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1.
《Chemical record (New York, N.Y.)》2018,18(6):556-569
Direct transformation of carbon–hydrogen bond (C–H) has emerged to be a trend for construction of molecules from building blocks with no or less prefunctionalization, leading high atom and step economy. Directing group (DG) strategy is widely used to achieve higher reactivity and selectivity, but additional steps are usually needed for installation and/or cleavage of DGs, limiting step economy of the overall transformation. To meet this challenge, we proposed a concept of automatic DG (DGauto), which is auto‐installed and/or auto‐cleavable. Multifunctional oxime and hydrazone DGauto were designed for C–H activation and alkyne annulation to furnish diverse nitrogen‐containing heterocycles. Imidazole was employed as an intrinsic DG (DGin) to synthesize ring‐fused and π‐extended functional molecules. The alkyne group in the substrates can also be served as DGin for ortho‐C–H activation to afford carbocycles. In this account, we intend to give a review of our progress in this area and brief introduction of other related advances on C–H functionalization using DGauto or DGin strategies. 相似文献
2.
Rhodium(III)‐Catalyzed CC and CO Coupling of Quinoline N‐Oxides with Alkynes: Combination of CH Activation with O‐Atom Transfer 下载免费PDF全文
Xueyun Zhang Zisong Qi Prof. Xingwei Li 《Angewandte Chemie (International ed. in English)》2014,53(40):10794-10798
[Cp*RhIII]‐catalyzed C? H activation of arenes assisted by an oxidizing N? O or N? N directing group has allowed the construction of a number of hetercycles. In contrast, a polar N? O bond is well‐known to undergo O‐atom transfer (OAT) to alkynes. Despite the liability of N? O bonds in both C? H activation and OAT, these two important areas evolved separately. In this report, [Cp*RhIII] catalysts integrate both areas in an efficient redox‐neutral coupling of quinoline N‐oxides with alkynes to afford α‐(8‐quinolyl)acetophenones. In this process the N? O bond acts as both a directing group for C? H activation and as an O‐atom donor. 相似文献
3.
Rhodium(III)‐Catalyzed ortho CH Heteroarylation of (Hetero)aromatic Carboxylic Acids: A Rapid and Concise Access to π‐Conjugated Poly‐heterocycles 下载免费PDF全文
Dr. Xurong Qin Xiaoyu Li Quan Huang Hu Liu Prof. Dr. Di Wu Qiang Guo Prof. Dr. Jingbo Lan Prof. Dr. Ruilin Wang Prof. Dr. Jingsong You 《Angewandte Chemie (International ed. in English)》2015,54(24):7167-7170
RhIII‐catalyzed oxidative C? H/C? H cross‐coupling between (hetero)aromatic carboxylic acids and various heteroarenes has been accomplished to construct highly functionalized ortho‐carboxy‐substituted bi(hetero)aryls. The use of a carboxy group as the directing group obviates tedious steps for installation and removal of extra directing groups, and enables a facile one‐step synthesis of ortho‐carboxy bi(hetero)aryls. The method provides opportunities for rapid assembly of a library of important fluorene and coumarin‐type poly‐heterocycles through intramolecular electrophilic substitution or oxidative lactonization. As illustrative examples, the strategy developed herein greatly streamlines accesses to a variety of appealing polyheterocycles such as DTPO (5H‐dithieno[3,2‐b:2′,3′‐d]pyran‐5‐one), CPDTO (cyclopentadithiophen‐4‐one), and indenothiophenes. 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.
Hai‐Tao Tang Yun‐Bing Zhou Yu Zhu Hong‐Chao Sun Min Lin Prof. Zhuang‐Ping Zhan 《化学:亚洲杂志》2014,9(5):1278-1281
An efficient Cs2CO3‐promoted synthesis of α‐amino ketones using hydrazines, aldehydes, and α‐haloketones as starting materials through a cascade condensation/nucleophilic substitution/N? N bond cleavage route is developed. The carbonyl group plays a key role in this novel N? N bond cleavage process. 相似文献
6.
Copper‐Mediated C6‐Selective Dehydrogenative Heteroarylation of 2‐Pyridones with 1,3‐Azoles 下载免费PDF全文
Riko Odani Dr. Koji Hirano Prof. Dr. Tetsuya Satoh Prof. Dr. Masahiro Miura 《Angewandte Chemie (International ed. in English)》2014,53(40):10784-10788
A copper‐mediated C6‐selective dehydrogenative heteroarylation of 2‐pyridones with 1,3‐azoles has been developed. The reaction proceeded smoothly by twofold C? H cleavage even in the absence of noble‐metal catalysts. The observed site selectivity was directed by a pyridyl substituent on the nitrogen atom of the pyridone ring. This directing group was readily removed after the coupling event, thus leading to 2‐pyridone derivatives with a free N? H group. Moreover, in some cases, catalytic turnover of the Cu salt was also possible with the ideal terminal oxidant: molecular oxygen in air. 相似文献
7.
