- Oxidative Annulation of 3-Aryl-2H-benzo[e][1,2,4]thiadiazine-1,1-dioxides with Aryl Aldehydes: An Easy Access to Hydroxyisoindolo[1,2-b] benzothiadiazinedioxide Scaffolds
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A novel and efficient approach has been developed for the synthesis of a diverse range of hydroxyisoindolo[1,2-b]benzothiadiazinedioxide derivatives through a sequential palladium catalyzed cross-dehydrogenative coupling (CDC) and intramolecular cyclizati
- Kumar, G. Ravi,Banik, Swarnayu,Ramesh, Boora,Sridhar, Balasubramanian,Venkata Subba Reddy, Basireddy
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- Metal-Free Oxidative Decarboxylative Acylation/Ring Expansion of Vinylcyclobutanols with α-Keto Acids by Visible Light Photoredox Catalysis
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A metal-free visible-light-mediated decarboxylative acylation/ring expansion of vinylcyclobutanols with α-keto acids has been developed. Hypervalent iodine reagent was found to be important for promoting decarboxylation of α-keto acids in this tandem radical process. This protocol has been successfully applied to synthesis of a variety of substituted 1,4-dicarbonyl compounds and tolerated some functional groups well.
- Zhang, Jin-Jiang,Cheng, Yuan-Bo,Duan, Xin-Hua
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- S-(Diethyl phosphonodifluoromethyl)Benzenesulfonothioate: A New Reagent for the Synthesis of SCF2PO(OEt)2-containing Molecules
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In this manuscript, the synthesis of an original SCF2PO(OEt)2-containing reagent was depicted. Thanks to the unique properties of this newly-designed source, an unprecedented transformation with aldehydes was conducted under radical
- Petit-Cancelier, Fabien,Fran?ois, Benjamin,Pannecoucke, Xavier,Couve-Bonnaire, Samuel,Besset, Tatiana
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- Aroylchlorination of 1,6-Dienes via a Photoredox Catalytic Atom-Transfer Radical Cyclization Process
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A method using aroyl chlorides as atom-transfer radical cyclization agents in a novel visible-light photocatalytic aroylchlorination reaction is developed. The overall transformation involves the formation of two new C-C bonds and one new C-Cl bond in a o
- Zhao, Quan-Sheng,Xu, Guo-Qiang,Liang, Hui,Wang, Zhu-Yin,Xu, Peng-Fei
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- The regioselective coupling of 2-arylquinazolinone C-H with aldehydes and benzyl alcohols under oxidative conditions
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The direct and regioselective palladium-catalyzed dehydrogenative coupling of aldehydes and benzyl alcohols with 2-aryl-quinazolinone C-H endowed with a quinazolinone nucleus, which is one of the most fascinating and vital core units, as an inherent directing group under oxidative conditions was developed. This atom/step economic aroylation offers an attractive handle and a very green approach for highly convergent and diversity-oriented synthetic modifications and the construction of vital molecules of therapeutic interest. This journal is
- Kshirsagar, Umesh A.,Waghmare, Deepali S.,Tambe, Shrikant D.
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- Decarboxylative cascade cyclization of α-keto acids with 2-cyano-3-arylaniline-derived acrylamides
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An oxidative decarboxylative cascade cyclization of α-keto acids with 2-cyano-3-arylaniline-derived acrylamides was developed. This cascade reaction exhibits a broad substrate scope, and provides an efficient access to carbonyl-containing pyrido[4,3,2-gh]
- Shang, Jia-Qi,Wang, Xiang-Xiang,Xin, Yangchun,Li, Yi,Zhou, Bin,Li, Ya-Min
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- Palladium-catalyzed late-stage mono-aroylation of the fully substituted pyrazoles via aromatic C–H bond activation
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The palladium-catalyzed late-stage aroylation of 4-methyl-1,5-diaryl-1H-pyrazole-3-carboxylates has been developed via direct and exclusive mono-Csp2–H bond activation with broad substrate scope and good functional group tolerance. A dual-core
- Chen, Miao-Miao,Shao, Ling-Yan,Lun, Li-Jun,Wu, Yu-Liang,Fu, Xiao-Pan,Ji, Ya-Fei
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- Diastereoselective Synthesis of Oxazoloisoindolinones via Cascade Pd-Catalyzed ortho-Acylation of N-Benzoyl α-Amino Acid Derivatives and Subsequent Double Intramolecular Cyclizations
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The first cascade diastereoselective synthesis of oxazoloisoindolinones via the palladium-catalyzed decarboxylative ortho-acylation of N-benzoyl α-amino acid derivatives followed by double intramolecular cyclizations has been demonstrated. This reaction, using α-amino acids as directing groups and α-oxocarboxylic acids as the acylation source, features a broad substrate scope, good functional group tolerance, high regioselectivity, and excellent diastereoselectivity.
- Jing, Kun,Wang, Xiang-Nan,Wang, Guan-Wu
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- Synthesis of Fused Pyran Derivatives via Visible-Light-Induced Cascade Cyclization of 1,7-Enynes with Acyl Chlorides
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A photocatalytic cascade cyclization of 1,7-enynes with acyl chlorides has been established. This method offers an operationally simple access to diverse fused pyran derivatives with a broad substrate scope in high yields from simple acyl chlorides via an acyl radical intermediate.
- Li, Chen-Guang,Xu, Guo-Qiang,Xu, Peng-Fei
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- Iron-Catalyzed Divergent Tandem Radical Annulation of Aldehydes with Olefins toward Indolines and Dihydropyrans
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Iron-catalyzed divergent tandem radical annulations of aldehydes with olefins are reported. The new strategy allows the rapid and efficient construction of various multifunctionlized indolines (R = Ar) and dihydropyrans (R = Me), which are significant skeletons in bioactive natural products and pharmaceuticals. The substituents of tertiary amines play vital roles to facilitate the desired transformation. Mechanistic studies on indoline formation disclose that the homolytic cleavage of the carbonyl C-H bond might be involved in the rate-determining step, while dissociation of the aromatic C-H bond was most likely included in the product-determining step.
