- Structure-based design of selective inhibitors of dihydrofolate reductase: Synthesis and antiparasitic activity of 2,4-diaminopteridine analogues with a bridged diarylamine side chain
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As part of a larger search for potent as well as selective inhibitors of dihydrofolate reductase (DHFR) enzymes from opportunistic pathogens found in patients with AIDS and other immune disorders, N-[(2,4-diaminopteridin-6- yl)methyl]dibenz[b,f]azepine (4a) and the corresponding dihydrodibenz[b,f]azepine, dihydroacridine, phenoxazine, phenothiazine, carbazole, and diphenylamine analogues were synthesized from 2,4-diamino-6- (bromomethyl)pteridine in 50-75% yield by reaction with the sodium salts of the amines in dry tetrahydrofuran at room temperature. The products were tested for the ability to inhibit DHFR from Pneumocystis carinii (pcDHFR), Toxoplasma gondii (tgDHFR), Mycobacterium avium (maDHFR), and rat liver (rlDHFR). The member of the series with the best combination of potency and species selectivity was 4a, with IC50 values against the four enzymes of 0.21, 0.043, 0.012, and 4.4μM, respectively. The dihydroacridine, phenothiazine, and carbazole analogues were also potent, but nonselective. Of the compounds tested, 4a was the only one to successfully combine the potency of trimetrexate with the selectivity of trimethoprim. Molecular docking simulations using published 3D structural coordinates for the crystalline ternary complexes of pcDHFR and hDHFR suggested a possible structural interpretation for the binding selectivity of 4a and the lack of selectivity of the other compounds. According to this model, 4a is selective because of a unique propensity of the seven-membered ring in the dibenz[b,f]azepine moiety to adopt a puckered orientation that allows it to fit more comfortably into the active site of the P. carinii enzyme than into the active site of the human enzyme. Compound 4a was also evaluated for the ability to be taken up into, and retard the growth of, P. carinii and T. gondii in culture. The IC50 of 4a against P. carinii trophozoites after 7 days of continuous drug treatment was 1.9μM as compared with previously observed IC50 values of >340μM for trimethoprim and 0.27 μM for trimetrexate. In an assay involving [3H]uracil incorporation into the nuclear DNA of T. gondii tachyzoites as the surrogate endpoint for growth, the IC50 of 4a after 5 h of drug exposure was 0.077 μM. The favorable combination of potency and enzyme selectivity shown by 4a suggests that this novel structure may be an interesting lead for structure-activity optimization.
- Rosowsky, Andre,Cody, Vivian,Galitsky, Nikolai,Fu, Hongning,Papoulis, Andrew T.,Queener, Sherry F.
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Read Online
- Birch Reduction of Arenes Using Sodium Dispersion and DMI under Mild Conditions
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An easy-to-handle sodium dispersion in paraffin oil (SD), in combination with inexpensive and environmentally benign 1,3- dimethyl-2-imidazolidinone (DMI) as an additive enables the Birch-type reduction of a variety of arenes with high yields, selectivity, and tolerance of functionality such as ether, alcohol, amine, amide, and carboxylic acid.
- Asako, Sobi,Ilies, Laurean,Kurogi, Takashi,Murakami, Yoshiaki,Takahashi, Ikko,Takai, Kazuhiko
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supporting information
p. 38 - 40
(2022/01/12)
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- Non-Cryogenic, Ammonia-Free Reduction of Aryl Compounds
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A method of reducing an aromatic ring or a cyclic, allylic ether in a compound includes preparing a reaction mixture including a compound including an aromatic moiety or a cyclic, allylic ether moiety, an alkali metal, and either ethylenediamine, diethylenetriamine, triethylenetetramine, or a combination thereof, in an ether solvent; and reacting the reaction mixture at from ?20° C. to 30° C. for a time sufficient to reduce a double bond in the aromatic moiety to a single bond or to reduce the cyclic, allylic ether moiety.
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- Pd/c catalyzed decarboxylation-transfer hydrogenation of quinoline carboxylic acids
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Pd/C catalyzed decarboxylation-transfer hydrogenation of quinoline carboxylic acids and transfer hydrogenation of quinolines had been developed for the synthesis of 1,2,3,4-tetrahydroquinolines. These two processes were implemented smoothly using Pd/C (0.9 mol%) as a catalyst with ammonium formate as a hydrogen source in ethanol at 80oC. The reaction system can also be applied to transfer hydrogenation of benzo[h]quinoline and 2,9-dimethyl-1,10-phenanthroline with good to excellent yields. And the gram scale and recycling of catalyst had been tested with good results. Furthermore, the mechanism of Pd/C catalyzed reduction of quino-line carboxylic acids and quinolines had been proposed.
- Chen, Xia,Zhou, Xiao-Yu
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p. 625 - 633
(2021/09/30)
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- Visible-Light-Enhanced Cobalt-Catalyzed Hydrogenation: Switchable Catalysis Enabled by Divergence between Thermal and Photochemical Pathways
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The catalytic hydrogenation activity of the readily prepared, coordinatively saturated cobalt(I) precatalyst, (R,R)-(iPrDuPhos)Co(CO)2H ((R,R)-iPrDuPhos = (+)-1,2-bis[(2R,5R)-2,5-diisopropylphospholano]benzene), is described. While efficient turnover was observed with a range of alkenes upon heating to 100 °C, the catalytic performance of the cobalt catalyst was markedly enhanced upon irradiation with blue light at 35 °C. This improved reactivity enabled hydrogenation of terminal, di-, and trisubstituted alkenes, alkynes, and carbonyl compounds. A combination of deuterium labeling studies, hydrogenation of alkenes containing radical clocks, and experiments probing relative rates supports a hydrogen atom transfer pathway under thermal conditions that is enabled by a relatively weak cobalt-hydrogen bond of 54 kcal/mol. In contrast, data for the photocatalytic reactions support light-induced dissociation of a carbonyl ligand followed by a coordination-insertion sequence where the product is released by combination of a cobalt alkyl intermediate with the starting hydride, (R,R)-(iPrDuPhos)Co(CO)2H. These results demonstrate the versatility of catalysis with Earth-abundant metals as pathways involving open-versus closed-shell intermediates can be switched by the energy source.
- Mendelsohn, Lauren N.,MacNeil, Connor S.,Tian, Lei,Park, Yoonsu,Scholes, Gregory D.,Chirik, Paul J.
