共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
Dr. Qiang Liu Hong Yi Jie Liu Yuhong Yang Xu Zhang Ziqi Zeng Prof. Aiwen Lei 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(16):5120-5126
Through the use of [Ru(bpy)3Cl2] (bpy=2,2′‐bipyridine) and [Ir(ppy)3] (ppy=phenylpyridine) as photocatalysts, we have achieved the first example of visible‐light photocatalytic radical alkenylation of various α‐carbonyl alkyl bromides and benzyl bromides to furnish α‐vinyl carbonyls and allylbenzene derivatives, prominent structural elements of many bioactive molecules. Specifically, this transformation is regiospecific and can tolerate primary, secondary, and even tertiary alkyl halides that bear β‐hydrides, which can be challenging with traditional palladium‐catalyzed approaches. The key initiation step of this transformation is visible‐light‐induced single‐electron reduction of C? Br bonds to generate alkyl radical species promoted by photocatalysts. The following carbon? carbon bond‐forming step involves a radical addition step rather than a metal‐mediated process, thereby avoiding the undesired β‐hydride elimination side reaction. Moreover, we propose that the Ru and Ir photocatalysts play a dual role in the catalytic system: they absorb energy from the visible light to facilitate the reaction process and act as a medium of electron transfer to activate the alkyl halides more effectively. Overall, this photoredox catalysis method opens new synthetic opportunities for the efficient alkenylation of alkyl halides that contain β‐hydrides under mild conditions. 相似文献
3.
Controlled Trifluoromethylation Reactions of Alkynes through Visible‐Light Photoredox Catalysis 下载免费PDF全文
Naeem Iqbal Jaehun Jung Sehyun Park Prof. Dr. Eun Jin Cho 《Angewandte Chemie (International ed. in English)》2014,53(2):539-542
The control of a reaction that can form multiple products is a highly attractive and challenging concept in synthetic chemistry. A set of valuable CF3‐containing molecules, namely trifluoromethylated alkenyl iodides, alkenes, and alkynes, were selectively generated from alkynes and CF3I by environmentally benign and efficient visible‐light photoredox catalysis. Subtle differences in the combination of catalyst, base, and solvent enabled the control of reactivity and selectivity for the reaction between an alkyne and CF3I. 相似文献
4.
Radical Fluoroalkylation of Isocyanides with Fluorinated Sulfones by Visible‐Light Photoredox Catalysis 下载免费PDF全文
Jian Rong Ling Deng Ping Tan Dr. Chuanfa Ni Dr. Yucheng Gu Prof. Dr. Jinbo Hu 《Angewandte Chemie (International ed. in English)》2016,55(8):2743-2747
The radical fluoroalkylation of isocyanides with fluorinated sulfones is enabled by visible‐light photoredox catalysis. A wide range of readily available mono‐, di‐, and trifluoromethyl heteroaryl sulfones can thus be used as efficient radical fluoroalkylation reagents under mild conditions. This method not only describes a new synthetic application of fluorinated sulfones, but also provides a new route to fluoroalkyl radicals. 相似文献
5.
A Desulfurative Strategy for the Generation of Alkyl Radicals Enabled by Visible‐Light Photoredox Catalysis 下载免费PDF全文
Dr. Fei Xue Falu Wang Jiazhen Liu Jiamei Di Qi Liao Huifang Lu Min Zhu Liping He Huan He Dr. Dan Zhang Dr. Hao Song Dr. Xiao‐Yu Liu Prof. Yong Qin 《Angewandte Chemie (International ed. in English)》2018,57(22):6667-6671
Herein, we present a new desulfurative method for generating primary, secondary, and tertiary alkyl radicals through visible‐light photoredox catalysis. A process that involves the generation of N‐centered radicals from sulfinamide intermediates, followed by subsequent fragmentation, is critical to forming the corresponding alkyl radical species. This strategy has been successfully applied to conjugate addition reactions that features mild reaction conditions, broad substrate scope (>60 examples), and good functional‐group tolerance. 相似文献
6.
Miguel Claros Felix Ungeheuer Federico Franco Vlad Martin‐Diaconescu Alicia Casitas Julio Lloret‐Fillol 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(15):4923-4928
The chemical inertness of abundant and commercially available alkyl chlorides precludes their widespread use as reactants in chemical transformations. Presented in this work is a metallaphotoredox methodology to achieve the catalytic intramolecular reductive cyclization of unactivated alkyl chlorides with tethered alkenes. The cleavage of strong C(sp3)?Cl bonds is mediated by a highly nucleophilic low‐valent cobalt or nickel intermediate generated by visible‐light photoredox reduction employing a copper photosensitizer. The high basicity and multidentate nature of the ligands are key to obtaining efficient metal catalysts for the functionalization of unactivated alkyl chlorides. 相似文献
7.