- Lv, Leiyang,Qi, Longying,Guo, Qiaoxia,Shen, Baojian,Li, Zhiping
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- Visible-light-promoted catalyst-/additive-free synthesis of aroylated heterocycles in a sustainable solvent
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A general visible-light-induced catalyst-/additive-free strategy was developed for the construction of various aroylated heterocycles (55 examples, up to 95% yield, including modification of pharmaceuticals and natural products) such as thioflavones, benzimidazo[2,1-a]isoquinolin-6(5H)-ones, indolo[2,1-a]isoquinolin-6(5H)ones, quaternary 3,3-dialkyl 2-oxindoles, quinoxalin-2(1H)-ones, and benzo[e][1,2,3]oxathiazine 2,2-dioxides in a green solvent (dimethyl carbonate) under air and room temperature conditions. This practical acylation process was achieved using 4-acyl-1,4-dihydropyridines (acyl-DHPs) as acylating reagents under mild conditions, avoiding the use of catalysts, bases, additional oxidants, and traditional organic solvents. This journal is
- Zeng, Fan-Lin,Xie, Kun-Chen,Liu, Yu-Ting,Wang, He,Yin, Peng-Cheng,Qu, Ling-Bo,Chen, Xiao-Lan,Yu, Bing
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p. 1732 - 1737
(2022/03/07)
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- N-Heterocyclic-Carbene-Catalyzed C–H Acylation via Radical Relay
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A method of N-fluorocarboxamide-directed N-heterocyclic-carbene (NHC)-catalyzed benzylic C–H acylation with aldehydes via the hydrogen atom transfer strategy is disclosed. This transformation involves a sequence of single-electron transfer, 1,5-hydrogen a
- Liu, Shiwen,Man, Yunquan,Xu, Bo,Zeng, Xiaojun
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supporting information
p. 944 - 948
(2022/02/05)
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- Photocatalytic synthesis of tetra-substituted furans promoted by carbon dioxide
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We report a simple protocol for the transition metal-free, visible-light-driven conversion of 1,3-diketones to tetra-substituted furan skeleton compounds in carbon dioxide (CO2) atmosphere under mild conditions. It was found that CO2could be incorporated at the diketone enolic OH position, which was key to enabling the cleavage of a C-O bond during the rearrangement of a cyclopropane intermediate. This method allows for the same-pot construction of two isomers of the high-value tetra-substituted furan scaffold. The synthetic scope and preliminary mechanistic investigations are presented.
- K?nig, Burkhard,Ritu,Tian, Ya-Ming,Wang, Huaiju
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p. 241 - 246
(2022/01/06)
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- Aromatization as an Impetus to Harness Ketones for Metallaphotoredox-Catalyzed Benzoylation/Benzylation of (Hetero)arenes
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Herein we report ketones as feedstock materials in radical cross-coupling reactions under Ni/photoredox dual catalysis. In this approach, simple condensation first converts ketones into prearomatic intermediates that then act as activated radical sources for cross-coupling with aryl halides. Our strategy enables the direct benzylation/benzoylation of (hetero)arenes under mild reaction conditions with high functional group tolerance.
- Lee, Shao-Chi,Li, Li-Yun,Tsai, Zong-Nan,Lee, Yi-Hsin,Tsao, Yong-Ting,Huang, Pin-Gong,Cheng, Cheng-Ku,Lin, Heng-Bo,Chen, Ting-Wei,Yang, Chung-Hsin,Chiu, Cheng-Chau,Liao, Hsuan-Hung
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- N-Heterocyclic Carbene-Photocatalyzed Tricomponent Regioselective 1,2-Diacylation of Alkenes Illuminates the Mechanistic Details of the Electron Donor-Acceptor Complex-Mediated Radical Relay Processes
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Progress in the development of photocatalytic reactions requires a detailed understanding of the mechanisms underpinning the observed reactivity, yet mechanistic details of many photocatalytic systems, especially those that involve electron donor-acceptor complexes, have remained elusive. We report herein the development and a combined mechanistic and computational study of photocatalytic alkene 1,2-diacylation that enables a regioselective installation of two different acyl groups, establishing direct, tricomponent access to 1,4-diketones, key intermediates in heterocyclic and medicinal chemistry. The studies revealed the central role of the electron donor-acceptor complex formed from an N-heterocyclic carbene (NHC) catalyst-derived intermediate and an acyl transfer reagent, providing a detailed description of the structural and electronic factors determining the characteristics of the photoinduced charge-transfer process that mediates photocatalytic transformation. The in-depth investigation also illuminated the roles of other radical intermediates and electron donors relevant to the catalytic activities of N-heterocyclic carbenes in radical reactions.
- Jin, Shengfei,Sui, Xianwei,Haug, Graham C.,Nguyen, Viet D.,Dang, Hang T.,Arman, Hadi D.,Larionov, Oleg V.
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p. 285 - 294
(2022/01/03)
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- Site-Selective Aerobic C-H Monoacylation of Carbazoles Using Palladium Catalysis
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This manuscript describes the development of a remarkably general palladium-catalyzed monoacylation of carbazoles using toluene derivatives playing the dual role of acyl source and organic solvent. The method uses NHPI as the cocatalyst and oxygen as the sole oxidant. Interestingly, the acylation of monosubstituted N-pyridylcarbazoles takes place regioselectively at the C-8 position. The scope of the method is explored using aldehyde as the acyl source. This highly site-selective acylation proceeds through a radical process.
