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Angewandte Chemie

Nika Mahne, Sara E Renfrew, Bryan D McCloskey, Stefan A Freunberger
Solid alkaline carbonates are universal passivation layer components of intercalation battery materials, common side products in metal-O₂ batteries, and are believed to form and decompose reversibly in metal-O₂/CO₂ cells. In all of these cathode chemistries, Li₂CO₃ decomposes to CO₂ when exposed to potentials >3.8 V vs. Li/Li+. Notably, though, O₂ evolution is not detected, as is expected according to the decomposition reaction 2 Li₂CO₃ → 4 Li+ + 4 e- + 2 CO₂ + O₂. O-moieties were therefore previously considered unaccounted for in unidentified parasitic reactions...
March 15, 2018: Angewandte Chemie
Xiaoqiang Huang, Jiahui Lin, Tianqi Shen, Klaus Harms, Marianna Marchini, Paola Ceroni, Eric Meggers
Here reported visible-light-activated catalytic asymmetric [3+2] photocycloadditions between cyclopropanes and alkenes or alkynes provide access to chiral cyclopentanes and cyclopentenes, respectively, in 63-99% yields and with excellent enantioselectivities of up to >99% ee. The reactions are catalyzed by a single bis-cyclometalated chiral-at-rhodium complex (2-8 mol%) which after coordination to the cyclopropane generates the visible-light-absorbing complex, lowers the reduction potential of the cyclopropane, and provides the asymmetric induction and overall stereocontrol...
March 15, 2018: Angewandte Chemie
Klaus Griesar, John Bessant, Sabine Bernschneider-Reif
The elephant is in the room-a metaphorical idiom for an obvious problem or risk that nobody wants to discuss. This abstract is not intended to be a summary, to reveal major findings, or unveil conclusions. On the contrary, it is aimed to provoke curiosity as to the question of corporate survival. Is there any recipe to be followed for companies to achieve this? The answer comes neither from the modest and traditional study rooms of philosophers nor the recent fact-based studies from the offices (and well-paid opinions) of business consultants...
March 15, 2018: Angewandte Chemie
Victor Laurent, Ekaterina Darii, Angelina Aujon, Marine Debacker, Jean-Louis Petit, Virgil Hélaine, Tibor Liptaj, Martin Breza, Aline Mariage, Lionel Nauton, Mounir Traikia, Marielle Lemaire, Marcel Salanoubat, Christine Guérard-Hélaine, Véronique De Berardinis
Dihydroxyacetone phosphate (DHAP)-dependent rhamnulose aldolases display an unprecedented versatility for ketones as electrophile substrates. We selected and characterized a rhamnulose aldolase from Bacteroides thetaiotaomicron (RhuABthet) to provide a proof of concept. DHAP was added as a nucleophile to several alpha-hydroxylated ketones used as electrophiles. This aldol addition was stereoselective and produced branched-chain monosaccharide adducts with a tertiary alcohol moiety. Several aldols were thus readily obtained in good to excellent yields (from 76 to 95%)...
March 15, 2018: Angewandte Chemie
Han Zuilhof, Digvijay Gahtory, Rickdeb Sen, Andriy R Kuzmyn, Jorge Escorihuela
Novel click reactions are of continued interest in fields as diverse as bio-conjugation, polymer science and surface chemistry. Qualification as a proper 'click' reaction requires stringent criteria, including fast kinetics and high conversion, to be met. Herein, we report a novel strain-promoted cycloaddition between cyclopropenes and o-quinones in solution and on a surface. We demonstrate the 'click character' of the reaction in solution and on surfaces for both monolayer and polymer brush functionalization...
March 15, 2018: Angewandte Chemie
Jessica Hill, Johnathan Matlock, Quentin Lefebvre, Katie Cooper, Jonathan Clayden
Tetrahydroisoquinolines and tetrahydrobenzazepines are prepared by acid-promoted ring contraction of cyclic ureas, themselves formed by ring expansion of indolines and tetrahydroquinolines. The consequent overall one-carbon insertion reaction gives these 6- and 7-membered heterocyclic scaffolds in three steps from readily available precursors. Other ring sizes may be formed by an alternative elimination reaction of bicyclic structures. Scalability of the method was demonstrated by operating it in a flow system...
March 14, 2018: Angewandte Chemie
Mathieu Denis, Jessica Pancholi, Kajally Jobe, Michael Watkinson, Stephen Michael Goldup
Although metal ion-binding interlocked molecules have been under intense investigation for over three decades, their application as scaffolds for the development of sensors for metal ions remains under-explored. Here we demonstrate the potential of simple rotaxane scaffolds as metal ion-responsive ligand scaffolds through the development of a proof-of-concept selective sensor for Zn2+.
