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1.
《Angewandte Chemie (International ed. in English)》2017,56(17):4877-4881
The dehydrogenative cross‐coupling of aniline derivatives to 2,2′‐diaminobiaryls is reported. The oxidation is carried out electrochemically, which avoids the use of metals and reagents. A large variety of biphenyldiamines were thus prepared. The best results were obtained when glassy carbon was used as the anode material. The electrosynthetic reaction is easily performed in an undivided cell at slightly elevated temperature. In addition, common amine protecting groups based on carboxylic acids were employed that can be selectively removed under mild conditions after the cross‐coupling, which provides quick and efficient access to important building blocks featuring free amine moieties. 相似文献
2.
《Angewandte Chemie (International ed. in English)》2017,56(46):14727-14731
The first electrochemical dehydrogenative C−C cross‐coupling of thiophenes with phenols has been realized. This sustainable and very simple to perform anodic coupling reaction enables access to two classes of compounds of significant interest. The scope for electrochemical C−H‐activating cross‐coupling reactions was expanded to sulfur heterocycles. Previously, only various benzoid aromatic systems could be converted, while the application of heterocycles was not successful in the electrochemical C−H‐activating cross‐coupling reaction. Here, reagent‐ and metal‐free reaction conditions offer a sustainable electrochemical pathway that provides an attractive synthetic method to a broad variety of bi‐ and terarylic products based on thiophenes and phenols. This method is easy to conduct in an undivided cell, is scalable, and is inherently safe. The resulting products offer applications in electronic materials or as [OSO]2− pincer‐type ligands. 相似文献
3.
Johannes L. Rckl Dieter Schollmeyer Robert Franke Siegfried R. Waldvogel 《Angewandte Chemie (International ed. in English)》2020,59(1):315-319
We herein present a metal‐free, electrosynthetic method that enables the direct dehydrogenative coupling reactions of phenols carrying electron‐withdrawing groups for the first time. The reactions are easy to conduct and scalable, as they are carried out in undivided cells and obviate the necessity for additional supporting electrolyte. As such, this conversion is efficient, practical, and thereby environmentally friendly, as production of waste is minimized. The method features a broad substrate scope, and a variety of functional groups are tolerated, providing easy access to precursors for novel polydentate ligands and even heterocycles such as dibenzofurans. 相似文献
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Selective Synthesis of Partially Protected Nonsymmetric Biphenols by Reagent‐ and Metal‐Free Anodic Cross‐Coupling Reaction
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Anton Wiebe Dr. Dieter Schollmeyer Dr. Katrin M. Dyballa Prof. Dr. Robert Franke Prof. Dr. Siegfried R. Waldvogel 《Angewandte Chemie (International ed. in English)》2016,55(39):11801-11805
The oxidative cross‐coupling of aromatic substrates without the necessity of leaving groups or catalysts is described. The selective formation of partially protected nonsymmetric 2,2′‐biphenols via electroorganic synthesis was accomplished with a high yield of isolated product. Since electric current is employed as the terminal oxidant, the reaction is reagent‐free; no reagent waste is generated as only electrons are involved. The reaction is conducted in an undivided cell, and is suitable for scale‐up and inherently safe. The implementation of O‐silyl‐protected phenols in this transformation results in both significantly enhanced yields and higher selectivity for the desired nonsymmetric 2,2′‐biphenols. The use of a bulky silyl group to block one hydroxyl moiety makes the final product less prone to oxidation. Furthermore, the partially silyl‐protected 2,2′‐biphenols are versatile building blocks that usually require tedious or low‐yielding synthetic pathways. Additionally, this strategy facilitates a large variety of new substrate combinations for oxidative cross‐coupling reactions. 相似文献
6.
《Chemical record (New York, N.Y.)》2018,18(2):165-229
The carbon‐carbon and carbon‐heteroatom bonds catalytic formation is among the most significant reactions in organic synthesis which extensively applied for synthesis of natural products, heterocycles, dendrimers, biologically active molecules and useful compounds. This review provides the latest advances in the preparation of graphene supported metal nanoparticles and their application in the catalytic formation of both carbon‐carbon (C−C) and carbon‐heteroatom (C−X) bonds including the Suzuki, Heck, Hiyama, Ullmann, Buchwald and Sonogashira coupling reactions. Numerous examples are given concerning the use of these catalysts in C−C and C−X coupling reactions along with the reliable and simple preparation methods of these catalysts, their characterization and catalytic properties and also the recycling possibilities. 相似文献
7.
Gerald Dyker 《Angewandte Chemie (International ed. in English)》1999,38(12):1698-1712
C−C coupling by transition metal catalyzed C−H activation has developed into a diverse area of research. The applicable catalysts are manifold, and the variety of products obtained range from basic chemicals to pharmaceuticals and building blocks for carbon networks. One reaction, in which several C−C bonds are formed under C−H activation of a methyl group, is the conversion of ortho-iodoanisole according to Equation (1). 相似文献
8.