- Maiti, Subhadip,Mandal, Tirtha,Dash, Barada Prasanna,Dash, Jyotirmayee
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supporting information
p. 1396 - 1407
(2021/02/05)
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- P-Silylation of Arenes via Organic Photoredox Catalysis: Use of p-Silylated Arenes for Exclusive o-Silylation, o-Acylation, and o-Alkylation Reactions
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Photocatalytic regiospecific p-silylation of arenes has been achieved by the coupling of in situ generated silyl radical with arene radical cation. The strategy involves reductive activation of PhSe-SiR3 and single electron transfer from the electron rich
- Pandey, Ganesh,Tiwari, Sandip Kumar,Singh, Pushpendra,Mondal, Pradip Kumar
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p. 7730 - 7734
(2021/10/25)
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- Cooperative NHC/Photoredox Catalyzed Ring-Opening of Aryl Cyclopropanes to 1-Aroyloxylated-3-Acylated Alkanes
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Cyclopropanes are an important class of building blocks in organic synthesis. Herein, a ring-opening/arylcarboxylation/acylation cascade reaction for the 1,3-difunctionalization of aryl cyclopropanes enabled by cooperative NHC and organophotoredox catalysis is reported. The cascade works on monosubstituted cyclopropanes that are in contrast to the heavily investigated donor–acceptor cyclopropanes more challenging to be difunctionalized. The key step is a radical/radical cross coupling of a benzylic radical generated in the photoredox catalysis cycle with a ketyl radical from the NHC catalysis cycle. The transformation features metal-free reaction conditions and tolerates a diverse range of functionalities.
- Daniliuc, Constantin G.,Studer, Armido,Zuo, Zhijun
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p. 25252 - 25257
(2021/10/29)
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- Controlled Relay Process to Access N-Centered Radicals for Catalyst-free Amidation of Aldehydes under Visible Light
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Nitrogen-centered radicals have attracted increasing attention as a versatile reactive intermediate for diverse C–N bond constructions. Despite the significant advances achieved in this realm, the controllable formation of such species under catalyst-free conditions remains highly challenging. Here, we report a new relay process involving the slow in situ generation of a photoactive N-chloro species via C–N bond formation, which subsequently enables mild and selective access to N-centered radicals under visible light conditions. The utility of this approach is demonstrated by the conversion of aldehydes to amides, employing N-chloro-N-sodio carbamates as a practical amidating source. This synthetic operation obviates the need for catalysts, external oxidants, and coupling reagents that are typically required in related processes, consequently allowing high functional group tolerance and excellent applicability for late-stage functionalization. Amides are an important class of structural motifs prevalently found in bioactive compounds and synthetic materials of great significance. Amidation of aldehydes has been established as an atom-efficient strategy for amide synthesis; however, current methods lack in applicability mainly due to the requirement of troublesome reagents. In this article, we describe an unconventional relay process to convert aldehydes to amides under catalyst-, oxidant-, and coupling-reagent-free conditions, which is enabled by the development of a new mechanistic platform that gives efficient and controllable access to N-centered radicals under visible light. A wide range of (hetero)aromatic and aliphatic aldehydes can be employed, including those derived from biologically relevant complex molecules. We anticipate that the accomplished methodological advances, combined with the unique mechanistic features, will lead to the widespread application of the present strategy in broad research fields. A catalyst-free approach for controlled access to N-centered radicals is described, which enables the conversion of aldehydes to amides via an unconventional relay process harnessing visible light. The key tactic relies on the use of photostable N-chloro-N-sodio-carbamate amidating reagent that leads to slow incorporations of a photoactive radical source via C–N formation and other involved intermediates thereafter. This methodology displays excellent applicability and sustainable chemistry credentials and, thus, holds a promise for finding broad applications.
- Chang, Sukbok,Jeon, Hyun Ji,Jung, Hoimin,Kim, Dongwook,Lee, Wongyu,Seo, Sangwon
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supporting information
p. 495 - 508
(2021/01/28)
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- Eosin Y as a direct hydrogen-atom transfer photocatalyst for the C3-H acylation of quinoxalin-2(1H)-ones
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Visible light promoted eosin Y catalyzed selective C3-H acylation of quinoxalin-2(1H)-ones has been developed in a green and sustainable manner. In contrast to the conventional anionic eosin Y-based photoredox process, neutral eosin Y acts as the actual c
- Ni, Hangcheng,Li, Yu,Shi, Xingzi,Pang, Yi,Jin, Congying,Zhao, Fei
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supporting information
(2021/03/03)
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- Photochemical Activation of Aromatic Aldehydes: Synthesis of Amides, Hydroxamic Acids and Esters
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A cheap, facile and metal-free photochemical protocol for the activation of aromatic aldehydes has been developed. Utilizing thioxanthen-9-one as the photocatalyst and cheap household lamps as the light source, a variety of aromatic aldehydes have been activated and subsequently converted in a one-pot reaction into amides, hydroxamic acids and esters in good to high yields. The applicability of this method was highlighted in the synthesis of Moclobemide, a drug against depression and social anxiety. Extended and detailed mechanistic studies have been conducted, in order to determine a plausible mechanism for the reaction.
- Nikitas, Nikolaos F.,Apostolopoulou, Mary K.,Skolia, Elpida,Tsoukaki, Anna,Kokotos, Christoforos G.