March 14, 2018: Angewandte Chemie
Chunyi Liu, Xusheng Wang, Wenjun Deng, Chang Li, Jitao Chen, Mianqi Xue, Rui Li, Feng Pan
Rechargeable aqueous metal-ion battery (RAMB) has attracted considerable attention due to its safety, low cost, and environmental friendliness. Yet the poor-performance electrode materials lead to a low feasibility of practical application. Hybrid aqueous battery (HAB) built by electrode materials with selective cation channels could increase the electrode applicability and thus enlarge the application of RAMB. In this work, we construct a high-voltage K-Na HAB based on K2FeFe(CN)6 cathode and carbon-coated NaTi2(PO4)3 (NTP/C) anode...
March 14, 2018: Angewandte Chemie
Seiichi Uchiyama, Toshikazu Tsuji, Kyoko Kawamoto, Kentaro Okano, Eiko Fukatsu, Takahiro Noro, Kumiko Ikado, Sayuri Yamada, Yuka Shibata, Teruyuki Hayashi, Noriko Inada, Masaru Kato, Hideki Koizumi, Hidetoshi Tokuyama
A cationic fluorescent nanogel thermometer based on thermo-responsive N-isopropylacrylamide and environment-sensitive benzothiadiazole was developed with a new azo compound bearing imidazolium rings as the first cationic radical initiator. This cationic fluorescent nanogel thermometer showed an excellent ability to enter live mammalian cells in a short incubation period (10 min), a high sensitivity to temperature variations in live cells (temperature resolution of 0.02-0.84 °C in the range 2040 °C), and remarkable non-cytotoxicity, which permitted ordinary cell proliferation and even differentiation of primary cultured cells...
March 14, 2018: Angewandte Chemie
Ronny Neumann, Alexander M Khenkin, Miriam Somekh, Raanan Carmieli
The sustainable, selective direct hydroxylation of arenes, such as benzene to phenol is an important research challenge. Mostly thermochemical approaches have been studied, but these still have various drawbacks. An electrocatalytic transformation using formic acid to oxidize benzene and its halogenated derivatives to selectively yield aryl formates that are easily hydrolyzed by water yielding the corresponding phenols is presented. The formylation reaction occurs on a Pt anode in the presence of [Co(III)W12O40]5- as catalyst and Li formate as electrolyte via formation of a formyloxyl radical as the reactive species, which was trapped by a BMPO spin trap and identified by EPR...
March 14, 2018: Angewandte Chemie
Tunga Salthammer, Yinping Zhang, Jinhan Mo, Holger M Koch, Charles J Weschler
There is an ongoing probing of the role of chemicals in the indoor environment. The majority of potential target substances are so-called very volatile, volatile and semi volatile organic compounds (VVOCs, VOCs and SVOCs). Depending on their physical properties and mass transfer conditions, they distribute in or between the gas phase, particle phase, settled house dust, surface films, clothing and other fabrics as well as the exposed skin and hair of the occupants themselves. Therefore, inhalation, ingestion and dermal uptake all must be considered as relevant pathways for the exposure assessment in human habitats...
March 14, 2018: Angewandte Chemie
Sunewang Wang, Dominic Prieschl, James Mattock, Merle Arrowsmith, Conor Pranckevicius, Tom Stennett, Rian Dewhurst, Alfredo Vargas, Holger Braunschweig
Herein we report the discovery that two bottleable, neutral, base-stabilized diborane(5) compounds are able to bind strongly to a number of copper(I) complexes exclusively through their B-B bond. The resulting complexes represent the first known complexes containing unsupported, neutral σB-B diborane ligands. Single-crystal X-ray analyses of these complexes show that the X-Cu moiety (X = Cl, OTf, C6F5) lies opposite the bridging hydrogen of the diborane and is near perpendicular to the B-B bond, interacting almost equally with both boron atoms and causing a B-B bond elongation...
March 14, 2018: Angewandte Chemie
Sreenivas Katukojvala, Vinaykumar Kanchupalli
Described herein is a dirhodium carboxylate catalyzed [1+1+3] annulation reaction of diazoenals and vinyl azides which gives synthetically important enal-functionalized 1-pyrroline derivatives. The reaction involves a novel rhodium-catalyzed olefination of diazoenals with vinyl azides via electrophilic enalcarbenoid, resulting in the new class of enal-acrylates. The annulation reaction was used for the direct synthesis of valuable deuterated 1-pyrrolines. Structural diversification of the enal-functionalized 1-pyrrolines resulted in the biologically important pyrrolidine fused oxaziridine, amino acid derivatives, and a 6-azabicyclo[3...
March 14, 2018: Angewandte Chemie
Yuan Li, Wan Zhang, Hui Zhang, Wenya Tian, Lian Wu, Shuwen Wang, Mengmeng Zheng, Jinru Zhang, Chenghai Sun, Zixin Deng, Yuhui Sun, Xudong Qu, Jiahai Zhou
Polyketides are a large family of pharmaceutically important natural products, and the structural modification of their scaffolds is significant for drug development. Herein, we report one apo- and two complex structures (with a pentynylmalonyl and benzylmalonyl, respectively) of the broadly selective acyltransferase (AT) from the splenocin polyketide synthase. These structures revealed the molecular basis of the stereo-selectivity and substrate specificity of SpnD-AT and enabled engineering the industrially important Ery-AT6 to broaden its substrate scope to include three new types of extender units...
