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Chemistry: a European Journal

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https://read.qxmd.com/read/30994950/visible-light-induced-sulfonylation-arylation-of-styrenes-in-a-double-radical-three-component-photoredox-reaction
#1
Benjamin Lipp, Lisa Kammer, Murat Kücükdisli, Adriana Luque, Jonas Kühlborn, Stefan Pusch, Gita Matulevičiūtė, Dieter Schollmeyer, Algirdas Šačkus, Till Opatz
Simultaneous sulfonylation/arylation of styrene derivatives is achieved in a photoredox-catalyzed three-component reaction using visible light. A broad variety of difunctionalized products is accessible in mostly excellent yields and high diastereoselectivity. The developed reaction is scalable and suitable for the modification of styrene-functionalized biomolecules. Mechanistic investigations suggest the transformation to be operating through a designed sequence of radical formation and radical combination...
April 17, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30994944/phosphinine-based-ligands-in-gold-catalyzed-reactions
#2
Massimo Rigo, Evi R M Habraken, Koyel Bhattacharyya, Manuela Weber, Andreas Ehlers, Nicolas Mézailles, Chris Slootweg, Christian Müller
A series of substituted phosphinines, 1-phosphabarrelenes and 5-phosphasemibullvalenes were synthesized and evaluated for their potential application as ligands in homogeneous catalytic reactions. While their buried volume %Vbur was calculated to get insight into the steric properties, [LNi(CO)3] complexes were prepared in order to determine the corresponding Tolman electronic parameter. ETS-NOCV calculations on [LAuCl] complexes further allowed an estimation of the σ- and π-contributions to the L-M interaction...
April 17, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30994943/noble-metal-corrosion-halogen-bonded-iodocarbenium-iodides-dissolve-elemental-gold-a-direct-access-to-gold-carbene-complexes
#3
Jana Holthoff, Elric Engelage, Alexander B Kowsari, Stefan Matthias Huber, Robert Weiss
A common method to dissolve elemental gold involves the combination of an oxidant with a Lewis base, coordinating to the gold surface and thus lowering the metal's redox potential. Herein we report the usage of organic iodide salts providing both oxidative power and coordinating ligand, to dissolve gold under formation of organo-gold complexes. The obtained products were identified as AuIII complexes, all featuring Au-C bonds, as shown by X-Ray single crystal analysis, and can be isolated in good yields. Additionally, our method is providing a direct access to NHC(-type) complexes and avoids costly organometallic precursors...
April 17, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30994214/light-lanthanide-metallocenium-cations-exhibiting-weak-equatorial-anion-interactions
#4
Jingjing Liu, Daniel Reta, Jake Cleghorn, Yu Xuan Yeoh, Fabrizio Ortu, Conrad Goodwin, Nicholas Chilton, David Paul Mills
As the dysprosocenium complex [Dy(Cpttt)2][B(C6F5)4] (Cpttt = C5H2tBu3-1,2,4, 1-Dy) exhibits magnetic hysteresis at 60 K, similar lanthanide (Ln) complexes have been targeted in order to provide insights into this remarkable property. We recently reported homologous [Ln(Cpttt)2][B(C6F5)4] (1-Ln) for all the heavier Ln from Gd-Lu; herein, we extend this motif to the early Ln. We find, for the largest LnIII cations, that contact ion pairs [Ln(Cpttt)2{(C6F5-κ1-F)B(C6F5)3}] (1-Ln; La-Nd) are isolated from reactions of parent [Ln(Cpttt)2(Cl)] (2-Ln) with [H(SiEt3)2][B(C6F5)4], where the anion binds weakly to the equatorial sites of [Ln(Cpttt)2]+ through a single fluorine atom in the solid state...
April 17, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30994213/cross-coupling-reaction-of-alkenyl-sulfoximines-and-alkenyl-aminosulfoxonium-salts-by-dual-nickel-catalysis-and-lewis-acid-promotion
#5
Hans-Joachim Gais
In this article we describe the cross-coupling reaction (CCR) of exocyclic, axially chiral and acyclic alkenyl (N-methyl)sulfoximines with alkyl- and arylzincs. The CCR generally requires dual Ni-catalysis and MgBr2 promo¬tion, which is effective in ether but not in THF. NMR spectroscopy revealed a complexation of alkenyl sulfoximines by MgB2 in ether. This suggests an acceleration of the oxidative addition through nucleofugal activation. The CCR proceeds with Ni(dppp)Cl2 as precatalyst and alkyl- and arylzincs with a high degree of stereoretention at both the C and S atom...
