- Compositional introduction of lithium ions into conductive polyoxovanadate-surfactant hybrid crystals
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Polyoxovanadate-surfactant hybrid layered crystals were successfully synthesized as single crystals by employing a primary alkylammonium cation, octylammonium ([C8H17NH3]+, C8NH3). Two types of hybrid crystals with the formulae [C8H17NH3]6[V10O28]·2H2O (C8NH3-V10) and [C8H17NH3]4Li2[V10O28]·4C2H5OH??6H2O (C8NH3-Li-V10) were obtained by different synthetic procedures. Changing the synthetic conditions enabled the precise introduction of lithium cations into the polyoxovanadate-surfactant hybrid crystals according to compositional control. C8NH3-V10 contained a discrete [V10O28]6- anion, while C8NH3-Li-V10 was composed of a [V10O28]6- anion associated with two lithium cations formulated as {[Li(H2O)3]2[V10O28]}4-. The conductivities of C8NH3-V10 and C8NH3-Li-V10 were investigated under anhydrous conditions at intermediate temperatures.
- Kiyota, Yoshiki,Taira, Minako,Otobe, Saki,Hanyuda, Koji,Naruke, Haruo,Ito, Takeru
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- Designing Simple Lipidated Lysines: Bifurcation Imparts Selective Antibacterial Activity
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In the global effort to thwart antimicrobial resistance, lipopeptides are an important class of antimicrobial agents, especially against Gram-negative infections. In an attempt to circumvent their synthetic complexities, we designed simple membrane-active agents involving only one amino acid and two lipid tails. Herein we show that the use of two short lipid tails instead of a single long one significantly increases selective antibacterial activity. This study yielded several selective antibacterial compounds, and investigations into the properties of this compound class were conducted with the most active compound. Fluorescence spectroscopic studies revealed the capacity of the representative compound to cause depolarization and permeabilization of bacterial cell membranes. This membrane-active nature of the compound imparts superior activity against persister cells, biofilms, and planktonic cells. Topical application of the compound decreased bacterial burden in mice inflicted with burn-infections caused by Acinetobacter baumannii. We anticipate that the design principles described herein will direct the development of several antimicrobial agents of clinical importance.
- Ghosh, Chandradhish,Konai, Mohini Mohan,Sarkar, Paramita,Samaddar, Sandip,Haldar, Jayanta
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- Micelle and oligomer kinetics in aqueous solutions of n-octylammonium chloride: Monomer exchange, protrusion and chain isomerization
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Based on measurements of ultrasonic spectra in the frequency range between 0.1 and 2000 MHz the ultrasonic relaxation properties of solutions of the short-chain cationic surfactant n-octylammonium chloride in water are reported at solute concentrations be
- Polacek, Rüdiger,Kaatze, Udo
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- Cyclic (Alkyl)(amino)carbene Ligand-Promoted Nitro Deoxygenative Hydroboration with Chromium Catalysis: Scope, Mechanism, and Applications
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Transition metal catalysis that utilizes N-heterocyclic carbenes as noninnocent ligands in promoting transformations has not been well studied. We report here a cyclic (alkyl)(amino)carbene (CAAC) ligand-promoted nitro deoxygenative hydroboration with cost-effective chromium catalysis. Using 1 mol % of CAAC-Cr precatalyst, the addition of HBpin to nitro scaffolds leads to deoxygenation, allowing for the retention of various reducible functionalities and the compatibility of sensitive groups toward hydroboration, thereby providing a mild, chemoselective, and facile strategy to form anilines, as well as heteroaryl and aliphatic amine derivatives, with broad scope and particularly high turnover numbers (up to 1.8 × 106). Mechanistic studies, based on theoretical calculations, indicate that the CAAC ligand plays an important role in promoting polarity reversal of hydride of HBpin; it serves as an H-shuttle to facilitate deoxygenative hydroboration. The preparation of several commercially available pharmaceuticals by means of this strategy highlights its potential application in medicinal chemistry.
- Zhao, Lixing,Hu, Chenyang,Cong, Xuefeng,Deng, Gongda,Liu, Liu Leo,Luo, Meiming,Zeng, Xiaoming
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supporting information
p. 1618 - 1629
(2021/01/25)
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- Hydrosilane Reduction of Nitriles to Primary Amines by Cobalt-Isocyanide Catalysts
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Reduction of nitriles to silylated primary amines was achieved by combination of 1,1,3,3-tetramethyldisiloxane (TMDS) as the hydrosilane and a catalytic amount of Co(OPIV)2 (PIV = COtBu) associated with isocyanide ligands. The resulting silylated amines were subjected to acid hydrolysis or treatment with acid chlorides to give the corresponding primary amines or imides in good yields. One-pot synthesis of primary amides to primary amines with hydrosilanes was also achieved by iron-cobalt dual catalyst systems.