March 14, 2018: Angewandte Chemie
Takayuki Nakamuro, Kohei Hagiwara, Tomoya Miura, Masahiro Murakami
Sulfonylation of 1H-tetrazoles with triflic anhydride in the presence of chiral rhodium(II) carboxylate dimers causes denitrogenation to generate alpha-azo rhodium(II) carbenoid species as new types of donor/acceptor carbenoids, which then readily react with styrenes to afford 3,5-diaryl-2-pyrazolines with induction of high levels of enantioselectivities.
March 13, 2018: Angewandte Chemie
Xizhen Lian, Yanyan Huang, Yuanyuan Zhu, Yu Fang, Rui Zhao, Elizabeth Joseph, Jialuo Li, Jean-Phillipe Pellois, Hongcai Zhou
Prodrug activation by exogenously administered enzymes for cancer therapy is an approach to achieve better selectivity and less systemic toxicity than conventional chemotherapy. However, the short half-lives of the activating enzymes in bloodstream has limited its success. Here, we demonstrate that a tyrosinase-MOF nanoreactor activates the prodrug paracetamol in cancer cells in a long-lasting manner. By generating reactive oxygen species (ROS) and depleting glutathione (GSH), the product of enzymatic conversion of paracetamol is toxic to drug-resistant cancer cells...
March 13, 2018: Angewandte Chemie
Roberto Christian Arbulu, Ying-Bing Jiang, Eric John Peterson, Yang Qin
New mechanisms of controlled growth of one-dimensional (1D) metal-organic framework (MOF) nano- and super-structures under size-confinement and surface directing effects have been discovered. Through applying interfacial synthesis templated by track-etched polycarbonate (PCTE) membranes, congruent polycrystalline zeolitic imidazolate framework-8 (ZIF-8) solid nanorods and hollow nanotubes were found to form within 100 nm membrane pores, while single crystalline ZIF-8 nanowires grew inside 30 nm pores, all of which possess large aspect ratios up to 60 and show preferential crystal orientation with the {100} planes aligned parallel to the pore's long axis...
March 13, 2018: Angewandte Chemie
Yanjun Wan, Xuchun Zheng, Cheng Ma
A novel strategy to generate functionalized 1-azatriene intermediates for 6π electrocyclizations was developed by using readily accessible dienyne-imides and various terminal olefins under Pd(II) catalysis. Taking advantage of the sequential cooperation between preloaded and incorporated functional handles at 1,3-dien-5-yne skeletons, this protocol not only enables the selective generation of putative 1-azatrienes but significantly accelerates their thermal 6π-electrocyclic ring closure processes to a series of highly substituted furo[2,3-b]dihydropyridine derivatives in good yields...
March 13, 2018: Angewandte Chemie
Stephen Liddle, Erli Lu, Josef Boronski, Matthew Gregson, Ashley Wooles
We report unprecedented silyl-phosphino-carbene complexes of uranium(IV), where before all covalent actinide-carbon double bonds were stabilised by phosphorus(V) substituents or restricted to matrix isolation experiments. Conversion of [U(BIPMTMS)(Cl)(μ-Cl)2Li(THF)2] (1, BIPMTMS = C(PPh2NSiMe3)2) to [U(BIPMTMS)(Cl){CH(Ph)(SiMe3)}] (2), and addition of [Li{CH(SiMe3)(PPh2)}(THF)] and Me2NCH2CH2NMe2 (TMEDA) gave [U{C(SiMe3)(PPh2)}(BIPMTMS)(μ-Cl)Li(TMEDA)(μ-TMEDA)0.5]2 (3) by α-hydrogen abstraction. Addition of 2,2,2-cryptand or two equivalents of 4-N,N-dimethylaminopyridine (DMAP) to 3 gave [U{C(SiMe3)(PPh2)}(BIPMTMS)(Cl)][Li(2,2,2-cryptand)] (4) or [U{C(SiMe3)(PPh2)}(BIPMTMS)(DMAP)2] (5)...
March 13, 2018: Angewandte Chemie
Il Jeon, Hiroshi Ueno, Seungju Seo, Kerttu Aitola, Ryosuke Nishikubo, Akinori Saeki, Hiroshi Okada, Gerrit Boschloo, Shigeo Maruyama, Yutaka Matsuo
Herein, we report use of [Li+ @C60 ]TFSI- as a dopant for spiro-MeOTAD in lead halide perovskite solar cells. This approach gave an air stability nearly 10-fold that of conventional devices using Li+ TFSI- . Such high stability is attributed to the hydrophobic nature of [Li+ @C60 ]TFSI- repelling moisture and absorbing intruding oxygen, thereby protecting the perovskite device from degradation. Furthermore, [Li+ @C60 ]TFSI- could oxidize spiro-MeOTAD without the need for oxygen. The encapsulated devices exhibited outstanding air stability for more than 1000 h while illuminated under ambient conditions...
March 13, 2018: Angewandte Chemie
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