共查询到20条相似文献,搜索用时 15 毫秒
1.
Luo‐Yan Liu Jennifer X. Qiao Kap‐Sun Yeung William R. Ewing Jin‐Quan Yu 《Angewandte Chemie (International ed. in English)》2020,59(33):13831-13835
Fluorine is known to promote ortho‐C?H metalation. Based upon this reactivity, we employed an activated norbornene that traps the ortho‐palladation intermediate and is then relayed to the meta position, leading to meta‐selective C?H arylation of fluoroarenes. Deuterium experiment suggests that this meta‐arylation is initiated by ortho C?H activation and the catalytic cycle is terminated by C‐2 protonation. A dual‐ligand system is crucial for the observed high reactivity and site selectivity. Applying this approach to simple benzene or other arenes also affords arylation products with good yield and site selectivity. 相似文献
2.
Santhivardhana Reddy Yetra Torben Rogge Svenja Warratz Julia Struwe Wentao Peng Philipp Vana Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2019,58(22):7490-7494
Chemoselective C?H arylations were accomplished through micellar catalysis by a versatile single‐component ruthenium catalyst. The strategy provided expedient access to C?H‐arylated ferrocenes with wide functional‐group tolerance and ample scope through weak chelation assistance. The sustainability of the C?H arylation was demonstrated by outstanding atom‐economy and recycling studies. Detailed computational studies provided support for a facile C?H activation through thioketone assistance. 相似文献
3.
Dr. Fanzhi Yang Julian Koeller Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2016,55(15):4759-4762
Room‐temperature azole C?H arylations were accomplished with inexpensive copper(I) compounds by means of photoinduced catalysis. The expedient copper catalysis set the stage for site‐selective C?H arylations of non‐aromatic oxazolines under mild reaction conditions, and provides step‐economical access to the alkaloid natural products balsoxin and texamine. 相似文献
4.
Chinky Binnani Deepika Tyagi Rohit K. Rai Dr. Shaikh M. Mobin Dr. Sanjay K. Singh 《化学:亚洲杂志》2016,11(21):3022-3031
Water‐soluble arene–ruthenium complexes coordinated with readily available aniline‐based ligands were successfully employed as highly active catalysts in the C?H bond activation and arylation of 2‐phenylpyridine with aryl halides in water. A variety of (hetero)aryl halides were also used for the ortho‐C?H bond arylation of 2‐phenylpyridine to afford the corresponding ortho‐ monoarylated products as major products in moderate to good yields. Our investigations, including time‐scaled NMR spectroscopy and mass spectrometry studies, evidenced that the coordinating aniline‐based ligands, having varying electronic and steric properties, had a significant influence on the catalytic activity of the resulting arene–ruthenium–aniline‐based complexes. Moreover, mass spectrometry identification of the cycloruthenated species, {(η6‐arene)Ru(κ2‐C,N‐phenylpyridine)}+, and several ligand‐coordinated cycloruthenated species, such as [(η6‐arene)Ru(4‐methylaniline)(κ2‐C,N‐phenylpyridine)]+, found during the reaction of 2‐phenylpyridine with the arene–ruthenium–aniline complexes further authenticated the crucial roles of these species in the observed highly active and tuned catalyst. At last, the structures of a few of the active catalysts were also confirmed by single‐crystal X‐ray diffraction studies. 相似文献
5.
Olivier Baudoin 《Angewandte Chemie (International ed. in English)》2020,59(41):17798-17809
In the past decade, multiple catalytic C?H bond functionalization has been successfully applied in natural product synthesis as a strategy to reduce the number of steps, increase overall yield and employ more easily available starting materials. This minireview presents selected examples making use of multiple C?H bond functionalization in conceptually different ways. First, linear syntheses are discussed, wherein multiple C?H functionalization is employed either from simple (hetero)cyclic cores, at a late stage, or to build polycyclic systems. Second, the use of multiple C?H functionalization as a strategic tool in convergent synthesis to access and couple complex fragments is discussed. Information on the scalability of the employed methods is provided when available. The presented cases indicate that multiple C?H functionalization strategies should play a great role to shape the future synthesis of functional complex molecules with improved sustainability. 相似文献
6.