- Sanagawa, Atsushi,Nagashima, Hideo
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p. 287 - 291
(2019/01/10)
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- Old Concepts, New Application – Additive-Free Hydrogenation of Nitriles Catalyzed by an Air Stable Alkyl Mn(I) Complex
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An efficient additive-free manganese-catalyzed hydrogenation of nitriles to primary amines with molecular hydrogen is described. The pre-catalyst, a well-defined bench-stable alkyl bisphosphine Mn(I) complex fac-[Mn(dpre)(CO)3(CH3)] (dpre=1,2-bis(di-n-propylphosphino)ethane), undergoes CO migratory insertion into the manganese-alkyl bond to form acyl complexes which upon hydrogenolysis yields the active coordinatively unsaturated Mn(I) hydride catalyst [Mn(dpre)(CO)2(H)]. A range of aromatic and aliphatic nitriles were efficiently and selectively converted into primary amines in good to excellent yields. The hydrogenation of nitriles proceeds at 100 °C with a catalyst loading of 2 mol % and a hydrogen pressure of 50 bar. Mechanistic insights are provided by means of DFT calculations. (Figure presented.).
- Weber, Stefan,Veiros, Luis F.,Kirchner, Karl
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supporting information
p. 5412 - 5420
(2019/11/13)
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- Synthesis of cobalt nanoparticles by pyrolysis of Vitamin B12: A non-noble-metal catalyst for efficient hydrogenation of nitriles
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A facile preparation of vitamin B12-derived carbonaceous cobalt particles supported on ceria is reported. The resulting composite material is obtained upon wet impregnation of ceria with natural cyanocobalamin and consecutive pyrolysis under inert conditions. The novel catalyst shows good to excellent performance in the industrially relevant heterogeneous hydrogenation of nitriles to the corresponding primary amines.
- Ferraccioli, Raffaella,Borovika, Diana,Surkus, Annette-Enrica,Kreyenschulte, Carsten,Topf, Christoph,Beller, Matthias
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p. 499 - 507
(2018/02/07)
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- Cobalt-based nanoparticles prepared from MOF-carbon templates as efficient hydrogenation catalysts
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The development of efficient and selective nanostructured catalysts for industrially relevant hydrogenation reactions continues to be an actual goal of chemical research. In particular, the hydrogenation of nitriles and nitroarenes is of importance for the production of primary amines, which constitute essential feedstocks and key intermediates for advanced chemicals, life science molecules and materials. Herein, we report the preparation of graphene shell encapsulated Co3O4- and Co-nanoparticles supported on carbon by the template synthesis of cobalt-terephthalic acid MOF on carbon and subsequent pyrolysis. The resulting nanoparticles create stable and reusable catalysts for selective hydrogenation of functionalized and structurally diverse aromatic, heterocyclic and aliphatic nitriles, and as well as nitro compounds to primary amines (>65 examples). The synthetic and practical utility of this novel non-noble metal-based hydrogenation protocol is demonstrated by upscaling several reactions to multigram-scale and recycling of the catalyst.
- Murugesan, Kathiravan,Senthamarai, Thirusangumurugan,Sohail, Manzar,Alshammari, Ahmad S.,Pohl, Marga-Martina,Beller, Matthias,Jagadeesh, Rajenahally V.
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p. 8553 - 8560
(2018/11/30)
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- Hydrogenation of Nitriles and Ketones Catalyzed by an Air-Stable Bisphosphine Mn(I) Complex
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Efficient hydrogenations of nitriles and ketones with molecular hydrogen catalyzed by a well-defined bench-stable bisphosphine Mn(I) complex are described. These reactions are environmentally benign and atomically economic, implementing an inexpensive, earth-abundant nonprecious metal catalyst. A range of aromatic and aliphatic nitriles and ketones were efficiently converted into primary amines and alcohols, respectively, in good to excellent yields. The hydrogenation of nitriles proceeds at 100 °C with catalyst loading of 2 mol % and 20 mol % base (t-BuOK), while the hydrogenation of ketones takes place already at 50 °C, with a catalyst loading of 1 mol % and 5 mol % of base. In both cases, a hydrogen pressure of 50 bar was applied.