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p. 1351 - 1360
(2021/02/01)
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- Cu-Catalyzed Chemoselective Reduction of N-Heteroaromatics with NH3·BH3 in Aqueous Solution
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An efficient catalytic system was successfully developed on reduction of N-heteroaromatics with H3N?BH3 as hydrogen source in CuSO4 solution, featuring excellent chemoselectivity as well as very broad functional group tolerance. Various challenging substrates, such as OH-, NH2-, Cl-, Br-, etc., contained quinolines, quinoxalines, 1,5-naphthyridines and quinazolines were all reduced smoothly. Mechanistic studies suggested that [Cu-H] intermediate might be generated from NH3?BH3, which was believed to form with H3N?BH3 in CuSO4 solution.
- Gao, Chao,Xuan, Qingqing,Song, Qiuling
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supporting information
p. 2504 - 2508
(2021/07/31)
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- Acid-catalyzed oxidative cross-coupling of acridans with silyl diazoenolates and a Rh-catalyzed rearrangement: two-step synthesis of γ-(9-acridanylidene)-β-keto esters
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A MsOH-catalyzed oxidative cross-coupling of acridans and silyl diazoenolates and a Rh2(OAc)4-catalyzed rearrangement of the resultant diazo products are described. The reactions provide various γ-(9-acridanylidene)-β-keto esters in good yields, which bear an active α-methylene unit for further functionalization.
- Li, Weiyu,Xu, Hao,Zhou, Lei
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p. 5649 - 5657
(2021/07/02)
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- Boric acid catalyzed chemoselective reduction of quinolines
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Boric acid promoted transfer hydrogenation of substituted quinolines to synthetically versatile 1,2,3,4-tetrahydroquinolines (1,2,3,4-THQs) was described under mild reaction conditions using a Hantzsch ester as a mild organic hydrogen source. This methodology is practical and efficient, where isolated yields are excellent and reducible functional groups are well tolerated in the N-heteroarene moiety. The reaction parameters and tentative mechanistic pathways are demonstrated by various control experiments and NMR studies. The present work can also be scaled up to obtain gram quantities and the utility of the developed process is illustrated by the transformation of 1,2,3,4-THQs into a series of biologically important molecules including the antiarrhythmic drug nicainoprol.
- Adhikari, Priyanka,Bhattacharyya, Dipanjan,Das, Animesh,Konwar, Monuranjan,Nandi, Sekhar,Sarmah, Bikash Kumar
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supporting information
p. 1214 - 1220
(2020/02/22)
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- Simple manganese carbonyl catalyzed hydrogenation of quinolines and imines
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Manganese-catalyzed hydrogenation of unsaturated molecules has made tremendous progresses recently benefiting from non-innocent pincer or bidentate ligands for manganese. Herein, we describe the hydrogenation of quinolines and imines catalyzed by simple manganese carbonyls, Mn2(CO)10 or MnBr(CO)5, thus eliminating the prerequisite pincer-type or bidentate ligands.
- Wang, Zelong,Chen, Lei,Mao, Guoliang,Wang, Congyang
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p. 1890 - 1894
(2020/03/04)
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- Fast and Efficient Nickel(II)-catalysed Transfer Hydrogenation of Quinolines with Ammonia Borane
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Herein we report the first Ni(II)-catalysed transfer hydrogenation of quinolines using ammonia borane (AB) as hydrogen (H2) source. An in situ generated Ni(II)-bis(pyrazolyl)pyridine pre-catalyst could hydrogenate quinoline and its derivatives in excellent yields of up to 90% at 25 °C in 30 minutes. Spectroscopic studies revealed that a Ni(II)-hydride is responsible for the transfer hydrogenation of quinoline to 1,2,3,4-tetrahydroquinoline via a 1,4-dihydroquinoline intermediate. (Figure presented.).
- Vermaak, Vincent,Vosloo, Hermanus C. M.,Swarts, Andrew J.
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supporting information
p. 5788 - 5793
(2020/12/01)
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- One-pot dual catalysis for the hydrogenation of heteroarenes and arenes
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A simple dinuclear monohydrido bridged ruthenium complex [{(η6-p-cymene)RuCl}2(μ-H-μ-Cl)] acts as an efficient and selective catalyst for the hydrogenation of various heteroarenes and arenes. The nature of the catalytically active species was investigated using a combination of techniques including in situ reaction monitoring, kinetic studies, quantitative poisoning experiments and electron microscopy, evidencing a dual reactivity. The results suggest that the hydrogenation of heteroarenes proceeds via molecular catalysis. In particular, monitoring the reaction progress by NMR spectroscopy indicates that [{(η6-p-cymene)RuCl}2(μ-H-μ-Cl)] is transformed into monomeric ruthenium intermediates, which upon subsequent activation of dihydrogen and hydride transfer accomplish the hydrogenation of heteroarenes under homogeneous conditions. In contrast, carbocyclic aryl motifs are hydrogenated via a heterogeneous pathway, by in situ generated ruthenium nanoparticles. Remarkably, these hydrogenation reactions can be performed using molecular hydrogen under solvent-free conditions or with 1,4-dioxane, and thus give access to a broad range of saturated heterocycles and carbocycles while generating no waste.
- Chatterjee, Basujit,Kalsi, Deepti,Kaithal, Akash,Bordet, Alexis,Leitner, Walter,Gunanathan, Chidambaram
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p. 5163 - 5170
(2020/09/07)
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- METHOD OF PRODUCING DIAMINES AND POLYAMINES OF THE DIPHENYLMETHANE SERIES
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The invention relates to a method for producing diamines and polyamines of the diphenylmethane series, by condensing aniline and formaldehyde followed by an acid-catalysed rearrangement at different production capacities with alteration of the isomer composition in the resulting diamines of the diphenylmethane series (altering the 2,4′-MDA content). Adapting the molar ratios of the total used aniline to the total used formaldehyde and of the total used acid catalyst to the total used aniline, and adapting the reaction temperature, allows the rearrangement reaction to be fully completed despite the change in dwell time inevitably associated with a change in production capacity, and allows the formation of undesired by-products to be avoided as far as possible; the intended modification to binuclear content is likewise achieved.
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Paragraph 0160-0161
(2020/03/28)
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- METHOD OF PRODUCING DIAMINES AND POLYAMINES OF THE DIPHENYLMETHANE SERIES
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The invention relates to a method for producing diamines and polyamines of the diphenylmethane series, by condensing aniline and formaldehyde followed by an acid-catalysed rearrangement at different production capacities with alteration of the content of diamines of the diphenylmethane series (altering the binuclear content). Adapting the molar ratio of the total used aniline to the total used formaldehyde and adapting the reaction temperature allows the rearrangement reaction to be fully completed despite the change in dwell time inevitably associated with a change in production capacity, and allows the formation of undesired by-products to be avoided as far as possible; the intended modification to binuclear content is likewise achieved.
