, Ekambaram
-
p. 2449 - 2457
(2019/05/10)
-
- Extending the Chemistry of Hexamethylenetetramine in Ruthenium-Catalyzed Amine Oxidation
-
A very efficient, highly atom economical, and environmentally benign oxidation of primary and secondary amines using an in situ catalyst system generated from commercially available ruthenium(II) benzene dichloride dimer and hexamethylenetetramine has been demonstrated. Mechanistic studies revealed that hexamethylenetetramine acted as a source of hydride to generate the active ruthenium hydride catalyst and amine oxidation involves a dehydrogenative pathway. In comparison to reported catalyst systems for the dehydrogenative oxidation of amines, this synthetic protocol makes use of a simple ruthenium precursor and a cheaper additive; it is very selective, leading to the exclusive formation of nitrile/imine compounds. Further, it releases hydrogen as the only side product, suggesting the potential application of the developed catalyst system in hydrogen storage.
- Kannan, Muthukumar,Muthaiah, Senthilkumar
-
supporting information
p. 3560 - 3567
(2019/11/13)
-
- Two-Dimensional Metal-Organic Layers for Electrochemical Acceptorless Dehydrogenation of N-Heterocycles
-
The catalytic acceptorless dehydrogenation (CAD) is an attractive synthetic route to unsaturated compounds because of its high atomic efficiency. Here we report electrochemical acceptorless dehydrogenation of N-heterocycles to obtain quinoline or indole derivatives using metal-organic layer (MOL) catalyst. MOL is the two-dimensional version of metal-organic frameworks (MOF), and it can be constructed on conductive multi-walled carbon nanotubes via facile solvothermal synthesis to overcome the conductivity constraint for MOFs in electrocatalysis. TEMPO-OPO3 2? was incorporated into the system through a ligand exchange with capping formate on the MOL surface to serve as the active catalytic centers. The hybrid catalyst is efficient in the organic conversion and can be readily recycled and reused.
- Yang, Ling,Ma, Fa-Xue,Xu, Fan,Li, Dong,Su, Liangmei,Xu, Hai-Chao,Wang, Cheng
-
supporting information
p. 3557 - 3560
(2019/06/04)
-
- Potassium tert-Butoxide-Promoted Acceptorless Dehydrogenation of N-Heterocycles
-
Potassium tert-butoxide-promoted acceptorless dehydrogenation of N-heterocycles was efficiently realized for the generation of N-heteroarenes and hydrogen gas under transition-metal-free conditions. In the presence of KOtBu base, a variety of six- and five-membered N-heterocyclic compounds efficiently underwent acceptorless dehydrogenation to afford the corresponding N-heteroarenes and H2 gas in o-xylene at 140 °C. The present protocol provides a convenient route to aromatic nitrogen-containing compounds and H2 gas. (Figure presented.).
- Liu, Tingting,Wu, Kaikai,Wang, Liandi,Yu, Zhengkun
-
supporting information
p. 3958 - 3964
(2019/08/01)
-
- Visible-Light-Mediated Photocatalytic Aerobic Dehydrogenation of N-heterocycles by Surface-Grafted TiO2 and 4-amino-TEMPO
-
Herein, the visible-light-induced dehydrogenation of N-heterocycles such as tetrahydroquinolines, tetrahydroisoquinolines, and indolines in O2-containing suspensions of a commercially available titanium dioxide photocatalyst yielding the corresponding heteroarenes is presented. 4-Amino-2,2,6,6-tetramethylpipiridinyloxyl (4-amino-TEMPO) was found to exhibit a beneficial role, as it increased the yield and improved the selectivity of the dehydrogenation reaction. Both the selectivity and the yield are further enhanced by grafting 0.1 wt % of Ni(II) ions onto the TiO2 surface. It is proposed that the basic reactant adsorbs at Lewis acid sites present at the TiO2 surface. The dehydrogenation reaction is initiated by visible-light excitation of the resulting surface complex and a subsequent single-electron transfer from the excited N-heterocycle via the conduction band of TiO2 to O2. Ni(II) ions possibly serve as an electron transfer bridge between the conduction band of TiO2 and O2, while the TEMPO derivative is assumed to act as a selective redox mediator involved in reactions of the generated reactive oxygen species.
