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Zhonglin Liu Haiwen Xiao Benxiang Zhang Haigen Shen Lin Zhu Chaozhong Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2532-2535
Reported herein is an unprecedented protocol for trifluoromethylation of unactivated aliphatic C(sp3)?H bonds. With Cu(OTf)2 as the catalyst, the reaction of N‐fluoro‐substituted carboxamides (or sulfonamides) with Zn(CF3)2 complexes provides the corresponding δ‐trifluoromethylated carboxamides (or sulfonamides) in satisfactory yields under mild reaction conditions. A radical mechanism involving 1,5‐hydrogen atom transfer of N‐radicals followed by CF3‐transfer from CuII?CF3 complexes to the thus formed alkyl radicals is proposed. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(9):2475-2479
In the presence of Ni0/PCy3, styrene was found to participate in oxidative cyclization with tetrafluoroethylene, thus leading to the corresponding nickelacycle with a unique η3‐π‐benzyl structure. In addition, the flexibility of the coordination mode in the η3‐benzyl moiety allowed the partially fluorinated nickelacycle to undergo unprecedented amine‐induced α‐fluorine elimination, thus leading to the construction of a fluorinated cyclobutyl skeleton. 相似文献
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Melissa A. Ashley Chiaki Yamauchi John C. K. Chu Shinya Otsuka Hideki Yorimitsu Tomislav Rovis 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(12):4042-4046
The synthetic utility of tertiary amines to oxidatively generate α‐amino radicals is well established, however, primary amines remain challenging because of competitive side reactions. This report describes the site‐selective α‐functionalization of primary amine derivatives through the generation of α‐amino radical intermediates. Employing visible‐light photoredox catalysis, primary sulfonamides are coupled with electron‐deficient alkenes to efficiently and mildly construct C?C bonds. Interestingly, a divergence between intermolecular hydrogen‐atom transfer (HAT) catalysis and intramolecular [1,5] HAT was observed through precise manipulation of the protecting group. This dichotomy was leveraged to achieve excellent α/δ site‐selectivity. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(25):7306-7310
Direct alkylation of a methyl group, on di‐ and trisubstituted ureas, with terminal alkenes by C(sp3)−H bond activation proceeded in the presence of a hydroxoiridium/bisphosphine catalyst to give high yields of the corresponding addition products. The hydroxoiridium/bisphosphine complex generates an amidoiridium intermediate by reaction with ureas having an N−H bond. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(35):10705-10708
By using mechanistic insight, a new ligand (EPhos) for the palladium‐catalyzed C−N cross‐coupling between primary amines and aryl halides has been developed. Employing an isopropoxy group at the C3‐position favors the C‐bound isomer of the ligand‐supported palladium(II) complexes and leads to significantly improved reactivity. The use of a catalyst system based on EPhos with NaOPh as a mild homogeneous base proved to be very effective in the formation of 4‐arylaminothiazoles and highly functionalized 2‐arylaminooxazoles. Previously, these were not readily accessible using palladium catalysis. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(48):15634-15637
Presented is a novel intermolecular radical trifluoromethylfluorosulfonylation of unactivated alkenes under mild reaction conditions with good functional‐group tolerance in the most atom‐economic manner by using readily available Ag(O2CCF2SO2F) and N ‐fluorobenzenesulfonimide (NFSI). Both the trifluoromethyl and sulfonyl groups in the products originate from Ag(O2CCF2SO2F). 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(52):16872-16876
A rhodium(II)‐catalyzed reaction of newly prepared 4‐acyl‐1‐sulfonyl‐1,2,3‐triazoles with benzene, and its derivatives, is investigated. Acceptor/acceptor carbenoids generated from 4‐acyltriazoles undergo selective insertion at aromatic C(sp2)−H bonds in the presence of benzylic C(sp3)−H bonds to produce N ‐sulfonylenaminones. 相似文献
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Peng‐Fei Dai Xiao‐Shan Ning Hua Wang Xian‐Chao Cui Jie Liu Jian‐Ping Qu Yan‐Biao Kang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(16):5446-5449
Organic chemists now can construct carbon–carbon σ‐bonds selectively and sequentially, whereas methods for the selective cleavage of carbon–carbon σ‐bonds, especially for unreactive hydrocarbons, remain limited. Activation by ring strain, directing groups, or in the presence of a carbonyl or a cyano group is usually required. In this work, by using a sequential strategy site‐selective cleavage and borylation of C(aryl)?CH3 bonds has been developed under directing group free and transition metal free conditions. Methyl groups of various arenes are selectively cleaved and replaced by boryl groups. Mechanistic analysis suggests that it proceeds by a sequential intermolecular oxidation and coupling of a transient aryl radical, generated by radical decarboxylation, involving a pyridine‐stabilized persistent boryl radical. 相似文献