Daniel Zell Qingqing Bu Dr. Milica Feldt Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2016,55(26):7408-7412
Cationic cobalt complexes enable unprecedented cobalt‐catalyzed C?H/C?C functionalizations with unique selectivity features. The versatile cobalt catalyst proved broadly applicable, enabled efficient C?H/C?C cleavage at room temperature, and delivered Z‐alkenes with excellent diastereocontrol. 相似文献
7.
Metal‐ and Oxidant‐Free Alkenyl C−H/Aromatic C−H Cross‐Coupling Using Electrochemically Generated Iodosulfonium Ions 下载免费PDF全文
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
8.
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
9.
Chiral Bifunctional Phosphine‐Carboxylate Ligands for Palladium(0)‐Catalyzed Enantioselective C−H Arylation 下载免费PDF全文
Dr. Lei Yang Dr. Markus Neuburger Prof. Dr. Olivier Baudoin 《Angewandte Chemie (International ed. in English)》2018,57(5):1394-1398
Previous enantioselective Pd0‐catalyzed C?H activation reactions proceeding via the concerted metalation‐deprotonation mechanism employed either a chiral ancillary ligand, a chiral base, or a bimolecular mixture thereof. This study describes the development of new chiral bifunctional ligands based on a binaphthyl scaffold which incorporates both a phosphine and a carboxylic acid moiety. The optimal ligand provided high yields and enantioselectivities for a desymmetrizing C(sp2)?H arylation leading to 5,6‐dihydrophenanthridines, whereas the corresponding monofunctional ligands showed low enantioselectivities. The bifunctional system proved applicable to a range of substituted dihydrophenanthridines, and allowed the parallel kinetic resolution of racemic substrates. 相似文献
10.
Benedikt S. Schreib Marlene Fadel Erick M. Carreira 《Angewandte Chemie (International ed. in English)》2020,59(20):7818-7822
Palladium‐catalyzed regio‐ and diastereoselective C?H functionalization with bromoalkynes and electronically unbiased olefins is reported. The picolinamide directing group enables the formation of putative 5 and 6‐exo‐metallacycles as intermediates to afford monoalkynylated products in up to 91 % yield in a stereospecific fashion. The systematic study reveals that substrates with a wide range of substituents on the olefin and bromoalkyne coupling partners are tolerated. Chemoselective transformations were demonstrated for the obtained amides, olefins, and alkynes. 相似文献
11.
Torben Rogge Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2019,58(44):15640-15645
Experimental and computational studies provide detailed insight into the selectivity‐ and reactivity‐controlling factors in bifurcated ruthenium‐catalyzed direct C?H arylations and dehydrogenative C?H/C?H functionalizations. Thorough investigations revealed the importance of arene‐ligand‐free complexes for the formation of biscyclometalated intermediates within a ruthenium(II/IV/II) mechanistic manifold. 相似文献
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13.
ortho‐C−H Arylation of Benzoic Acids with Aryl Bromides and Chlorides Catalyzed by Ruthenium 下载免费PDF全文
Agostino Biafora Thilo Krause Dagmar Hackenberger Florian Belitz Prof. Dr. Lukas J. Gooßen 《Angewandte Chemie (International ed. in English)》2016,55(47):14752-14755
A system consisting of catalytic amounts of [(p‐cym)RuCl2]2/PEt3?HBF4, K2CO3 as the base, and NMP as the solvent efficiently mediates the ortho‐C?H arylation of benzoic acids with aryl bromides at 100 °C. Replacing the phosphine ligand with the amino acid dl ‐pipecolinic acid enables the analogous transformation with aryl chlorides. The key advantage of this broadly applicable transformation is the use of an inexpensive ruthenium catalyst in combination with simple carboxylates as directing groups, which can either be tracelessly removed or used as anchor points for decarboxylative ipso substitutions. 相似文献
14.
