共查询到20条相似文献,搜索用时 46 毫秒
1.
Christoph Zippel Dr. Eduard Spuling Dr. Zahid Hassan Dr. Mika Polamo Dr. Martin Nieger Prof. Dr. Stefan Bräse 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(61):13771-13775
Selective activation/functionalization of C−H bonds has emerged as an atom- and step-economical process at the forefront of modern synthetic chemistry. This work reports palladium-catalyzed exclusively para-selective C−H activation/aryl–aryl bond formation with a preference over N-arylation under the Buchwald–Hartwig amination reaction of 4-phenylamino[2.2]paracyclophane. This innovative synthetic strategy allows a facile preparation of [2.2]paracyclophane derivatives featuring disparate para-substitutions at C-4 and C-7 positions in a highly selective manner, gives access to a series of potential candidates for [2.2]paracyclophane-derived new planar chiral ligands. The unprecedented behavior in reactivity and preferential selectivity of C−C coupling over C−N bond formation via C−H activation is unique to the [2.2]paracyclophane scaffold compared to the non-cyclophane analogue under the same reaction conditions. Selective C−H activation/aryl–aryl bond formation and sequential C−N coupling product formation is evidenced unambiguously by X-ray crystallography. 相似文献
2.
Yandong Dou Kenry Dr. Jiang Liu Jianze Jiang Prof. Qing Zhu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(28):6896-6901
o-Alkenylation of unprotected phenols has been developed by direct C−H functionalization catalyzed by PdII. This work features phenol group as a directing group and realizes highly site-selective C−H bond functionalization of phenols to achieve the corresponding products in moderate to excellent yields at 60 °C. The advantages of this reaction include unprecedented C−H functionalization using phenol as a directing group, high regioselectivity, good substrate scope, mild reaction conditions, and high efficiency. To the best of our knowledge, this is the first example of a regioselective C−H alkenylation of unprotected phenols utilizing phenolic hydroxyl group as a directing group. The alkenylation of unprotected tyrosine and intramolecular cyclization are also successfully carried out under this catalytic system in good yields. Furthermore, this novel method enables a late-stage modification of complex phenol-containing bioactive molecules toward a diversity-oriented drug discovery. 相似文献
3.
Dr. Hui Cao Dr. Qiang Cheng Prof. Dr. Armido Studer 《Angewandte Chemie (International ed. in English)》2023,62(42):e202302941
The pyridine moiety is an important core structure for a variety of drugs, agrochemicals, catalysts, and functional materials. Direct functionalization of C−H bonds in pyridines is a straightforward approach to access valuable substituted pyridines. Compared to the direct ortho- and para-functionalization, meta-selective pyridine C−H functionalization is far more challenging due to the inherent electronic properties of the pyridine entity. This review summarizes currently available methods for pyridine meta-C−H functionalization using a directing group, non-directed metalation, and temporary dearomatization strategies. Recent advances in ligand control and temporary dearomatization are highlighted. We analyze the advantages as well as limitations of current techniques and hope to inspire further developments in this important area. 相似文献
4.
Sulphonamides and N-sulphonyl ketimines/aldimines have turned out to be versatile motifs in the field of synthetic and medicinal chemistry. The field of C−H activation/functionalization flourished remarkably due to their synthetic applicability and directing group plays a remarkable role to achieve regioselectivity in these reactions. The current review summarizes recent tactics by utilizing sulphonamides and N-sulphonyl ketimines/aldimines as directing groups for C−H activation or functionalization. As a directing group, they also facilitate site selectivity and late-stage functionalization of drug molecules in order to construct complex scaffolds of therapeutic importance by C−H activation. 相似文献
5.