Zhen Wang Jizhi Ni Prof. Dr. Yoichiro Kuninobu Prof. Dr. Motomu Kanai 《Angewandte Chemie (International ed. in English)》2014,53(13):3496-3499
The first copper‐catalyzed intramolecular C(sp3)? H and C(sp2)? H oxidative amidation has been developed. Using a Cu(OAc)2 catalyst and an Ag2CO3 oxidant in dichloroethane solvent, C(sp3)? H amidation proceeded at a terminal methyl group, as well as at the internal benzylic position of an alkyl chain. This reaction has a broad substrate scope, and various β‐lactams were obtained in excellent yield, even on gram scale. Use of CuCl2 and Ag2CO3 under an O2 atmosphere in dimethyl sulfoxide, however, leads to 2‐indolinone selectively by C(sp2)? H amidation. Kinetic isotope effect (KIE) studies indicated that C? H bond activation is the rate‐determining step. The 5‐methoxyquinolyl directing group could be removed by oxidation. 相似文献
8.
The Mechanism of NO Bond Cleavage in Rhodium‐Catalyzed CH Bond Functionalization of Quinoline N‐oxides with Alkynes: A Computational Study 下载免费PDF全文
Yingzi Li Song Liu Zisong Qi Xiaotian Qi Prof. Dr. Xingwei Li Prof. Dr. Yu Lan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(28):10131-10137
Metal‐catalyzed C?H activation not only offers important strategies to construct new bonds, it also allows the merge of important research areas. When quinoline N‐oxide is used as an arene source in C?H activation studies, the N?O bond can act as a directing group as well as an O‐atom donor. The newly reported density functional theory method, M11L, has been used to elucidate the mechanistic details of the coupling between quinoline N?O bond and alkynes, which results in C?H activation and O‐atom transfer. The computational results indicated that the most favorable pathway involves an electrophilic deprotonation, an insertion of an acetylene group into a Rh?C bond, a reductive elimination to form an oxazinoquinolinium‐coordinated RhI intermediate, an oxidative addition to break the N?O bond, and a protonation reaction to regenerate the active catalyst. The regioselectivity of the reaction has also been studied by using prop‐1‐yn‐1‐ylbenzene as a model unsymmetrical substrate. Theoretical calculations suggested that 1‐phenyl‐2‐quinolinylpropanone would be the major product because of better conjugation between the phenyl group and enolate moiety in the corresponding transition state of the regioselectivity‐determining step. These calculated data are consistent with the experimental observations. 相似文献
9.
Regioselective Ruthenium‐Catalyzed Carbonylative Direct Arylation of Five‐Membered and Condensed Heterocycles 下载免费PDF全文
Jola Pospech Dr. Anis Tlili Dr. Anke Spannenberg Dr. Helfried Neumann Prof. Dr. Matthias Beller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(11):3135-3141
A ruthenium‐catalyzed carbonylative C?H bond arylation process for the three‐component synthesis of complex aryl–(hetero)aryl ketones in an aqueous solution has been developed. By exploiting the ortho‐activating effect of nitrogen‐containing directing groups, a regioselective, successive twofold C(sp2)?C(sp2) bond formation has been achieved. This straightforward catalytic process provides access to versatile products prevalent in multiple bioactive compounds and supplies a valuable functional group for subsequent transformations. 相似文献
10.
Rhodium(III)‐Catalyzed N‐Nitroso‐Directed CH Addition to Ethyl 2‐Oxoacetate for Cycloaddition/Fragmentation Synthesis of Indazoles 下载免费PDF全文
Dr. Jinsen Chen Pei Chen Chao Song Prof. Dr. Jin Zhu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(44):14245-14249
RhIII‐catalyzed N‐nitroso‐directed C?H addition to ethyl 2‐oxoacetate allows subsequent construction of indazoles, a privileged heterocycle scaffold in synthetic chemistry, through the exploitation of reactivity between the directing group and installed group. The formal [2+2] cycloaddition/fragmentation reaction pathway identified herein, a unique reactivity pattern hitherto elusive for the N‐nitroso group, emphasizes the importance of forward reactivity analysis in the development of useful C?H functionalization‐based synthetic tools. The synthetic utility of the protocol is demonstrated with the synthesis of a tricyclic‐fused ring system. The diversity of covalent linkages available for the nitroso group should enable the extension of the genre of reactivity reported herein to the synthesis of other types of heterocycles. 相似文献
11.
