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1.
Synthesis of Dibenzo[c,e]oxepin‐5(7H)‐ones from Benzyl Thioethers and Carboxylic Acids: Rhodium‐Catalyzed Double CH Activation Controlled by Different Directing Groups 下载免费PDF全文
Xi‐Sha Zhang Yun‐Fei Zhang Zhao‐Wei Li Fei‐Xian Luo Prof. Dr. Zhang‐Jie Shi 《Angewandte Chemie (International ed. in English)》2015,54(18):5478-5482
A rhodium(III)‐catalyzed cross‐coupling of benzyl thioethers and aryl carboxylic acids through the two directing groups is reported. Useful structures with diverse substituents were efficiently synthesized in one step with the cleavage of four bonds (C? H, C? S, O? H) and the formation of two bonds (C? C, C? O). The formed structure is the privileged core in natural products and bioactive molecules. This work highlights the power of using two different directing groups to enhance the selectivity of a double C? H activation, the first of such examples in cross‐oxidative coupling. 相似文献
2.
Direct C? H arylation of unactivated benzene with aryl halides was achieved using a readily available copper catalyst. The reaction was carried out at 80 °C, using CuBr as catalyst, proline as ligand and t‐BuOK as base. This radical cross‐coupling reaction between unactivated benzene and aryl iodides proceeds via homolytic aromatic substitution and offers an efficient method for the synthesis of various biaryls in good to excellent yields. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
3.
Palladium‐Catalyzed Zinc‐Amide‐Mediated CH Arylation of Fluoroarenes and Heteroarenes with Aryl Sulfides 下载免费PDF全文
Shinya Otsuka Prof. Dr. Hideki Yorimitsu Prof. Dr. Atsuhiro Osuka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(42):14703-14707
C?H arylation of polyfluoroarenes and heteroarenes with aryl sulfides proceeds smoothly with the aid of a palladium–N‐heterocyclic carbene catalyst. A bulky zinc amide, TMPZnCl ? LiCl, plays a key role as an effective base to generate the corresponding arylzinc species in situ. This arylation protocol is practically much easier to perform than our previous method, which necessitates preparation of the arylzinc reagents in advance from the corresponding aryl halides. Aryl sulfides that are prepared through sulfur‐specific reactions, such as SNAr sulfanylation and extended Pummerer reactions, undergo this direct arylation, offering interesting transformations that are otherwise difficult to achieve with conventional halogen‐based organic synthesis. 相似文献
4.
Dehydrogenative Carbon–Carbon Bond Formation Using Alkynyloxy Moieties as Hydrogen‐Accepting Directing Groups 下载免费PDF全文
Dr. Yasunori Minami Tatsuro Kodama Prof. Dr. Tamejiro Hiyama 《Angewandte Chemie (International ed. in English)》2015,54(40):11813-11816
In the presence of a catalyst system consisting of Pd(OAc)2, PCy3, and Zn(OAc)2, the reaction of alkynyl aryl ethers with bicycloalkenes, α,ß‐unsaturated esters, or heteroarenes results in the site‐selective cleavage of two C? H bonds followed by the formation of C? C bonds. In all cases, the alkynyloxy group acts as a directing group for the activation of an ortho C? H bond and as a hydrogen acceptor, thus rendering the use of additives such as an oxidant or base unnecessary. 相似文献
5.
Modular Synthesis of Phenanthro[9,10‐c]thiophenes by a Sequence of CH Activation,Suzuki Cross‐Coupling and Photocyclization Reactions 下载免费PDF全文
Dr. Ingo Schnapperelle Prof. Dr. Thorsten Bach 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(31):9725-9732
A total number of 15 different 3,4‐diarylthiophenes were synthesized, which bear a chlorine atom in ortho‐position of one of the aryl substituents. One aryl group was introduced by an oxidative cross‐coupling reaction, involving a C?H activation at C4(3) of the thiophene core. The other aryl group was in most cases introduced by a Suzuki cross‐coupling reaction, which succeeded the oxidative cross‐coupling step. Photocyclization reactions of the 3,4‐diarylthiophenes were performed in a solvent mixture of benzene and acetonitrile (50:50 v/v) at λ=254 nm and proceeded to the title compounds in yields of 60–82 %. The selectivity of the photocyclization was determined at the ortho‐chloro‐substituted aryl ring by the position of the chlorine substituent. At the other ring, a single regioisomer was observed for phenyl and para‐substituted phenyl groups. For 2‐naphthyl and ortho‐substituted phenyl rings a clear preference was observed in favor of a major regioisomer, while meta‐substitution in the phenyl ring led to a about 1:1 mixture of 5‐ and 7‐substituted phenanthro[9,10‐c]thiophenes. Mechanistically, the photocyclization is likely to occur as a photochemically allowed, conrotatory [(4n+2)π] process accompanied by elimination of HCl. It was shown for two phenanthro[9,10‐c]thiophene products that they can be readily brominated in positions C1 and C3 (74–77 %), which in turn allows for further functionalization at these positions, for example, in the course of halogen–metal exchange and polymerization reactions. 相似文献
6.
