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1.
Pidiyara Karishma Devesh S. Agarwal Biswajit Laha Sanjay K. Mandal Rajeev Sakhuja 《化学:亚洲杂志》2019,14(23):4274-4288
A direct ortho‐Csp2‐H acylmethylation of 2‐aryl‐2,3‐dihydrophthalazine‐1,4‐diones with α‐carbonyl sulfoxonium ylides is achieved through a RuII‐catalyzed C?H bond activation process. The protocol featured high functional group tolerance on the two substrates, including aryl‐, heteroaryl‐, and alkyl‐substituted α‐carbonyl sulfoxonium ylides. Thereafter, 2‐(ortho‐acylmethylaryl)‐2,3‐dihydrophthalazine‐1,4‐diones were used as potential starting materials for the expeditious synthesis of 6‐arylphthalazino[2,3‐a]cinnoline‐8,13‐diones and 5‐acyl‐5,6‐dihydrophthalazino[2,3‐a]cinnoline‐8,13‐diones under Lawesson's reagent and BF3?OEt2 mediated conditions, respectively. Of these, the BF3?OEt2‐mediated cyclization proceeded in DMSO as a solvent and a methylene source via dual C?C and C?N bond formations. 相似文献
2.
Dr. Shubhankar Kumar Bose Andrea Deißenberger Antonius Eichhorn Prof. Dr. Patrick G. Steel Prof. Dr. Zhenyang Lin Prof. Dr. Todd B. Marder 《Angewandte Chemie (International ed. in English)》2015,54(40):11843-11847
A zinc‐catalyzed combined C? X and C? H borylation of aryl halides using B2pin2 (pin=OCMe2CMe2O) to produce the corresponding 1,2‐diborylarenes under mild conditions was developed. Catalytic C? H bond activation occurs ortho to the halide groups if such a site is available or meta to the halide if the ortho position is already substituted. This method thus represents a novel use of a group XII catalyst for C? H borylation. This transformation does not proceed via a free aryne intermediate, but a radical process seems to be involved. 相似文献
3.
ortho‐Benzoxylation of N‐Alkyl Benzamides with Aromatic Acids Catalyzed by Ruthenium(II) Complex 下载免费PDF全文
Kishor Padala Dr. Masilamani Jeganmohan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(14):4092-4097
A highly regioselective ortho‐benzoxylation of N‐alkyl benzamides with aromatic acids in the presence of [{RuCl2(p‐cymene)}2], AgSbF6, and (NH4)2S2O8 in 1,2‐dichloroethane at 100 °C for 24 h affording ortho‐benzoxylated N‐alkyl benzamides by C?H bond activation is described. Further, Ru‐catalyzed alkenylation is done at the ortho C?H bond of benzoxylated N‐alkyl benzamides with alkenes in water solvent. Subsequently, the benzoxyl moiety of N‐alkyl benzamides was converted into a hydroxyl group in the presence of base or acid. A possible reaction mechanism was proposed to account for the present coupling reaction. 相似文献
4.
Jian Wen Ben Dong Jinjun Zhu Yue Zhao Zhuangzhi Shi 《Angewandte Chemie (International ed. in English)》2020,59(27):10909-10912
The first aromatic C?H silylation between arylphosphines and hydrosilanes enabled by a ruthenium complex has been developed. The excellent ortho‐selectivity results from a four‐membered metallacyclic intermediate involving phosphorus chelation. The developed system can be extended to the benzylic C?H silylation of arylphosphines. Diverse silylated arylphosphines are produced, exhibiting broad functional group compatibility. Further functionalization of the products under mild conditions renders the formed compounds useful building blocks. 相似文献
5.
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
6.
Palladium(II)‐Catalyzed ortho‐CH Arylation/Alkylation of N‐Benzoyl α‐Amino Ester Derivatives 下载免费PDF全文
Dr. Luis C. Misal Castro Prof. Naoto Chatani 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(16):4548-4553
The palladium‐catalyzed arylation/alkylation of ortho‐C?H bonds in N‐benzoyl α‐amino ester derivatives is described. In such a system both the NH‐amido and the CO2R groups in the α‐amino ester moieties play a role in successful C?H activation/C?C bond formation using iodoaryl coupling partners. A wide variety of functional groups and electron‐rich/deficient iodoarenes are tolerated. The yields obtained range from 20 to 95 %. 相似文献
7.