Copper‐Catalyzed Direct Sulfoximination of Heteroaromatic N‐Oxides by Dual C−H/N−H Dehydrogenative Cross‐Coupling 下载免费PDF全文
A dual C?H/N?H dehydrogenative coupling of quinoline‐type N‐oxides with sulfoximines that leads to N‐(hetero)arylsulfoximines in high yields has been realized by using a catalytic amount of CuBr in air. The method does not require any additional ligand, base, reactivity modifier or oxidant and provides a practical route towards a series of sulfoximidoyl‐functionalized quinolines and derivatives. 相似文献
15.
Thioketone‐Directed Palladium(II)‐Catalyzed C−H Arylation of Ferrocenes with Aryl Boronic Acids 下载免费PDF全文
Zhong‐Jian Cai Chen‐Xu Liu Dr. Qing Gu Prof. Dr. Shu‐Li You 《Angewandte Chemie (International ed. in English)》2018,57(5):1296-1299
A palladium(II)‐catalyzed thioketone‐chelation‐assisted direct C?H arylation of ferrocenes is described. With thioketone as an efficient directing group, various monoaryl‐ and diaryl‐substituted thiocarbonylferrocenes were obtained by palladium‐catalyzed direct C?H functionalization in high yields under mild and base‐free reaction conditions. Furthermore, the arylated thiocarbonylferrocene could undergo diverse transformations. 相似文献
16.
Shibo Xu Kazutaka Takamatsu Prof. Dr. Koji Hirano Prof. Dr. Masahiro Miura 《Angewandte Chemie (International ed. in English)》2018,57(36):11797-11801
A Ni(OAc)2‐catalyzed C?H coupling of 8‐aminoquinoline‐derived benzamides with epoxides has been developed. The reaction proceeds with concomitant removal of the 8‐aminoquinoline auxiliary to form the corresponding 3,4‐dihydroisocoumarins directly. Additionally, the nickel catalysis is stereospecific, and the cis‐ and trans‐epoxides are converted into the corresponding cis‐ and trans‐dihydroisocoumarins with retention of configuration, which is complementary to previously reported palladium catalysis. Moreover, while still preliminary, the C ?H functionalization is also achieved in the presence of modified NiCl2 catalysts. 相似文献
17.
Axially Chiral Dibenzazepinones by a Palladium(0)‐Catalyzed Atropo‐enantioselective C−H Arylation 下载免费PDF全文
Dr. Christopher G. Newton Elena Braconi Jennifer Kuziola Dr. Matthew D. Wodrich Prof. Dr. Nicolai Cramer 《Angewandte Chemie (International ed. in English)》2018,57(34):11040-11044
Atropo‐enantioselective C?H functionalization reactions are largely limited to the dynamic kinetic resolution of biaryl substrates through the introduction of steric bulk proximal to the axis of chirality. Reported herein is a highly atropo‐enantioselective palladium(0)‐catalyzed methodology that forges the axis of chirality during the C?H functionalization process, enabling the synthesis of axially chiral dibenzazepinones. Computational investigations support experimentally determined racemization barriers, while also indicating C?H functionalization proceeds by an enantio‐determining CMD to yield configurationally stable eight‐membered palladacycles. 相似文献
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19.
Direct C−H Arylation Meets Perovskite Solar Cells: Tin‐Free Synthesis Shortcut to High‐Performance Hole‐Transporting Materials 下载免费PDF全文
In contrast to the traditional multistep synthesis, we demonstrate herein a two‐step synthesis shortcut to triphenylamine‐based hole‐transporting materials (HTMs) through sequential direct C?H arylations. These hole‐transporting molecules are fabricated in perovskite‐based solar cells (PSCs) that exhibit promising efficiencies up to 17.69 %, which is comparable to PSCs utilizing commercially available 2,2′,7,7′‐tetrakis[N,N‐di(4‐methoxyphenyl)amino]‐9,9′‐spirobifluorene (spiro‐OMeTAD) as the HTM. This is the first report describing the use of step‐saving C?H activations/arylations in the facile synthesis of small‐molecule HTMs for perovskite solar cells. 相似文献
20.
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