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141.
Tao Wang Shuai Shi Daniel Pflästerer Eva Rettenmeier Dr. Matthias Rudolph Dr. Frank Rominger Prof. Dr. A. Stephen K. Hashmi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(1):292-296
The conversion of simple, easily available urea‐substituted 3‐phenylpropargyl alcohols catalyzed by a simple IPr–gold(I) catalyst in a gold(I)‐catalyzed cascade reaction composing of a gold‐catalyzed nucleophilic addition and a subsequent gold‐catalyzed substitution reaction delivers 1H‐imidazo[1, 5?a]indol‐3(2 H)‐ones. Other gold(I) catalysts or silver catalysts gave lower yields and often gave other side products. Gold(III) and copper(II) catalysts decomposed the starting material. Twelve examples, including donor and acceptor substituents on the distal nitrogen of the urea substructure, are provided. An X‐ray crystal structure analysis confirmed the structural assignment. The mechanistic investigation including isolation and further conversion of intermediates and reactions with enantiopure starting materials indicated that after the nucleophilic‐addition step, the substrate undergoes an SN1‐type benzylic substitution reaction at the indolyl alcohol intermediate or an intramolecular hydroamination reaction of the 2‐vinylindole intermediate. 相似文献
142.
Electrochemically Generated Nanoparticles of Halogen‐Bridged Mixed‐Valence Binuclear Metal Complex Chains 下载免费PDF全文
Emiliano Martínez‐Periñán Mohammad‐Reza Azani Dr. José M. Abad Dr. Eva Mateo‐Martí Dr. Félix Pariente Dr. Rubén Mas‐Ballesté Dr. Félix Zamora Prof. Encarnación Lorenzo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(23):7107-7115
Spherical nanoparticles composed of MMX chains can be made by a polymerization strategy driven by electrochemical processes. In particular, the [Pt2(MeCS2)4I2] (MMI2) dimetal subunit is employed as a monomer for the formation of [Pt2(MeCS2)4I]n spherical nanostructures on surfaces. We have paid particular attention to elucidating the general mechanism of the deposition process on the basis of in situ electrochemical measurements. The reduction of MMI2 to give the electrodeposition of nanostructures agrees well with formation of the reduced [MMI2]? species followed by a disproportionation mechanism mediated by iodide anions. The chemical composition of the particles was determined by energy‐dispersive X‐ray spectroscopy (EDX) and X‐ray photoelectron spectroscopy (XPS) to reveal the MMI2 polymer. 相似文献
143.
Magnetobiosensors Based on Viral Protein p19 for MicroRNA Determination in Cancer Cells and Tissues 下载免费PDF全文
Dr. Susana Campuzano Dr. Eva López‐Hernández Felipe Conzuelo Dr. Rosario Granados Dr. José M. Sánchez‐Puelles Prof. José M. Pingarrón 《Angewandte Chemie (International ed. in English)》2014,53(24):6168-6171
MicroRNAs (miRs) have emerged as important clinical biomarkers with both diagnostic and prognostic value for relevant diseases, such as cancer. MiRs pose unique challenges for detection and are currently detected by northern blotting, real‐time PCR, and microarray techniques. These expensive, complicated, and time‐consuming techniques are not feasible for on‐site miR determination. In this study, amperometric magnetobiosensors involving RNA‐binding viral protein p19 as a selective biorecognition element were developed for miR quantification. The p19‐based magnetosensors were able to detect 0.4 fmol of a synthetic target and endogenous miR‐21 (selected as a model for its role in a wide variety of cancers) in only 2 h in total RNA extracted from cancer cells and human breast‐tumor specimens without PCR amplification and sample preprocessing. These results open up formidable perspectives for the diagnosis and prognosis of human cancers and for drug‐discovery programs. 相似文献
144.