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Paragraph 0168-0170
(2020/05/02)
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- Combined KOH/BEt3Catalyst for Selective Deaminative Hydroboration of Aromatic Carboxamides for Construction of Luminophores
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The selective catalytic C-N bond cleavage of amides into value-added amine products is a desirable but challenging transformation. Molecules containing iminodibenzyl motifs are prevalent in pharmaceutical molecules and functional materials. Here we established a combined KOH/BEt3 catalyst for deaminative hydroboration of acyl-iminodibenzyl derivatives, including nonheterocyclic carboxamides, to the corresponding amines. This novel transition-metal-free methodology was also applied to the construction of Clomipramine and luminophores.
- Li, Jinshan,Wang, Jiali,Yang, Jianguo,Yao, Wubing,Zhong, Aiguo
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p. 8086 - 8090
(2020/11/03)
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- Scalable and safe synthetic organic electroreduction inspired by Li-ion battery chemistry
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Reductive electrosynthesis has faced long-standing challenges in applications to complex organic substrates at scale. Here, we show how decades of research in lithium-ion battery materials, electrolytes, and additives can serve as an inspiration for achieving practically scalable reductive electrosynthetic conditions for the Birch reduction. Specifically, we demonstrate that using a sacrificial anode material (magnesium or aluminum), combined with a cheap, nontoxic, and water-soluble proton source (dimethylurea), and an overcharge protectant inspired by battery technology [tris(pyrrolidino)phosphoramide] can allow for multigram-scale synthesis of pharmaceutically relevant building blocks. We show how these conditions have a very high level of functional-group tolerance relative to classical electrochemical and chemical dissolving-metal reductions. Finally, we demonstrate that the same electrochemical conditions can be applied to other dissolving metal-type reductive transformations, including McMurry couplings, reductive ketone deoxygenations, and epoxide openings.
- Peters, Byron K.,Rodriguez, Kevin X.,Reisberg, Solomon H.,Beil, Sebastian B.,Kawamata, Yu,Baran, Phil S.,Hickey, David P.,Klunder, Kevin,Gorey, Timothy J.,Anderson, Scott L.,Minteer, Shelley D.,Collins, Michael,Starr, Jeremy,Chen, Longrui,Udyavara, Sagar,Neurock, Matthew
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p. 838 - 845
(2019/04/30)
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- Homogeneous Hydrogenation with a Cobalt/Tetraphosphine Catalyst: A Superior Hydride Donor for Polar Double Bonds and N-Heteroarenes
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The development of catalysts based on earth abundant metals in place of noble metals is becoming a central topic of catalysis. We herein report a cobalt/tetraphosphine complex-catalyzed homogeneous hydrogenation of polar unsaturated compounds using an air- and moisture-stable and scalable precatalyst. By activation with potassium hydroxide, this cobalt system shows both high efficiency (up to 24 000 TON and 12 000 h-1 TOF) and excellent chemoselectivities with various aldehydes, ketones, imines, and even N-heteroarenes. The preference for 1,2-reduction over 1,4-reduction makes this method an efficient way to prepare allylic alcohols and amines. Meanwhile, efficient hydrogenation of the challenging N-heteroarenes is also furnished with excellent functional group tolerance. Mechanistic studies and control experiments demonstrated that a CoIH complex functions as a strong hydride donor in the catalytic cycle. Each cobalt intermediate on the catalytic cycle was characterized, and a plausible outer-sphere mechanism was proposed. Noteworthy, external inorganic base plays multiple roles in this reaction and functions in almost every step of the catalytic cycle.
- Duan, Ya-Nan,Du, Xiaoyong,Cui, Zhikai,Zeng, Yiqun,Liu, Yufeng,Yang, Tilong,Wen, Jialin,Zhang, Xumu
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supporting information
p. 20424 - 20433
(2019/12/27)
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- Reduction of Acridine and 9-Chloroacridine with Red Phosphorus in the KOH/DMSO System
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Abstract: Acridine reacts with red phosphorus in the KOH/DMSO(H2O) system on heating (100°C, 3 h) to give 9,10-dihydroacridine regioselectively in quantitative yield. Under similar conditions, 9-chloroacridine reacts with Pred/KOH/DMSO(H2O) system to afford 9,10-dihydroacridine and acridone in 51 and 40% yield, respectively.
- Kuimov,Gusarova,Malysheva,Kon’kova,Trofimov
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p. 177 - 179
(2019/08/26)
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- Transfer Hydrogenation of Carbonyl Groups, Imines and N-Heterocycles Catalyzed by Simple, Bipyridine-Based MnI Complexes
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Utilization of hydroxy-substituted bipyridine ligands in transition metal catalysis mimicking [Fe]-hydrogenase has been shown to be a promising approach in developing new catalysts for hydrogenation. For example, MnI complexes with 6,6′-dihydroxy-2,2′-bipyridine ligand have been previously shown to be active catalysts for CO2 hydrogenation. In this work, simple bipyridine-based Mn catalysts were developed that act as active catalysts for transfer hydrogenation of ketones, aldehydes and imines. For the first time, Mn-catalyzed transfer hydrogenation of N-heterocycles was reported. The highest catalytic activity among complexes with variously substituted ligands was observed for the complex bearing two OH groups in bipyridine. Deuterium labeling experiments suggest a monohydride pathway.
- Dubey, Abhishek,Rahaman, S. M. Wahidur,Fayzullin, Robert R.,Khusnutdinova, Julia R.
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p. 3844 - 3852
(2019/04/08)
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- Uncatalyzed Oxidative C?H Amination of 9,10-Dihydro-9-Heteroanthracenes: A Mechanistic Study
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A new method for the one-step C?H amination of xanthene and thioxanthene with sulfonamides is reported, without the need for any metal catalyst. A benzoquinone was employed as a hydride (or two-electron and one-proton) acceptor. Moreover, a previously unknown and uncatalyzed reaction between iminoiodanes and xanthene, thioxanthene and dihydroacridines (9,10-dihydro-9-heteroanthracenes or dihydroheteroanthracenes) is disclosed. The reactions proceed through hydride transfer from the heteroarene substrate to the iminoiodane or benzoquinone, followed by conjugate addition of the sulfonamide to the oxidized heteroaromatic compounds. These findings may have important mechanistic implications for metal-catalyzed C?H amination processes involving nitrene transfer from iminoiodanes to dihydroheteroanthracenes. Due to the weak C?H bond, xanthene is an often-employed substrate in mechanistic studies of C?H amination reactions, which are generally proposed to proceed via metal-catalyzed nitrene insertion, especially for reactions involving nitrene or imido complexes that are less reactive (i.e., less strongly oxidizing). However, these substrates clearly undergo non-catalyzed (proton-coupled) redox coupling with amines, thus providing alternative pathways to the widely assumed metal-catalyzed pathways.