Copper‐Catalyzed Aerobic Oxidative Inert CC and CN Bond Cleavage: A New Strategy for the Synthesis of Tertiary Amides 下载免费PDF全文
Xiuling Chen Dr. Tieqiao Chen Qiang Li Dr. Yongbo Zhou Prof. Li‐Biao Han Prof. Shuang‐Feng Yin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(38):12234-12238
A copper‐catalyzed aerobic oxidative amidation reaction of inert C?C bonds with tertiary amines has been developed for the synthesis of tertiary amides, which are significant units in many natural products, pharmaceuticals, and fine chemicals. This method combines C?C bond activation, C?N bond cleavage, and C?H bond oxygenation in a one‐pot protocol, using molecular oxygen as the sole oxidant without any additional ligands. 相似文献
12.
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
13.
Synthesis of Indazoles and Azaindazoles by Intramolecular Aerobic Oxidative CN Coupling under Transition‐Metal‐Free Conditions 下载免费PDF全文
Jiantao Hu Huacheng Xu Pengju Nie Xiaobo Xie Prof. Dr. Zongxiu Nie Prof. Dr. Yu Rao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(14):3932-3938
A transition‐metal‐free oxidative C?N coupling method has been developed for the synthesis of 1H‐azaindazoles and 1H‐indazoles from easily accessible hydrazones. The procedure uses TEMPO, a basic additive, and dioxygen gas as the terminal oxidant. This reaction demonstrates better reactivity, functional group tolerance, and broader scope than comparable metal catalyzed reactions. 相似文献
14.
Regioselective Acceptorless Dehydrogenative Coupling of N‐Heterocycles toward Functionalized Quinolines,Phenanthrolines, and Indoles 下载免费PDF全文
Dinesh Talwar Angela Gonzalez‐de‐Castro Dr. Ho Yin Li Prof. Jianliang Xiao 《Angewandte Chemie (International ed. in English)》2015,54(17):5223-5227
A new strategy has been developed for the oxidant‐ and base‐free dehydrogenative coupling of N‐heterocycles at mild conditions. Under the action of an iridium catalyst, N‐heterocycles undergo multiple sp3 C? H activation steps, generating a nucleophilic enamine that reacts in situ with various electrophiles to give highly functionalized products. The dehydrogenative coupling can be cascaded with Friedel–Crafts addition, resulting in a double functionalization of the N‐heterocycles. 相似文献
15.
Readily Removable Directing Group Assisted Chemo‐ and Regioselective C(sp3)H Activation by Palladium Catalysis 下载免费PDF全文
Yun‐Fei Zhang Prof. Dr. Hong‐Wei Zhao Hui Wang Jiang‐Bo Wei Prof. Dr. Zhang‐Jie Shi 《Angewandte Chemie (International ed. in English)》2015,54(46):13686-13690
Currently used directing groups for selective aliphatic β‐functionalization of carbonyl compounds show excellent reactivity and selectivity with an amide as a linker. Described herein is 2‐piconimide, used for the first time with commercially available 2‐picolinamide/2‐picolic acid as precursors, to direct C? H arylation/alkenylation by palladium catalysis. The directing group is essential for promoting the sequnetial primary and secondary C(sp3)? H arylation with different aryl iodides in one substrate. The directing group was easily removed under simple reaction conditions at room temperature. 相似文献
16.
Activation of CH Bonds through Oxidant‐Free Photoredox Catalysis: Cross‐Coupling Hydrogen‐Evolution Transformation of Isochromans and β‐Keto Esters 下载免费PDF全文
Ming Xiang Dr. Qing‐Yuan Meng Jia‐Xin Li Yi‐Wen Zheng Chen Ye Dr. Zhi‐Jun Li Dr. Bin Chen Prof. Dr. Chen‐Ho Tung Prof. Dr. Li‐Zhu Wu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(50):18080-18084
The direct and controlled activation of a C(sp3)?H bond adjacent to an O atom is of particular synthetic value for the conventional derivatization of ethers or alcohols. In general, stoichiometric amounts of an oxidant are required to remove an electron and a hydrogen atom of the ether for subsequent transformations. Herein, we demonstrate that the activation of a C?H bond next to an O atom could be achieved under oxidant‐free conditions through photoredox‐neutral catalysis. By using a commercial dyad photosensitizer (Acr+‐Mes ClO4?, 9‐mesityl‐10‐methylacridinium perchlorate) and an easily available cobaloxime complex (Co(dmgBF2)2?2 MeCN, dmg=dimethylglyoxime), the nucleophilic addition of β‐keto esters to oxonium species, which is rarely observed in photocatalysis, leads to the corresponding coupling products and H2 in moderate to good yields under visible‐light irradiation. Mechanistic studies suggest that both isochroman and the cobaloxime complex quench the electron‐transfer state of this dyad photosensitizer and that benzylic C?H bond cleavage is probably the rate‐determining step of this cross‐coupling hydrogen‐evolution transformation. 相似文献
17.
