共查询到20条相似文献,搜索用时 15 毫秒
1.
Rhodium‐Catalyzed Annulative Coupling of 3‐Phenylthiophenes with Alkynes Involving Double C‐H Bond Cleavages 下载免费PDF全文
Tomonori Iitsuka Dr. Koji Hirano Prof. Dr. Tetsuya Satoh Prof. Dr. Masahiro Miura 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(2):385-389
Double C?H bond activation took place efficiently upon treatment of 3‐phenylthiophenes with alkynes in the presence of a rhodium catalyst and a copper salt oxidant to form the corresponding naphthothiophene derivatives. Dehydrogenative coupling with alkenes was also found to occur on the phenyl moiety rather than the thiophene ring. These reactions provide straightforward synthetic methods for π‐conjugated molecules involving a thiophene unit from readily available, simple building blocks. 相似文献
2.
Regioselective C3 Alkenylation of 4 H‐pyrido[1,2‐a]pyrimidin‐4‐ones via Palladium‐Catalyzed CH Activation 下载免费PDF全文
Dr. Wenjie Liu Dr. Shaohua Wang Qi Zhang Jingwen Yu Jiahe Li Zhiwei Xie Prof. Hua Cao 《化学:亚洲杂志》2014,9(9):2436-2439
A general and efficient palladium‐catalyzed direct C3 alkenylation of 4H‐pyrido[1,2‐a]pyrimidin‐4‐ones using AgOAc/O2 as the oxidant has been developed. A variety of 4H‐pyrido[1,2‐a]pyrimidin‐4‐ones were successfully coupled with acrylate esters, styrenes, methylvinylketone, and acrylamide in moderate to excellent yields. The reaction exhibited complete regio‐ and stereoselectivity. This transformation provides an attractive new approach to functionalize 4H‐pyrido[1,2‐a]pyrimidin‐4‐ones. 相似文献
3.
Rhodium(II)‐Catalyzed Nondirected Oxidative Alkenylation of Arenes: Arene Loading at One Equivalent 下载免费PDF全文
Dr. Harit U. Vora Anthony P. Silvestri Casper J. Engelin Prof. Dr. Jin‐Quan Yu 《Angewandte Chemie (International ed. in English)》2014,53(10):2683-2686
A bimetallic RhII catalyst promoted the C? H alkenylation of simple arenes at 1.0 equivalent without the use of a directing group. A phosphine ligand as well as cooperative reoxidation of RhII with Cu(TFA)2 and V2O5 proved essential in providing monoalkenylated products in good yields and selectivities, especially with di‐ and trisubstituted arenes. 相似文献
4.
Rhodium(III)‐Catalyzed Selective ortho‐Olefinations of N‐Acyl and N‐Aroyl Sulfoximines by CH Bond Activation 下载免费PDF全文
Dr. Kanniyappan Parthasarathy Prof. Dr. Carsten Bolm 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(17):4896-4900
Two new rhodium‐catalyzed oxidative couplings between sulfoximine derivatives and alkenes by regioselective C?H activation, affording ortho‐olefinated (Heck‐type) products, are reported. A synthetic application of the ortho‐alkenylated products into the corresponding cyclic derivatives has been demonstrated, and a mechanistic rational for the rhodium catalysis is presented. 相似文献
5.
All‐Carbon [3+3] Oxidative Annulations of 1,3‐Enynes by Rhodium(III)‐Catalyzed CH Functionalization and 1,4‐Migration 下载免费PDF全文
Dr. David J. Burns Dr. Daniel Best Dr. Martin D. Wieczysty Prof. Hon Wai Lam 《Angewandte Chemie (International ed. in English)》2015,54(34):9958-9962
1,3‐Enynes containing allylic hydrogens cis to the alkyne function as three‐carbon components in rhodium(III)‐catalyzed, all‐carbon [3+3] oxidative annulations to produce spirodialins. The proposed mechanism of these reactions involves the alkenyl‐to‐allyl 1,4‐rhodium(III) migration. 相似文献
6.
Fen Wang Xinzhang Yu Zisong Qi Prof. Dr. Xingwei Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(2):511-516
Rhodium‐catalyzed sulfonylation, thioetherification, thiocyanation, and other heterofunctionalizations of arenes bearing a heterocyclic directing group have been realized. The reaction proceeds by initial RhIII‐catalyzed C?H hyperiodination of arene at room temperature followed by uncatalyzed nucleophilic functionalization. A diaryliodonium salt is isolated as an intermediate, which represents umpolung of the arene substrate, in contrast to previous studies that suggested umpolung of the coupling partner. 相似文献
7.
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
8.
A Convenient Synthesis of N‐Aryl Benzamides by Rhodium‐Catalyzed ortho‐Amidation and Decarboxylation of Benzoic Acids 下载免费PDF全文
Dr. Xian‐Ying Shi Ke‐Yan Liu Juan Fan Xue‐Fen Dong Prof. Dr. Jun‐Fa Wei Prof. Dr. Chao‐Jun Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(5):1900-1903
The rhodium‐catalyzed amidation of substituted benzoic acids with isocyanates by directed C?H functionalization followed by decarboxylation to afford the corresponding N‐aryl benzamides is demonstrated, in which the carboxylate serves as a unique, removable directing group. Notably, less common meta‐substituted N‐aryl benzamides are generated readily from more accessible para‐ or ortho‐substituted groups by employing this strategy. 相似文献
9.
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
10.
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
11.
《化学:亚洲杂志》2017,12(3):289-292
A rhodium‐catalyzed regioselective C−H olefination of indazole is described. This protocol relies on the use of an efficient and removable N ,N ‐diisopropylcarbamoyl directing group, which offers facile access to C7‐olefinated indazoles with high regioselectivity, ample substrate scope and broad functional group tolerance. 相似文献
12.
