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1.
《Angewandte Chemie (International ed. in English)》2017,56(9):2478-2481
Carbon–carbon bond cleavage/functionalization is synthetically valuable, and selective carbonyl−C(sp3) bond cleavage/alkynylation presents a new perspective in constructing ynamides, ynoates, and ynones. Reported here is the first alkoxyl‐radical‐enabled carbonyl−C(sp3) bond cleavage/alkynylation reaction by photoredox catalysis. The use of novel cyclic iodine(III) reagents are essential for β‐carbonyl alkoxyl radical generation from β‐carbonyl alcohols, including alcohols with high redox potential ( >2.2 V vs. SCE in MeCN). β‐Amide, β‐ester, and β‐ketone alcohols yield ynamides, ynoates, and ynones, respectively, for the first time, with excellent regio‐ and chemoselectivity under mild reaction conditions. 相似文献
2.
α‐Aminoxy‐Acid‐Auxiliary‐Enabled Intermolecular Radical γ‐C(sp3)−H Functionalization of Ketones
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Dr. Heng Jiang Prof. Dr. Armido Studer 《Angewandte Chemie (International ed. in English)》2018,57(6):1692-1696
A method for site‐specific intermolecular γ‐C(sp3)?H functionalization of ketones has been developed using an α‐aminoxy acid auxiliary applying photoredox catalysis. Regioselective activation of an inert C?H bond is achieved by 1,5‐hydrogen atom abstraction by an oxidatively generated iminyl radical. Tertiary and secondary C‐radicals thus formed at the γ‐position of the imine functionality undergo radical conjugate addition to various Michael acceptors to provide, after reduction and imine hydrolysis, the corresponding γ‐functionalized ketones. 相似文献
3.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(9):2518-2521
Carbon–carbon bond cleavage/functionalization is synthetically valuable, and selective carbonyl−C(sp3) bond cleavage/alkynylation presents a new perspective in constructing ynamides, ynoates, and ynones. Reported here is the first alkoxyl‐radical‐enabled carbonyl−C(sp3) bond cleavage/alkynylation reaction by photoredox catalysis. The use of novel cyclic iodine(III) reagents are essential for β‐carbonyl alkoxyl radical generation from β‐carbonyl alcohols, including alcohols with high redox potential ( >2.2 V vs. SCE in MeCN). β‐Amide, β‐ester, and β‐ketone alcohols yield ynamides, ynoates, and ynones, respectively, for the first time, with excellent regio‐ and chemoselectivity under mild reaction conditions. 相似文献
4.
Daisuke Uraguchi Yuto Tsuchiya Tsuyoshi Ohtani Takafumi Enomoto Shigeyuki Masaoka Daisuke Yokogawa Takashi Ooi 《Angewandte Chemie (International ed. in English)》2020,59(9):3665-3670
Unlike carbonyl compounds, it has long been common understanding that excited imines show virtually no photoreactivity, and hence their properties and potential utility in chemical science remain largely unexplored. Now, a strategy is presented for eliciting latent photoreactivity of imines based on the introduction of a donor–acceptor (D‐A) structure to extend the lifetime of their photoexcited states. A series of spectroscopic analyses and density functional theory calculations reveal unique photophysical properties of the D‐A‐type imines. Furthermore, the reactivity of the D‐A‐type imines is demonstrated by using them as a photoredox catalyst for atom‐transfer radical addition. These findings illuminate a previously neglected chemical space in the field of photochemistry, which will be exploited by taking advantage of the inherent structural modularity of imines. 相似文献
5.
Dr. Xingwei Guo Prof. Dr. Oliver S. Wenger 《Angewandte Chemie (International ed. in English)》2018,57(9):2469-2473
The excitation of a RuII photosensitizer in the presence of ascorbic acid leads to the reduction of iminium ions to electron‐rich α‐aminoalkyl radical intermediates, which are rapidly converted into reductive amination products by thiol‐mediated hydrogen atom transfer (HAT). As a result, the reductive amination of carbonyl compounds with amines by photoredox catalysis proceeds in good to excellent yields and with broad substrate scope and good functional group tolerance. The three key features of this work are 1) the rapid interception of electron‐rich α‐aminoalkyl radical intermediates by polarity‐matched HAT in a photoredox reaction, 2) the method of reductive amination by photoredox catalysis itself, and 3) the application of this new method for temporally and spatially controlled reactions on a solid support, as demonstrated by the attachment of a fluorescent dye on an activated cellulose support by photoredox‐catalyzed reductive amination. 相似文献
6.