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supporting information
p. 7915 - 7922
(2021/05/03)
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- Iron-Catalyzed Dearomatization of Biaryl Ynones with Aldehydes via Double C-H Functionalization in Eco-Benign Solvents: Highly Atom-Economical Synthesis of Acylated Spiro[5.5]trienones
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The multiple C-H bonds of biaryl ynones render the 6-exo-trig regioselective C-H activation dearomatization to spiro[5.5]trienones challenging since the competing reactions of C-H bonds on Ar1 or the ortho-C-H bonds on Ar3 may result in 5-exo-trig cyclization to indenones or 6-exo-trig ortho-dearomatization, respectively. We here report an unprecendented dearomatization of biaryl ynones with aldehydes via double C-H functionalization where a regiospecific remote unactivated para-C-H functionalization of biaryl ynones efficiently furnishes acylated spiro[5.5]trienones. This cascade cyclization features a green catalyst and solvent and high atom- and step-economy.
- Xia, Dong,Duan, Xin-Fang
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p. 15263 - 15275
(2021/11/01)
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- The visible-light-induced acylation/cyclization of alkynoates with acyl oximes for the construction of 3-acylcoumarins
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A nitrogen-centered radical-mediated carbon-carbon bond cleavage strategy is described to synthesize functionalized 3-acylcoumarins. The strategy is enabled by the visible-light-induced acylation/cyclization of alkynoates with various acyl oxime compounds in acetonitrile. The difunctionalization of carbon-carbon triple bonds precedes the generation of iminyl radicals, which is followed by the formation of acyl radicals. The acyl radicals then attack the carbon-carbon triple bonds, followed by 5-exo-trigcyclization and 1,2-ester migration. This strategy has wide substrate adaptability and good substituent tolerance.
- Chen, Pu,Liu, Yu,Tang, Ke-Wen,Xiong, Bi-Quan,Xiong, Fang-Ting,Zhou, Quan
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supporting information
p. 9012 - 9020
(2021/11/04)
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- Visible-Light-Mediated Nitrogen-Centered Radical Strategy: Preparation of 3-Acylated Spiro[4,5]trienones
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A nitrogen-centered radical strategy for the preparation of 3-acylated spiro[4,5]trienones via visible-light-mediated acylation/ipso-cyclization of alkynes with acyl oxime esters is reported. The alkyl- and aryl-substituted acyl radicals, which generate from the cleavage of carbon-carbon σ-bonds in acyl oxime esters via nitrogen-centered radical pathway, attack the carbon-carbon triple bonds in propiolamides and then undergo ipso-cyclization. This method provides a way for the construction of 3-acyl-substituted spiro[4,5]trienones, which can introduce aryl- or alkyl-substituted acyl into spiro[4,5]trienone skeletons. (Figure presented.).
- Chen, Pu,Xie, Jun,Chen, Zan,Xiong, Bi-Quan,Liu, Yu,Yang, Chang-An,Tang, Ke-Wen
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supporting information
p. 4440 - 4446
(2021/08/25)
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- Direct α-Acylation of Alkenes via N-Heterocyclic Carbene, Sulfinate, and Photoredox Cooperative Triple Catalysis
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N-Heterocyclic carbene (NHC) catalysis has emerged as a versatile tool in modern synthetic chemistry. Further increasing the complexity, several processes have been introduced that proceed via dual catalysis, where the NHC organocatalyst operates in concert with a second catalytic moiety, significantly enlarging the reaction scope. In biological transformations, multiple catalysis is generally used to access complex natural products. Guided by that strategy, triple catalysis has been studied recently, where three different catalytic modes are merged in a single process. In this Communication, direct α-C-H acylation of various alkenes with aroyl fluorides using NHC, sulfinate, and photoredox cooperative triple catalysis is reported. The method allows the preparation of α-substituted vinyl ketones in moderate to high yields with excellent functional group tolerance. Mechanistic studies reveal that these cascades proceed through a sequential radical addition/coupling/elimination process. In contrast to known triple catalysis processes that operate via two sets of interwoven catalysis cycles, in the introduced process, all three cycles are interwoven.
- Liu, Kun,Studer, Armido
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supporting information
p. 4903 - 4909
(2021/05/04)
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- Photoinduced homolytic decarboxylative acylation/cyclization of unactivated alkenes with α-keto acid under external oxidant and photocatalyst free conditions: access to quinazolinone derivatives
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A novel and green strategy for the synthesis of acylated quinazolinone derivativesviaphoto-induced decarboxylative cascade radical acylation/cyclization of quinazolinone bearing unactivated alkenes has been developed. The protocol provides a novel route to access acyl radicals from α-keto acids through a self-catalyzed energy transfer process. Most importantly, the reaction proceeded smoothly without any external photocatalyst, additive or oxidant, and could be easily scaled-up in flow conditions with sunlight irradiation.
- Sun, Bin,Shi, Rongcheng,Zhang, Kesheng,Tang, Xiaoli,Shi, Xiayue,Xu, Jiayun,Yang, Jin,Jin, Can
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supporting information
p. 6050 - 6053
(2021/06/21)
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- Visible-light-induced direct construction of amide bond from carboxylic acids with amines in aqueous solution
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A novel visible-light-promoted N-acylation for the synthesis of amides from easily available carboxylic acids with amines in the presence of I2 within 2.5 h in aqueous solution has been developed. Using sunlight as the visible light source greatly reduces the cost of experiments and produces almost no toxic effects. Hence, this study provides an alternative catalytic system for the construction of a wide range of amides with readily available materials. Moreover, the strategy was successfully applied in the preparation of N-(3-(2,6-dimethoxyphenoxy)-7-nitroquinoxalin-2-yl)benzohydrazide, which displayed a signification anti-proliferation effect on A549, MCF-7 and HCT116 cell lines.