- Weber, Stefan,St?ger, Berthold,Kirchner, Karl
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supporting information
p. 7212 - 7215
(2018/11/25)
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- Sustainable organophosphorus-catalysed Staudinger reduction
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A highly efficient and sustainable catalytic Staudinger reduction for the conversion of organic azides to amines in excellent yields has been developed. The reaction displays excellent functional group tolerance to functionalities that are otherwise prone to reduction, such as sulfones, esters, amides, ketones, nitriles, alkenes, and benzyl ethers. The green nature of the reaction is exemplified by the use of PMHS, CPME, and a lack of column chromatography.
- Lenstra, Danny C.,Lenting, Peter E.,Mecinovi?, Jasmin
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supporting information
p. 4418 - 4422
(2018/10/17)
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- HIGHLY TUNABLE COLLOIDAL PEROVSKITE NANOPLATELETS
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Colloidal perovskite nanoplatelets can provide a material platform, with tunability extending from the deep UV, across the visible, into the near-IR. The high degree of spectral tunability can be achieved through variation of the cation, metal, and halide composition as well as nanoplatelet thickness.
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Paragraph 0074; 0075; 0076
(2017/11/29)
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- Hexafluoro-2-propanol-assisted quick and chemoselective nitro reduction using iron powder as catalyst under mild conditions
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Hexafluoro-2-propanol as the promoter for the quick nitro reduction using a combination of iron powder and 2 N HCl aqueous solution is reported. This methodology has several positive features, as it is of room temperature, remarkably short reaction time. A wide range of substrates including those bearing reducible functional groups such as aldehyde, ketone, acid, ester, amide, nitrile, halogens, even allyl, propargyl and heterocycles are chemoselectively reduced in good to excellent yields, even on gram scale. Notably, the highly selective reduction of 3-nitrophenylboronic acid is achieved quantitatively. The reduction is also tolerant of common protecting groups, and aliphatic nitro compound, 1-nitrooctane can be reduced successfully.
- Chen, Xu-Ling,Ai, Bai-Ru,Dong, Yu,Zhang, Xiao-Mei,Wang, Ji-Yu
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supporting information
p. 3646 - 3649
(2017/08/23)
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- Boron-Catalyzed Silylative Reduction of Nitriles in Accessing Primary Amines and Imines
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Silylative reduction of nitriles was studied under transition metal-free conditions by using B(C6F5)3 as a catalyst with hydrosilanes as a reductant. Alkyl and (hetero)aryl nitriles were efficiently converted to primary amines or imines under mild conditions. The choice of silanes was found to determine the selectivity: while a full reduction of nitriles was highly facile, the use of sterically bulky silanes allowed for the partial reduction leading to N-silylimines.
- Gandhamsetty, Narasimhulu,Jeong, Jinseong,Park, Juhyeon,Park, Sehoon,Chang, Sukbok
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p. 7281 - 7287
(2015/07/28)
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- Ion-pair complexation with a cavitand receptor
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The capability of resorcinarenes to bind anions within the alkyl feet at the lower rim has been exploited as the starting point for developing a new cavitand able to engulf contact ion pairs of primary ammonium salts in chlorinated solvents with association constants (Kass) in the range of 103104M-1. Methylene bridges were introduced into the upper rim to freeze the resorcinarene in the cone conformation with the four Hdown protons converging in the lower pocket, thereby maximizing the CH-anion interactions responsible for the anion binding. Four additional phosphate moieties were introduced into the lower rim in close prox-imity to the anionic site to provide hydrogen-bonding-acceptor P=O groups and promote cation complexation at the bottom of the cavitand. The binding ability of the synthesized ligands was analyzed by 1H NMR spectroscopy and, when possible, by isothermal titration calorimetry (ITC); the data were in agreement when complementary techniques were used.
- Tancini, Francesca,Gottschalk, Thomas,Bernd Schweizer,Diederich, Francois,Dalcanale, Enrico
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experimental part
p. 7813 - 7819
(2010/09/05)
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- Transfer hydrogenation of nitriles with 2-propanol and Raney nickel
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Raney nickel in refluxing 2-propanol containing 2% KOH is an effective catalytic system for reducing nitriles to amines.
- Mebane, Robert C.,Jensen, David R.,Rickerd, Kerry R.,Gross, Benjamin H.
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p. 3373 - 3379
(2007/10/03)
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