Alex Cartier Etienne Levernier Vincent Corc Takahide Fukuyama Anne‐Lise Dhimane Cyril Ollivier Ilhyong Ryu Louis Fensterbank 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(6):1803-1807
Primary, secondary, and tertiary alkyl radicals formed by the photocatalyzed oxidation of organosilicates underwent efficient carbonylation with carbon monoxide (CO) to give a variety of unsymmetrical ketones. This study introduces the possibility of radical carbonylation under a photooxidative regime. 相似文献
8.
Metal‐Free,Room‐Temperature,Radical Alkoxycarbonylation of Aryldiazonium Salts through Visible‐Light Photoredox Catalysis 下载免费PDF全文
Wei Guo Dr. Liang‐Qiu Lu Yue Wang Ya‐Ni Wang Jia‐Rong Chen Prof. Dr. Wen‐Jing Xiao 《Angewandte Chemie (International ed. in English)》2015,54(7):2265-2269
The first radical alkoxycarboxylation of aryldiazonium salts using CO gas through visible‐light‐induced photoredox catalysis (16 W blue LEDs) has been developed. This reaction is entirely metal‐free, is carried out at room temperature with a low loading of an organic dye as a photocatalyst (0.5 mol %), and provides a wide range of arylcarboxylic acid esters in high yields. Importantly, this photocatalytic system can be successfully extended to other carboxylation reactions. 相似文献
9.
Organic Photocatalytic Cyclization of Polyenes: A Visible‐Light‐Mediated Radical Cascade Approach 下载免费PDF全文
Zhongbo Yang Han Li Dr. Long Zhang Prof. Ming‐Tian Zhang Prof. Dr. Jin‐Pei Cheng Prof. Dr. Sanzhong Luo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(42):14723-14727
A visible‐light‐mediated, organic photocatalytic stereoselective radical cascade cyclization of polyprenoids is described. The desired cascade cyclization products are achieved in good yields and high stereoselectivities with eosin Y as photocatalyst in hexafluoro‐2‐propanol. The catalyst system is also suitable for 1,3‐dicarbonyl compounds, which require only catalytic amounts of LiBr to promote the formation of the corresponding enols. 相似文献
10.
Visible‐Light Photoredox‐Catalyzed C−H Difluoroalkylation of Hydrazones through an Aminyl Radical/Polar Mechanism 下载免费PDF全文
Pan Xu Guoqiang Wang Yuchen Zhu Weipeng Li Prof. Dr. Yixiang Cheng Prof. Dr. Shuhua Li Prof. Dr. Chengjian Zhu 《Angewandte Chemie (International ed. in English)》2016,55(8):2939-2943
An unprecedented visible‐light‐induced direct C?H bond difluoroalkylation of aldehyde‐derived hydrazones was developed. This reaction represents a new way to synthesize substituted hydrazones. The salient features of this reaction include difluorinated hydrazone synthesis rather than classical amine synthesis, extremely mild reaction conditions, high efficiency, wide substrate scope, ease in further transformations of the products, and one‐pot syntheses. Mechanistic analyses and theoretical calculations indicate that this reaction is enabled by a novel aminyl radical/polar crossover mechanism, with the aminyl radical being oxidized into the corresponding aminyl cation through a single electron transfer (SET) process. 相似文献
11.
Dual Catalysis Sees the Light: Combining Photoredox with Organo‐, Acid,and Transition‐Metal Catalysis 下载免费PDF全文
Dr. Jun‐Long Li Prof. Dr. Frank Glorius 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(14):3874-3886
The photoredox activation of organic substrates with visible light is a powerful methodology that generates reactive radical species under very mild conditions. When combined with another catalytic process in a dual catalytic system, novel, visible‐light‐promoted transformations have been realized that do not proceed using either catalyst in isolation. In this minireview, the state of the art in organic reactions mediated by dual catalytic systems merging photoredox activation with organo‐, acid or metal catalysis is discussed. 相似文献
12.
13.
14.
A Visible‐Light‐Mediated Radical Smiles Rearrangement and its Application to the Synthesis of a Difluoro‐Substituted Spirocyclic ORL‐1 Antagonist 下载免费PDF全文
Dr. James J. Douglas Haley Albright Martin J. Sevrin Dr. Kevin P. Cole Prof. Corey R. J. Stephenson 《Angewandte Chemie (International ed. in English)》2015,54(49):14898-14902
A visible‐light‐mediated radical Smiles rearrangement has been developed to address the challenging synthesis of the gem‐difluoro group present in an opioid receptor‐like 1 (ORL‐1) antagonist that is currently in development for the treatment of depression and/or obesity. This method enables the direct and efficient introduction of the difluoroethanol motif into a range of aryl and heteroaryl systems, representing a new disconnection for the synthesis of this versatile moiety. When applied to the target compound, the photochemical step could be conducted on 15 g scale using industrially relevant [Ru(bpy)3Cl2] catalyst loadings of 0.01 mol %. This transformation is part of an overall five‐step route to the antagonist that compares favorably to the current synthetic sequence and demonstrates, in this specific case, a clear strategic benefit of photocatalysis. 相似文献
15.
