共查询到20条相似文献，搜索用时 15 毫秒
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Arunachalam Sagadevan Michael F. Greaney 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(29):9931-9935
Ruthenium‐catalyzed meta‐C?H activation of arenes at room temperature is reported to proceed under blue‐light irradiation. A variety of heteroarenes are compatible with this photochemical process, which leads to the corresponding meta C?C coupling products in good to very good yields. Initial mechanistic studies suggest a single‐electron transfer process occurs between a photoexcited RuII‐cyclometalated complex and alkyl halides, enabling meta‐C?H functionalization reaction via carbon‐centered radicals. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(7):1903-1906
Despite recent progress in the catalytic transformation of inert phenol derivatives as alternatives to aryl halides and triflates, attempts at the cross‐coupling of inert phenol derivatives with the C−H bonds of arenes have met with limited success. Herein, we report the rhodium‐catalyzed cross‐coupling of aryl carbamates with arenes bearing a convertible directing group. The key to success is the use of an in situ generated rhodium bis(N‐heterocyclic carbene) species as the catalyst, which can promote activation of the inert C(sp2)−O bond in aryl carbamates. 相似文献
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Shangda Li Hang Wang Yunxiang Weng Gang Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(51):18673-18678
The first example of carboxy group assisted, remote‐selective C(sp2)?H activation with a PdII catalyst has been developed and proceeds through a possible κ2 coordination of the carboxy group, thus suppressing the ortho‐C?H activation through κ1 coordination. Besides meta‐C?H olefination, direct meta‐arylation of hydrocinnamic acid derivatives with low‐cost aryl iodides has been achieved for the first time. These findings may motivate the exploration of novel reactivities of the carboxy assisted C?H activation reactions with intriguing selectivities. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(3):892-897
The formation of aryl C−S bonds is an important chemical transformation because aryl sulfides are valuable building blocks for the synthesis of biologically and pharmaceutically active molecules and organic materials. Aryl sulfides have traditionally been synthesized through the transition‐metal‐catalyzed cross‐coupling of aryl halides with thiols. However, the aryl halides used are usually bromides and iodides; readily available, low‐cost aryl chlorides often not reactive enough. Furthermore, the deactivation of transition‐metal catalysts by thiols has forced chemists to use high catalyst loadings, specially designed ligands, high temperatures, and/or strong bases, thus leading to high costs and the incompatibility of some functional groups. Herein, we describe a simple and efficient visible‐light photoredox arylation of thiols with aryl halides at room temperature. More importantly, various aryl chlorides are also effective arylation reagents under the present conditions. 相似文献
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Nathaniel Corrigan Jonathan Yeow Peter Judzewitsch Jiangtao Xu Cyrille Boyer 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(16):5224-5243
The application of photochemistry to polymer and material science has led to the development of complex yet efficient systems for polymerization, polymer post‐functionalization, and advanced materials production. Using light to activate chemical reaction pathways in these systems not only leads to exquisite control over reaction dynamics, but also allows complex synthetic protocols to be easily achieved. Compared to polymerization systems mediated by thermal, chemical, or electrochemical means, photoinduced polymerization systems can potentially offer more versatile methods for macromolecular synthesis. We highlight the utility of light as an energy source for mediating photopolymerization, and present some promising examples of systems which are advancing materials production through their exploitation of photochemistry. 相似文献
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Thomas O. Ronson Evelien Renders Ben F. Van&#x;Steijvoort Xubin Wang Clarence C. D. Wybon Hana Prokopcov Lieven Meerpoel Bert U. W. Maes 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(2):492-497
A new three‐component reductive arylation of amides with stable reactants (iPrOH and arylboronate esters), making use of a 2‐pyridinyl (Py) directing group, is described. The N‐Py‐amide substrates are readily prepared from carboxylic acids and PyNH2, and the resulting N‐Py‐1‐arylalkanamine reaction products are easily transformed into the corresponding chlorides by substitution of the HN‐Py group with HCl. The 1‐aryl‐1‐chloroalkane products allow substitution and cross‐coupling reactions. Therefore, a general protocol for the transformation of carboxylic acids into a variety of functionalities is obtained. The Py‐NH2 by‐product can be recycled. 相似文献
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Shuo Wu Xinxin Wu Dongping Wang Chen Zhu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(5):1513-1517
Regioselective incorporation of a particular functional group into aliphatic sites by direct activation of unreactive C?H bonds is of great synthetic value. Despite advances in radical‐mediated functionalization of C(sp3)?H bonds by a hydrogen‐atom transfer process, the site‐selective vinylation of remote C(sp3)?H bonds still remains underexplored. Reported herein is a new protocol for the regioselective vinylation of unactivated C(sp3)?H bonds. The remote C(sp3)?H activation is promoted by a C‐centered radical instead of the commonly used N and O radicals. The reaction possesses high product diversity and synthetic efficiency, furnishing a plethora of synthetically valuable E alkenes bearing tri‐/di‐/mono‐fluoromethyl and perfluoroalkyl groups. 相似文献
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Jompol Thongpaen Romane Manguin Vincent Dorcet Thomas Vives Carine Duhayon Marc Mauduit Olivier Basl 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(43):15388-15392
An efficient visible light induced rhodium(I)‐catalyzed regioselective borylation of aromatic C?H bonds is reported. The photocatalytic system is based on a single NHC?RhI complex capable of both harvesting visible light and enabling the bond breaking/forming at room temperature. The chelating nature of the NHC‐carboxylate ligand was critical to ensure the stability of the RhI complex and to provide excellent photocatalytic activities. Experimental mechanistic studies evidenced a photooxidative ortho C?H bond addition upon irradiation with blue LEDs, leading to a cyclometalated RhIII‐hydride intermediate. 相似文献
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Padon Chuentragool Dongari Yadagiri Taiki Morita Sumon Sarkar Marvin Parasram Yang Wang Vladimir Gevorgyan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(6):1808-1812
The Mizoroki–Heck reaction is one of the most efficient methods for alkenylation of aryl, vinyl, and alkyl halides. Given its innate nature, this protocol requires the employment of compounds possessing a halogen atom at the site of functionalization. However, the accessibility of organic molecules possessing a halogen atom at a particular site in aliphatic systems is extremely limited. Thus, a protocol that allows a Heck reaction to occur at a specific nonfunctionalized C(sp3)?H site is desirable. Reported here is a radical relay Heck reaction which allows selective remote alkenylation of aliphatic alcohols at unactivated β‐, γ‐, and δ‐C(sp3)?H sites. The use of an easily installed/removed Si‐based auxiliary enables selective I‐atom/radical translocation events at remote C?H sites followed by the Heck reaction. Notably, the reaction proceeds smoothly under mild visible‐light‐mediated conditions at room temperature, producing highly modifiable and valuable alkenol products from readily available alcohols feedstocks. 相似文献
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Laura Trump Agostinho Lemos Bndicte Lallemand Patrick Pasau Joël Mercier Christian Lemaire Andr Luxen Christophe Genicot 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(37):13283-13288
Despite a growing interest in CHF2 in medicinal chemistry, there is a lack of efficient methods for the insertion of CHF18F into druglike compounds. Herein described is a photoredox flow reaction for 18F‐difluoromethylation of N‐heteroaromatics that are widely used in medicinal chemistry. Following the two‐step synthesis for a new 18F‐difluoromethylation reagent, the photoredox reaction is completed within two minutes and proceeds by C?H activation, circumventing the need for pre‐functionalization of the substrate. The method is operationally simple and affords straightforward access to radiolabeled N‐heteroaromatics with high molar activity suitable for biological in vivo studies and clinical application. 相似文献
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