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211.
212.
Dr. Sabin Llona‐Minguez Dr. Matthieu Desroses Artin Ghassemian Dr. Sylvain A. Jacques Dr. Lars Eriksson Rebecka Isacksson Tobias Koolmeister Dr. Pål Stenmark Dr. Martin Scobie Prof. Thomas Helleday 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(20):7394-7398
A two‐step synthesis of structurally diverse pyrrole‐containing bicyclic systems is reported. ortho‐Nitro‐haloarenes coupled with vinylic N‐methyliminodiacetic acid (MIDA) boronates generate ortho‐vinyl‐nitroarenes, which undergo a “metal‐free” nitrene insertion, resulting in a new pyrrole ring. This novel synthetic approach has a wide substrate tolerance and it is applicable in the preparation of more complex “drug‐like” molecules. Interestingly, an ortho‐nitro‐allylarene derivative furnished a cyclic β‐aminophosphonate motif. 相似文献
213.
Dendronized Hyperbranched Macromolecules: Soft Matter with a Novel Type of Segmental Distribution 下载免费PDF全文
Priv.‐Doz. Dr. Albena Lederer Prof. Dr. Walther Burchard Tobias Hartmann Johannes S. Haataja Dr. Nikolay Houbenov Andreas Janke Dr. Peter Friedel Dr. Ralf Schweins Dr. Peter Lindner 《Angewandte Chemie (International ed. in English)》2015,54(43):12578-12583
Dendronization of a hyperbranched polyester with different generation dendrons leads to pseudo‐dendritic structures. The hyperbranched core is modified by the divergent coupling of protected monomer units to the functional groups. Compared to dendrimers, the synthetic effort is significantly less, but the properties are very close to those of high‐generation dendrimers. The number of functional groups, molar mass, and rheology behavior even in the early generation (G1–G4) pseudo‐dendrimers strongly resembles the behavior of dendrimers in higher generations (G5–G8). Comparison of the segmental and internal structure with perfect dendrimers is performed using SANS, dynamic light scattering and viscosity analysis, microscopy and molecular dynamics simulation. The interpretation of the results reveals unique structural characteristics arising from lower segmental density of the core, which turns into a soft nano‐sphere with a smooth surface even in the first generation. 相似文献
214.
Olivia Schimming Dr. Victoria L. Challinor Dr. Nicholas J. Tobias Dr. Hélène Adihou Peter Grün Laura Pöschel Dr. Christian Richter Prof. Dr. Harald Schwalbe Prof. Dr. Helge B. Bode 《Angewandte Chemie (International ed. in English)》2015,54(43):12702-12705
Pyrrolizidine alkaloids (PAs) are widespread plant natural products with potent toxicity and bioactivity. Herein, the identification of bacterial PAs from entomopathogenic bacteria using differential analysis by 2D NMR spectroscopy (DANS) and mass spectrometry is described. Their biosynthesis was elucidated to involve a non‐ribosomal peptide synthetase. The occurrence of these biosynthesis gene clusters in Gram‐negative and Gram‐positive bacteria indicates an important biological function in bacteria. 相似文献
215.
Dr. Tobias W. Giessen Florian Altegoer Annika J. Nebel Roman M. Steinbach Dr. Gert Bange Prof. Dr. Mohamed A. Marahiel 《Angewandte Chemie (International ed. in English)》2015,54(8):2492-2496
The incorporation of non‐proteinogenic amino acids represents a major challenge for the creation of functionalized proteins. The ribosomal pathway is limited to the 20–22 proteinogenic amino acids while nonribosomal peptide synthetases (NRPSs) are able to select from hundreds of different monomers. Introduced herein is a fusion‐protein‐based design for synthetic tRNA‐aminoacylation catalysts based on combining NRPS adenylation domains and a small eukaryotic tRNA‐binding domain (Arc1p‐C). Using rational design, guided by structural insights and molecular modeling, the adenylation domain PheA was fused with Arc1p‐C using flexible linkers and achieved tRNA‐aminoacylation with both proteinogenic and non‐proteinogenic amino acids. The resulting aminoacyl‐tRNAs were functionally validated and the catalysts showed broad substrate specificity towards the acceptor tRNA. Our strategy shows how functional tRNA‐aminoacylation catalysts can be created for bridging the ribosomal and nonribosomal worlds. This opens up new avenues for the aminoacylation of tRNAs with functional non‐proteinogenic amino acids. 相似文献
216.