Michael C. Haibach Nicholas Lease Prof. Alan S. Goldman 《Angewandte Chemie (International ed. in English)》2014,53(38):10160-10163
The development of efficient catalytic methods to cleave the relatively unreactive C? O bonds of ethers remains an important challenge in catalysis. Building on our group’s recent work, we report the dehydroaryloxylation of aryl alkyl ethers using pincer iridium catalysts. This method represents a rare fully atom‐economical method for ether C? O bond cleavage. 相似文献
7.
Transition‐Metal‐Free α‐Arylation of Enolizable Aryl Ketones and Mechanistic Evidence for a Radical Process 下载免费PDF全文
Martin Pichette Drapeau Indira Fabre Dr. Laurence Grimaud Dr. Ilaria Ciofini Prof. Dr. Thierry Ollevier Dr. Marc Taillefer 《Angewandte Chemie (International ed. in English)》2015,54(36):10587-10591
The α‐arylation of enolizable aryl ketones can be carried out with aryl halides under transition‐metal‐free conditions using KOtBu in DMF. The α‐aryl ketones thus obtained can be used for step‐ and cost‐economic syntheses of fused heterocycles and Tamoxifen. Mechanistic studies demonstrate the synergetic role of base and solvent for the initiation of the radical process. 相似文献
8.
Efficient Synthesis of 1,2,3‐Triazoles by Copper‐Mediated CN and NN Bond Formation Starting From N‐Tosylhydrazones and Amines 下载免费PDF全文
Zhengkai Chen Qiangqiang Yan Hong Yi Zhanxiang Liu Prof. Dr. Aiwen Lei Prof. Dr. Yuhong Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(42):13692-13697
An effective copper‐mediated synthesis of 1,5‐dialkyl‐4‐aryl‐1,2,3‐triazoles and 1,4‐dialkyl‐5‐aryl‐1,2,3‐triazoles has been achieved by the use of different N‐tosylhydrazones and alkyl amines. The scope of the substrates could be extended from anilines to aliphatic amines when 30 mol % amino acid is added into the reaction mixture. This methodology exhibits many notable features, such as broad substrates scope, high efficiency, and good regioselectivity. Preliminary mechanistic studies indicated that the reaction probably proceeded through a 1‐tosyl‐2‐vinyldiazene intermediate and subsequent aza‐Michael addition and N?N bond formation process. 相似文献
9.
Debasish Kundu Manisha Tripathy Pintu Maity Prof. Dr. Brindaban C. Ranu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(24):8727-8732
Cobalt(II)‐catalyzed C(sp2)?O cross‐coupling between aryl/heteroaryl alcohols and vinyl/aryl halides in the presence of CuI has been achieved under ligand‐free conditions. In this reaction, copper plays a significant role in transmetalation rather than being directly involved in the C?O coupling. This unique Co/Cu‐dual catalyst system provides an easy access to a library of aryl–vinyl, heteroaryl–styryl, aryl–aryl, and heteroaryl–heteroaryl ethers in the absence of any ligand or additive. 相似文献
10.
Rhodium‐Catalyzed CH Annulation of Nitrones with Alkynes: A Regiospecific Route to Unsymmetrical 2,3‐Diaryl‐Substituted Indoles 下载免费PDF全文
Hao Yan Dr. Haolong Wang Dr. Xincheng Li Dr. Xiaoyi Xin Dr. Chunxiang Wang Prof. Dr. Boshun Wan 《Angewandte Chemie (International ed. in English)》2015,54(36):10613-10617
The direct C? H annulation of anilines or related compounds with internal alkynes provides straightforward access to 2,3‐disubstituted indole products. However, this transformation proceeds with poor regioselectivity in the synthesis of unsymmetrically 2,3‐diaryl substituted indoles. Herein, we report the rhodium(III)‐catalyzed C? H annulation of nitrones with symmetrical diaryl alkynes as an alternative method to prepare 2,3‐diaryl‐substituted N‐unprotected indoles with two different aryl groups. One of the aryl substituents is derived from N?C‐aryl ring of the nitrone and the other from the alkyne substrate, thus providing the indole products with exclusive regioselectivity. 相似文献
11.