Room Temperature CP Bond Formation Enabled by Merging Nickel Catalysis and Visible‐Light‐Induced Photoredox Catalysis
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Jun Xuan Ting‐Ting Zeng Prof. Dr. Jia‐Rong Chen Dr. Liang‐Qiu Lu Prof. Dr. Wen‐Jing Xiao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(13):4962-4965
A novel and efficient C?P bond formation reaction of diarylphosphine oxides with aryl iodides was achieved by combining nickel catalysis and visible‐light‐induced photoredox catalysis. This dual‐catalytic reaction showed a broad substrate scope, excellent functional group tolerance, and afforded the corresponding products in good to excellent yields. Compared with the previously reported use of photoredox/nickel dual catalysis in the construction of C?C bonds, the methodology described herein was observed to be the first to allow for C‐heteroatom bond formation. 相似文献
7.
Catalytic Asymmetric C
−H Functionalization under Photoredox Conditions by Radical Translocation and Stereocontrolled Alkene Addition
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Chuanyong Wang Dr. Klaus Harms Prof. Dr. Eric Meggers 《Angewandte Chemie (International ed. in English)》2016,55(43):13495-13498
This work demonstrates how photoredox‐mediated C(sp3)?H activation through radical translocation can be combined with asymmetric catalysis. Upon irradiation with visible light, α,β‐unsaturated N‐acylpyrazoles react with N‐alkoxyphthalimides in the presence of a rhodium‐based chiral Lewis acid catalyst and the photosensitizer fac‐[Ir(ppy)3] to provide a C?C bond‐formation product with high enantioselectivity (up to 97 % ee) and, where applicable, with some diastereoselectivity (3.0:1 d.r.). Mechanistically, the synthetic strategy exploits a radical translocation (1,5‐hydrogen transfer) from an oxygen‐centered to a carbon‐centered radical with a subsequent stereocontrolled radical alkene addition. 相似文献
8.
Visible‐Light‐Induced Decarboxylative Functionalization of Carboxylic Acids and Their Derivatives
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Dr. Jun Xuan Prof. Dr. Zhao‐Guo Zhang Prof. Dr. Wen‐Jing Xiao 《Angewandte Chemie (International ed. in English)》2015,54(52):15632-15641
Visible‐light‐induced radical decarboxylative functionalization of carboxylic acids and their derivatives has recently received considerable attention as a novel and efficient method to create C? C and C? X bonds. Generally, this visible‐light‐promoted decarboxylation process can smoothly occur under mild reaction conditions with a broad range of substrates and an excellent functional‐group tolerance. The radical species formed from the decarboxylation step can participate in not only single photocatalytic transformations, but also dual‐catalytic cross‐coupling reactions by combining photoredox catalysis with other catalytic processes. Recent advances in this research area are discussed herein. 相似文献
9.
Qixue Qin Heng Jiang Zhentao Hu Daan Ren Shouyun Yu 《Chemical record (New York, N.Y.)》2017,17(8):754-774
Visible‐light photoredox catalysis has been successfully used in the functionalization of inert C?H bonds including C(sp2)‐H bonds of arenes and C(sp3)‐H bonds of aliphatic compounds over the past decade. These transformations are typically promoted by the process of single‐electron‐transfer (SET) between substrates and photo‐excited photocatalyst upon visible light irradiation (household bulbs or LEDs). Compared with other synthetic strategies, such as the transition‐metal catalysis and traditional radical reactions, visible‐light photoredox approach has distinct advantages in terms of operational simplicity and practicability. Versatile direct functionalization of inert C(sp2)‐H and C(sp3)‐H bonds including alkylation, trifluoromethylation, arylation and amidation, has been achieved using this practical strategy. 相似文献
10.
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
11.
