共查询到20条相似文献，搜索用时 15 毫秒
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Jose R. Cabrero‐Antonino Rosa Adam Matthias Beller 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(37):12950-12968
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Tuhin Patra Satobhisha Mukherjee Jiajia Ma Felix Strieth‐Kalthoff Frank Glorius 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(31):10624-10630
Despite significant progress in aliphatic decarboxylation, an efficient and general protocol for radical aromatic decarboxylation has lagged far behind. Herein, we describe a general strategy for rapid access to both aryl and alkyl radicals by photosensitized decarboxylation of the corresponding carboxylic acids esters followed by their successive use in divergent carbon–heteroatom and carbon–carbon bond‐forming reactions. Identification of a suitable activator for carboxylic acids is the key to bypass a competing single‐electron‐transfer mechanism and “switch on” an energy‐transfer‐mediated homolysis of unsymmetrical σ‐bonds for a concerted fragmentation/decarboxylation process. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2018,130(17):4606-4610
An experimental study on protonation of simple weakly basic molecules (L) by the strongest solid superacid, H(CHB11F11), showed that basicity of SO2 is high enough (during attachment to the acidic H atoms at partial pressure of 1 atm) to break the bridged H‐bonds of the polymeric acid and to form a mixture of solid mono‐ LH+⋅⋅⋅An−, and disolvates, L−H+−L. With a decrease in the basicity of L=CO (via C), N2O, and CO (via O), only proton monosolvates are formed, which approach L−H+−An− species with convergence of the strengths of bridged H‐bonds. The molecules with the weakest basicity, such as CO2 and weaker, when attached to the proton, cannot break the bridged H‐bond of the polymeric superacid, and the interaction stops at stage of physical adsorption. It is shown here that under the conditions of acid monomerization, it is possible to protonate such weak bases as CO2, N2, and Xe. 相似文献
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Tucker R. Huffman Yebin Wu Alexis Emmerich Ryan A. Shenvi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2393-2398
Pd0‐catalyzed Mizoroki–Heck reactions traditionally exhibit poor reactivity with polysubstituted, unbiased alkenes. Intermolecular reactions with simple, all‐carbon tetrasubstituted alkenes are unprecedented. Herein we report that pendant carboxylic acids, combined with bulky monophospine ligands on palladium, can direct the arylation of tri‐ and tetrasubstituted olefins. Quaternary carbons are established at high Fsp3 attached‐ring junctures and the carboxylate directing group can be removed after coupling. Carboxylate directivity prevents over‐arylation of the new, less substituted alkene, which can be diversified in subsequent reactions. 相似文献
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Ugo Castelli Jean‐Franois Lohier Ines Drukenmüller Agns Mingot Christian Bachman Carole Alayrac Jrme Marrot Karin Stierstorfer Andreas Kornath Annie‐Claude Gaumont Sbastien Thibaudeau 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(5):1369-1374
Unambiguously confirmed by low‐temperature in situ NMR experiments, X‐ray diffraction and vibrational spectroscopy, phosphonium‐carbenium superelectrophiles are shown to be generated in strong acidic conditions. Representing crucial intermediates, their exploitation allows for the synthesis of unprecedented fluorinated (cyclic) phosphine oxides. 相似文献
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Giulia Bergonzini Carlo Cassani Carl‐Johan Wallentin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(47):14272-14275
Simple and abundant carboxylic acids have been used as acyl radical precursor by means of visible‐light photoredox catalysis. By the transient generation of a reactive anhydride intermediate, this redox‐neutral approach offers a mild and rapid entry to high‐value heterocyclic compounds without the need of UV irradiation, high temperature, high CO pressure, tin reagents, or peroxides. 相似文献
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Charles S. Yeung 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(17):5546-5556
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2018,130(23):7026-7030
A new catalyst for the carboxylative synthesis of arylacetic and benzoic acids using formic acid (HCOOH) as the CO surrogate was developed. In an improvement over previous work, CO is generated in situ without the need for any additional activators. Key to success was the use of a specific system consisting of palladium acetate and 1,2‐bis((tert‐butyl(2‐pyridinyl)phosphinyl)methyl)benzene. The generality of this method is demonstrated by the synthesis of more than 30 carboxylic acids, including non‐steroidal anti‐inflammatory drugs (NSAIDs), under mild conditions in good yields. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(9):2522-2526
Transformation of aromatic thioesters into arylboronic esters was achieved efficiently using a rhodium catalyst. The broad functional‐group tolerance and mild conditions of the method have allowed for the two‐step decarboxylative borylation of a wide range of aromatic carboxylic acids, including commercially available drugs. 相似文献
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