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401.
Prasenjit Mondal Marta Lovisari Brendan Twamley Aidan R. McDonald 《Angewandte Chemie (International ed. in English)》2020,59(31):13044-13050
In the search for highly reactive oxidants we have identified high‐valent metal–fluorides as a potential potent oxidant. The high‐valent Ni–F complex [NiIII(F)(L)] ( 2 , L=N,N′‐(2,6‐dimethylphenyl)‐2,6‐pyridinedicarboxamidate) was prepared from [NiII(F)(L)]? ( 1 ) by oxidation with selectfluor. Complexes 1 and 2 were characterized by using 1H/19F NMR, UV‐vis, and EPR spectroscopies, mass spectrometry, and X‐ray crystallography. Complex 2 was found to be a highly reactive oxidant in the oxidation of hydrocarbons. Kinetic data and products analysis demonstrate a hydrogen atom transfer mechanism of oxidation. The rate constant determined for the oxidation of 9,10‐dihydroanthracene (k2=29 m ?1 s?1) compared favorably with the most reactive high‐valent metallo‐oxidants. Complex 2 displayed reaction rates 2000–4500‐fold enhanced with respect to [NiIII(Cl)(L)] and also displayed high kinetic isotope effect values. Oxidative hydrocarbon and phosphine fluorination was achieved. Our results provide an interesting direction in designing catalysts for hydrocarbon oxidation and fluorination 相似文献
402.
Xiao-Han Yang Zi-Cen Zuo Zi-Wen Tao Ding Yuan Yan Chen Qin Chen Kai Liu Guang-Ying Chen Zheng-Rong Mo Gao-Nan Li Zhi-Gang Niu 《中国化学会会志》2020,67(1):80-87
Two new iridium (III) complexes ( Ir1-Ir2 ) bearing different fluorinated 2-(biphenyl-4-yl)-2H-indazole-based compounds as cyclometalated ligands and Xantphos as an ancillary ligand were synthesized and fully characterized. The ultraviolet (UV)–vis absorption, photoluminescence, and electrochemistry properties were studied. The single crystal structures of Ir1-Ir2 were determined by X-ray diffraction, showing each adopts the distorted octahedral coordination geometry. To gain insights into the lowest energy electron transitions and the lowest triplet excited states, density functional theory calculations were used to further investigate the origination. Two complexes emit yellow photoluminescence with quantum yields of 49.7–72.5% in solution at room temperature. Their Commission Internationale de L'Eclairage color coordinates are (0.42, 0.53) and (0.39, 0.47), respectively. 相似文献
403.
Dr. Ye Liu Jinfeng Liu Dr. Dandan Chen Xiaosha Wang Zhe Zhang Yicheng Yang Prof. Lihui Jiang Weizhi Qi Ziyuan Ye Prof. Shuqing He Prof. Quanying Liu Prof. Lei Xi Prof. Yingping Zou Prof. Changfeng Wu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(47):21235-21243
Here, we describe a fluorination strategy for semiconducting polymers for the development of highly bright second near-infrared region (NIR-II) probes. Tetrafluorination yielded a fluorescence QY of 3.2 % for the polymer dots (Pdots), over a 3-fold enhancement compared to non-fluorinated counterparts. The fluorescence enhancement was attributable to a nanoscale fluorous effect in the Pdots that maintained the molecular planarity and minimized the structure distortion between the excited state and ground state, thus reducing the nonradiative relaxations. By performing through-skull and through-scalp imaging of the brain vasculature of live mice, we quantitatively analyzed the vascular morphology of transgenic brain tumors in terms of the vessel lengths, vessel branches, and vessel symmetry, which showed statistically significant differences from the wild type animals. The bright NIR-II Pdots obtained through fluorination chemistry provide insightful information for precise diagnosis of the malignancy of the brain tumor. 相似文献
404.