Danqing Zheng Armido Studer 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(44):15950-15954
An enantioselective three‐component radical reaction of quinolines or pyridines with enamides and α‐bromo carbonyl compounds by dual photoredox and chiral Brønsted acid catalysis is presented. A range of valuable chiral γ‐amino‐acid derivatives are accessible in high chemo‐, regio‐, and enantioselectivity from simple, readily available starting materials under mild reaction conditions. Using the same strategy, the asymmetric synthesis of 1,2‐diamine derivatives is also reported. 相似文献
12.
Iron‐Carbonyl‐Catalyzed Redox‐Neutral [4+2] Annulation of N−H Imines and Internal Alkynes by C−H Bond Activation
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Teng Jia Chongyang Zhao Dr. Ruoyu He Prof. Dr. Hui Chen Prof. Dr. Congyang Wang 《Angewandte Chemie (International ed. in English)》2016,55(17):5268-5271
Stoichiometric C?H bond activation of arenes mediated by iron carbonyls was reported by Pauson as early as in 1965, yet the catalytic C?H transformations have not been developed. Herein, an iron‐catalyzed annulation of N?H imines and internal alkynes to furnish cis‐3,4‐dihydroisoquinolines is described, and represents the first iron‐carbonyl‐catalyzed C?H activation reaction of arenes. Remarkablely, this is also the first redox‐neutral [4+2] annulation of imines and alkynes proceeding by C?H activation. The reaction also features only cis stereoselectivity and excellent atom economy as neither base, nor external ligand, nor additive is required. Experimental and theoretical studies reveal an oxidative addition mechanism for C?H bond activation to afford a dinuclear ferracycle and a synergetic diiron‐promoted H‐transfer to the alkyne as the turnover‐determining step. 相似文献
13.
《中国化学》2017,35(10):1491-1500
In recent years, a methodology merging photoredox catalysis with organocatalysis termed “photoredox organocatalysis” has emerged to allow the direct, selective and efficient functionalization of the α /β ‐C of carbonyl compounds under mild reaction condition. In this review, photophysics background of photoredox catalysis is introduced, followed by a report on recent advances in direct α ‐ and β ‐functionalization of carbonyls with photoredox organocatalysis methodology. With this different reaction modes, valuable synthetic targets including different α /β ‐functionalized carbonyls are accessible. 相似文献
14.
Jill B. Williamson Sally E. Lewis Robert R. Johnson Irene M. Manning Frank A. Leibfarth 《Angewandte Chemie (International ed. in English)》2019,58(26):8654-8668
Synthetic manipulation of polymer substrates is one of the oldest and most reliable methods to increase the functional diversity of soft materials. Modifying the chemical structure of polymers that are already produced on a commodity scale leverages the current high‐volume and low‐cost production of commodity plastics for the discovery of modern materials. A myriad of polymer C?H functionalization methods have been developed which enable the modification of material properties on both a laboratory and industrial scale. More recently, driven by advances in C?H activation, photoredox catalysis, and radical chemistry, chemoselective approaches have emerged as a means to impart precise functionality onto commodity polymer substrates. This Review discusses the historical significance of and contemporary advances in the C?H functionalization of commodity polymers. The conceptual approach outlined herein presents exciting new directions for the field, including increasing the value of otherwise pervasive materials, uncovering entirely new material properties, and a viable path to upcycle post‐consumer plastic waste. 相似文献
15.
Kai Guo Zhongchao Zhang Anding Li Yuanhe Li Jun Huang Zhen Yang 《Angewandte Chemie (International ed. in English)》2020,59(28):11660-11668
Photoredox‐catalyzed isomerization of γ‐carbonyl‐substituted allylic alcohols to their corresponding carbonyl compounds was achieved for the first time by C?H bond activation. This catalytic redox‐neutral process resulted in the synthesis of 1,4‐dicarbonyl compounds. Notably, allylic alcohols bearing tetrasubstituted olefins can also be transformed into their corresponding carbonyl compounds. Density functional theory calculations show that the carbonyl group at the γ‐position of allylic alcohols are beneficial to the formation of their corresponding allylic alcohol radicals with high vertical electron affinity, which contributes to the completion of the photoredox catalytic cycle. 相似文献
16.