Copper‐Catalyzed Trifluoromethylation of Internal Olefinic CH Bonds: Efficient Routes to Trifluoromethylated Tetrasubstituted Olefins and N‐Heterocycles 下载免费PDF全文
Zhifeng Mao Fei Huang Dr. Haifeng Yu Prof. Dr. Jiping Chen Prof. Dr. Zhengkun Yu Prof. Dr. Zhaoqing Xu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(12):3439-3445
The functionalization of internal olefins has been a challenging task in organic synthesis. Efficient CuII‐catalyzed trifluoromethylation of internal olefins, that is, α‐oxoketene dithioacetals, has been achieved by using Cu(OH)2 as a catalyst and TMSCF3 as a trifluoromethylating reagent. The push–pull effect from the polarized olefin substrates facilitates the internal olefinic C?H trifluoromethylation. Cyclic and acyclic dithioalkyl α‐oxoketene acetals were used as the substrates and various substituents were tolerated. The internal olefinic C?H bond cleavage was not involved in the rate‐determining step, and a mechanism that involves radicals is proposed based on a TEMPO‐quenching experiment of the trifluoromethylation reaction. Further derivatization of the resultant CF3 olefins led to multifunctionalized tetrasubstituted CF3 olefins and trifluoromethylated N‐heterocycles. 相似文献
18.
Regio‐ and Diastereoselective and Enantiospecific Metal‐Free C(sp3)H Arylation: Facile Access to Optically Active 5‐Aryl 2,5‐Disubstituted Pyrrolidines 下载免费PDF全文
Surajit Haldar Subhra Kanti Roy Bholanath Maity Prof. Dr. Debasis Koley Prof. Dr. Chandan K. Jana 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(43):15290-15298
Optically active 5‐aryl 2,5‐disubstituted pyrrolidines are the principal structural moiety of many bioactive compounds including natural products and catalysts for asymmetric synthesis. A highly regio‐ and diastereoselective and enantiospecific method for direct C?H arylation of aliphatic amine has been developed. Structurally diverse enantiopure arylated pyrrolidines were synthesized from commercially available starting materials, through a single‐step three‐component reaction under metal‐ and oxidant‐free conditions. Furthermore, the complex analogous structure of CCK antagonist RP 66803 and angiotensin‐converting enzyme inhibitors was easily constructed using the synthesized arylated pyrrolidine derivative. Detailed theoretical calculations (M06‐2X/TZVPP/SMD//M06‐2X/6‐31+G(d,p) level) were also carried to investigate the mechanism and high level of stereocontrol involved in this direct sp3 C?H arylation reaction. Preference for a given regio‐ and stereoselectivity in the arylated product can be explained through elucidation of the mechanism for dehydration, generating azomethine ylide, and for the final re‐aromatization step. The calculated energies reveals that the re‐aromatization step is essentially rate determining, accompanying an activation barrier of Δ≠${G{{{\rm S}\hfill \atop {\rm L}\hfill}}}$ =25.6 kcal mol?1. 相似文献
19.
PdII‐Catalyzed Mild CH ortho Arylation and Intramolecular Amination Oriented by a Phosphinamide Group 下载免费PDF全文
Jing Guan Guo‐Jie Wu Dr. Fu‐She Han 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(12):3301-3305
A novel protocol for the Pd‐catalyzed ortho‐arylation of aryl phosphinamide with boronic acid is reported. By using phosphinamide as a new directing group, the reaction proceeds efficiently under mild conditions at 40 °C. Mechanistic studies reveal that the reaction proceeds via a PdII to Pd0 cycle. The phosphinamide group is also shown to be an effective orienting group for direct C?H amination. 相似文献
20.
Palladium(II)‐Catalyzed meta‐CH Olefination: Constructing Multisubstituted Arenes through Homo‐Diolefination and Sequential Hetero‐Diolefination 下载免费PDF全文
Dr. Milan Bera Arun Maji Dr. Santosh K. Sahoo Prof. Debabrata Maiti 《Angewandte Chemie (International ed. in English)》2015,54(29):8515-8519
Divinylbenzene derivatives represent an important class of molecular building blocks in organic chemistry and materials science. Reported herein is the palladium‐catalyzed synthesis of divinylbenzenes by meta‐C? H olefination of sulfone‐based arenes. Successful sequential olefinations in a position‐selective manner provided a novel route for the synthesis of hetero‐dialkenylated products, which are difficult to access using conventional methods. Additionally, 1,3,5‐trialkenylated compounds can be generated upon successful removal of the directing group. 相似文献