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1.
《中国化学》2018,36(3):213-216
Transition‐metal catalyzed C—H functionalization of benzaldehydes is of great interest in organic synthesis. Herein, we developed a transient directing group assisted amidation of benzaldehydes catalyzed by rhodium catalyst. With the employment of 10 mol% of 4‐trifluoromethyl aniline, the in situ generated imine groups as the directing group efficiently enable this transformation. By using this protocol, a wide range of benzaldehydes were efficiently converted into the corresponding N‐(2‐formylphenyl)benzamides utilizing dioxazolones as the nitrogen source. 相似文献
2.
Thomas Müller Prof. Dr. Lutz Ackermann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(40):14151-14154
The C?H thiolation of aniline derivatives was accomplished with a versatile nickel(II) catalyst under ligand‐free conditions. The robust nature of the nickel catalysis system was reflected by the C?H thiolation with a good functional group tolerance and an ample scope, employing anilines possessing removable directing groups. The widely applicable nickel catalyst also allowed for aniline C?H selenylations, while mechanistic studies provided strong support that the rate‐determining step is the C?H activation. 相似文献
3.
Catalytic C(sp3)−H Arylation of Free Primary Amines with an exo Directing Group Generated In Situ
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Chengpeng Wang David M. Magness Prof. Guangbin Dong 《Angewandte Chemie (International ed. in English)》2016,55(31):9084-9087
Herein, we report the palladium‐catalyzed direct arylation of unactivated aliphatic C?H bonds in free primary amines. This method takes advantage of an exo‐imine‐type directing group (DG) that can be generated and removed in situ. A range of unprotected aliphatic amines are suitable substrates, undergoing site‐selective arylation at the γ‐position. Methyl as well as cyclic and acyclic methylene groups can be activated. Furthermore, when aniline‐derived substrates were used, preliminary success with δ‐C?H arylation was achieved. The feasibility of using the DG component in a catalytic fashion was also demonstrated. 相似文献
4.
Rhodium(III)‐Catalyzed ortho CH Heteroarylation of (Hetero)aromatic Carboxylic Acids: A Rapid and Concise Access to π‐Conjugated Poly‐heterocycles
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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
5.
Juntao Ye Wu Fan Prof. Dr. Shengming Ma 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(2):716-720
A highly efficient and enantioselective synthesis of axially chiral α‐allenols was realized in practical yields with 96–99 % ee or de from TBS‐protected propargylic alcohols, aldehydes, and a commercially available, inexpensive, chiral, secondary amine (S)‐α,α‐diphenylprolinol or its enantiomer followed by desilylation. The easily removable TBS group not only acts as a protecting group, but also as a possible sterically directing group for the excellent enantioselectivity and in situ prevention of possible allene racemization. 相似文献
6.
A facile and low-cost approach has been developed for tailoring polyaniline rectangular sub-microtubes as a novel nanostructure of a conducting polymer in dilute sodium dodecyl sulfate (SDS) solution by the oxidation polymerization of aniline at room temperature. It was found that the size and uniformity of polyaniline rectangular sub-microtubes could be appropriately adjusted by tuning the concentration of aniline and the molar ratio of oxidant to aniline, respectively. The morphological evolution of rectangular sub-microtubes under different reaction times has been followed, and a possible formation mechanism has also been discussed in this report. The directing role of other anionic surfactants with -SO3(-) as the hydrophilic group for constructing polyaniline rectangular sub-microtubes has been investigated in detail. 相似文献
7.
2‐Methylphenyl ketones undergo site‐selective acylation at the benzylic position when treated with acid anhydride under UV irradiation in the presence of a palladium catalyst. The benzoyl carbonyl group serves as the photo‐directing group so that the ortho benzylic C?H bond is activated site‐selectively. 相似文献
8.
Metal‐Free Annulation of Arenes with 2‐Aminopyridine Derivatives: The Methyl Group as a Traceless Non‐Chelating Directing Group
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Srimanta Manna Dr. Kiran Matcha Dr. Andrey P. Antonchick 《Angewandte Chemie (International ed. in English)》2014,53(31):8163-8166
A novel annulation reaction between 2‐aminopyridine derivatives and arenes under metal‐free conditions is described. The presented intermolecular transformation provided straightforward access to the important pyrido[1,2‐a]benzimidazole scaffold under mild reaction conditions. The unprecedented application of the methyl group of methylbenzenes as a traceless, non‐chelating, and highly regioselective directing group is reported. 相似文献
9.