Formal anti‐Carbopalladation Reactions of Non‐Activated Alkynes: Requirements,Mechanistic Insights,and Applications 下载免费PDF全文
M.Sc. Martin Pawliczek Dr. Tobias F. Schneider Dr. Christian Maaß Prof. Dr. Dietmar Stalke Prof. Dr. Daniel B. Werz 《Angewandte Chemie (International ed. in English)》2015,54(13):4119-4123
Formal anti‐carbopalladation reactions of C? C triple bonds are uncommon, but highly useful transformations. Alkynes can be designed to give anti‐carbopalladation products. Prerequisite is the exclusion of other reaction pathways to provoke the cis–trans isomerization of the syn‐carbopalladation intermediate. Detailed mechanistic studies of this crucial step by experimental and computational means were performed. Application of an intramolecular version for the synthesis of oligocyclic compounds and substituted dibenzofurans is also described. 相似文献
217.
M. Sc. Yasemin Akbulut Hannah J. Gaunt Prof. Katsuhiko Muraki Dr. Melanie J. Ludlow Dr. Mohamed S. Amer Dr. Alexander Bruns Dr. Naveen S. Vasudev Dr. Lea Radtke Dr. Matthieu Willot M. Sc. Sven Hahn M. Sc. Tobias Seitz Dr. Slava Ziegler Prof. Dr. Mathias Christmann Prof. Dr. David J. Beech Prof. Dr. Herbert Waldmann 《Angewandte Chemie (International ed. in English)》2015,54(12):3787-3791
Current therapies for common types of cancer such as renal cell cancer are often ineffective and unspecific, and novel pharmacological targets and approaches are in high demand. Here we show the unexpected possibility for the rapid and selective killing of renal cancer cells through activation of calcium‐permeable nonselective transient receptor potential canonical (TRPC) calcium channels by the sesquiterpene (?)‐englerin A. This compound was found to be a highly efficient, fast‐acting, potent, selective, and direct stimulator of TRPC4 and TRPC5 channels. TRPC4/5 activation through a high‐affinity extracellular (?)‐englerin A binding site may open up novel opportunities for drug discovery aimed at renal cancer. 相似文献
218.
219.
Synthesis and Coordination Behaviour of (Ph3SnO)3As. The Crystal Structures of (Ph3SnO)3As and [{(Ph3SnO)3As}Fe(CO)4] (Ph3SnO)3As ( 1 ) was obtained from the reaction of Ph3SnOH with As2O3 in a dichloromethane/water mixture as solvent. Upon recrystallization from DMF 1 forms orthorhombic crystals, space group P212121, with a = 977.3(2), b = 1903.5(3) and c = 2600.9(5) pm (at 220 K). In 1 the As atom is bound to three OSnPh3 groups with As–O distances of 171.9(3)–174.9(3) pm. Reaction of 1 with Fe2(CO)9 gives [{(Ph3SnO)3As}Fe(CO)4] ( 2 ). 2 crystallizes monoclinic, space group P21/n with a = 2242.3(5), b = 1112.6(2), c = 2353.0(5) pm and β = 111,46(2)° (at 220 K). In 2 the iron atom exhibits a trigonal bipyramidal coordination with the (Ph3SnO)3As ligand in an axial position. The Fe–As bond length is 230.5(1) pm. 相似文献
220.
Obstacles and possible solutions for the application of microchip capillary electrophoresis in quantitative analysis are described and critically discussed. Differences between the phenomena occurring during conventional capillary electrophoresis and microchip-based capillary electrophoresis are pointed out, with particular focus on electrolysis, bubble formation, clogging, surface interactions, injection and aspects related to the power supply. Current drawbacks are specified and improvements for successful quantitative microchip capillary electrophoresis are suggested. 相似文献