共查询到20条相似文献,搜索用时 15 毫秒
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Dr. Gianluca Destro Kaisa Horkka Olivier Loreau David-Alexandre Buisson Lee Kingston Dr. Antonio Del Vecchio Dr. Magnus Schou Dr. Charles S. Elmore Dr. Frédéric Taran Dr. Thibault Cantat Dr. Davide Audisio 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(32):13592-13597
A transition-metal-free carbon isotope exchange procedure on phenyl acetic acids is described. Utilizing the universal precursor CO2, this protocol allows the carbon isotope to be inserted into the carboxylic acid position, with no need of precursor synthesis. This procedure enabled the labeling of 15 pharmaceuticals and was compatible with carbon isotopes [14C] and [13C]. A proof of concept with [11C] was also obtained with low molar activity valuable for distribution studies. 相似文献
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Late‐Stage Isotopic Carbon Labeling of Pharmaceutically Relevant Cyclic Ureas Directly from CO2 下载免费PDF全文
Antonio Del Vecchio Dr. Fabien Caillé Dr. Arnaud Chevalier Olivier Loreau Kaisa Horkka Prof. Dr. Christer Halldin Dr. Magnus Schou Dr. Nathalie Camus Dr. Pascal Kessler Dr. Bertrand Kuhnast Dr. Frédéric Taran Dr. Davide Audisio 《Angewandte Chemie (International ed. in English)》2018,57(31):9744-9748
A robust, click‐chemistry‐inspired procedure for radiolabeling of cyclic ureas was developed. This protocol, suitable for all carbon isotopes (11C, 13C, 14C), is based on the direct functionalization of carbon dioxide: the universal building block for carbon radiolabeling. The strategy is operationally simple and reproducible in different radiochemistry centers, exhibits remarkably wide substrate scope with short reaction times, and demonstrates superior reactivity as compared to previously reported systems. With this procedure, a variety of pharmaceuticals and an unprotected peptide were labeled with high radiochemical efficiency. 相似文献
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Prof. Frédéric‐Georges Fontaine Marc‐André Courtemanche Marc‐André Légaré 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(11):2990-2996
Metal‐free systems, including frustrated Lewis pairs (FLPs) have been shown to bind CO2. By reducing the Lewis acidity and basicity of the ambiphilic system, it is possible to generate active catalysts for the deoxygenative hydroboration of carbon dioxide to methanol derivatives with conversion rates comparable to those of transition‐metal‐based catalysts. 相似文献
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Enguerrand Blondiaux Dr. Jacky Pouessel Dr. Thibault Cantat 《Angewandte Chemie (International ed. in English)》2014,53(45):12186-12190
The first metal‐free catalysts are reported for the methylation of amines with carbon dioxide. Proazaphosphatrane superbases prove to be highly active catalysts in the reductive functionalization of CO2, in the presence of hydroboranes. The new methodology enables the methylation of N? H bonds in a wide variety of amines, including secondary amines, with increased chemoselectivity. 相似文献
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Wenchao Zhang Chuangang Hu Zaiping Guo Liming Dai 《Angewandte Chemie (International ed. in English)》2020,59(9):3470-3474
Metal–CO2 batteries have attracted much attention owing to their high energy density and use of greenhouse CO2 waste as the energy source. However, the increasing cost of lithium and the low discharge potential of Na–CO2 batteries create obstacles for practical applications of Li/Na–CO2 batteries. Recently, earth‐abundant potassium ions have attracted considerable interest as fast ionic charge carriers for electrochemical energy storage. Herein, we report the first K–CO2 battery with a carbon‐based metal‐free electrocatalyst. The battery shows a higher theoretical discharge potential (E?=2.48 V) than that of Na–CO2 batteries (E?=2.35 V) and can operate for more than 250 cycles (1500 h) with a cutoff capacity of 300 mA h g?1. Combined DFT calculations and experimental observations revealed a reaction mechanism involving the reversible formation and decomposition of P121/c1‐type K2CO3 at the efficient carbon‐based catalyst. 相似文献
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Zhen Zhang Li‐Li Liao Si‐Shun Yan Lei Wang Yun‐Qi He Jian‐Heng Ye Dr. Jing Li Prof. Dr. Yong‐Gang Zhi Prof. Dr. Da‐Gang Yu 《Angewandte Chemie (International ed. in English)》2016,55(25):7068-7072
The first direct use of carbon dioxide in the lactamization of alkenyl and heteroaryl C?H bonds to synthesize important 2‐quinolinones and polyheterocycles in moderate to excellent yields is reported. Carbon dioxide, a nontoxic, inexpensive, and readily available greenhouse gas, acts as an ideal carbonyl source. Importantly, this transition‐metal‐free and redox‐neutral process is eco‐friendly and desirable for the pharmaceutical industry. Moreover, these reactions feature a broad substrate scope, good functional group tolerance, facile scalability, and easy product derivatization. 相似文献
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Benjamin M. Reeves Hamish B. Hepburn Alexandru Grozavu Peter J. Lindsay‐Scott Timothy J. Donohoe 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(44):15844-15848