- Balayeva, Narmina O.,Zheng, Nan,Dillert, Ralf,Bahnemann, Detlef W.
-
p. 10694 - 10704
(2019/11/14)
-
- Hydrophobic Metal Halide Perovskites for Visible-Light Photoredox C?C Bond Cleavage and Dehydrogenation Catalysis
-
Two-dimensional lead and tin halide perovskites were prepared by intercalating the long alkyl group 1-hexadecylammonium (HDA) between the inorganic layers. We observed visible-light absorption, narrow-band photoluminescence, and nanosecond photoexcited lifetimes in these perovskites. Owing to their hydrophobicity and stability even in humid air, we applied these perovskites in the decarboxylation and dehydrogenation of indoline-2-carboxylic acids. (HDA)2PbI4 or (HDA)2SnI4 were investigated as photoredox catalysts for these reactions, and quantitative conversion and high yields were observed with the former.
- Hong, Zonghan,Chong, Wee Kiang,Ng, Andrew Yun Ru,Li, Mingjie,Ganguly, Rakesh,Sum, Tze Chien,Soo, Han Sen
-
p. 3456 - 3460
(2019/02/13)
-
- Cobalt Nanoparticles Apically Encapsulated by Nitrogen-doped Carbon Nanotubes for Oxidative Dehydrogenation and Transfer Hydrogenation of N-Heterocycles
-
It is important to develop a highly active and stable transition-metal catalyst with dual-functional properties in the reversible transformations between various saturated and unsaturated N-heterocycles. Herein, we prepared the cobalt nanoparticles (Co NPs) apically encapsulated by the N-doped carbon nanotubes catalyst (Co@NCNTs) via a multiple pyrolysis of low-cost dicyandiamide and cobalt (II) acetylacetonate. The catalyst shows excellent activity and recyclability towards the oxidative dehydrogenation (ODH) and the catalytic transfer hydrogenation (CTH) for various N-heterocycles. The structure of outer N-doped carbon nanotubes (NCNTs) can protect Co NPs from aggregation and leaching. Moreover, the encapsulated Co NPs and the NCNTs may generate a synergistic effect. Both of them facilitate the high performance. The poisoning tests with KSCN were to clarify the different active sites for ODH and CTH reactions: the Co NPs could modify the NCNTs through electrons redistribution, therefore the NCNTs could directly activate O2 in ODH. The encapsulated Co NPs is enhanced by the doped N atoms which is good for the H2 activation in CTH. What's more, the mechanisms of ODH and CTH reactions were also proposed. This work provides a facile and low-cost method to design catalysts, which are dual-functional, highly active and stable, for industrial applications.
- Xu, Dan,Zhao, Hong,Dong, Zhengping,Ma, Jiantai
-
p. 5475 - 5486
(2019/11/05)
-
- Supported dual-acidic 1,3-disulfoimidazolium chlorozincate@HZSM-5 as a promising heterogeneous catalyst for synthesis of indole derivatives
-
HZSM-5-supported Br?nsted and Lewis acidic ionic solid 1,3-disulfoimidazolium chlorozincate materials ([dsim]2[ZnCl4]@HZSM-5) were synthesized with various ratios (3, 6, 9, 17 and 50% w/w). The heterogeneous materials were characterized via a variety of spectroscopic techniques. Dual acidity of these materials was determined using specified techniques. These acidic solids were examined as stable heterogeneous catalysts for the Fischer indole reaction of equimolar amounts of phenylhydrazine hydrochloride and various aliphatic or aromatic ketones at 80–90°C in neat condition to produce substituted indole derivatives. The efficient 17% ionic salt-loaded HZSM-5 composite was easily reused for ten consecutive cycles with a slight loss of its activity. The recycled catalyst was further analysed using powder X-ray diffraction and inductively coupled plasma optical emission spectrometric techniques.