- van Leest, Nicolaas P.,Grooten, Lars,van der Vlugt, Jarl Ivar,de Bruin, Bas
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supporting information
p. 5987 - 5993
(2019/04/03)
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- Silver-Catalyzed Reduction of Quinolines in Water
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A ligand- and base-free silver-catalyzed reduction of quinolines and electron-deficient aromatic N-heteroarenes in water has been described. Mechanistic studies revealed that the effective reducing species was Ag-H. This versatile catalytic protocol provided facile, environmentally friendly, and practical access to a variety of 1,2,3,4-tetrahydroquinoline derivatives at room temperature.
- Wang, Yan,Dong, Baobiao,Wang, Zikun,Cong, Xuefeng,Bi, Xihe
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supporting information
p. 3631 - 3634
(2019/05/24)
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- Method for conducting catalytic hydrogenation on nitrogen-containing unsaturated heterocyclic compound
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The invention provides a method for conducting catalytic hydrogenation on a nitrogen-containing unsaturated heterocyclic compound, and belongs to the technical field of catalytic hydrogenation. The provided method for conducting catalytic hydrogenation on the nitrogen-containing unsaturated heterocyclic compound comprises the following step: in the presence of hydrogen and a manganese catalyst, with the nitrogen-containing unsaturated heterocyclic compound as a substrate, carrying out a hydrogenation reaction. According to the method for conducting catalytic hydrogenation on the nitrogen-containing unsaturated heterocyclic compound, he adopted manganese catalyst is an NNP-type pincer manganese catalyst, has the advantages of being cheap, easy to obtain and low in toxicity compared with noble metal catalysts, has the advantages of being wide in substrate applicability and high in target product yield compared with an existing cheap metal iron catalyst or cobalt catalyst, and is higher in electron donating ability and smaller in steric hindrance compared with a PNP-type pincer manganese catalyst, and thus shows higher reaction activity in a series of hydrogenation reactions, and thetarget product yield is up to 99%.
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Paragraph 0095; 0106-0109
(2020/01/03)
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- Promoting Frustrated Lewis Pairs for Heterogeneous Chemoselective Hydrogenation via the Tailored Pore Environment within Metal–Organic Frameworks
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Frustrated Lewis pairs (FLPs) have recently been advanced as efficient metal-free catalysts for catalytic hydrogenation, but their performance in chemoselective hydrogenation, particularly in heterogeneous systems, has not yet been achieved. Herein, we demonstrate that, via tailoring the pore environment within metal–organic frameworks (MOFs), FLPs not only can be stabilized but also can develop interesting performance in the chemoselective hydrogenation of α,β-unsaturated organic compounds, which cannot be achieved with FLPs in a homogeneous system. Using hydrogen gas under moderate pressure, the FLP anchored within a MOF that features open metal sites and hydroxy groups on the pore walls can serve as a highly efficient heterogeneous catalyst to selectively reduce the imine bond in α,β-unsaturated imine substrates to afford unsaturated amine compounds.
- Niu, Zheng,Zhang, Weijie,Lan, Pui Ching,Aguila, Briana,Ma, Shengqian
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supporting information
p. 7420 - 7424
(2019/04/27)
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- Birch-Type Photoreduction of Arenes and Heteroarenes by Sensitized Electron Transfer
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The direct reduction of arenes and heteroarenes by visible-light irradiation remains challenging, as the energy of a single photon is not sufficient for breaking aromatic stabilization. Shown herein is that the energy accumulation of two visible-light photons allows the dearomatization of arenes and heteroarenes. Mechanistic investigations confirm that the combination of energy-transfer and electron-transfer processes generates an arene radical anion, which is subsequently trapped by hydrogen-atom transfer and finally protonated to form the dearomatized product. The photoreduction converts planar aromatic feedstock compounds into molecular skeletons that are of use in organic synthesis.
- Chatterjee, Anamitra,K?nig, Burkhard
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supporting information
p. 14289 - 14294
(2019/08/30)
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- Hydride-catalyzed selectively reductive cleavage of unactivated tertiary amides using hydrosilane
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The first hydride-catalyzed reductive cleavage of various unactivated tertiary amides, including the biologically active aryl-phenazine carboxamides and the challenging non-heterocyclic carbonyl functions, using low-cost hydrosilane as a reducing reagent has been developed. The novel catalyst system exhibits high efficiency and exclusive selectivity, providing the desired amines in useful to excellent yields under mild conditions. Overall, this transition metal-free process may offer a versatile alternative to currently employed expensive reducing reagents, high-pressure hydrogen or metal systems for the selective reductive cleavage of amides.
- Yao, Wubing,Li, Rongrong,Yang, Jianguo,Hao, Feiyue
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p. 3874 - 3878
(2019/08/07)
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- A Practical and Chemoselective Ammonia-Free Birch Reduction
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A novel protocol for a significantly improved, practical, and chemoselective ammonia-free Birch reduction mediated by bench-stable sodium dispersions and recoverable 15-crown-5 ether is reported. A broad range of aromatic and heteroaromatic compounds is reduced with excellent yields.
- Lei, Peng,Ding, Yuxuan,Zhang, Xiaohe,Adijiang, Adila,Li, Hengzhao,Ling, Yun,An, Jie
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supporting information
p. 3439 - 3442
(2018/06/26)
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- A robust iron catalyst for the selective hydrogenation of substituted (iso)quinolones
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By applying N-doped carbon modified iron-based catalysts, the controlled hydrogenation of N-heteroarenes, especially (iso)quinolones, is achieved. Crucial for activity is the catalyst preparation by pyrolysis of a carbon-impregnated composite, obtained from iron(ii) acetate and N-aryliminopyridines. As demonstrated by TEM, XRD, XPS and Raman spectroscopy, the synthesized material is composed of Fe(0), Fe3C and FeNx in a N-doped carbon matrix. The decent catalytic activity of this robust and easily recyclable Fe-material allowed for the selective hydrogenation of various (iso)quinoline derivatives, even in the presence of reducible functional groups, such as nitriles, halogens, esters and amides. For a proof-of-concept, this nanostructured catalyst was implemented in the multistep synthesis of natural products and pharmaceutical lead compounds as well as modification of photoluminescent materials. As such this methodology constitutes the first heterogeneous iron-catalyzed hydrogenation of substituted (iso)quinolones with synthetic importance.