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Isaac Chogii Jon T. Njardarson 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(46):13910-13914
An asymmetric [3+2] annulation reaction to form 3‐pyrroline products is reported. Upon treatment with lithium diisopropylamide, readily available ethyl 4‐bromocrotonate is deprotonated and trapped with Ellman imines selectively at the α‐position to yield enantiopure 3‐pyrroline products. This new method is compatible with aryl, alkyl, and vinyl imines. The efficacy of the method is showcased by short asymmetric total syntheses of (−)‐supinidine, (−)‐isoretronecanol, and (+)‐elacomine. This novel annulation approach also works for an aldehyde, thus providing access to a 2,5‐dihydrofuran product in a single step from simple precursors. By modifying the structure of the carbanion nucleophile, an asymmetric vinylogous aza‐Darzens reaction can be realized. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(1):312-315
Selective bromination of γ‐methylene C(sp3)−H bonds of aliphatic amides and δ‐methylene C(sp3)−H bonds of nosyl‐protected alkyl amines are developed using NBS as the brominating reagent and catalytic amount of CuII/phenanthroline complexes as the catalyst. Aryl and benzylic C−H bonds at other locations remain intact during this directed radical abstraction reaction. 相似文献
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Dong Jing Cong Lu Zhuo Chen Songyang Jin Lijuan Xie Ziyi Meng Zhishan Su Ke Zheng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(41):14808-14814
Reported herein is a visible‐light‐driven intramolecular C?N cross‐coupling reaction under mild reaction conditions (metal‐ and photocatalyst‐free, at room temperature) via a long‐lived photoactive photoisomer complex. This strategy was used to rapidly prepare the N‐substituted polycyclic quinazolinone derivatives with a broad substrate scope (>50 examples) and further exploited to synthesize the natural products tryptanthrin, rutaecarpine, and their analogues. The success of gram‐scale synthesis and solar‐driven transformation, as well as promising tumor‐suppressing biological activity, proves the potential of this strategy for practical applications. Mechanistic investigations, including control experiments, DFT calculations, UV‐vis spectroscopy, EPR, and X‐ray single‐crystal structure of the key intermediate, provides insight into the mechanism. 相似文献
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Dengke Ma Zhihan Zhang Min Chen Zhenyang Lin Jianwei Sun 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(44):16063-16068
Described here is a direct catalytic asymmetric functionalization of unactivated alkyl indoles using organocatalysis. In the presence of an effective chiral urea catalyst and a phosphoric acid additive, the intermolecular C?C bond formation between alkyl indoles and trifluoropyruvates proceeded with high efficiency and enantiocontrol. Unlike previous asymmetric C(sp3?H) functionalizations of α‐azaarenes, this process does not require the use of either a strong base or an electron‐deficient substrate. The excellent enantiocontrol is particularly noteworthy in view of the severe background reaction as well as the complete inability of other types of catalysts evaluated. Control experiments, kinetic studies, and DFT calculations provided important insights into the mechanism. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(43):13509-13513
The first oxidative C(sp3)−H/C(sp3)−H cross‐dehydrogenative coupling (CDC) reaction promoted by an internal oxidant is reported. This copper‐catalyzed CDC reaction of oxime acetates and trifluoromethyl ketones provides a simple and efficient approach towards 2‐trifluoromethyldihydropyrrol‐2‐ol derivatives in a highly diastereoselective manner by cascade C(sp3)−C(sp3) bond formation and cyclization. These products were further transformed into various significant and useful trifluoromethylated heterocyclic compounds, such as trifluoromethylated furan, thiophene, pyrrole, dihydropyridazine, and pyridazine derivatives. A trifluoromethylated analogue of an Aβ42 lowering agent was also synthesized smoothly. Preliminary mechanistic studies indicated that this reaction involves a copper(I)/copper(III) catalytic cycle with the oxime acetate acting as an internal oxidant. 相似文献
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Intermolecular Amination of Unactivated C(sp3)−H Bonds with Cyclic Alkylamines: Formation of C(sp3)−N Bonds through Copper/Oxygen‐Mediated C(sp3)−H/N−H Activation 下载免费PDF全文
Quan Gou Yu‐Wen Yang Zi‐Ning Liu Prof. Jun Qin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(45):16057-16061
The first example of intermolecular amination of unactivated C(sp3)?H bonds by cyclic alkylamines mediated by Cu(OAc)2/O2 is reported. This method avoids the use of benzoyloxyamines as the aminating reagent, which are normally prepared from alkylamines in extra steps. A variety of unnatural β2, 2‐amino acid analogues are synthesized by this simple and efficient procedure. This approach offers a solution to the previous unmet challenge of C(sp3)?H/N?H activation for the formation of C(sp3)?N bonds. 相似文献