- Wang, Jin,Hou, Huiqing,Hu, Yongzhi,Lin, Jin,Wu, Min,Zheng, Zhiqiang,Xu, Xiuzhi
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- Ynonylation of Acyl Radicals by Electroinduced Homolysis of 4-Acyl-1,4-dihydropyridines
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Herein we report the conversion of 4-Acyl-1,4-dihydropyridines (DHPs) into ynones under electrochemical conditions. The reaction proceeds via the homolysis of acyl-DHP under electron activation. The resulting acyl radicals react with hypervalent iodine(III) reagents to form the target ynones or ynamides in acceptable yields. This mild reaction condition allows wider functionality tolerance that includes halides, carboxylates, or alkenes. The synthetic utility of this methodology is further demonstrated by the late-stage modification of complex molecules.
- Luo, Xiaosheng,Wang, Ping
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p. 4960 - 4965
(2021/07/20)
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- Iron-catalyzed oxidative amidation of acylhydrazines with amines
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A new approach for amide bond formation via a mild and efficient Iron-catalyzed cross-coupling reaction of acylhydrazines and amines using TBHP as oxidant is described. This protocol is compatible with a wide range of amines and acylhydrazines. In addition, the synthetic application of the reaction is presented.
- Wang, Yi-Jie,Zhang, Guo-Yu,Shoberu, Adedamola,Zou, Jian-Ping
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- Diazotrifluoroethyl Radical: A CF3-Containing Building Block in [3 + 2] Cycloaddition
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We present herein a visible-light-induced [3 + 2] cycloaddition of a hypervalent iodine(III) reagent with α-ketoacids for the construction of 5-CF3-1,3,4-oxadiazoles that are of importance in medicinal chemistry. The reaction proceeds smoothly without a photocatalyst, metal, or additive under mild conditions. Different from the well-established trifluorodiazoethane (CF3CHN2), the diazotrifluoroethyl radical [CF3C(·)N2], a trifluoroethylcarbyne (CF3C?:) equivalent and an unusual CF3-containing building block, is involved in the present reaction system.
- Zhao, Wen-Wen,Shao, Yong-Chao,Wang, An-Ni,Huang, Jia-Li,He, Chun-Yang,Cui, Bao-Dong,Wan, Nan-Wei,Chen, Yong-Zheng,Han, Wen-Yong
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p. 9256 - 9261
(2021/12/06)
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- Photoredox Catalyzed Radical Cascade Aroylation (Sulfonylation)/Cyclization Enables Access to Fused Indolo-pyridones
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A visible-light-initiated radical cascade reaction toward the synthesis of structurally diverse fused Indolo-pyridones is described. The reaction involves the addition of aroyl or sulfonyl radicals to N-alkyl-acryloyl-1H-indole-3-carboxamides, cyclization, and oxidative aromatization. This telescoped method circumvents lengthy prefunctionalization steps of radical precursors, which is further underpinned by the superior compatibility with a series of C-centered radicals, allowing the rapid and facile construction of numerous valuable architectures.
- Yang, De-Yong,Liu, Liang,Gu, Jia-Yi,He, Yan-Hong,Guan, Zhi
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p. 18042 - 18055
(2021/12/17)
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- Direct 1,2-Dicarbonylation of Alkenes towards 1,4-Diketones via Photocatalysis
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1,4-Dicarbonyl compounds are intriguing motifs and versatile precursors in numerous pharmaceutical molecules and bioactive natural compounds. Direct incorporation of two carbonyl groups into a double bond at both ends is straightforward, but also challenging. Represented herein is the first example of 1,2-dicarbonylation of alkenes by photocatalysis. Key to success is that N(n-Bu)4+ not only associates with the alkyl anion to avoid protonation, but also activates the α-keto acid to undergo electrophilic addition. The α-keto acid is employed both for acyl generation and electrophilic addition. By tuning the reductive and electrophilic ability of the acyl precursor, unsymmetric 1,4-dicarbonylation is achieved for the first time. This metal-free, redox-neutral and regioselective 1,2-dicarbonylation of alkenes is executed by a photocatalyst for versatile substrates under extremely mild conditions and shows great potential in biomolecular and drug molecular derivatization.
- Chen, Bin,Cheng, Yuan-Yuan,Hou, Hong-Yu,Lei, Tao,Tung, Chen-Ho,Wu, Li-Zhu,Yu, Ji-Xin
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supporting information
p. 26822 - 26828
(2021/11/17)
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- A copper-promoted synthesis of epoxy-bridged [60]fullerene-fused lactones and further derivatization
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A facile copper-promoted decarboxylative annulation of [60]fullerene (C60) with two identical α-oxocarboxylic acidsviaan unprecedented cascade addition pathway has been exploited to synthesize the unique epoxy-bridged C60-fused lactones for the first time. Further transformations into the rare epoxy-bridged C60-fused hemiacetals and bicyclic-fused 1,2,3,4-adducts as well as application in a perovskite solar cell device of the obtained products have also been demonstrated. The structures of the epoxy-bridged C60-fused lactones and derived reductive products have been unequivocally established by single-crystal X-ray crystallography. Plausible reaction mechanisms leading to the observed products are proposed.
- Lu, Wen-Qiang,Zhou, Dian-Bing,Yin, Zheng-Chun,Liu, Qing-Song,Wang, Guan-Wu
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supporting information
p. 7043 - 7046
(2021/07/21)
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- Metal free decarboxylative aminoxylation of carboxylic acids using a biphasic solvent system
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The smooth oxidative radical decarboxylation of carboxylic acids with TEMPO and other derivatives as radical scavengers is reported. The key to success was the use of a two-phase solvent system to avoid otherwise predominant side reactions such as the oxidation of TEMPO by persulfate and enabled the selective formation of synthetically useful alkoxyamines. The method does not require transition metals and was successfully used in a new synthetic approach for the antidepressant indatraline.