Yuhang Zhu Yilei Liao Shuqi Jin Liyuan Ding Prof. Dr. Guofu Zhong Prof. Dr. Jian Zhang 《Chemical record (New York, N.Y.)》2023,23(5):e202300012
Aryl alkenes represents one of the most widely occurring structural motif in countless drugs and natural products, and direct C−H functionalization of aryl alkenes provides atom- step efficient access toward valuable analogues. Among them, group-directed selective olefinic α- and β-C−H functionalization, bearing a directing group on the aromatic ring, has attracted remarkable attentions, including alkynylation, alkenylation, amino-carbonylation, cyanation, domino cyclization and so on. These transformations proceed by endo- and exo−C−H cyclometallation and provide aryl alkene derivatives in excellent site- stereo-selectivity. Enantio-selective α- and β- olefinic C−H functionalization were also covered to synthesis axially chiral styrenes. 相似文献
6.
Wenbin Liu Tobias Babl Alexander Röther Prof. Dr. Oliver Reiser Prof. Dr. Huw M. L. Davies 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(19):4236-4241
Rhodium-catalyzed C−H insertions and cyclopropanations of donor/acceptor carbenes have been used for the synthesis of positional analogues of methylphenidate. The site selectivity is controlled by the catalyst and the amine protecting group. C−H functionalization of N-Boc-piperidine using Rh2(R-TCPTAD)4, or N-brosyl-piperidine using Rh2(R-TPPTTL)4 generated 2-substitited analogues. In contrast, when N-α-oxoarylacetyl-piperidines were used in combination with Rh2(S-2-Cl-5-BrTPCP)4, the C−H functionalization produced 4-susbstiuted analogues. Finally, the 3-substituted analogues were prepared indirectly by cyclopropanation of N-Boc-tetrahydropyridine followed by reductive regio- and stereoselective ring-opening of the cyclopropanes. 相似文献
7.
Shan Chen Binbin Yuan Dr. Yulei Wang Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2023,62(26):e202301168
Twofold distal C−H functionalization was accomplished by difunctionalization of nonactivated alkenes to provide rapid access to multifunctionalized molecules. The multicomponent ruthenium-catalyzed remote 1,n-difunctionalization (n=6,7) of nonactivated alkenes with fluoroalkyl halides and heteroarenes in a modular manner is reported. The meta-C(sp2)−H/C-6(sp3)−H distal functionalization featured mild conditions, unique selectivity, and broad substrate scope with a domino process for twofold remote C(sp2)−H/C(sp3)−H activation of the sequential formation of three different carbon-centered radicals. A plausible mechanism was proposed based on detailed experimental and computational studies. 相似文献
8.
9.
Abhinay S. Chillal Rajesh T. Bhawale Dr. Umesh A. Kshirsagar 《European journal of organic chemistry》2023,26(34):e202300665
A lenient approach for regioselective C3−H chalcogenation and thiocyanation of 4H-pyrido[1,2-a] pyrimidin-4-ones is developed using visible light photocatalysis. This operationally straightforward method furnishes a broad array of C-3, Ar−S/Ar−Se and -SCN functionalized derivatives in moderate to high yields. This protocol employs visible light as an environmentally friendly energy source, cost effective inorganic persulfate-based oxidant and easily procurable dichalcogenides for regioselective C−H chalcogenation of the substrate at room temperature. Further, regioselective thiocyanation of 4H-pyrido[1,2-a] pyrimidin-4-ones was also developed. Mechanistic path for these transformations has been proposed based on light on/off and Stern-Volmer studies as well as quantum yield calculations. 相似文献
10.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(19):5401-5405
One long‐standing issue in directed C−H functionalization is that either nitrogen or sulfur atoms present in heterocyclic substrates may bind preferentially to a transition‐metal catalyst rather than to the desired directing group. This competitive binding has largely hindered the application of C−H functionalization in late‐stage heterocycle drug discovery. Reported here is the use of an oxazoline‐based directing group capable of overriding the poisoning effect of a wide range of heterocycle substrates. The potential use of this directing group in pharmaceutical drug discovery is illustrated by diversification of Telmisartan (an antagonist for the angiotensin II receptor) through copper‐mediated C−H amination, hydroxylation, thiolation, arylation, and trifluoromethylation. 相似文献
11.
