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61.
Systematic Comparison of Peptidic Proteasome Inhibitors Highlights the α‐Ketoamide Electrophile as an Auspicious Reversible Lead Motif 下载免费PDF全文
Martin L. Stein Haissi Cui Philipp Beck Christian Dubiella Constantin Voss Prof. Dr. Achim Krüger Prof. Dr. Boris Schmidt Prof. Dr. Michael Groll 《Angewandte Chemie (International ed. in English)》2014,53(6):1679-1683
The ubiquitin–proteasome system (UPS) has been successfully targeted by both academia and the pharmaceutical industry for oncological and immunological applications. Typical proteasome inhibitors are based on a peptidic backbone endowed with an electrophilic C‐terminus by which they react with the active proteolytic sites. Although the peptide moiety has attracted much attention in terms of subunit selectivity, the target specificity and biological stability of the compounds are largely determined by the reactive warheads. In this study, we have carried out a systematic investigation of described electrophiles by a combination of in vitro, in vivo, and structural methods in order to disclose the implications of altered functionality and chemical reactivity. Thereby, we were able to introduce and characterize the class of α‐ketoamides as the most potent reversible inhibitors with possible applications for the therapy of solid tumors as well as autoimmune disorders. 相似文献
62.
M. Sc. Shih‐Fan Hsu Dipl.‐Chem. Susanne Rommel M. Sc. Philipp Eversfield Dr. Keven Muller Prof. Dr. Elias Klemm Prof. Dr. Werner R. Thiel Prof. Dr. Bernd Plietker 《Angewandte Chemie (International ed. in English)》2014,53(27):7074-7078
Apart from energy generation, the storage and liberation of energy are among the major problems in establishing a sustainable energy supply chain. Herein we report the development of a rechargeable H2 battery which is based on the principle of the Ru‐catalyzed hydrogenation of CO2 to formic acid (charging process) and the Ru‐catalyzed decomposition of formic acid to CO2 and H2 (discharging process). Both processes are driven by the same catalyst at elevated temperature either under pressure (charging process) or pressure‐free conditions (discharging process). Up to five charging–discharging cycles were performed without decrease of storage capacity. The resulting CO2/H2 mixture is free of CO and can be employed directly in fuel‐cell technology. 相似文献
63.
Mechanism of Host–Guest Complex Formation and Identification of Intermediates through NMR Titration and Diffusion NMR Spectroscopy 下载免费PDF全文
M. Sc. Jan‐Hendrik Lamm B. Sc. Philipp Niermeier Dr. Andreas Mix Dr. Jasmin Chmiel Beate Neumann Dr. Hans‐Georg Stammler Prof. Dr. Norbert W. Mitzel 《Angewandte Chemie (International ed. in English)》2014,53(30):7938-7942
The formation of host–guest (H‐G) complexes between 1,8‐bis[(diethylgallanyl)ethynyl]anthracene (H) and the N‐heterocycles pyridine and pyrimidine (G) was studied in solution using a combination of NMR titration and diffusion NMR experiments. For the latter, diffusion coefficients of potential host–guest structures in solution were compared with those of tailor‐made reference compounds of similar shape (synthesized and characterized by NMR, HRMS, and in part XRD). Highly dynamic behavior was observed in both cases, but with different host–guest species and equilibria. With increasing concentrations of the pyridine guest, the equilibrium H2?H2κ1‐G1?HG2 is observed (in the second step a host dimer coordinates one guest molecule); for pyrimidine the equilibrium H2→H1κ2‐G1?HG2 is observed (the formation of a 1:1 aggregate is the second step). 相似文献
64.
Dr. Philipp Klahn Hellmuth Erhardt Dr. Andreas Kotthaus Prof. Dr. Stefan F. Kirsch 《Angewandte Chemie (International ed. in English)》2014,53(30):7913-7917
Three simple methods for the synthesis of geminal triazides are described: Starting from 1) 3‐oxocarboxylic acids, 2) iodomethyl ketones, or 3) terminal olefins, a range of triazidomethyl ketones can be constructed under mild oxidative reaction conditions by the use of IBX‐SO3K, a sulfonylated derivative of 2‐iodoxybenzoic acid (IBX), and NaN3 as an azide source. This is the first report of representatives of this novel class of triazide compounds: Despite their high nitrogen content, the geminal triazides are easy to handle, even when preparative‐scale syntheses are performed. (Caution: These procedures still require protective measures!) The triazides are now broadly available for further studies regarding their properties and reactivity. Furthermore, we show how the method can be used to provide α‐azidoesters, which are potential building blocks for amino acids. 相似文献
65.