Wengang Xu Prof. Naohiko Yoshikai 《Angewandte Chemie (International ed. in English)》2016,55(41):12731-12735
N‐alkyl and N‐aryl imines have been frequently used as directing groups in rhodium‐ and cobalt‐catalyzed hydroarylation reactions of olefins and alkynes. However, the scope of such hydroarylation reactions has been limited by the difficulty of preparation of sterically hindered imines by condensation, and also by the steric bulkiness of the imine group itself. Reported herein is that an N?H imine serves as an alternative and highly effective directing group for cobalt‐catalyzed hydroarylation of olefins, and unlocks many of the limitations associated with the previously employed N‐aryl imine directing group. The power of this minimal nitrogen directing group is manifested in a fourfold ortho alkylation of benzophenone imine, and it occurs rapidly at ambient temperature. 相似文献
10.
Photocatalytic/Cu‐Promoted C−H Activations: Visible‐light‐Induced ortho‐Selective Perfluoroalkylation of Benzamides
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Xiang Chen Prof. Dr. Ze Tan Qingwen Gui Liang Hu Jidan Liu Jing Wu Prof. Guangwei Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(18):6218-6222
A visible‐light‐induced and copper‐promoted perfluoroalkylation of benzamides was successfully developed under the assistance of an 8‐aminoquinoline directing group. It provides a straightforward method for the synthesis of ortho‐perfluoroalkyl‐substituted benzoic acid derivatives. The reaction employs a cheap organic dye eosin Y as the photoredox catalyst and is run under the irradiation of a 26 W fluorescent LED light bulb. 相似文献
11.
Pd‐Catalyzed C−H Alkylation of Arenes Using PyrDipSi,a Transformable and Removable Silicon‐Tethered Directing Group
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Dhruba Sarkar Prof. Dr. Vladimir Gevorgyan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(32):11201-11204
An efficient Pd‐catalyzed ortho‐C?H alkylation reaction of arenes using a transformable and removable Si‐tethered pyridyldiisopropylsilyl (PyrDipSi) directing group has been developed. In addition, the PyrDipSi directing group allows for an efficient sequential double‐fold C?H alkylation/oxygenation of arenes to produce meta‐alkylated phenols. This directing group can easily be removed or converted into valuable functionalities, such as aryl, iodo, boronic ester, or phenol. 相似文献
12.
Sungsik Baek Jason J. Ree Moonhor Ree 《Journal of polymer science. Part A, Polymer chemistry》2002,40(8):983-994
Poly(o‐aminophenethyl alcohol) and its copolymers containing the aniline unit were synthesized in aqueous hydrochloric acid medium by chemical oxidative polymerization. The chemical composition of these novel polymers was determined spectroscopically, and their viscosities were measured. These polymers exhibit good solubility in organic solvents that is attributed mainly to the polar hydroxyethyl side groups. Their structures (chain conformation and morphological structure) and properties (conductivity, electrochemical characteristics, glass transition, and degradation behavior) were characterized and then interpreted on the basis of the chemical composition along with the electronic and steric hindrance effects associated with the hydroxyethyl side group. Overall, the side group has a significant effect on the polymerization and influences the structure, chain conformation, and properties of the resultant polymer. The poly(aniline‐co‐o‐aminophenethyl alcohol)s containing 20–40 mol % o‐aminophenethyl alcohol units are potential conducting materials for microelectronic and electromagnetic shielding applications because they are easier to process than polyaniline but retain its beneficial properties. These polymers can also be used as a functional conducting polymer intermediate owing to the reactivity of the side group. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 983–994, 2002 相似文献
13.
Nickel‐Catalyzed Insertion of Alkynes and Electron‐Deficient Olefins into Unactivated sp3 CH Bonds
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Arif Mahammad Earsad Avijit Hazra Prof. Debabrata Maiti 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(32):11320-11324
Insertion of unsaturated systems such as alkynes and olefins into unactivated sp3 C?H bonds remains an unexplored problem. We herein address this issue by successfully incorporating a wide variety of functionalized alkynes and electron‐deficient olefins into the unactivated sp3 C?H bond of pivalic acid derivatives with excellent syn‐ and linear‐ selectivity. A strongly chelating 8‐aminoquinoline directing group proved beneficial for these insertion reactions, while an air‐stable and inexpensive NiII salt has been employed as the active catalyst. 相似文献
14.