April 17, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30994212/total-synthesis-of-aspidosperma-and-strychnos-alkaloids-via-indole-dearomatization
#6
Romano Orru, Jordy Saya, Eelco Ruijter
Monoterpenoid indole alkaloids are the major class of tryptamine-derived alkaloids found in Nature. Together with their structural complexity, this has attracted great interest from synthetic organic chemists. In this review we discuss total syntheses of Aspidosperma and Strychnos alkaloids via dearomatization of indoles.
April 17, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30994211/reductive-silylation-using-a-bis-silylated-diaza-2-5-cyclohexadiene
#7
Daniel M Beagan, I J Huerfano, Alexander V Polezhaev, Kenneth G Caulton
1,4-bis(trimethylsilyl)-1,4-diaza-2,5-cyclohexadiene, 1, is tested as a reagent for the reductive silylation of various unsaturated functionalities, including N-heterocycles, quinones, and other redox-active moieties in addition to deoxygenation of main group oxides. Whereas most reactions tested are thermodynamically favorable, based on DFT calculations, a few do not occur, perhaps giving limited insight on the mechanism of this very attractive reductive process. Of note, reductive silylation reactions show a strong solvent dependence where a polar solvent facilitates conversions...
April 17, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30994210/iodine-clathrated-a-solid-state-analog-of-the-iodine-starch-complex
#8
Kari Rissanen, Fangfang Pan, Yingchun Chen, Siyu Li, Minzhi Jiang
Co-crystallizing iodine with a simple dicationic salt (1,8-diammoniumoctane chloride) results in the clathration of the iodine (I2) molecules inside trigonal and hexagonal helical channels of the crystal lattice with 72 wt% overall I2 loading. The I2 inside the bigger trigonal channel forms a I-I•••I-I•••I-I halogen-bonded infinite helical chain, while the I2 in the smaller hexagonal channel is disordered. In both channels the I2 interaction with the channel wall happens through I-I•••Cl- halogen bonds...
April 17, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30990932/few-layer-boron-nitride-with-engineered-nitrogen-vacancies-for-promoting-conversion-of-polysulfide-as-a-cathode-matrix-for-lithium-sulfur-batteries
#9
Yikun Yi, Hongping Li, Honghong Chang, Pu Yang, Xiaolu Tian, Pei Liu, Long Qu, Mingtao Li, Bolun Yang, Huaming Li, Wenshuai Zhu, Sheng Dai
Lithium-sulfur (Li-S) batteries have become one of the most promising candidates as the next generation batteries, due to their high specific capacity, low-cost, and environmental benignity. Although lots of strategies have been proposed to restrain the shuttle of lithium polysulfides (LiPSs) through physical trapping and chemical binding, the sluggish kinetics of PS conversion still degrade the capacity, rate and cycling performance of Li-S batteries. Herein, a novel kind of few-layer BN with engineered nitrogen vacancies (v-BN) has been developed as a cathode matrix for Li-S batteries...
April 16, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30990919/interaction-between-spirosilanes-and-lewis-bases-from-coordination-to-frustration
#10
Fabrizio Medici, Julien Maury, Gilles Lemière, Louis Fensterbank
In this work we describe the interaction between Lewis bases, especially N-Heterocyclic Carbenes (NHCs), and hindered neutral silicon derivatives featuring high Lewis acid properties. It has been established that the formation of normal and abnormal Lewis adducts can be controlled by playing with the acidity of the corresponding tetravalent spiro organosilane. Some DFT calculations have been performed in order to gain insight into the thermodynamics of the NHC-spirosilane interaction featuring various NHCs differing in size and σ-donor capacity...