- Sahoo, Basudev,Kreyenschulte, Carsten,Agostini, Giovanni,Lund, Henrik,Bachmann, Stephan,Scalone, Michelangelo,Junge, Kathrin,Beller, Matthias
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p. 8134 - 8141
(2018/11/20)
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- Cu-catalyzed reduction of azaarenes and nitroaromatics with diboronic acid as reductant
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A ligand-free copper-catalyzed reduction of azaarenes with diboronic acid as reductant in an aprotic solvent under mild conditions has been developed. Most interestingly, the nitroazaarenes could be reduced exclusively to give the corresponding amines without touching the azaarene moieties. Furthermore, the reductive amination of aromatic nitro compounds and aromatic aldehydes has also been realized. A series of hydrogenated azaarenes and secondary amines were obtained with good functional group tolerance.
- Pi, Danwei,Zhou, Haifeng,Zhou, Yanmei,Liu, Qixing,He, Renke,Shen, Guanshuo,Uozumi, Yasuhiro
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p. 2121 - 2129
(2018/03/23)
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- Novel electronic salt system and method for reducing unsaturated hydrocarbon compound
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The invention discloses an electronic salt system and a method for reducing unsaturated hydrocarbon compounds by using the electronic salt system, belongs to the field of organic synthesis, and solvesthe problems such as complicated operation, harsh conditions, easy generation of complex over-reduction products of methods for reducing the unsaturated hydrocarbon compounds in the prior art. An electron salt may be synthesized by an alkali metal reagent, an ether and an alcohol, the ether can be a crown ether or a cryptand; and the method adopts the electronic salt system, the unsaturated hydrocarbon compounds is reduced by the electronic salt system in an organic solvent. The method for reducing the unsaturated hydrocarbon compounds is used for reducing the unsaturated hydrocarbon compounds.
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Paragraph 0095-0099
(2018/09/08)
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- Metal-Organic Framework Anchored with a Lewis Pair as a New Paradigm for Catalysis
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Lewis pair (LP) chemistry has shown broad applications in the catalysis field. However, one significant challenge has been recognized as the instability for most homogeneous LP catalysts upon recycling, thus inevitably leading to dramatic loss in catalytic activity. Additionally, current heterogeneous LP catalysts suffer from low surface area, which largely limits their catalytic efficiency, thereby restricting their potential applications. In this work, we report the successful introduction of LPs, classical and frustrated, into a metal-organic framework (MOF) that features high surface and ordered pore structure via a stepwise anchoring strategy. Not only can the LP be stabilized by the strong coordination interaction between the LP and MOF, but the resultant MOF-LP also demonstrates excellent catalysis performance with interesting size and steric selectivity. Given the broad applicability of LPs, our work therefore paves a way for advancing MOF-LP as a new paradigm for catalysis. Lewis pairs (LPs), classical and frustrated, are excellent prospects in catalysis, organic syntheses, biology, and material sciences. However, the instability of most LP catalysts leads to a dramatic loss in activities, thereby largely restricting their industrial applications. As robust porous materials, metal-organic frameworks (MOFs) offer a platform to stabilize homogeneous catalysts. Here, we show a strategy that grafts the LP catalyst on the MOF to minimize loss of LPs during catalysis and recycling. Our work reveals the enormous potential of MOFs as an appealing paradigm for the construction of efficient heterogeneous catalysts with interesting steric and size selectivity worthy of exploration. In addition, the strategies for anchoring a LP into a MOF as contributed herein can be readily applied for the task-specific design of functional catalysis materials for various applications. Lewis pairs (LPs), classical and frustrated, have been successfully introduced into and stabilized in a metal-organic framework (MOF). Benefiting from the robust framework and tunable porous structure of MOFs, the resultant MOF-LP demonstrates not only great recyclability but also excellent performance in the catalytic reduction of imines and hydrogenation of alkenes. The combination of LP and MOF therefore lays a foundation for developing a MOF-LP as a new paradigm for catalysis, particularly heterogeneous catalysis.
- Niu, Zheng,Bhagya Gunatilleke, Wilarachchige D.C.,Sun, Qi,Lan, Pui Ching,Perman, Jason,Ma, Jian-Gong,Cheng, Yuchuan,Aguila, Briana,Ma, Shengqian
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p. 2587 - 2599
(2018/12/02)
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- Ru-Catalyzed Transfer Hydrogenation of Nitriles, Aromatics, Olefins, Alkynes and Esters
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This paper reports the preparation of new ruthenium(II) complexes supported by a pyrazole-phosphine ligand and their application to transfer hydrogenation of various substrates. These Ru complexes were found to be efficient catalysts for the reduction of nitriles and olefins. Heterocyclic compounds undergo transfer hydrogenation with good to moderate yields, affording examples of unusual hydrogenation of all-carbon-rings. Internal alkynes with bulky substituents show selective reduction to olefins with the unusual E–selectivity. Esters with strong electron-withdrawing groups can be reduced to the corresponding alcohols, if ethanol is used as the solvent. Possible mechanisms of hydrogenation and olefin isomerization are suggested on the basis of kinetic studies and labelling experiments.
- Alshakova, Iryna D.,Gabidullin, Bulat,Nikonov, Georgii I.
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p. 4860 - 4869
(2018/10/02)
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- Gold Particles Supported on Amino-Functionalized Silica Catalyze Transfer Hydrogenation of N-Heterocyclic Compounds
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In this work we demonstrate that exceptionally small gold particles (d=0.6±0.2 nm) supported on amino-functionalized mesoporous silicate SBA-15 are highly active in transfer hydrogenation of structurally diverse unsaturated N-heterocyclic compounds. The heterocyclic ring is reduced selectively. The gold particles aggregate to a diameter of 4–5 nm in the presence of formic acid/triethylamine (hydrogen donor) during the first catalytic run. In subsequent cycles the nanoparticles maintain their size, yielding a very stable catalytic system that was recycled more than five times. In contrast, analogous SBA catalysts featuring larger (~5–35 nm) gold particles are not active. Excess formic acid also leads to the formation of formamide derivatives of the products of hydrogenation, which can be deformylated quantitatively. Fifteen structurally different substrates, including the scaffolds of quinoline, isoquinoline, quinoxaline, acridine, phenanthroline, quinazoline, and phenanthridine are hydrogenated and deformylated to give the amine products in >90% overall yield. Deuterium labeling experiments indicate that 1,2-addition with subsequent disproportionation of the formed intermediate is the preferred reaction path over the 1,4-addition one, suggesting the participation of a gold hydride species. (Figure presented.).