An “Ortho Effect” in Electrophilic Aromatic Nitrations: Theoretical Analysis and Experimental Validation
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Hui‐Jing Li Yan‐Chao Wu Jian‐Hong Dai b Yan Song Runjiao Cheng Yuanyuan Qiao 《中国化学会会志》2014,61(12):1307-1312
Usually, a π‐donor substituent acts as an ortho/para directing group in an electrophilic aromatic substitution reaction, and a π‐acceptor substituent acts as a meta directing group. Interestingly, when a π‐acceptor substituent is meta to a π‐donor substituent, certain electrophilic aromatic nitration occurs ortho to the acceptor substituent rather than para. The “ortho effect”, highlighted in various text books, has been tentatively analyzed here based on ab initio calculations. The reliability of the calculations was verified by the corresponding experimental data, including a new‐designed electrophilic aromatic nitration that also gave reasonable product distributions. 相似文献
15.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(28):8295-8298
Palladium(II)‐catalyzed meta ‐C−H arylation and alkylation of benzylsulfonamide using 2‐carbomethoxynorbornene (NBE‐CO2Me) as a transient mediator are realized by using a newly developed electron‐deficient directing group and isoquinoline as a ligand. This protocol features broad substrate scope and excellent functional‐group tolerance. The meta ‐substituted benyzlsulfonamides can be readily transformed into sodium sulfonates, sulfonate esters, and sulfonamides, as well as styrenes by Julia‐type olefination. The unique impact of the isoquinoline ligand underscores the importance of subtle matching between ligands and the directing groups. 相似文献
16.
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
17.
PdII‐Catalyzed Mild CH ortho Arylation and Intramolecular Amination Oriented by a Phosphinamide Group
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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
18.
R. R. Gataullin A. M. Sotnikov L. V. Spirikhin I. B. Abdrakhmanov 《Russian Journal of Organic Chemistry》2005,41(5):715-722
N-Mesyl-2-(1-methyl-1-butenyl)-6-methylaniline reacted with Br2 to afford N-mesyl-2-(3-bromo-1-penten-2-yl)aniline that under treatment with NH3 or amines underwent cyclization into N-mesyl-7-methyl-3-methylene-2-ethylindoline. The reaction of N-mesyl-2-(1-methyl-1-buten-1-yl)-4-methyl- and 2-(1-methyl-1-buten-1-yl)aniline with Br2 gave rise to the corresponding N-mesyl-2-(2-bromo-1-methyl-1-buten-1-yl)anilines. Under the similar conditions N-tosyl-2-(1-cyclohexen-1-yl)aniline was converted into N-tosyl-2-(6-bromo-1-cyclohexen-1-yl)aniline that under treatment with NH3 furnished N-tosyl-1,2,3,9a-tetrahydrocarbazole. The reaction of N-mesyl-1,2,3,9a-tetrahydrocarbazole with CuBr2 in MeOH afforded N-mesyl-4-methoxy-1,2,3,4-tetrahydrocarbazole. N-Mesyl-6-methyl-2-(1-cyclopenten-1-yl)aniline in reaction with Br2 in the presence of NaHCO3 was oxidized into the corresponding cyclopentenone, and with NBS it gave N-mesyl-2-(2-bromo-1-cyclopenten-1-yl)aniline.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 5, 2005, pp. 730–737.Original Russian Text Copyright © 2005 by Gataullin, Sotnikov, Spirikhin, Abdrakhmanov. 相似文献
19.
Palladium‐Catalyzed Arylation of Unactivated γ‐Methylene C(sp3)H and δ‐CH Bonds with an Oxazoline‐Carboxylate Auxiliary
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Peng‐Xiang Ling Sheng‐Long Fang Xue‐Song Yin Kai Chen Bo‐Zheng Sun Prof. Dr. Bing‐Feng Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(48):17503-17507
A palladium‐catalyzed arylation of unactivated γ‐methylene C(sp3)?H and remote δ‐C?H bonds by using an oxazoline‐carboxylate directing group has been developed. Arylation occurs with a broad substrate scope and high tolerance of functional groups (i.e., halogen, nitro, cyano, ether, trifluoromethyl, amine, and ester). The oxazoline‐type auxiliary can be removed under acidic conditions. 相似文献
20.
Readily Removable Directing Group Assisted Chemo‐ and Regioselective C(sp3)H Activation by Palladium Catalysis
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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