Metal‐ and Oxidant‐Free Alkenyl C−H/Aromatic C−H Cross‐Coupling Using Electrochemically Generated Iodosulfonium Ions
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Dr. Ryutaro Hayashi Dr. Akihiro Shimizu Jonathan A. Davies Yu Ishizaki Prof. Dr. Chris Willis Prof. Dr. Jun‐ichi Yoshida 《Angewandte Chemie (International ed. in English)》2018,57(39):12891-12895
A three‐step transformation consisting of 1) addition of electrochemically generated iodosulfonium ions to vinylarenes to give (1‐aryl‐2‐iodoethoxy)sulfonium ions, 2) nucleophilic substitution by subsequently added aromatic compounds to give 1,1‐diaryl‐2‐iodoethane, and 3) elimination of HI with a base to give 1,1‐diarylethenes was developed. The transformation serves as a powerful metal‐ and chemical‐oxidant‐free method for alkenyl C?H/aromatic C?H cross‐coupling. 相似文献
9.
C−H Coupling Reactions Directed by Sulfoxides: Teaching an Old Functional Group New Tricks
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Dr. Alexander P. Pulis Prof. David J. Procter 《Angewandte Chemie (International ed. in English)》2016,55(34):9842-9860
Sulfoxides are classical functional groups for directing the stoichiometric metalation and functionalization of C?H bonds. In recent times, sulfoxides have been given a new lease on life owing to the development of modern synthetic methods that have arisen because of their unique reactivity. They have recently been used in catalytic C?H activation proceeding via coordination of an internal sulfoxide to a metal or through the action of an external sulfoxide ligand. Furthermore, sulfoxides are able to capture nucleophiles and electrophiles to give sulfonium salts, which subsequently enable the formation of C?C bonds at the expense of C?H bonds. This Review summarizes a renaissance period in the application of sulfoxides arising from their versatility in directing C?H functionalization. 相似文献
10.
Sergio Fombona Dr. Maialen Espinal‐Viguri Dr. Miguel A. Huertos Dr. Jesús Díaz Dr. Ramón López Dr. M. Isabel Menéndez Dr. Julio Pérez Dr. Lucía Riera 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(48):17160-17164
4,4’‐Disubstituted‐2,2′‐bipyridine ligands coordinated to MoII and ReI cationic fragments become dearomatized by an intramolecular nucleophilic attack from a deprotonated N‐alkylimidazole ligand in cis disposition. The subsequent protonation of these neutral complexes takes place on a pyridine carbon atom rather than at nitrogen, weakening an aromatic C?C bond and affording a dihydropyridyl moiety. Computational calculations allowed for the rationalization of the formation of the experimentally obtained products over other plausible alternatives. 相似文献
11.
Cover Picture: Selective Synthesis of Partially Protected Nonsymmetric Biphenols by Reagent‐ and Metal‐Free Anodic Cross‐Coupling Reaction (Angew. Chem. Int. Ed. 39/2016)
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Anton Wiebe Dr. Dieter Schollmeyer Dr. Katrin M. Dyballa Prof. Dr. Robert Franke Prof. Dr. Siegfried R. Waldvogel 《Angewandte Chemie (International ed. in English)》2016,55(39):11689-11689
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Catalyst‐Dependent Chemoselective Formal Insertion of Diazo Compounds into C−C or C−H Bonds of 1,3‐Dicarbonyl Compounds
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Zhaohong Liu Dr. Paramasivam Sivaguru Prof. Giuseppe Zanoni Prof. Edward A. Anderson Prof. Xihe Bi 《Angewandte Chemie (International ed. in English)》2018,57(29):8927-8931
A catalyst‐dependent chemoselective one‐carbon insertion of diazo compounds into the C?C or C?H bonds of 1,3‐dicarbonyl species is reported. In the presence of silver(I) triflate, diazo insertion into the C(=O)?C bond of the 1,3‐dicarbonyl substrate leads to a 1,4‐dicarbonyl product containing an all‐carbon α‐quaternary center. This reaction constitutes the first example of an insertion of diazo‐derived carbenoids into acyclic C?C bonds. When instead scandium(III) triflate was applied as the catalyst, the reaction pathway switched to formal C?H insertion, affording 2‐alkylated 1,3‐dicarbonyl products. Different reaction pathways are proposed to account for this powerful catalyst‐dependent chemoselectivity. 相似文献
14.
Runze Mao Jonathan Balon Prof. Dr. Xile Hu 《Angewandte Chemie (International ed. in English)》2018,57(41):13624-13628
Alkyl aryl ethers are an important class of compounds in medicinal and agricultural chemistry. Catalytic C(sp3)?O cross‐coupling of alkyl electrophiles with phenols is an unexplored disconnection strategy to the synthesis of alkyl aryl ethers, with the potential to overcome some of the major limitations of existing methods such as C(sp2)?O cross‐coupling and SN2 reactions. Reported here is a tandem photoredox and copper catalysis to achieve decarboxylative C(sp3)?O coupling of alkyl N‐hydroxyphthalimide (NHPI) esters with phenols under mild reaction conditions. This method was used to synthesize a diverse set of alkyl aryl ethers using readily available alkyl carboxylic acids, including many natural products and drug molecules. Complementarity in scope and functional‐group tolerance to existing methods was demonstrated. 相似文献
15.