Lihong Zhou Prof. Dr. Wenjun Lu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(3):634-642
An overview of recent progress in the Fujiwara–Moritani reaction, which is the palladium‐catalyzed oxidative coupling of arenes with olefins to afford alkenyl arenes, is described. It is emphasized that regioselectivity on aryl ortho‐ or meta‐C?H activation could be controlled very well in the presence of Pd, Rh, or Ru catalysts with the assistance of various chelation groups on aromatic rings in this coupling reaction. Catalytic alkenylation of aryl C?H bonds from simple arenes is also discussed, especially from electron‐deficient arenes. These advanced protocols would not only make the Fujiwara–Moritani reaction more useful and applicable in organic synthesis but also light the way for the further development of the functionalization of normal C?H bonds. 相似文献
12.
Substrate‐Directed Hydroacylation: Rhodium‐Catalyzed Coupling of Vinylphenols and Nonchelating Aldehydes 下载免费PDF全文
Stephen K. Murphy Dr. Achim Bruch Dr. Vy M. Dong 《Angewandte Chemie (International ed. in English)》2014,53(9):2455-2459
We report a protocol for the hydroacylation of vinylphenols with aryl, alkenyl, and alkyl aldehydes to form branched products with high selectivity. This cross‐coupling yields α‐aryl ketones that can be cyclized to benzofurans, and it enables access to eupomatenoid natural products in four steps or less from eugenol. Excellent reactivity and high levels of regioselectivity for the formation of the branched products were observed. We propose that aldehyde decarbonylation is avoided by the use of an anionic directing group on the alkene and a diphosphine ligand with a small bite angle. 相似文献
13.
Rhodium(III)‐Catalyzed CH Activation and Indole Synthesis With Hydrazone as an Auto‐Formed and Auto‐Cleavable Directing Group 下载免费PDF全文
Liyao Zheng Prof. Dr. Ruimao Hua 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(8):2352-2356
An efficient, practical, and external‐oxidant‐free indole synthesis from readily available aryl hydrazines was developed, by using hydrazone as a directing group for RhIII‐catalyzed C?H activation and alkyne annulation. The hydrazone group was formed by in situ condensation of hydrazines and C?O source, whereas its N?N bond was served as an internal oxidant, for which we termed it as an auto‐formed and auto‐cleavable directing group (DGauto). This method needs no step for pre‐installation and post‐cleavage of the directing group, making it a quite easily scalable approach to access unprotected indoles with high step economy. The DGauto strategy was also applicable for isoquinoline synthesis. In addition, synthetic utilities of this chemistry for rapid assembly of π‐extended nitrogen‐doped polyheterocycles and bioactive molecules were demonstrated. 相似文献
14.
Rhodium‐Catalyzed Cyclization of Diynes with Nitrones: A Formal [2+2+5] Approach to Bridged Eight‐Membered Heterocycles 下载免费PDF全文
Dr. Chunxiang Wang Dr. Dongping Wang Hao Yan Dr. Haolong Wang Dr. Bin Pan Dr. Xiaoyi Xin Dr. Xincheng Li Fan Wu Prof. Dr. Boshun Wan 《Angewandte Chemie (International ed. in English)》2014,53(44):11940-11943
N‐aryl‐substituted nitrones were employed as five‐atom coupling partners in the rhodium‐catalyzed cyclization with diynes. In this reaction, the nitrone moiety served as a directing group for the catalytic C? H activation of the N‐aryl ring. This formal [2+2+5] approach allows rapid access to bridged eight‐membered heterocycles with broad substrate scope. The results of this study may provide new insight into the chemistry of nitrones and find applications in the synthesis of other heterocycles. 相似文献
15.
SBA‐15‐functionalized melamine–pyridine group‐supported palladium(0) as an efficient heterogeneous and recyclable nanocatalyst for N‐arylation of indoles through Ullmann‐type coupling reactions 下载免费PDF全文
SBA‐15‐functionalized melamine–pyridine group‐supported palladium(0) was found to serve as a heterogeneous and recyclable nanocatalyst for N‐arylation of indoles with aryl iodides under a low catalyst loading (0.3 mol% of Pd) through Ullmann‐type C? N coupling reactions. A variety of aryl iodides could be aminated to provide the N‐arylated products in good to excellent yields without the need of an inert atmosphere. Also, this catalyst was found to be an efficient system for the N‐arylation of other nitrogen‐containing heterocycles with aryl iodides. The heterogeneous palladium catalyst could be recovered by simple filtration of the reaction solution and reused for six cycles without significant loss in its activity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
16.