- Schulz, G?ran,Kirschning, Andreas
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supporting information
p. 273 - 278
(2021/01/14)
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- Ruthenium(II)-Catalyzed Cross-Coupling of Benzoyl Formic Acids with Toluenes: Synthesis of 2-Phenylacetophenones
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Herein, we report a direct method to synthesize 2-phenylacetophenone through a ruthenium(II)-catalyzed cross-coupling reaction between acyl and benzyl radical. The various derivatives of 2-phenylacetophenone were prepared easily in moderate to good yields. These reactions provide a straightforward pathway to synthesize a variety of ketones bearing various functional groups.
- Chen, Yujie,Dai, Chenyang,Huang, Zhibin,Jiang, Yaqiqi,Shu, Sai,Yang, Shan,Zhao, Yingsheng
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p. 2955 - 2961
(2021/07/22)
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- Acyl Radicals from α-Keto Acids: Metal-Free Visible-Light-Promoted Acylation of Heterocycles
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A general and metal-free visible-light-induced decarboxylative arylation procedure at room temperature was described for the construction of acylated heterocyclic derivatives, such as benzimidazo/indolo[2,1-a]isoquinolin-6(5H)-ones, aroylazaspiro[4.5]trie
- Zhu, Hu-Lin,Zeng, Fan-Lin,Chen, Xiao-Lan,Sun, Kai,Li, Hao-Cong,Yuan, Xiao-Ya,Qu, Ling-Bo,Yu, Bing
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supporting information
p. 2976 - 2980
(2021/05/05)
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- Photo-redox catalyzed dehydrazinative acylation of N-heterocycles: Via Minisci reaction
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Visible light-induced acylation of heteroaromatic compounds have been achieved using benzoyl hydrazides as an efficient acyl source under mild reaction conditions. The photo-redox catalyzed oxidative cleavage of hydrazides leads to in situ formation of ac
- Hafeez, Saira,Saeed, Aamer
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p. 38683 - 38689
(2021/12/20)
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- Electron Donor-Acceptor Complex-Initiated Photochemical Cyanation for the Preparation of α-Amino Nitriles
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An electron donor-acceptor complex-initiated α-cyanation of tertiary amines has been described. The reaction protocol provides a novel method to synthesize various α-amino nitriles under mild conditions. The reaction can proceed smoothly without the presence of photocatalysts and transition metal catalysts, and either oxidants are unnecessary or O2 is the only oxidant. The practicality of this method is showcased not only by the late-stage functionalization of natural alkaloid derivatives and pharmaceutical intermediate, but also by the applicability of a stop-flow microtubing reactor.
- Xia, Qing,Li, Yufei,Cheng, Lan,Liang, Xin,Cao, Chenlin,Dai, Peng,Deng, Hongping,Zhang, Weihua,Wang, Qingmin
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supporting information
p. 9638 - 9643
(2020/12/21)
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- Two-step continuous flow synthesis of amide via oxidative amidation of methylarene
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A green and efficient method for the synthesis of amides has been developed through oxidative amidation between methylarenes with amines in a two-step continuous flow system. This method integrates methylarene oxidation and amide formation into a single operation which is usually accomplished separately. Oxidation with tert-butyl hydroperoxide (TBHP) as “green” oxidant, the synthesis of amides under mild reaction conditions in continuous flow system and the utilization of methylarenes as starting material make this methodology novel and environment friendly. The practical value of this method is highlighted through the synthesis of high-profile pharmaceutical agents, acetylprocainamide.
- Fang, Zheng,Guo, Kai,He, Wei,Liu, Chengkou,Shi, Tingting,Yang, Yuhang,Yang, Zhao,Zhang, Zhimin
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supporting information
(2020/02/28)
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- Divergent Synthesis of α-Aroyloxy Ketones and Indenones: A Controlled Domino Radical Reaction for Di- A nd Trifunctionalization of Alkynes
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Three different modes of aldehyde/alkyne assembly through a controlled radical reaction are devised. While a double C-H activation/annulation leads to indenones, a concurrent oxidation of both aldehydes and alkynes in the course of their connection offers
- Jafarpour, Farnaz,Azizzade, Meysam,Golpazir-Sorkheh, Yekta,Navid, Hamed,Rajai-Daryasarei, Saideh
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p. 8287 - 8294
(2020/07/15)
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- Iron-catalyzed acylation-functionalization of unactivated alkenes with aldehydes
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Herein, an iron-catalyzed acylation-functionalization of unactivated alkenes with aldehydes via distal group ipso-migration is reported. This strategy overcame the energy barrier and reversibility in the difunctionalization of unactivated alkenes with nuc
- Tian, Tian,Wang, Xin,Lv, Leiyang,Li, Zhiping
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supporting information
p. 14637 - 14640
(2020/12/02)
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- LiBr-promoted photoredox neutral Minisci hydroxyalkylations of quinolines with aldehydes
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Photoredox-neutral hydroxyalkylations of quinolines with aldehydes, induced by sustainable visible light under mild conditions, are described. Non-toxic and inexpensive LiBr is found to be the key for the success of the atom-economical Minisci method. Combined with a highly oxidative photocatalyst and visible light irradiation, the bromide additive mediates the H abstraction/acyl radical formation directly from aldehydes. The present mild photoredox neutral protocol provides an important alternative, especially for the challenging Minisci hydroalkylations, as well as a promising approach for atom-economical Minisci reactions with broader N-heterocycle spectra.
- Ji, Xiaochen,Liu, Qiong,Wang, Zhongzhen,Wang, Pu,Deng, Guo-Jun,Huang, Huawen
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supporting information
p. 8233 - 8237
(2020/12/29)
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- Visible-Light-Induced Decarboxylative Cyclization/Hydrogenation Cascade Reaction to Access Phenanthridin-6-yl(aryl)methanol by an Electron Donor-Acceptor Complex
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A novel and efficient visible-light-induced decarboxylative cyclization/hydrogenation cascade reaction of α-oxocarboxylic acids and 2-isocyanobiaryls has been developed. Without the need of any external photosensitizer, oxidant, and reductant, this method offers a mild and green approach for the synthesis of diverse alcohols in moderate to good yields. A mechanism indicated that an electron donor-acceptor complex-driven decarboxylation, radical addition/cyclization, and in situ photochemical reduction of ketones to alcohols could be involved in the reaction.