Wen‐Hao Guo Qiao‐Qiao Min Ji‐Wei Gu Prof. Dr. Xingang Zhang 《Angewandte Chemie (International ed. in English)》2015,54(31):9075-9078
An ortho‐selective C? F bond borylation between N‐heterocycle‐substituted polyfluoroarenes and Bpin‐Bpin with simple and commercially available [Rh(cod)2]BF4 as a catalyst is now reported. The reaction proceeds under mild reaction conditions with high efficiency and broad substrate scope, even toward monofluoroarene, thus providing a facile access to a wide range of borylated fluoroarenes that are useful for photoelectronic materials. Preliminary mechanistic studies reveal that a RhIII/V catalytic cycle via a key intermediate rhodium(III) hydride complex [(H)RhIIILn(Bpin)] may be involved in the reaction. 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.
Practical Synthesis of anti‐β‐Hydroxy‐α‐Amino Acids by PdII‐Catalyzed Sequential C(sp3)H Functionalization 下载免费PDF全文
Kai Chen Shuo‐Qing Zhang Huai‐Zhi Jiang Jing‐Wen Xu Prof. Dr. Bing‐Feng Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(8):3264-3270
An improved and practical procedure for the stereoselective synthesis of anti‐β‐hydroxy‐α‐amino acids (anti‐βhAAs), by palladium‐catalyzed sequential C(sp3)?H functionalization directed by 8‐aminoquinoline auxiliary, is described. followed by a previously established monoarylation and/or alkylation of the β‐methyl C(sp3)?H of alanine derivative, β‐acetoxylation of both alkylic and benzylic methylene C(sp3)?H bonds affords various anti‐β‐hydroxy‐α‐amino acid derivatives. As an example, the synthesis of β‐mercapto‐α‐amino acids, which are highly important to the extension of native chemical ligation chemistry beyond cysteine, is described. The synthetic potential of this protocol is further demonstrated by the synthesis of diverse β‐branched α‐amino acids. The observed diastereoselectivities are strongly influenced by electronic effects of aromatic AAs and steric effects of the linear side‐chain AAs, which could be explained by the competition of intramolecular C?OAc bond reductive elimination from PdIV intermediates vs. intermolecular attack by an external nucleophile (AcO?) in an SN2‐type process. 相似文献
15.
Dr. Yaxi Yang Dr. Wei Hou Lihuai Qin Dr. Juanjuan Du Huijin Feng Dr. Bing Zhou Dr. Yuanchao Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(2):416-420
The rhodium‐catalyzed intermolecular direct C?H thiolation of arenes with aryl and alkyl disulfides was developed for the first time to provide a convenient route to aryl thioethers. This strategy is compatible with many different directing groups and exhibits excellent functional group tolerance. More significantly, mono‐ or dithiolation can be selectively achieved, thus providing a straightforward way for selective preparation of aryl thioethers and dithioethers. 相似文献
16.
Dr. Nicolas Gigant Dr. Laëtitia Chausset‐Boissarie Prof. Dr. Isabelle Gillaizeau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(25):7548-7564
Enamides are stable enamine surrogates and provide key intermediates for the synthesis of small but complex nitrogen‐containing compounds. Metal‐catalyzed regioselective functionalization of enamides provides a rapid method to synthesize useful nitrogen containing heterocycles. This review discloses the recent progress made in the development of the C?H functionalization of enamides involving efficient and atom‐economical routes. Syntheses of different heterocycles are classified based on the site reactivity of enamides and key mechanistic insights are given for each transformation. 相似文献
17.
The catalytic cross‐dehydrogenative coupling (CDC) reaction has received intense attention in recent years. The attractive feature of this coupling process is the formation of a C? C bond from two C? H moieties under oxidative conditions. In this Focus Review, recent advances in the palladium‐catalyzed CDC reactions of C(sp2)? H bond are summarized, with a focus on the period from 2011 to early 2013. 相似文献
18.
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
19.
Regioselective Hydroarylation Reactions of C3 Electrophilic N‐Acetylindoles Activated by FeCl3: An Entry to 3‐(Hetero)arylindolines 下载免费PDF全文
Rodolphe Beaud Dr. Régis Guillot Prof. Cyrille Kouklovsky Dr. Guillaume Vincent 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(24):7492-7500
A method for the direct and rare umpolung of the 3 position of indoles is reported. The activation of N‐acetylindole with iron(III) chloride allows the C?H addition of aromatic and heteroaromatic substrates to the C2?C3 double bond of the indole nucleus to generate a quaternary center at C3 and leads regioselectively to 3‐arylindolines. Optimization, scope (50 examples), practicability (gram scale, air atmosphere, room temperature), and mechanistic insights of this process are presented. Synthetic transformations of the indoline products into drug‐like compounds are also described. 相似文献
20.
Synthesis of Spirocyclic Enones by Rhodium‐Catalyzed Dearomatizing Oxidative Annulation of 2‐Alkenylphenols with Alkynes and Enynes 下载免费PDF全文
Szymon Kujawa Dr. Daniel Best Dr. David J. Burns Prof. Hon Wai Lam 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(28):8599-8602
The dearomatizing oxidative annulation of 2‐alkenylphenols with alkynes and enynes proceeds with high yields and regioselectivities under RhIII catalysis. These reactions are successful using Cu(OAc)2 or air as the stoichiometric oxidant, and provide spirocyclic enones, the basic ring system of which appears in several natural products. Application of this process to the preparation of a highly functionalized tetracycle is also demonstrated. 相似文献