- Saikia, Susmita,Puri, Krishna,Borah, Ruli
-
-
- Chameleon-like Behavior of the Directing Group in the Rh(III)-Catalyzed Regioselective C-H Amidation of Indole: An Experimental and Computational Study
-
The Rh(III)-catalyzed regioselective C-H amidation of N-methoxy-1H-indole-1-carboxamides by 1,4,2-dioxazol-5-ones was studied. N-Methoxy amide, the directing group (DG) of interest, undergoes four different transformations through DG-retained, -coupled, -eliminated, or -migrated processes under moderately varied reaction conditions. Solvents, additives, and temperature play important roles in these selective transformations; a trace addition of water favors the functional group (FG)-assisted DG elimination; extra addition of KHSO4 greatly enhances the formation of the DG-coupled product; high-temperature and proper FG together can shift the position of DG through intermolecular Friedel-Crafts-like acylation. The catalytic mechanisms underlying these reactions were further investigated through density functional theory calculations and experimental studies including the characterization of amido-inserted rhodacycle. An overall catalytic pathway was proposed to illustrate the reactions involved in the regioselective amidation of N-methoxy-1H-indole-1-carboxamide.
- Zhang, Jinquan,Xie, Hujun,Zhu, Huajian,Zhang, Shuaizhong,Reddy Lonka, Madhava,Zou, Hongbin
-
p. 10233 - 10244
(2019/10/28)
-
- Synthesis of Benzofuran and Indole Derivatives Catalyzed by Palladium on Carbon
-
Benzofurans and indoles are key moieties in many natural products and pharmaceuticals. Herein, we describe a cheap and easy-to-execute strategy for the synthesis of benzofurans and indoles, employing Pd/C as the promoter. A variety of substituted allyl-anilines and allyl-phenols were converted into the desired products in good to excellent yields. Recycling of Pd/C was possible up to five cycles, keeping similar levels of reactivity.
- Savvidou, Anatoli,IoannisTzaras, Dimitrios,Koutoulogenis, Giorgos S.,Theodorou, Alexis,Kokotos, Christoforos G.
-
supporting information
p. 3890 - 3897
(2019/06/27)
-
- Reductive dehalogenation and dehalogenative sulfonation of phenols and heteroaromatics with sodium sulfite in an aqueous medium
-
Prototropic tautomerism was used as a tool for the reductive dehalogenation of (hetero)aryl bromides and iodides, or dehalogenative sulfonation of (hetero)aryl chlorides and fluorides, using sodium sulfite as the sole reagent in an aqueous medium. This protocol does not require a metal or phase transfer catalyst and avoids using organic solvent as the reaction medium. This method is especially suitable for substrates that readily tautomerize (such as 2-or 4-halogenated aminophenols and 4-halogenated resorcinols), for which dehalogenation or sulfonation proceeds under mild reaction conditions (≤60 °C). As sodium sulfite is an inexpensive, safe, and environmentally less hazardous reagent, this method has at least three potential applications: (i) in the deprotection of halogens as protecting groups, using sodium sulfite as a reducing agent; (ii) in the sulfonation of aromatic halides under mild reaction conditions avoiding hazardous and corrosive reagents/solvents; and (iii) in the transformation of toxic halogenated aromatics into less harmful compounds.
- Tomanová, Monika,Jedinák, Luká?,Canka?, Petr
-
supporting information
p. 2621 - 2628
(2019/06/03)
-
- Electrochemical Acceptorless Dehydrogenation of N-Heterocycles Utilizing TEMPO as Organo-Electrocatalyst
-
Catalytic acceptorless dehydrogenation (CAD) has been a basically important organic transformation to ubiquitous unsaturated compounds without the usage of a sacrificial hydrogen acceptor. In this work, we successfully developed the first electrochemical acceptorless dehydrogenation (ECAD) of N-heterocycles using TEMPO as the organo-electrocatalyst. We have achieved the catalytic dehydrogenation of N-heterocycles in an anode and the release of H2 in a cathode using an undivided-cell system. A variety of six-membered and five-membered nitrogen-heteroarenes can be synthesized in good yields in this system. In addition, this protocol can also be used in the application of important molecular synthesis. Our electrochemical strategy provides a mild and metal-free route for (hetero)aromatic compounds synthesis via the CAD strategy.
- Wu, Yong,Yi, Hong,Lei, Aiwen
-
p. 1192 - 1196
(2018/02/14)
-