Isolation of a Neutral Boron‐Containing Radical Stabilized by a Cyclic (Alkyl)(Amino)Carbene 下载免费PDF全文
Dr. Philipp Bissinger Prof. Dr. Holger Braunschweig Dr. Alexander Damme Dr. Ivo Krummenacher Dr. Ashwini K. Phukan Dr. Krzysztof Radacki Shun Sugawara 《Angewandte Chemie (International ed. in English)》2014,53(28):7360-7363
Utilizing a cyclic (alkyl)(amino)carbene (CAAC) as a ligand, neutral CAAC‐stabilized radicals containing a boryl functionality could be prepared by reduction of the corresponding haloborane adducts. The radical species with a duryl substituent was fully characterized by single‐crystal X‐ray structural analysis, EPR spectroscopy, and DFT calculations. Compared to known neutral boryl radicals, the isolated radical species showed larger spin density on the boron atom. Furthermore, the compound that was isolated is extraordinarily stable to high temperatures under inert conditions, both in solution and in the solid state. Electrochemical investigations of the radical suggest the possibility to generate a stable formal boryl anion species. 相似文献
66.
67.
Dr. Bidyut B. Sarma Jonglack Kim Jonas Amsler Dr. Giovanni Agostini Dr. Claudia Weidenthaler Norbert Pfänder Dr. Raul Arenal Dr. Patricia Concepción Dr. Philipp Plessow Prof. Dr. Felix Studt Dr. Gonzalo Prieto 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(14):5855-5864
Realizing the full potential of oxide-supported single-atom metal catalysts (SACs) is key to successfully bridge the gap between the fields of homogeneous and heterogeneous catalysis. Here we show that the one-pot combination of Ru1/CeO2 and Rh1/CeO2 SACs enables a highly selective olefin isomerization-hydrosilylation tandem process, hitherto restricted to molecular catalysts in solution. Individually, monoatomic Ru and Rh sites show a remarkable reaction specificity for olefin double-bond migration and anti-Markovnikov α-olefin hydrosilylation, respectively. First-principles DFT calculations ascribe such selectivity to differences in the binding strength of the olefin substrate to the monoatomic metal centers. The single-pot cooperation of the two SACs allows the production of terminal organosilane compounds with high regio-selectivity (>95 %) even from industrially-relevant complex mixtures of terminal and internal olefins, alongside a straightforward catalyst recycling and reuse. These results demonstrate the significance of oxide-supported single-atom metal catalysts in tandem catalytic reactions, which are central for the intensification of chemical processes. 相似文献
68.
Philipp Rotering Lukas F. B. Wilm Janina A. Werra Dr. Fabian Dielmann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(2):406-411
Electron-rich tertiary phosphines are valuable species in chemical synthesis. However, their broad application as ligands in catalysis and reagents in stoichiometric reactions is often limited by their costly synthesis. Herein, we report the synthesis and properties of a series of phosphines with 1-alkylpyridin-4-ylidenamino and 1-alkylpyridin-2-ylidenamino substituents that are accessible in a very short and scalable route starting from commercially available aminopyridines and chlorophosphines. The determination of the Tolman electronic parameter (TEP) value reveals that the electron donor ability can be tuned by the substituent pattern at the aminopyridine backbone and it can exceed that of common alkylphosphines and N-heterocyclic carbenes. The potential of the new phosphines as strong nucleophiles in phosphine-mediated transformations is demonstrated by the formation of Lewis base adducts with CO2 and CS2. In addition, the coordination chemistry of the new phosphines towards CuI, AuI, and PdII metal centers has been explored, and a convenient procedure to introduce the most basic phosphine into metal complexes starting from air-stable phosphonium salt is described. 相似文献
69.
Ferdinand H. Lutter Lucie Grokenberger Philipp Spieß Jeffrey M. Hammann Konstantin Karaghiosoff Paul Knochel 《Angewandte Chemie (International ed. in English)》2020,59(14):5546-5550
A combination of 10 % CoCl2 and 20 % 2,2′‐bipyridine ligands enables cross‐coupling of functionalized primary and secondary alkylzinc reagents with various (hetero)aryl halides. Couplings with 1,3‐ and 1,4‐substituted cycloalkylzinc reagents proceeded diastereoselectively leading to functionalized heterocycles with high diastereoselectivities of up to 98:2. Furthermore, alkynyl bromides react with primary and secondary alkylzinc reagents providing the alkylated alkynes. 相似文献