Palladium-catalyzed directing group assisted C−H bond activation has emerged as a powerful tool in synthetic organic chemistry. However, only recently, among various directing groups, widely available carboxylate moiety is recognized as a versatile candidate for the regioselective transformations. Notably, palladium-catalyzed carboxylate directed C(sp3)−H bond activation and diverse functionalization is highly challenging and has gained huge attention for its versatile applications. Mono- and bidentate ligands have proven to be useful for accelerating the C(sp3)−H bond activation step, which helps to control reactivity and selectivity (including enantioselectivity). In this Minireview, we discuss the recent progress made in palladium-catalyzed C(sp3)−H bond functionalization reactions for the construction of C−C and C−Heteroatom bonds with the direction of free carboxylic acid. 相似文献
12.
Dr. David F. León Rayo Ali Mansour Dr. Wenbin Wu Dr. Benjamin N. Bhawal Prof. Fabien Gagosz 《Angewandte Chemie (International ed. in English)》2023,62(3):e202212893
Direct C−H bond functionalization is a useful strategy for the straightforward formation of C−C and C−Heteroatom bonds. In the present work, a unique approach for the challenging electrophilic Au-catalyzed α-C−H bond functionalization of tertiary amines is presented. Electronic, steric and conformational synergistic effects exerted by the use of a malonate unit in the substrate were key to the success of this transformation. This new reactivity was applied to the synthesis of tetrahydro-γ-carboline products which, under oxidative conditions, could be converted into valuable structural motifs found in bioactive alkaloid natural products. 相似文献
13.
Zhao Li Xu Wang Yu-Ming Cui Jun-Han Ma Li-Lei Fang Lu-Lu Han Qin Yang Dr. Zheng Xu Prof. Dr. Li-Wen Xu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(13):4336-4340
Although asymmetric C−H functionalization has been available for the synthesis of structurally diverse molecules, catalytic dynamic kinetic resolution (DKR) approaches to change racemic stereogenic axes remain synthetic challenges in this field. Here, a concise palladium-catalyzed DKR was combined with C−H functionalization involving olefination and alkynylation for the highly efficient synthesis of non-biaryl-atropisomer-type (NBA) axially chiral oragnosilanes. The chemistry proceeded through two different and distinct DKR: first, an atroposelective C−H olefination or alkynylation produced axially chiral vinylsilanes or alkynylsilanes as a new family of non-biaryl atropisomers (NBA), and second, the extension of this DKR strategy to twofold o,o′-C−H functionalization led to the multifunctional axially chiral organosilicon compounds with up to >99 % ee. 相似文献
14.
Dr. Luo-Yan Liu Dr. Zhoulong Fan Dr. Md Emdadul Hoque Dr. Shaoqun Qian Dr. Guangrong Meng Nikita Chekshin Dr. Keita Tanaka Dr. Jennifer X. Qiao Dr. Kap-Sun Yeung Prof. Dr. Jin-Quan Yu 《Angewandte Chemie (International ed. in English)》2023,62(37):e202307581
Remote C−H functionalization of heterocyclic biaryls will be of great importance in synthesis and medicinal chemistry. Through adjusting the geometric relationship of the directing atom and target C−H bonds, two new catalytic templates have been developed to enable the functionalization of the more hindered ortho-C−H bonds of heterobiaryls bearing directing heteroatom at the meta- or para-positions, affording unprecedented site-selectivity. The use of template chaperone also overcomes product inhibition and renders the directing templates catalytic. The utility of this protocol was demonstrated by olefination of heterocyclic biaryls with various substituents, overriding conventional steric and electronic effects. These ortho-C−H olefinated heterobiaryls are sterically hindered and can often be challenging to prepare through aryl-aryl coupling reactions. 相似文献
15.