Long Huang Chen Zhu Liang Yi Huifeng Yue Rajesh Kancherla Magnus Rueping 《Angewandte Chemie (International ed. in English)》2020,59(1):457-464
Chemical transformations based on cascade reactions have the potential to simplify the preparation of diverse and architecturally complex molecules dramatically. Herein, we disclose an unprecedented and efficient method for the cross‐coupling of radical precursors, dienes, and electrophilic coupling partners via a photoredox‐ and nickel‐enabled cascade cross‐coupling process. The cascade reaction furnishes a diverse array of saturated carbo‐ and heterocyclic scaffolds, thus providing access to a quick gain in C?C bond saturation. 相似文献
16.
Fengjin Wu Dr. Leifeng Wang Prof. Dr. Jiean Chen Prof. Dr. David A. Nicewicz Prof. Dr. Yong Huang 《Angewandte Chemie (International ed. in English)》2018,57(8):2174-2178
Aldehydes are among the most versatile functional groups for synthetic chemistry. However, access to polysubstituted alkyl aldehydes is very limited and requires lengthy synthetic routes that involve multiple‐step functional‐group conversion. This paper reports a one‐step synthesis of polysubstituted aldehydes from readily available olefin substrates using visible‐light photoredox catalysis. Despite a number of competing reaction pathways, commercial styrenes react with vinyl ethers selectively in the presence of an acridinium salt photooxidant and a disulfide hydrogen‐atom‐transfer catalyst under blue LED irradiation. Alkyl aldehydes with different substitution patterns are prepared in good yields. This strategy can be applied to structurally sophisticated substrates. 相似文献
17.
Itaru Natori Shizue Natori 《Journal of polymer science. Part A, Polymer chemistry》2012,50(4):772-779
Synthesis of the polymer whose end is functionalized by fac‐Ir(ppy)3 (ppy = 2‐phenylpyridyl) was achieved by using (living) anionic polymerization of 1,3‐cyclohexadiene: the reaction of poly(1,3‐cyclohexadienyl)lithium (PCHDLi) with fac‐Ir(ppy)2(vppy) [vppy = 2‐(4‐vinylphenyl)pyridyl] resulted in nucleophilic attack of the carbanion in PCHDLi on the vinyl group of fac‐Ir(ppy)2(vppy) selectively. Complexation of the pyridyl ring protected the α‐carbons of fac‐Ir(ppy)2(vppy) from the reaction of the anionic polymer. The homopolymerization of fac‐Ir(ppy)2(vppy) did not occur, and only one molecule of fac‐Ir(ppy)2(vppy) reacted with the carbanion of PCHDLi and was selectively incorporated into an end of poly(1,3‐cyclohexadiene) (PCHD). Thus, the PCHD with fac‐Ir(ppy)3 end‐group was obtained with a well‐controlled and defined polymer structure and molecular weight. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
18.
《Angewandte Chemie (International ed. in English)》2017,56(35):10521-10524
Cleavage of unstrained C−C bonds under mild, redox‐neutral conditions represents a challenging endeavor which is accomplished here in the context of a flexible, visible‐light‐mediated, γ‐functionalization of amines. In situ generated C‐centered radicals are harvested in the presence of Michael acceptors, thiols and alkyl halides to efficiently form new C(sp3)−C(sp3), C(sp3)−H and C(sp3)−Br bonds, respectively. 相似文献
19.
Shuang Wang Wen‐Liang Jia Lin Wang Prof. Dr. Qiang Liu Prof. Dr. Li‐Zhu Wu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(39):13794-13798
A new domino reaction has been developed that allows the combination of styrenes and α‐alkyl ketone radicals to afford a wide array of polysubstituted furans in good to excellent yields under mild and simple reaction conditions. The key to success of this novel protocol is the use of photocatalyst fac‐Ir(ppy)3 and oxidant K2S2O8. Mechanistic studies by a radical scavenger and photoluminescence quenching suggest that a radical addition/oxidation pathway is operable. 相似文献
20.
Visible‐Light‐Mediated Decarboxylative Radical Additions to Vinyl Boronic Esters: Rapid Access to γ‐Amino Boronic Esters 下载免费PDF全文
Dr. Adam Noble Riccardo S. Mega Dr. Daniel Pflästerer Dr. Eddie L. Myers Prof. Dr. Varinder K. Aggarwal 《Angewandte Chemie (International ed. in English)》2018,57(8):2155-2159
The synthesis of alkyl boronic esters by direct decarboxylative radical addition of carboxylic acids to vinyl boronic esters is described. The reaction proceeds under mild photoredox catalysis and involves an unprecedented single‐electron reduction of an α‐boryl radical intermediate to the corresponding anion. The reaction is amenable to a diverse range of substrates, including α‐amino, α‐oxy, and alkyl carboxylic acids, thus providing a novel method to rapidly access boron‐containing molecules of potential biological importance. 相似文献