Hee-Jeong Cha Se-Yeun Hwang Da-Som Lee Dr. Akula Ravi Kumar Prof. Dr. Yong-Uk Kwon Moritz Voß Eva Schuiten Prof. Dr. Uwe T. Bornscheuer Prof. Dr. Frank Hollmann Prof. Dr. Deok-Kun Oh Prof. Dr. Jin-Byung Park 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(18):7090-7094
Long-chain aliphatic amines such as (S,Z)-heptadec-9-en-7-amine and 9-aminoheptadecane were synthesized from ricinoleic acid and oleic acid, respectively, by whole-cell cascade reactions using the combination of an alcohol dehydrogenase (ADH) from Micrococcus luteus, an engineered amine transaminase from Vibrio fluvialis (Vf-ATA), and a photoactivated decarboxylase from Chlorella variabilis NC64A (Cv-FAP) in a one-pot process. In addition, long chain aliphatic esters such as 10-(heptanoyloxy)dec-8-ene and octylnonanoate were prepared from ricinoleic acid and oleic acid, respectively, by using the combination of the ADH, a Baeyer–Villiger monooxygenase variant from Pseudomonas putida KT2440, and the Cv-FAP. The target compounds were produced at rates of up to 37 U g−1 dry cells with conversions up to 90 %. Therefore, this study contributes to the preparation of industrially relevant long-chain aliphatic chiral amines and esters from renewable fatty acid resources. 相似文献
145.
Theo Maulbetsch Dr. Eva Jürgens Prof. Dr. Doris Kunz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(46):10634-10640
The use of carbon monoxide as a direct reducing agent for the deoxygenation of terminal and internal epoxides to the respective olefins is presented. This reaction is homogeneously catalyzed by a carbonyl pincer-iridium(I) complex in combination with a Lewis acid co-catalyst to achieve a pre-activation of the epoxide substrate, as well as the elimination of CO2 from a γ-2-iridabutyrolactone intermediate. Especially terminal alkyl epoxides react smoothly and without significant isomerization to the internal olefins under CO atmosphere in benzene or toluene at 80–120 °C. Detailed investigations reveal a substrate-dependent change in the mechanism for the epoxide C−O bond activation between an oxidative addition under retention of the configuration and an SN2 reaction that leads to an inversion of the configuration. 相似文献
146.
Jos Javier Conesa Ana C. Carrasco Vanessa Rodríguez‐Fanjul Yang Yang Jos L. Carrascosa Peter Cloetens Eva Pereiro Ana M. Pizarro 《Angewandte Chemie (International ed. in English)》2020,59(3):1270-1278
The iridium half‐sandwich complex [Ir(η5:κ1‐C5Me4CH2py)(2‐phenylpyridine)]PF6 is highly cytotoxic: 15–250× more potent than clinically used cisplatin in several cancer cell lines. We have developed a correlative 3D cryo X‐ray imaging approach to specifically localize and quantify iridium within the whole hydrated cell at nanometer resolution. By means of cryo soft X‐ray tomography (cryo‐SXT), which provides the cellular ultrastructure at 50 nm resolution, and cryo hard X‐ray fluorescence tomography (cryo‐XRF), which provides the elemental sensitivity with a 70 nm step size, we have located the iridium anticancer agent exclusively in the mitochondria. Our methodology provides unique information on the intracellular fate of the metallodrug, without chemical fixation, labeling, or mechanical manipulation of the cells. This cryo‐3D correlative imaging method can be applied to a number of biochemical processes for specific elemental localization within the native cellular landscape. 相似文献
147.
Sebastian Grieger Beata M. Szydowska Vaishnavi J. Rao Eva Steinmann Marcus Dodds Zahra Gholamvand Georg S. Duesberg Jana Zaumseil Claudia Backes 《Angewandte Chemie (International ed. in English)》2020,59(33):13785-13792
In recent years, various functionalization strategies for transition‐metal dichalcogenides have been explored to tailor the properties of materials and to provide anchor points for the fabrication of hybrid structures. Herein, new insights into the role of the surfactant in functionalization reactions are described. Using the spontaneous reaction of WS2 with chloroauric acid as a model reaction, the regioselective formation of gold nanoparticles on WS2 is shown to be heavily dependent on the surfactant employed. A simple model is developed to explain the role of the chosen surfactant in this heterogeneous functionalization reaction. The surfactant coverage is identified as the crucial element that governs the dominant reaction pathway and therefore can severely alter the reaction outcome. This study shows the general importance of the surfactant choice and how detrimental or beneficial a certain surfactant can be to the desired functionalization. 相似文献
148.
149.
A rapid conversion of aldehydes to corresponding nitriles has been achieved under microwave irradiation using hydroxylamine and phthalic anhydride or hydroxylamine and Envirocatalyst EPZGR in solvent free conditions. 相似文献
150.