- Vilhanová, Beáta,van Bokhoven, Jeroen A.,Ranocchiari, Marco
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supporting information
p. 677 - 686
(2017/02/23)
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- A General and Highly Selective Cobalt-Catalyzed Hydrogenation of N-Heteroarenes under Mild Reaction Conditions
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Herein, a general and efficient method for the homogeneous cobalt-catalyzed hydrogenation of N-heterocycles, under mild reaction conditions, is reported. Key to success is the use of the tetradentate ligand tris(2-(diphenylphosphino)phenyl)phosphine). This non-noble metal catalyst system allows the selective hydrogenation of heteroarenes in the presence of a broad range of other sensitive reducible groups.
- Adam, Rosa,Cabrero-Antonino, Jose R.,Spannenberg, Anke,Junge, Kathrin,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 3216 - 3220
(2017/03/17)
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- B(C6F5)3-Promoted hydrogenations of N-heterocycles with ammonia borane
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A transition-metal-free method for the B(C6F5)3-promoted hydrogenations of N-heterocycles using ammonia borane under mild reaction conditions has been developed. The reaction affords a broad range of hydrogenated products in moderate to good yields. The enantioselective versions for the corresponding products were also investigated via our approach, showing good feasibility.
- Ding, Fangwei,Zhang, Yiliang,Zhao, Rong,Jiang, Yanqiu,Bao, Robert Li-Yuan,Lin, Kaifeng,Shi, Lei
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supporting information
p. 9262 - 9264
(2017/08/21)
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- The photochemical alkylation and reduction of heteroarenes
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The functionalization of heteroarenes has been integral to the structural diversification of medicinally active molecules such as quinolines, pyridines, and phenanthridines. Electron-deficient heteroarenes are electronically compatible to react with relatively nucleophilic free radicals such as hydroxyalkyl. However, the radical functionalization of such heteroarenes has been marked by the use of transition-metal catalyzed processes that require initiators and stoichiometric oxidants. Herein, we describe the photochemical alkylation of quinolines, pyridines and phenanthridines, where through direct excitation of the protonated heterocycle, alcohols and ethers, such as methanol and THF, can serve as alkylating agents. We also report the discovery of a photochemical reduction of these heteroarenes using only iPrOH and HCl. Mechanistic studies to elucidate the underlying mechanism of these transformations, and preliminary results on catalytic methylations are also reported.
- McCallum,Pitre,Morin,Scaiano,Barriault
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p. 7412 - 7418
(2017/10/31)
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- REACTIONS OF STANNYL CATIONS
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The present invention relates to a method of reducing, cleaving and/or coupling at least one C=O, C-O, C=C or C=N bond of a compound, using a reagent comprising a stannyl cation.
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Page/Page column 20
(2018/01/17)
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- A disubstituted amide derivatives decarbonylation hydrogenation green new method (by machine translation)
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The invention relates to a high efficiency, high selectivity of the disubstituted amide derivatives of decarbonylation hydrogenation reaction green new method. For the first time to the metallic compound triethylborane as catalyst, under mild conditions can be conveniently catalytic N, N - di-aryl substituted amide and its derivative and cheap and easy to obtain organic silicon reagent selective preparation of secondary organic amine product. Compared with the traditional method, the new method generally has the wide substrate universality, functional group compatibility outstanding, simple operation and the like. For the first time in order to realize the organic silicon reagent as reducing agent and amide compounds decarbonylation hydrogenation reaction, is the reduction of amides and derivatives thereof, in particular the organic light-emitting diodes (OLEDs) material unit - diaryl amine compound of the laboratory preparation or industrial production provides a brand-new "green" response strategies. (by machine translation)
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Paragraph 0050; 0051; 0052; 0053
(2018/02/04)
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- Visible-Light-Promoted C-H Arylation by Merging Palladium Catalysis with Organic Photoredox Catalysis
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The use of a dual palladium/organic photoredox catalytic system enables the directed arylation of arenes with aryldiazonium salts with a broad substrate scope at room temperature under mild reaction conditions. This study thus serves as not only an alternative route for the biaryl motifs but also a new example for the application of an organic photoredox catalyst.
- Jiang, Jian,Zhang, Wen-Man,Dai, Jian-Jun,Xu, Jun,Xu, Hua-Jian
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p. 3622 - 3630
(2017/04/11)
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- Efficient Hydrogenation of Nitrogen Heterocycles Catalyzed by Carbon-Metal Covalent Bonds-Stabilized Palladium Nanoparticles: Synergistic Effects of Particle Size and Water
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We reveal here the first hydrogenation of nitrogen heterocycles catalyzed by carbon–metal covalent bonds-stabilized palladium nanoparticles in water under mild conditions. Using a one-phase reduction method, smaller metal–carbon covalent bond-stabilized Pd nanoparticles were prepared with a size distribution of 2.5±0.5 nm, which showed extraordinary synergistic effects with water in the catalytic hydrogenation of nitrogen heterocycles. Water was supposed to accelerate substrate absorption and synergistic activation of molecular hydrogen on the Pd nanoparticles surface. The nanosized Pd catalyst could be easily recovered and reused for 5 runs. (Figure presented.).
- Zhang, Yu,Zhu, Jie,Xia, Yun-Tao,Sun, Xiao-Tao,Wu, Lei
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supporting information
p. 3039 - 3045
(2016/10/09)
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- Cobalt Encapsulated in N-Doped Graphene Layers: An Efficient and Stable Catalyst for Hydrogenation of Quinoline Compounds
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Porous nitrogen-doped graphene layers encapsulating cobalt nanoparticles (NPs) were prepared by the direct pyrolysis process. The resulting hybrids catalyze the hydrogenation of diverse quinoline compounds to access the corresponding tetrahydro derivatives (THQs), important molecules present in fine and bulk chemicals. Near-quantitative yields of the corresponding THQs were obtained under optimized conditions. Notably, various useful substituted quinolines and other biologically important N-heteroarenes are also viable. The enhanced stability of the catalyst is ascribed to the encapsulation structure, which can enormously reduce the extent of leaching of base metals and protect metal NPs from growing larger. The achieved success in the encapsulation of metal NPs within graphene layers opens an avenue for the design of highly active and reusable heterogeneous catalysts for more challenging molecules.
