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Development of a syn‐Selective Mannich Reaction of Aldehydes with Propargylic Imines by Dual Catalysis: Asymmetric Synthesis of Functionalized Propargylic Amines 下载免费PDF全文
Irati Lapuerta Dr. Silvia Vera Prof. Mikel Oiarbide Prof. Claudio Palomo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(21):7229-7237
Direct coupling of enolizable aldehydes with C‐alkynyl imines is realized affording the corresponding propargylic Mannich adducts of syn configuration, thus complementing previous methods that gave access to the anti‐isomers. The combination of proline and a urea Brønsted base cocatalyst is key for the reactions to proceed under very mild conditions (3–10 mol % catalyst loading, dichloromethane as solvent, ?20 °C, 1.2 molar equivalents of aldehyde) and with virtually total stereocontrol (syn/anti ratio up to 99:1; ee up to 99 %). Some possibilities of further chemical elaboration of adducts are also briefly illustrated. 相似文献
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Dr. Lei Dong Mengqi Fu Prof. Lifang Liu Hai-Hao Han Prof. Yi Zang Prof. Guo-Rong Chen Jia Li Prof. Xiao-Peng He Dr. Sébastien Vidal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(63):14445-14452
Two red-emitting dicyanomethylene-4H-pyran (DM) based fluorescent probes were designed and used for peroxynitrite (ONOO−) detection. Nevertheless, the aggregation-caused quenching effect diminished the fluorescence and restricted their further applications. To overcome this problem, tetraphenylethylene (TPE) based glycoclusters were used to self-assemble with these DM probes to obtain supramolecular water-soluble glyco-dots. This self-assembly strategy enhanced the fluorescence intensity, leading to an enhanced selectivity and activity of the resulting glyco-dot comparing to DM probes alone in PBS buffer. The glyco-dots also exhibited better results during fluorescence sensing of intracellular ONOO− than the probes alone, thereby offering scope for the development of other similar supramolecular glyco-systems for chemical biological studies. 相似文献
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Dr. Yanira Méndez Dr. Aldrin V. Vasco Galway Ivey Ana Laura Dias Dr. Peter Gierth Bárbara B. Sousa Dr. Claudio D. Navo Angel Torres-Mozas Dr. Tiago Rodrigues Dr. Gonzalo Jiménez-Osés Prof. Gonçalo J. L. Bernardes 《Angewandte Chemie (International ed. in English)》2023,62(44):e202311186
Multicomponent reactions are of utmost importance at generating a unique, wide, and complex chemical space. Herein we describe a novel multicomponent approach based on the combination of the isonitrile-tetrazine (4+1) cycloaddition and the Ugi four-component reaction to generate pyrazole amide derivatives. The scope of the reaction as well as mechanistic insights governing the 4H-pyrazol-4-imine tautomerization are provided. This multicomponent process provides access to a new chemical space of pyrazole amide derivatives and offers a tool for peptide modification and stapling. 相似文献
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Prof. Dr. Carmine Capacchione Prof. Dr. Fabia Grisi Prof. Dr. Marina Lamberti Prof. Dr. Mina Mazzeo Prof. Dr. Barbara Milani Prof. Dr. Stefano Milione Prof. Dr. Daniela Pappalardo Prof. Dr. Cristiano Zuccaccia Prof. Dr. Claudio Pellecchia 《欧洲无机化学杂志》2023,26(6):e202200644
Metal catalyzed polymerizations are among the most important chemical reactions, accounting for the production of about 400 million tons per year of polymeric materials, 50 % of which are polyolefins. The CIRCC research units at the University of Salerno, founded by the late Professor Adolfo Zambelli, a coworker of Giulio Natta and a pioneer in the studies of stereospecific polymerization catalysts, has a consolidated expertise in this field. Although often considered a “mature” area of research, olefin polymerization catalysis continues to drive great interest of both industrial and academic scientists. On the other hand, strong political and economic pressure toward the development of “green” and possibly biodegradable alternatives to olefin-based polymers stimulated our group to direct increasing research efforts in the area of sustainable polymers. In this perspective, we focus on the most recent work from the CIRCC research units involved in homogeneous catalysis for polymerization of a variety of monomers, with the aim to address how the concepts and the expertise developed for olefin polymerization can be applied to the development of different metal-catalyzed polymerizations and copolymerizations. Of course, although the results are discussed in the frame of the most important literature contributions, a comprehensive review of such a wide and diversified topic is out of the scope of the paper. References to reviews covering the different types of metal catalyzed polymerizations are provided in each chapter. 相似文献
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Determination of Allura Red and Tartrazine in Food Samples by Sequential Injection Analysis Combined with Voltammetric Detection at Antimony Film Electrode 下载免费PDF全文
J. A. Rodríguez M. G. Juárez C. A. Galán‐Vidal J. M. Miranda E. Barrado 《Electroanalysis》2015,27(10):2329-2334
An antimony film electrode prepared on‐line and installed as part of a sequential injection system, was used as an electrochemical detector to determine azo dyes in food samples. The influence of several flow variables were evaluated using a central composite design. In optimal conditions, the linear range of the calibration curve varied from 1–5 µM, with a limit of detection limit of 0.3 µM. The relative standard deviation of analytical repeatability was <5.0 %.The method was validated by comparing the results obtained with those provided by HPLC; no significant difference were seen. 相似文献
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Organocatalytic,Asymmetric Eliminative [4+2] Cycloaddition of Allylidene Malononitriles with Enals: Rapid Entry to Cyclohexadiene‐Embedding Linear and Angular Polycycles 下载免费PDF全文
Dr. Nicoletta Brindani Dr. Gloria Rassu Dr. Luca Dell'Amico Dr. Vincenzo Zambrano Dr. Luigi Pinna Dr. Claudio Curti Dr. Andrea Sartori Prof. Dr. Lucia Battistini Prof. Dr. Giovanni Casiraghi Prof. Dr. Giorgio Pelosi Dr. Daniela Greco Prof. Dr. Franca Zanardi 《Angewandte Chemie (International ed. in English)》2015,54(25):7386-7390
A direct aminocatalytic synthesis has been developed for the chemo‐, regio‐, diastereo‐, and enantioselective construction of densely substituted polycyclic carbaldehydes containing fused cyclohexadiene rings. The chemistry utilizes, for the first time, remotely enolizable π‐extended allylidenemalononitriles as electron‐rich 1,3‐diene precursors in a direct eliminative [4+2] cycloaddition with both aromatic and aliphatic α,β‐unsaturated aldehydes. The generality of the process is demonstrated by approaching 6,6‐, 5,6‐, 7,6‐, 6,6,6‐, and 6,5,6‐fused ring systems, as well as biorelevant steroid‐like 6,6,6,6,5‐ and 6,6,6,5,6‐rings. A stepwise reaction mechanism for the key [4+2] addition is proposed as a domino bis‐vinylogous Michael/Michael/retro‐Michael reaction cascade. The utility of the malononitrile moiety as traceless activating group of the dicyano nucleophilic substrates is demonstrated. 相似文献