Rueping M Nachtsheim BJ Ieawsuwan W Atodiresei I 《Angewandte Chemie (International ed. in English)》2011,50(30):6706-6720
Recently, chiral highly acidic Brønsted acids have emerged as powerful catalysts for enantioselective C C and C X bond‐forming reactions. Their strong acidity renders them valuable tools for the activation of imines, carbonyl compounds, and other weakly basic substrates. As a result, new perspectives are opened and highly stereoselective transformations based on the concept of chiral contact‐ion‐pair catalysis can be realized. This Minireview gives an overview of the design and application of these new organocatalysts and presents recent results in this rapidly growing field. 相似文献
17.
Carbon‐Centered Radical Addition to OC of Amides or Esters as a Route to CO Bond Formations
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Dong Liu Shan Tang Hong Yi Dr. Chao Liu Xiaotian Qi Prof. Yu Lan Prof. Aiwen Lei 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(47):15605-15610
Among various types of radical reactions, the addition of carbon radicals to unsaturated bonds is a powerful tool for constructing new chemical bonds, in which the typical applied unsaturated substrates include alkenes, alkynes and imines. Carbonyl is perhaps the most common unsaturated group in nature. This work demonstrates a novel C?O bond formation through carbon‐centered radical addition to the carbonyl oxygen of amide or ester, in which amide and ester groups are easily activated through the radical process. EPR spectroscopy and radical clock experiments support the radical process for this transformation, and density functional theory (DFT) calculations support the possibility of carbon‐centered radical addition to the carbonyl oxygen of amides or esters. 相似文献
18.
Rick C. Betori Catherine M. May Karl A. Scheidt 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(46):16642-16646
Chemical transformations that install heteroatoms into C?H bonds are of significant interest because they streamline the construction of value‐added small molecules. Direct C?H oxyfunctionalization, or the one step conversion of a C?H bond to a C?O bond, could be a highly enabling transformation due to the prevalence of the resulting enantioenriched alcohols in pharmaceuticals and natural products,. Here we report a single‐flask photoredox/enzymatic process for direct C?H hydroxylation that proceeds with broad reactivity, chemoselectivity and enantioselectivity. This unified strategy advances general photoredox and enzymatic catalysis synergy and enables chemoenzymatic processes for powerful and selective oxidative transformations. 相似文献
19.
One‐Pot Tandem Photoredox and Cross‐Coupling Catalysis with a Single Palladium Carbodicarbene Complex
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Yu‐Cheng Hsu Vincent C.‐C. Wang Ka‐Chun Au‐Yeung Chung‐Yu Tsai Chun‐Chi Chang Bo‐Chao Lin Prof. Yi‐Tsu Chan Prof. Chao‐Ping Hsu Prof. Glenn P. A. Yap Prof. Titel Jurca Prof. Tiow‐Gan Ong 《Angewandte Chemie (International ed. in English)》2018,57(17):4622-4626
The combination of conventional transition‐metal‐catalyzed coupling (2 e? process) and photoredox catalysis (1 e? process) has emerged as a powerful approach to catalyze difficult cross‐coupling reactions under mild reaction conditions. Reported is a palladium carbodicarbene (CDC) complex that mediates both a Suzuki–Miyaura coupling and photoredox catalysis for C?N bond formation upon visible‐light irradiation. These two catalytic pathways can be combined to promote both conventional transition‐metal‐catalyzed coupling and photoredox catalysis to mediate C?H arylation under ambient conditions with a single catalyst in an efficient one‐pot process. 相似文献
20.
Anna V. Davies Keegan P. Fitzpatrick Rick C. Betori Karl A. Scheidt 《Angewandte Chemie (International ed. in English)》2020,59(23):9143-9148
As a key element in the construction of complex organic scaffolds, the formation of C?C bonds remains a challenge in the field of synthetic organic chemistry. Recent advancements in single‐electron chemistry have enabled new methods for the formation of various C?C bonds. Disclosed herein is the development of a novel single‐electron reduction of acyl azoliums for the formation of ketones from carboxylic acids. Facile construction of the acyl azolium in situ followed by a radical–radical coupling was made possible merging N‐heterocyclic carbene (NHC) and photoredox catalysis. The utility of this protocol in synthesis was showcased in the late‐stage functionalization of a variety of pharmaceutical compounds. Preliminary investigations using chiral NHCs demonstrate that enantioselectivity can be achieved, showcasing the advantages of this protocol over alternative methodologies. 相似文献