A transition‐metal‐free reductive hydroxymethylation reaction has been developed, enabling the preparation of tetrahydroisoquinolines bearing C4‐quaternary centers from the corresponding isoquinolines. Deuterium labelling studies and control experiments enable a potential mechanism to be elucidated which features a key Cannizzaro‐type reduction followed by an Evans–Tishchenko reaction. When isoquinolines featuring a proton at the 4‐position are used, a tandem methylation‐hydroxymethylation occurs, leading to the formation of 2 new C?C bonds in one pot. 相似文献
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Julio Romero‐Ibaez Silvano Cruz‐Gregorio Jacinto Sandoval‐Lira Julio M. Hernndez‐Prez Leticia Quintero Fernando Sartillo‐Piscil 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(26):8959-8963
One of the major challenges in organic synthesis is the activation or deconstructive functionalization of unreactive C(sp3)–C(sp3) bonds, which requires using transition or precious metal catalysts. We present here an alternative: the deconstructive lactamization of piperidines without using transition metal catalysts. To this end, we use 3‐alkoxyamino‐2‐piperidones, which were prepared from piperidines through a dual C(sp3)–H oxidation, as transitory intermediates. Experimental and theoretical studies confirm that this unprecedented lactamization occurs in a tandem manner involving an oxidative deamination of 3‐alkoxyamino‐2‐piperidones to 3‐keto‐2‐piperidones, followed by a regioselective Baeyer–Villiger oxidation to give N‐carboxyanhydride intermediates, which finally undergo a spontaneous and concerted decarboxylative intramolecular translactamization. 相似文献
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Metal‐Free Catalyst for the Chemoselective Methylation of Amines Using Carbon Dioxide as a Carbon Source 下载免费PDF全文
Dr. Shoubhik Das Felix D. Bobbink Prof. Dr. Gabor Laurenczy Prof. Dr. Paul J. Dyson 《Angewandte Chemie (International ed. in English)》2014,53(47):12876-12879
N‐methylation of amines is an important step in the synthesis of many pharmaceuticals and has been widely applied in the preparation of other key intermediates and chemicals. Therefore, the development of efficient methylation methods has attracted considerable attention. In this respect, carbon dioxide is an attractive C1 building block because it is an abundant, renewable, and nontoxic carbon source. Consequently, we developed a highly chemoselective, metal‐free catalytic system that operates under ambient conditions for the N‐methylation of amines. 相似文献
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Prof. Dr. Frank Glorius 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8047-8051
A general and efficient methodology for the direct transition metal free trifluoromethylthiolation of a broad range of biologically relevant N‐heteroarenes is reported employing abundant sodium chloride as the catalyst. This method is operationally simple, exhibits high functional group tolerance, and does not require protecting groups. 相似文献
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Jeffrey M. Hammann Teresa A. Unzner Dr. Thomas Magauer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(22):6733-6738
Herein, we describe a transition‐metal‐free protocol for the conversion of simple 2‐allyl‐3‐(trifluoromethyl)phenols into substituted 5‐fluoronaphthalen‐1‐ols. The key events of this reaction include the selective activation of two C?F bonds and formation of an intermediate hexatriene system, which undergoes a 6π electrocyclization, followed by rearomatization. This concept enables the rapid conversion (three steps) of various commercially available 3‐(trifluoromethyl)phenols into novel fluorine‐containing naphthols, which are difficult to prepare by previous methods. The reported sequence was also extended to a one‐pot transformation of 3‐(trifluoromethyl)phenols into 5‐fluoronaphthalen‐1‐ols. 相似文献
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A novel and simple t‐BuOLi/I2‐mediated synthesis of 1,2,4‐trisubstituted imidazoles was developed without transition‐metal added. The transition‐metal‐free strategy tolerated a range of substrates and provided products in moderate to good yields with 100% regioselectivity. 相似文献
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Defect‐Free Mixed‐Matrix Membranes with Hydrophilic Metal‐Organic Polyhedra for Efficient Carbon Dioxide Separation 下载免费PDF全文
Yang No Yun Muhammad Sohail Dr. Jong‐Ho Moon Dr. Tae Woo Kim Dr. Kyeng Min Park Dr. Dong Hyuk Chun Dr. Young Cheol Park Prof. Dr. Churl‐Hee Cho Prof. Dr. Hyunuk Kim 《化学:亚洲杂志》2018,13(6):631-635
Defect‐free mixed‐matrix membranes (MMMs) were prepared by incorporating hydrophilic metal‐organic polyhedra (MOPs) into cross‐linked polyethylene oxide (XLPEO) for efficient CO2 separation. Hydrophilic MOPs with triethylene glycol pendant groups, which were assembled by 5‐tri(ethylene glycol) monomethyl ether isophthalic acid and CuII ions, were uniformly dispersed in XLPEO without particle agglomeration. Compared to conventional neat XLPEO, the homogenous dispersion of EG3‐MOPs in XLPEO enhanced CO2 permeability of MMMs. Upon increasing the amount of EG3‐MOPs, the membrane performance such as CO2/N2 selectivity was steadily improved because of unsaturated CuII sites at paddle‐wheel units, which was confirmed by Cu K‐edge XANES and TPD analysis. Therefore, such defect‐free MMMs with unsaturated metal sites would contribute to enhance CO2 separation performance. 相似文献