Prof. Dr. Kazuaki Ishihara Kazuki Nishimura Katsuya Yamakawa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(40):17794-17800
Catalytic enantioselective α-fluorination reactions of carbonyl compounds are among the most powerful and efficient synthetic methods for constructing optically active α-fluorinated carbonyl compounds. Nevertheless, α-fluorination of α-nonbranched carboxylic acid derivatives is still a big challenge because of relatively high pKa values of their α-hydrogen atoms and difficulty of subsequent synthetic transformation without epimerization. Herein we show that chiral copper(II) complexes of 3-(2-naphthyl)-l -alanine-derived amides are highly effective catalysts for the enantio- and site-selective α-fluorination of N-(α-arylacetyl) and N-(α-alkylacetyl) 3,5-dimethylpyrazoles. The substrate scope of the transformation is very broad (25 examples including a quaternary α-fluorinated α-amino acid derivative). α-Fluorinated products were converted into the corresponding esters, secondary amides, tertiary amides, ketones, and alcohols with almost no epimerization in high yield. 相似文献
405.
406.
Daniel Bafaluy Zoritsa Georgieva Kilian Muiz 《Angewandte Chemie (International ed. in English)》2020,59(34):14241-14245
Iodine catalysis was developed for aliphatic fluorination through light‐promoted homolytic C?H bond cleavage. The intermediary formation of amidyl radicals enables selective C?H functionalization via carbon‐centered radicals. For the subsequent C?F bond formation, previous methods have typically been limited by a requirement for electrophilic fluorine reagents. We here demonstrate that the intermediary instalment of a carbon–iodine bond sets the stage for an umpolung, thereby establishing an unprecedented nucleophilic fluorination pathway. 相似文献
407.
Chenyang Wang Yongliang Tu Ding Ma Carsten Bolm 《Angewandte Chemie (International ed. in English)》2020,59(33):14134-14137
Reactions of difluoroiodotoluene with NH‐sulfoximines provide new hypervalent iodine(III) reagents, which photocatalytically transfer a fluoro and a sulfoximidoyl group onto styrenes with high regioselectivity. The substrate scope is broad with respect to both sulfoximines and olefins. Following an operationally simple protocol, a large library of fluorine‐containing N‐functionalized sulfoximines can be accessed. Results from mechanistic investigations revealed the importance of radical intermediates. 相似文献
408.
Silver‐Catalyzed Oxidative Activation of Benzylic CH Bonds for the Synthesis of Difluoromethylated Arenes 下载免费PDF全文
Peng Xu Shuo Guo Liyan Wang Prof. Dr. Pingping Tang 《Angewandte Chemie (International ed. in English)》2014,53(23):5955-5958
A mild and catalytic method to form difluoromethylated arenes through the activation of benzylic C? H bonds has been developed. Utilizing AgNO3 as the catalyst, various arenes with diverse functional groups undergo activation/fluorination of benzylic C? H bonds with commercially available Selectfluor reagent as a source of fluorine in aqueous solution. The reaction is operationally simple and amenable to gram‐scale synthesis. 相似文献
409.
Aileen P. LothianChristopher A. Ramsden Maxine M. ShawRachel G. Smith 《Tetrahedron》2011,67(15):2788-2793
Reaction of aryltrimethylsilanes with xenon difluoride in C6F6/Pyrex® at room temperature gives aryl fluorides in good yield. The reaction is inhibited when acetonitrile is used as solvent but proceeds well in CFCl3/Pyrex® or CH2Cl2/Pyrex®. Pyrex® appears to be a very effective heterogeneous catalyst for this ipso-fluorination. The reaction does not proceed in PTFE, quartz, soda glass or glassy-carbon flasks or Pyrex® flasks pre-rinsed with 2 M NaOH. Aryltrimethylstannanes and arylboronic acids and their esters do not undergo ipso-fluorination under similar conditions. Plausible mechanisms involving electrophilic addition of polarised xenon difluoride [FXeδ+?F→Pyrexδ−] followed by ligand coupling are discussed. 相似文献
410.
The fluorination and hydrogenation reactions on (6, 6) and (10, 0) single-walled carbon nanotubes (SWCNTs) have been examined
via computing the reaction energy for the chemisorption. The examined nanotubes have comparable lengths and diameters, with
or without Stone-Wales defects on the sidewall. The two fluorine or hydrogen atoms are anchored to the external walls of the
SWCNTs. The computed chemisorption energies of these virtual reactions reveal that the fluorination and hydrogenation of the
nanotubes are moderately sensitive to the nanotube chirality and the sidewall topology, and the (10, 0) SWCNT with Stone-Wales
defect can be easily fluorinated and hydrogenated.
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