- Shi, Wei,Ma, Fang,Li, Pinhua,Wang, Lei,Miao, Tao
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supporting information
p. 13808 - 13817
(2020/11/20)
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- Visible-Light-Mediated Hydroacylation of Azobenzenes with α-Keto Acids
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A visible-light-mediated protocol for the hydroacylation of azobenzenes with α-keto acids has been developed. In the absence of any catalyst or additive, decarboxylative hydroacylation proceeded smoothly under visible-light irradiation at room temperature. A wide range of azobenzenes and α-keto acids were well-tolerated and afforded hydroacylation products in high to excellent yields. Preliminary investigations indicated that photoactive azobenzenes absorb visible light to enable the transformation.
- Yang, Jingya,Song, Menghui,Zhou, Hongyan,Wang, Ganggang,Ma, Ben,Qi, Yuanyuan,Huo, Congde
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supporting information
p. 8407 - 8412
(2020/11/03)
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- Selective photoredox decarboxylation of α-ketoacids to allylic ketones and 1,4-dicarbonyl compounds dependent on cobaloxime catalysis
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A photoredox/cobaloxime co-catalyzed coupling reaction of α-ketoacids and methacrylates to obtain allylic ketones is described. Without the cobaloxime catalyst, 1,4-dicarbonyl compounds are generated. The cobaloxime catalyst enables dehydrogenation to generate the formation of new olefins. The generality, good substrate scope and mild conditions are good features in the photoredox/cobaloxime catalysis protocol, and this method will provide new opportunities for the functionalization of more olefins.
- Zhang, Hong,Xiao, Qian,Qi, Xu-Kuan,Gao, Xue-Wang,Tong, Qing-Xiao,Zhong, Jian-Ji
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supporting information
p. 12530 - 12533
(2020/11/02)
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- Visible Light-Promoted Friedel-Crafts-Type Chloroacylation of Alkenes to β-Chloroketones
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The photoredox chloroacylation of alkenes has been developed as a substitute for the Friedel-Crafts acylation of alkenes to β-chloroketones. The direct generation of acyl radical species from acid chlorides under the photoredox conditions allows the formation of β-chloroketones without dehydrochlorination with the help of KHCO3. The synthetic utility of the current method is demonstrated in the one-pot synthesis of dihydroisoxazole, dihydropyrazole, and dihydropyrimidine-2-thione in 1 mmol scale.
- Patil, Dilip V.,Kim, Hun Young,Oh, Kyungsoo
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supporting information
p. 3018 - 3022
(2020/04/09)
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- Palladium (0)-catalyzed C(sp2)-H oxygenation with carboxylic acids
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Palladium (0)-catalyzed Ortho-benzoxylation of the sp2 C–H bond of arylbenzoxazinones with carboxylic acid is reported. With benzoxazinone as directing group, the reaction went smoothly under the benign condition and gave the desired product wi
- Gong, Ai-Jun,Li, Xu-Qin,Vu, Huu-Manh,Yong, Jia-Yuan
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supporting information
(2020/02/15)
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- Radical hydroalkylation and hydroacylation of alkenes by the use of benzothiazoline under thermal conditions
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The hydroalkylation and hydroacylation of electrondeficient alkenes proceeded smoothly by using benzothiazoline derivatives as radical-transfer reagents under thermal conditions without light irradiation or any additive. Both benzyl and benzoyl moieties were transferred efficiently.
- Akiyama, Takahiko,Uchikura, Tatsuhiro,Toda, Mitsuhiro,Mouri, Toshiki,Fujii, Tatsuya,Moriyama, Kaworuko,Ibanez, Ignacio
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p. 12715 - 12723
(2020/11/09)
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- Metal-free benzoylation of imidazoheterocycles by oxidative decarboxylation of arylglyoxylic acids
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A simple and straightforward approach has been realized for the direct benzoylation of imidazoheterocycles by oxidative decarboxylation of arylglyoxylic acids in the presence of K2S2O8 as an oxidant. Various functional groups were tolerated on both imidazoheterocycles and arylglyoxylic acids and a wide range of C5-benzoyl-imidazoheterocycles were obtained in good to high yields (50-84%). Radical trapping experiments confirmed the involvement of the radical pathway. The developed protocol is amenable for a scale-up reaction. This journal is
- Jaspal, Sonam,Shinde, Vikki N.,Meena, Neha,Nipate, Dhananjay S.,Rangan, Krishnan,Kumar, Anil
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p. 9072 - 9080
(2020/11/27)
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- Photochemical generation of acyl and carbamoyl radicals using a nucleophilic organic catalyst: Applications and mechanism thereof
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We detail a strategy that uses a commercially available nucleophilic organic catalyst to generate acyl and carbamoyl radicals upon activation of the corresponding chlorides and anhydrides via a nucleophilic acyl substitution path. The resulting nucleophilic radicals are then intercepted by a variety of electron-poor olefins in a Giese-type addition process. The chemistry requires low-energy photons (blue LEDs) to activate acyl and carbamoyl radical precursors, which, due to their high reduction potential, are not readily prone to redox-based activation mechanisms. To elucidate the key mechanistic aspects of this catalytic photochemical radical generation strategy, we used a combination of transient absorption spectroscopy investigations, electrochemical studies, quantum yield measurements, and the characterization of key intermediates. We identified a variety of off-the-cycle intermediates that engage in a light-regulated equilibrium with reactive radicals. These regulated equilibriums cooperate to control the overall concentrations of the radicals, contributing to the efficiency of the overall catalytic process and facilitating the turnover of the catalyst. This journal is
- Balletti, Matteo,De Pedro Beato, Eduardo,Mazzarella, Daniele,Melchiorre, Paolo
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p. 6312 - 6324
(2020/08/24)
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- Palladium-Catalyzed Decarboxylative ortho-C(sp2)?H Aroylation of N-Sulfoximine Benzamides at Room Temperature
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A palladium-catalyzed method for the decarboxylative ortho C?H acylation of N-sulfoximine benzamides is developed at room temperature. The catalytic method enables easy access to various functionalized 2-aroylaromatic carboxylic acid derivatives in good isolated yields. Based on our mechanistic studies, a Pd(II)/Pd(IV) catalytic cycle that involves aroyl radical intermediate is proposed for the reaction.