- Wei, Zhongzhe,Chen, Yiqing,Wang, Jing,Su, Diefeng,Tang, Minghui,Mao, Shanjun,Wang, Yong
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p. 5816 - 5822
(2016/09/09)
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- Hydrogenation and Transfer Hydrogenation Promoted by Tethered Ru?S Complexes: From Cooperative Dihydrogen Activation to Hydride Abstraction/Proton Release from Dihydrogen Surrogates
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Hydrogenation and transfer hydrogenation of imines with cyclohexa-1,4-dienes, as well as with a representative Hantzsch ester dihydrogen surrogate, are reported. Both processes are catalyzed by tethered Ru?S complexes but differ in the activation mode of the dihydrogen source: cooperative activation of the H?H bond at the Ru?S bond leads to the corresponding Ru?H complex and protonation of the sulfur atom, whereas the same cationic Ru?S catalyst abstracts a hydride from a donor-substituted cyclohexa-1,4-diene to form the neutral Ru?H complex and a low-energy Wheland intermediate. A sequence of proton and hydride transfers on the imine substrate then yields an amine. The reaction pathways are analyzed computationally, and the established mechanistic pictures are in agreement with the experimental observations.
- Lefranc, Alice,Qu, Zheng-Wang,Grimme, Stefan,Oestreich, Martin
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supporting information
p. 10009 - 10016
(2016/07/19)
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- Diboron-assisted palladium-catalyzed transfer hydrogenation of N-heteroaromatics with water as hydrogen donor and solvent
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A Pd-catalyzed transfer hydrogenation of various N-heteroaromatic compounds with B2pin2 as a mediator and environmentally benign water as both solvent and hydrogen donor has been disclosed. This reaction proceeded under ambient temperature with a broad range of N-heteroaromatic compounds among which imidazo[1,2-a]pyridine derivatives were for the first time selectively reduced to 5,6,7,8-tetrahydroimidazo[1,2-a]pyridines, which are the core structural motifs of an inhibitor of human O-GlcNAcase. Mechanistic studies suggested that the new protons in products are from water and Pd-H might be the key intermediate with B2pin2 as the H2O activator.
- Xuan, Qingqing,Song, Qiuling
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supporting information
p. 4250 - 4253
(2016/09/09)
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- Transfer Hydrogenation of Nitriles, Olefins, and N-Heterocycles Catalyzed by an N-Heterocyclic Carbene-Supported Half-Sandwich Complex of Ruthenium
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In the presence of KOBut, N-heterocyclic carbene-supported half-sandwich complex [Cp(IPr)Ru(pyr)2][PF6] (3) (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) catalyzes transfer hydrogenation (TH) of nitriles, activated N-heterocycles, olefins, and conjugated olefins in isopropanol at the catalyst loading of 0.5%. The TH of nitriles leads to imines, produced as a result of coupling of the initially formed amines with acetone (produced from isopropanol), and showed good chemoselectivity. Reduction of N-heterocycles occurs for activated polycyclic substrates (e.g., quinoline) and takes place exclusively in the heterocycle. The TH also works well for linear and cyclic olefins but fails for trisubstituted substrates. However, the C = C bond of α,β-unsaturated esters, amides, and acids is easily reduced even for trisubstituted species, such as isovaleriates. Mechanistic studies suggest that the active species in these catalytic reactions is the trihydride Cp(IPr)RuH3 (5), which can catalyze these reactions in the absence of any base. Kinetic studies are consistent with a classical inner sphere hydride-based mechanism of TH.
- Mai, Van Hung,Nikonov, Georgii I.
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p. 943 - 949
(2016/05/09)
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- Versatile Catalytic Hydrogenation Using A Simple Tin(IV) Lewis Acid
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Despite the rapid development of frustrated Lewis pair (FLP) chemistry over the last ten years, its application in catalytic hydrogenations remains dependent on a narrow family of structurally similar early main-group Lewis acids (LAs), inevitably placing limitations on reactivity, sensitivity and substrate scope. Herein we describe the FLP-mediated H2activation and catalytic hydrogenation activity of the alternative LA iPr3SnOTf, which acts as a surrogate for the trialkylstannylium ion iPr3Sn+, and is rapidly and easily prepared from simple, inexpensive starting materials. This highly thermally robust LA is found to be competent in the hydrogenation of a number of different unsaturated functional groups (which is unique to date for main-group FLP LAs not based on boron), and also displays a remarkable tolerance to moisture.
- Scott, Daniel J.,Phillips, Nicholas A.,Sapsford, Joshua S.,Deacy, Arron C.,Fuchter, Matthew J.,Ashley, Andrew E.
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supporting information
p. 14738 - 14742
(2016/11/23)
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- Reduction method of nitrogen-containing heterocyclic compound
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The invention discloses a reduction method of a nitrogen-containing heterocyclic compound. The reduction method comprises the following steps: firstly, adding bis(pinacolato)diboron, palladium acetate and cesium carbonate into a pressure-resisting sealing reaction vessel; filling with nitrogen, adding water and quinoline compounds, performing stirring reaction at room temperature, and tracking by using TLC and GC in a reaction process so as to decide specific reaction time; secondly, after the reaction is ended, taking out a reaction product in the first step from the pressure-resisting sealing reaction vessel, cooling to room temperature, then adding ethyl acetate for fully mixing, and subsequently performing filtering and washing of ethyl acetate to obtain an organic phase; thirdly, performing spin drying on a solvent in the organic phase obtained in the second step, purifying by using a silica gel column, and then leaching with an eluant to obtain a product. The eluant is a mixed solution of petroleum ether and the ethyl acetate. The reduction method disclosed by the invention accords with the idea of green chemistry, and is better in economy and simple in operation.
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Paragraph 0030; 0031; 0032; 0033; 0034
(2017/02/09)
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- Methanol dehydrogenation by iridium N-heterocyclic carbene complexes
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A series of homogeneous iridium bis(N-heterocyclic carbene) catalysts are active for three transformations involving dehydrogenative methanol activation: acceptorless dehydrogenation, transfer hydrogenation, and amine monoalkylation. The acceptorless dehydrogenation reaction requires base, yielding formate and carbonate, as well as 2-3 equivalents of H2. Of the few homogeneous systems known for this reaction, our catalysts tolerate air and employ simple ligands. Transfer hydrogenation of ketones and imines from methanol is also possible. Finally, N-monomethylation of anilines occurs through a borrowing hydrogen reaction. Notably, this reaction is highly selective for the monomethylated product.