April 16, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30990916/cyclometalated-au-iii-complexes-for-cysteine-arylation-in-zinc-finger-protein-domains-towards-controlled-reductive-elimination
#11
Margot Wenzel, Riccardo Bonsignore, Sophie Thomas, Didier Bourissou, Giampaolo Barone, Angela Casini
With the aim of exploiting the use of organometallic species for the efficient modification of proteins through C-atom transfer, we report here on the gold-mediated cysteine arylation via reductive elimination process occurring from the reaction of cyclometalated Au(III) C^N complexes with a zinc finger peptide (Cys2His2 type). Among the four selected Au(III) cyclometallated compounds, the [Au(CCON)Cl2] complex featuring the 2-benzoylpyridine (CCON) scaffold was identified as the most prone to reductive elimination and Cys arylation in buffered aqueous solution (pH 7...
April 16, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30990914/high-field-detection-of-biomarkers-with-fast-field-cycling-mri-the-example-of-zinc-sensing
#12
Markus Bödenler, Kyangwi P Malikidogo, Jean-François Morfin, Christoph Aigner, Éva Tóth, Célia S Bonnet, Hermann Scharfetter
Many smart MRI probes provide response to a biomarker based on modulation of their rotational correlation time. The magnitude of such MRI signal changes is highly dependent on the magnetic field and the response decreases dramatically at high fields (> 2 T). To overcome the loss of efficiency of responsive probes at high field, with FFC-MRI we exploit field-dependent information rather than the absolute difference in the relaxation rate measured in the absence and in the presence of the biomarker at a given imaging field...
April 16, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30990231/benchmarking-three-ruthenium-phosphide-phases-for-hydrogen-evolution-reaction-electrocatalysis-experimental-and-theoretical-insights
#13
Tingting Liu, Jianmei Wang, Changyin Zhong, Shiyu Lu, Wenrong Yang, Jian Liu, Weihua Hu, Chang Ming Li
The outstanding electrocatalytic activity of transition metal ruthenium (Ru) phosphides toward hydrogen evolution reaction (HER) has received wide attentions. However, it remains unclear regarding the effect of ruthenium phosphide phase on the HER performance. Herein, a two-step method is developed to synthesize three types of ruthenium phosphides including Ru2P, RuP and RuP2 nanoparticles with similar morphology, dimension, loading density and electrochemical surface area (ECSA) on graphene nanosheets by simply controlling the phytic acid (PA) dosage as a P source and metal complexing reagent...
April 16, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30990230/covalently-linked-bis-amido-corroles-inter-and-intramolecular-hydrogen-bond-driven-supramolecular-assembly
#14
Rafał Orłowski, Grzegorz Cichowicz, Olga Staszewska-Krajewska, Wojciech Schilf, Michał K Cyrański, Daniel T Gryko
Four bis-corroles linked via diamide bridges were synthesized via peptide-type coupling of a trans-A2B-corrole-acid with aliphatic and aromatic diamines. In the solid state, the hydrogen bond pattern in these bis-corroles is strongly affected by the type of solvent used in the crystallization process. Although intramolecular hydrogen bonds play a decisive role, they are supported by intermolecular hydrogen bonds and weak N-H∙∙∙π interactions between molecules of toluene and corrole cores. In an analogy to mono(amido-corroles), both in crystalline state and in solutions, the aliphatic or aromatic bridge is located directly above the corrole ring...
April 16, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30989743/alloyed-tetranuclear-metal-chains-of-pd4-nptn-n-0-3-scaffolded-by-a-new-linear-tetraphosphine-containing-a-pnp-bridge
#15
Tomoaki Tanase, Miho Tanaka, Mami Hamada, Yuka Morita, Kanako Nakamae, Yasuyuki Ura, Takayuki Nakajima
A new linear tetraphosphine containing a PNP phosphazane bridge, rac-bis[(diphenylphosphinomethyl)phenyl-phosphino]-phen-yl-amine (rac-dpmppan), was synthesized and utilized to support a series of Pd/Pt mixed metal tetranuclear chains, [Pd4-nPtn(μ-rac-dpmppan)2(XylNC)2](PF6)2 (n = 0: Pd4 (1), 1: PtPd3 (2), 2: PtPd2Pt (3), 2: Pt2Pd2 (4), 3: Pt2PdPt (5)), in which the number and positions of additional Pt atoms were successfully controlled depending on the respective synthetic procedures using transformations from 1 to 3 through 2 and from 4 to 5 by redox-coupled exchange reactions...