Luca C. Greiner Dr. Norihito Arichi Prof. Dr. Shinsuke Inuki Prof. Dr. Hiroaki Ohno 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(3):e202213653
Phenyl azides substituted by an (alkylphenyl)ethynyl group facilitate benzylic sp3(C−H) functionalization in the presence of a JohnPhosAu catalyst, resulting in indole-fused tetra- and pentacycles via divergent N- or C-cyclization. The chemoselectivity is influenced depending on the counter-anion, the electron density of the α-imino gold(I) carbene, and the alkyl groups stabilizing the benzylic carbocation originating from a 1,5-hydride shift. An isotopic labeling experiment demonstrates the involvement of an indolylgold(I) species resulting from a tautomerization that is much faster than the deauration. The formation of a benzylic sp3(C−H) functionalization leading to an indole-fused seven-membered ring is also demonstrated. 相似文献
16.
Dr. David F. León Rayo Ali Mansour Dr. Wenbin Wu Dr. Benjamin N. Bhawal Prof. Fabien Gagosz 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(3):e202212893
Direct C−H bond functionalization is a useful strategy for the straightforward formation of C−C and C−Heteroatom bonds. In the present work, a unique approach for the challenging electrophilic Au-catalyzed α-C−H bond functionalization of tertiary amines is presented. Electronic, steric and conformational synergistic effects exerted by the use of a malonate unit in the substrate were key to the success of this transformation. This new reactivity was applied to the synthesis of tetrahydro-γ-carboline products which, under oxidative conditions, could be converted into valuable structural motifs found in bioactive alkaloid natural products. 相似文献
17.
Dr. Uttam Dutta Sandip Porey Sandeep Pimparkar Astam Mandal Jagrit Grover Adithyaraj Koodan Dr. Debabrata Maiti 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(47):21017-21022
Biaryl compounds are extremely important structural motifs in natural products, biologically active components and pharmaceuticals. Selective synthesis of biaryls by distinguishing the subtle reactivity difference of distal arene C−H bonds are significantly challenging. Herein, we describe para-selective C−H arylation, which is acheived by a unique combination of a meta-directing group and norbornene as a transient mediator. Upon direct meta-C−H palladation, one-bond relay palladation occurs in presence of norbornene and subsequently para-C−H arylation is achieved for sulfonates, phosphonates and phenols bearing 2,6-disubstitution patterns. The protocol is amenable to electron-deficient aryl iodides. Multisubstituted arenes and phenols are obtained by postsynthetic modification of the products. The protocol allows the synthesis of hexa-substituted benzene by sequential selective distal C−H functionalization. 相似文献
18.
《化学:亚洲杂志》2017,12(15):1865-1868
A facile synthesis of 2‐amino‐1,3‐oxazoles via CuI‐catalyzed oxidative cyclization of enamines and N ,N ‐dialkyl formamides has been developed. The reaction proceeds through an oxidative C−N bond formation, followed by an intramolecular C(sp2)−H bond functionalization/C−O cyclization in one pot. This protocol provides direct access to useful 2‐amino‐1,3‐oxazoles and features protecting‐group‐free nitrogen sources, readily available starting materials, a broad substrate scope and mild reaction conditions. 相似文献
19.
Marianela G. Pizzio Dr. Ernesto G. Mata Dr. Philippe Dauban Dr. Tanguy Saget 《European journal of organic chemistry》2023,26(37):e202300616
Herein, we report a photocatalytic strategy for the C−H functionalization of saturated azaheterocycles under mild conditions with only one equivalent of starting material. Our strategy is based on a redox active benzamide protecting group that is activated via a halogen-atom transfer (XAT) process to trigger the formation of an α-amino radical. This nucleophilic radical intermediate was then engaged in Giese additions and radical cross couplings to afford C−H alkylated and arylated products. 相似文献
20.
Ruthenium(II)‐Catalyzed meta C−H Mono‐ and Difluoromethylations by Phosphine/Carboxylate Cooperation
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(8):2077-2081
Ruthenium(II)‐catalyzed meta ‐selective C−H (di)fluoromethylation was accomplished by phosphine and carboxylate cooperation. The remote C−H functionalization was characterized by ample substrate scope, thereby setting the stage for meta ‐(di)fluoromethylation through facile C−H cleavage. 相似文献