- Campos, Jesús,Sharninghausen, Liam S.,Manas, Michael G.,Crabtree, Robert H.
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supporting information
p. 5079 - 5084
(2015/06/16)
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- B(C6F5)3-catalyzed transfer hydrogenation of imines and related heteroarenes using cyclohexa-1,4-dienes as a dihydrogen source
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The strong boron Lewis acid tris(pentafluorophenyl) borane, B(C6F5)3, is shown to abstract a hydride from suitably donor-substituted cyclohexa-1,4-dienes, eventually releasing dihydrogen. This process is coupled with the FLPtype (FLP = frustrated Lewis pair) hydrogenation of imines and nitrogen-containing heteroarenes that are catalyzed by the same Lewis acid. The net reaction is a B(C 6F5)3-catalyzed, i.e., transition-metal-free, transfer hydrogenation using easy-toaccess cyclohexa-1,4-dienes as reducing agents. Competing reaction pathways with or without the involvement of free dihydrogen are discussed.
- Chatterjee, Indranil,Oestreich, Martin
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supporting information
p. 1965 - 1968
(2015/02/19)
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- Selective Catalytic Hydrogenation of Heteroarenes with N-Graphene-Modified Cobalt Nanoparticles (Co3O4-Co/NGratα-Al2O3)
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Cobalt oxide/cobalt-based nanoparticles featuring a core-shell structure and nitrogen-doped graphene layers on alumina are obtained by pyrolysis of Co(OAc)2/phenanthroline. The resulting core-shell material (Co3O4-Co/NGratα-Al2O3) was successfully applied in the catalytic hydrogenation of a variety of N-heteroarenes including quinolines, acridines, benzo[h], and 1,5-naphthyridine as well as unprotected indoles. The peculiar structure of the novel heterogeneous catalyst enables activation of molecular hydrogen at comparably low temperature. Both high activity and selectivity were achieved in these hydrogenation processes, to give important building blocks for bioactive compounds as well as the pharmaceutical industry.
- Chen, Feng,Surkus, Annette-Enrica,He, Lin,Pohl, Marga-Martina,Radnik, J?rg,Topf, Christoph,Junge, Kathrin,Beller, Matthias
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supporting information
p. 11718 - 11724
(2015/09/28)
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- A simple iridicycle catalyst for efficient transfer hydrogenation of n-heterocycles in water
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A cyclometalated iridium complex is shown to catalyse the transfer hydrogenation of various nitrogen heterocycles, including but not limited to quinolines, isoquinolines, indoles and pyridinium salts, in an aqueous solution of HCO2H/HCO2Na under mild conditions. The catalyst shows excellent functional-group compatibility and high turnover number (up to 7500), with catalyst loadings as low as 0.01 mol % being feasible. Mechanistic investigation of the quinoline reduction suggests that the transfer hydrogenation proceeds via both 1,2- and 1,4-addition pathways, with the catalytic turnover being limited by the step of hydride transfer. An easily accessible iridicycle catalyst effects the transfer hydrogenation of a wide variety of N-heterocycles in water, including quinolines, isoquinolines, indoles, quinoxalines, and pyridines. The catalyst shows excellent functional-group compatibility and high turnover number (up to 7500), even with low catalyst loadings.
- Talwar, Dinesh,Li, Ho Yin,Durham, Emma,Xiao, Jianliang
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supporting information
p. 5370 - 5379
(2015/03/30)
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- Experimental and computational studies of borohydride catalyzed hydrosilylation of a variety of C=O and C=N functionalities including esters, amides and heteroarenes
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Sodium borohydride and a series of related borohydrides catalyze a transition metal-free hydrosilylation of a variety of C=O and C=N functionalities under mild conditions. Importantly, many of these reactions are possible using the cheap and environmentally benign hydrosilane polymethylhydrosiloxane. A mechanism is proposed based on experimental and computational results.
- Manas, Michael G.,Sharninghausen, Liam S.,Balcells, David,Crabtree, Robert H.
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supporting information
p. 1694 - 1700
(2014/05/06)
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- Ruthenium nanoparticles supported on magnesium oxide: A versatile and recyclable dual-site catalyst for hydrogenation of mono- and poly-cyclic arenes, N-heteroaromatics, and S-heteroaromatics
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The development of catalysts capable of promoting hydrogenation of aromatics while being resistant to poisoning by nitrogen- and sulfur-containing species is of much interest in connection with hydrotreating of fossil fuels. We report a catalyst composed of ruthenium nanoparticles supported on magnesia, designed to promote heterolytic hydrogen splitting and surface ionic hydrogenation pathways. The catalyst, prepared through a one-pot procedure, promotes the hydrogenation of mono- and poly-cyclic arenes, as well as N- and S-heteroaromatics representative of fossil fuels components. Of particular significance are the superior activity and wider substrate scope of the catalyst, in relation to other known supported noble metals, and the excellent recyclability and long catalyst lifetime. Based on our experimental data, a dual-site catalyst structure and an associated dual-pathway mechanism are proposed, which may have interesting implications for the development of new poison-tolerant noble metal catalytic systems.
- Fang, Minfeng,Sanchez-Delgado, Roberto A.
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p. 357 - 368
(2014/02/14)
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- Synthesis of a human urate transporter-1 inhibitor, an arginine vasopressin antagonist, and a 17β-hydroxysteroid dehydrogenase type-3 inhibitor, using ring-expansion of cyclic ketoximes with DIBALH
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Synthesis of three clinical candidates for medicines, a human urate transporter-1 inhibitor, an arginine vasopressin antagonist, and a 17β-hydroxysteroid dehydrogenase type-3 inhibitor, is described. These compounds were synthesized via construction of their 3,4-dihydro-2H-benzo[b][1, 4]oxazine, dibenzodiazepine, and dibenzazocine skeletons, respectively, using the reductive ring-expansion reaction of the corresponding bicyclic or tricyclic oximes with diisobutylaluminum hydride.
- Cho, Hidetsura,Iwama, Yusuke,Okano, Kentaro,Tokuyama, Hidetoshi
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p. 354 - 363
(2014/04/17)
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