April 15, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30989709/alkylative-carboxylation-of-ynamides-and-allenamides-with-functionalized-alkylzinc-halides-and-carbon-dioxide-by-a-copper-catalyst
#16
Masanori Takimoto, Sandeep Suryabhan Gholap, Zhaomin Hou
The alkylative carboxylation of ynamides and allenamides with CO2 and alkylzinc halides catalyzed by a copper catalyst has been developed. A variety of alkylzinc halides bearing functional groups could be used for this transformation to afford α,β-unsaturated carboxylic acids, which contain the α,β-dehydroamino acid skeleton, introducing the corresponding alkyl group and CO2 across the carbon-carbon triple or double bond. This alkylative carboxylation formally consists of Cu-catalyzed carbozincation of ynamides or allenamides with alkylzinc halides and the subsequent nucleophilic carboxylation of the resulting alkenylzinc species with CO2...
April 15, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30986324/synthesis-and-thermal-decomposition-of-heavy-tetrylenes-bearing-n-aminocarbazolyl-substituents
#17
Alexander Hinz
The synthesis of the N-aminocarbazole R-NH2 (2) is reported. Subsequent reaction with bis(bis(trimethylsilyl)-amidotetrylenes E[N(SiMe3)2]2 (E = Ge, Sn, Pb) allowed the isolation of formal hydrazidotetrylene derivatives, R-N(H)EN(SiMe3)2 (3), that includes the first example of a hydrazidoplumbylene to date. Thermal decomposition of these compounds resulted in the elimination of "NH" and afforded the tetrylenes R-EN(SiMe3)2 (4).
April 15, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30986323/kinetic-control-of-self-assembly-pathway-towards-hidden-chiral-microcoils
#18
Yongxian Guo, Yin Liu, Yanjun Gong, Wei Xiong, Chuang Zhang, Jincai Zhao, Yanke Che
Manipulating the self-assembly pathway is essentially important in the supramolecular synthesis of organic nano- and micro-architectures. Here we design a series of photoisomerizable chiral molecules, and realize the precise control over pathway complexity with external light stimuli. The hidden single-handed microcoils, rather than the straight microribbons via spontaneous assembly, are obtained through the kinetics-controlled pathway. The competition between molecular interactions in metastable photostationary intermediates gives rise to the variety of molecular packing and thereby the possibility of chirality transfer from molecules to supramolecular assemblies...
April 15, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30986322/organocatalytic-transformation-of-aldehydes-to-thioesters-with-visible-light
#19
Wei Wang, Yueteng Zhang, Peng Ji, Wenbo Hu, Yongyi Wei, He Huang
Here we describe a metal free and oxidant free catalytic method of accessing structurally diverse thioesters from readily accessible, widespread aldehydes. A strategy of a simple organic 9,10-phenanthrenequinone promoted hydrogen atom transfer (HAT) with visible light is successfully implemented to selectively generate acyl radicals without inducing crossover reactivity of thioester products. The preparative power of the method is demonstrated by broad substrate scope and wide functional group tolerance, and enables the late-stage modification of complex structures, which are difficult to achieve with the existing protocols...
April 15, 2019: Chemistry: a European Journal
https://read.qxmd.com/read/30985948/intramolecular-hydroamination-of-selenoalkynes-to-2-selenylindole-in-absence-of-catalyst
#20
Paulo Henrique Schneider, Felipe L Coelho, Paulo F B Gonçalves, Leandra F Campo, Eduarda S Gil
In this work, a series of 2-chalcogenylindoles were synthesized by an efficient new methodology, starting from chalcogenoalkynes, including an inedited tellurium indole derivative. For the first time, these 2-substituted chalcogenylindoles were obtained in the absence of metal catalyst or base, under thermal conditions only. In addition, the results described herein represent a methodology with inverse regioselectivity for the chalcogen functionalisation of indoles.
April 15, 2019: Chemistry: a European Journal
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