Copper‐Catalyzed Aerobic Oxidative NS Bond Functionalization for CS Bond Formation: Regio‐ and Stereoselective Synthesis of Sulfones and Thioethers 下载免费PDF全文
Xianwei Li Yanli Xu Dr. Wanqing Wu Chang Jiang Dr. Chaorong Qi Prof. Dr. Huanfeng Jiang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(26):7911-7915
A regio‐ and stereoselective synthesis of sulfones and thioethers by means of CuI‐catalyzed aerobic oxidative N?S bond cleavage of sulfonyl hydrazides, followed by cross‐coupling reactions with alkenes and aromatic compounds to form the C?S bond, is described herein. N2 and H2O are the byproducts of this transformation, thus offering an environmentally benign process with a wide range of potential applications in organic synthesis and medicinal chemistry. 相似文献
17.
Prof. Dr. Li‐Jun Gu Cheng Jin Hong‐Tao Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(24):8741-8744
A novel nickel N‐heterocyclic carbene catalyzed cross‐coupling reaction of aryl aldehydes with boronic esters for the synthesis of aryl ketones was developed. This reaction provides a mild, practical method toward aryl ketones, which are versatile intermediates and building blocks in organic synthesis. 相似文献
18.
Pd‐Catalyzed Csp2H Functionalization of Heteroarenes via Isocyanide Insertion: Concise Synthesis of Di‐(Hetero)Aryl Ketones and Di‐(Hetero)Aryl Alkylamines 下载免费PDF全文
Dr. Upendra K. Sharma Dr. Nandini Sharma Jun Xu Prof. Dr. Gonghua Song Prof. Dr. Erik V. Van der Eycken 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(13):4908-4912
We report herein an efficient Pd‐catalyzed direct C?H bond functionalization of heteroarenes via an isocyanide insertion strategy for the synthesis of di‐(hetero)aryl ketones and di‐(hetero)aryl alkylamines. The methodology involves a three component reaction between an azole, a haloarene and an isocyanide resulting in the formation of an imine, which in turn is either hydrolyzed or reduced to get the desired product. 相似文献
19.
Microwave‐Assisted,Rhodium(III)‐Catalyzed N‐Annulation Reactions of Aryl and α,β‐Unsaturated Ketones with Alkynes 下载免费PDF全文
Hyejeong Lee Yong‐Kyun Sim Dr. Jung‐Woo Park Prof. Dr. Chul‐Ho Jun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(1):323-333
New RhIII‐catalyzed, one‐pot N‐annulation reactions of aryl and α,β‐unsaturated ketones with alkynes in the presence of ammonium acetate have been developed. Under microwave irradiation conditions, the processes lead to rapid formation of the respective isoquinoline and pyridine derivatives with efficiencies that are strongly dependent on the steric nature of the aryl ring and enone substituents. By employing this protocol, a variety of isoquinoline and pyridine derivatives were prepared in high yields. In addition, a new one‐pot approach to the synthesis of pyridines, involving four‐component reactions of ketones, formaldehyde, NH4OAc, and alkynes, has been uncovered. This process takes place through a route involving initial aldol condensation of the ketone with formaldehyde to generate a branched α,β‐unsaturated ketone that then undergoes RhIII‐catalyzed N‐annulation with NH4OAc and the alkyne. 相似文献
20.
RhIII‐Catalyzed Hydroacylation Reactions between N‐Sulfonyl 2‐Aminobenzaldehydes and Olefins 下载免费PDF全文
Tao Zhang Zisong Qi Xueyun Zhang Prof. Lamei Wu Prof. Dr. Xingwei Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(12):3283-3287
Metal‐catalyzed hydroacylation of olefins represents an important atom‐economic synthetic process in C?H activation. For the first time highly efficient RhIIICp*‐catalyzed hydroacylation was realized in the coupling of N‐sulfonyl 2‐aminobenzaldehydes with both conjugated and aliphatic olefins, leading to the synthesis of various aryl ketones. Occasionally, oxidative coupling occurred when a silver(I) oxidant was used. 相似文献