- Das, Prasenjit,Biswas, Promita,Guin, Joyram
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supporting information
p. 920 - 925
(2020/03/04)
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- Photoredox Catalyst Free, Visible Light-Promoted C3?H Acylation of Quinoxalin-2(1H)-ones in Water
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A method for the synthesis of 3-acyl quinoxalin-2(1H)-ones through visible-light promoted decarboxylative acylation of α-oxo-carboxylic acids with quinoxalin-2(1H)-ones was developed. The reaction was performed in aqueous phase and photoredox catalyst was not required to run the process. (Figure presented.).
- Lu, Juan,He, Xiang-Kui,Cheng, Xiao,Zhang, Ai-Jun,Xu, Guo-Yong,Xuan, Jun
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supporting information
p. 2178 - 2182
(2020/03/19)
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- Decarboxylative/Oxidative Amidation of Aryl α-Ketocarboxylic Acids with Nitroarenes and Nitroso Compounds in Aqueous Medium
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The decarboxylative/oxidative amidation of aryl α-ketocarboxylic acids with 5-aryl-3-nitroisoxazole-4-carboxylates and substituted dinitrobenzenes under oxidative aqueous conditions to afford N-aryl amides is described. The reaction is suggested to proceed via a radical pathway in which a benzoyl nitroxyl radical, the key intermediate formed from reaction between nitroarene and benzoyl radical from glyoxalic acid, couples with hydroxyl radical from water to produce amide. Mechanistic insight allowed the scope of the strategy to be expanded to the synthesis of amides via reaction between aryl α-ketocarboxylic acids and nitroso compounds.
- Barak, Dinesh S.,Dahatonde, Dipak J.,Dighe, Shashikant U.,Kant, Ruchir,Batra, Sanjay
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supporting information
p. 9381 - 9385
(2020/11/30)
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- Acyl radicals from α-keto acids using a carbonyl photocatalyst: Photoredox-catalyzed synthesis of ketones
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Acyl radicals have been generated from α-keto acids using inexpensive and commercially available 2-chloro-thioxanthen-9-one as the photoredox catalyst under visible light illumination. These reactive species added to olefins or coupled with aryl halides via a bipyridylstabilized Ni(II) catalyst, enabling easy access to a diverse range of ketones. This reliable, atom-economical, and eco-friendly protocol is compatible with a wide range of functional groups.
- Zhu, Da-Liang,Wu, Qi,Young, David James,Wang, Hao,Ren, Zhi-Gang,Li, Hong-Xi
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supporting information
p. 6832 - 6837
(2020/10/12)
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- Aroylation of Electron-Rich Pyrroles under Minisci Reaction Conditions
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The development of Minisci acylation on electron-rich pyrroles under silver-free neutral conditions has been reported featuring the regioselective monoacylation of (NH)-free pyrroles. Unlike conventional Minisci conditions, the avoidance of any acid that could result in the polymerization of pyrroles was the key to success. The umpolung reactivity of the nucleophilic acyl radical, generated in situ from arylglyoxylic acid, could help explain the mechanism of product formation with electron-rich pyrroles. Alternatively, the nucleophilic substitution of the acyl radical on the electron-deficient pyrrole radical cation is proposed.
- Laha, Joydev K.,Kaur Hunjan, Mandeep,Hegde, Shalakha,Gupta, Anjali
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supporting information
p. 1442 - 1447
(2020/02/22)
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- Visible-light-induced decarboxylative acylation of quinoxalin-2(1: H)-ones with α-oxo carboxylic acids under metal-, strong oxidant- And external photocatalyst-free conditions
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A mild and eco-friendly visible-light-induced decarboxylative acylation of quinoxalin-2(1H)-ones and α-oxo carboxylic acids with ambient air as the sole oxidant at room temperature was established. The reaction proceeded efficiently without any metal cata
- Xie, Long-Yong,Bai, You-Shu,Xu, Xiang-Qin,Peng, Xia,Tang, Hai-Shan,Huang, Ying,Lin, Ying-Wu,Cao, Zhong,He, Wei-Min
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supporting information
p. 1720 - 1725
(2020/03/26)
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- Visible light promoted synthesis of N-aroylsulfoximines by oxidative C-H acylation of NH-sulfoximines
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The visible light-promoted synthesis of N-aroylsulfoximines has been accomplished via an oxidative dehydrogenative coupling at room temperature under air without the addition of a photosensitizer, metal catalyst, or base. This process exhibits good functional group tolerance, allows facile isolation and purification, and affords N-aroylsulfoximines with high efficiency. The efficiency of the newly developed protocol is described in detail with 27 examples with yields ranging from 80% to 96%. Furthermore, the chirality of the NH-sulfoximine is completely maintained in the desired N-aroylsulfoximine product (99% ee).
- Jiang, Wenlong,Huang, Youming,Zhou, Lihong,Zeng, Qingle
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p. 1213 - 1220
(2019/07/17)
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