Because the construction of the C?C bond is one of the most significant reactions in organic chemistry, the development of an efficient strategy has attracted much attention throughout the synthetic community. Among various protocols to form C?C bonds, organoboron compounds are not just limited to stoichiometric reagents, but have also made great achievements as catalysts because of the easy modification of the electronic and steric impacts on the boron center. This review presents recent developments of boron‐based catalysts applied in the field of C?C bond‐formation reactions, which are classified into four kinds on the basis of the type of boron catalyst: 1) highly Lewis acidic borane, B(C6F5)3; 2) organoboron acids, RB(OH)2, and their ester derivatives; 3) borenium ions, (R2BL)X; and 4) other miscellaneous kinds. 相似文献
16.
Tomohiro Tsuda Yuka Kawakami Seung‐Min Choi Ryo Shintani 《Angewandte Chemie (International ed. in English)》2020,59(21):8057-8061
A new and efficient synthesis of 8H‐benzo[e]phenanthro[1,10‐bc]silines from 2‐((2‐(arylethynyl)aryl)silyl)aryl triflates under palladium catalysis has been developed. The reaction mechanism was experimentally investigated and a catalytic cycle involving C?H/C?H coupling through a new mode of 1,4‐palladium migration with concomitant alkene stereoisomerization is proposed. 相似文献
17.
Guangying Tan Shuang He Xiaolei Huang Xingrong Liao Yangyang Cheng Prof. Dr. Jingsong You 《Angewandte Chemie (International ed. in English)》2016,55(35):10414-10418
The first example of cobalt‐catalyzed oxidative C?H/C?H cross‐coupling between two heteroarenes is reported, which exhibits a broad substrate scope and a high tolerance level for sensitive functional groups. When the amount of Co(OAc)2?4 H2O is reduced from 6.0 to 0.5 mol %, an excellent yield is still obtained at an elevated temperature with a prolonged reaction time. The method can be extended to the reaction between an arene and a heteroarene. It is worth noting that the Ag2CO3 oxidant is renewable. Preliminary mechanistic studies by radical trapping experiments, hydrogen/deuterium exchange experiments, kinetic isotope effect, electron paramagnetic resonance (EPR), and high resolution mass spectrometry (HRMS) suggest that a single electron transfer (SET) pathway is operative, which is distinctly different from the dual C?H bond activation pathway that the well‐described oxidative C?H/C?H cross‐coupling reactions between two heteroarenes typically undergo. 相似文献
18.
Pin Xu Peng‐Yu Chen Hai‐Chao Xu 《Angewandte Chemie (International ed. in English)》2020,59(34):14275-14280
Heteroarenes are structural motifs found in many bioactive compounds and functional materials. Dehydrogenative cross‐coupling of heteroarenes with aliphatic C?H bonds provides straightforward access to functionalized heteroarenes from readily available materials. Established methods employ stoichiometric chemical oxidants under conditions of heating or light irradiation. By merging electrochemistry and photochemistry, we have achieved efficient photoelectrochemical dehydrogenative cross‐coupling of heteroarenes and C(sp3)?H donors through H2 evolution, without the addition of metal catalysts or chemical oxidants. Mechanistically, the C(sp3)?H donor is converted to a nucleophilic carbon radical through H‐atom transfer with chlorine atom, which is produced by light irradiation of anodically generated Cl2 from Cl?. The carbon radical then undergoes radical substitution to the heteroarene to afford alkylated heteroarene products. 相似文献
19.
Gaowen Zhai Xueting Liu Wentao Ma Guoqiang Wang Liu Yang Shuhua Li Youting Wu Xingbang Hu 《化学:亚洲杂志》2020,15(19):3082-3086
Tandem Friedel‐Crafts (FC) and C?H/C?O coupling reactions catalyzed by tris(pentafluorophenyl) borane (B(C6F5)3) were achieved without using any other additive in the absence of solvent. This process can be used for the reactions between a series of dialkylanilines and vinyl ethers with good isolated yields of bis(4‐dialkylaminophenyl) compounds. Based on combined theoretical and experimental studies, the possible reaction mechanism was proposed. B(C6F5)3 can activate the C=C and C?O bond for FC and C?H/C?O coupling reactions respectively. The FC reaction is slow, which is followed by a fast C?H/C?O coupling. 相似文献
20.
Cobalt(III)‐Catalyzed Intramolecular Cross‐Dehydrogenative C−H/X−H Coupling: Efficient Synthesis of Indoles and Benzofurans
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Jayanta Ghorai Angula Chandra Shekar Reddy Prof. Dr. Pazhamalai Anbarasan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(45):16042-16046
An efficient cobalt(III)‐catalyzed intramolecular cross‐dehydrogenative C?H/N?H coupling of ortho‐alkenylanilines has been developed utilizing O2 as a terminal oxidant. The developed reaction tolerates various reactive functional groups and allows the synthesis of diverse indole derivatives in good to excellent yields. The method was successfully extended to the synthesis of benzofurans through the intramolecular cross‐dehydrogenative C?H/O?H coupling of ortho‐alkenylphenols. 相似文献