Exceedingly Fast Copper(II)‐Promoted ortho CH Trifluoromethylation of Arenes using TMSCF3 下载免费PDF全文
Ming Shang Shang‐Zheng Sun Dr. Hong‐Li Wang Dr. Brian N. Laforteza Prof. Dr. Hui‐Xiong Dai Prof. Dr. Jin‐Quan Yu 《Angewandte Chemie (International ed. in English)》2014,53(39):10439-10442
The direct ortho‐trifluoromethylation of arenes, including heteroarenes, with TMSCF3 has been accomplished by a copper(II)‐promoted C? H activation reaction which completes within 30 minutes. Mechanistic investigations are consistent with the involvement of C? H activation, rather than a simple electrophilic aromatic substitution (SEAr), as the key step. 相似文献
8.
Leen E. E. Broeckx Sabriye Güven Frank J. L. Heutz Dr. Martin Lutz Prof. Dr. Dieter Vogt Prof. Dr. Christian Müller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(39):13087-13098
A series of 2,4,6‐triarylphosphinines were prepared and investigated in the base‐assisted cyclometalation reaction using [Cp*IrCl2]2 (Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl) as the metal precursor. Insight in the mechanism of the C? H bond activation of phosphinines as well as in the regioselectivity of the reaction was obtained by time‐dependent 31P{1H} NMR spectroscopy. At room temperature, 2,4,6‐triarylphosphinines instantaneously open the Ir‐dimer and coordinate in an η1‐fashion to the metal center. Upon heating, a dissociation step towards free ligand and an Ir‐acetate species is observed and proven to be a first‐order reaction with an activation energy of ΔEA=56.6 kJ mol?1 found for 2,4,6‐triphenylphosphinine. Electron‐donating substituents on the ortho‐phenyl groups of the phosphorus heterocycle facilitate the subsequent cyclometalation reaction, indicating an electrophilic C? H activation mechanism. The cyclometalation reaction turned out to be very sensitive to steric effects as even small substituents can have a large effect on the regioselectivity of the reaction. The cyclometalated products were characterized by means of NMR spectroscopy and in several cases by single‐crystal X‐ray diffraction. Based on the observed trends during the mechanistic investigation, a concerted base‐assisted metalation–deprotonation (CMD) mechanism, which is electrophilic in nature, is proposed. 相似文献
9.
Nitrone Directing Groups in Rhodium(III)‐Catalyzed C−H Activation of Arenes: 1,3‐Dipoles versus Traceless Directing Groups 下载免费PDF全文
Dr. Fang Xie Dr. Songjie Yu Dr. Zisong Qi Prof. Dr. Xingwei Li 《Angewandte Chemie (International ed. in English)》2016,55(49):15351-15355
Functionalizable directing groups (DGs) are highly desirable in C?H activation chemistry. The nitrone DGs are explored in rhodium(III)‐catalyzed C?H activation of arenes and couplings with cyclopropenones. N‐tert‐butyl nitrones bearing a small ortho substituent coupled to afford 1‐naphthols, where the nitrone acts as a traceless DG. In contrast, coupling of N‐tert‐butyl nitrones bearing a bulky ortho group follows a C?H acylation/[3+2] dipolar addition pathway to give bicyclics. The coupling of N‐arylnitrones follows the same acylation/[3+2] addition process but delivers different bicyclics. 相似文献
10.
Ruijie Mi Guangfan Zheng Zisong Qi Xingwei Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(49):17830-17834
C?H bond activation is mostly limited to ortho selectivity. Activation of both ortho and meta C?H bonds constitutes a particularly important strategy for annulation, but has rarely been studied in enantioselective systems. Reported herein is rhodium(III)‐catalyzed asymmetric [3+2] transannulation of arenes with 7‐azabenzonorbornadienes. Two distinct classes of arenes have been identified as substrates, and the coupling proceeded with high enantioselectivity and excellent diastereoselectivity through sequential activation of ortho and meta C?H bonds. 相似文献
11.
Cobalt(III)‐Catalyzed Intramolecular Cross‐Dehydrogenative C−H/X−H Coupling: Efficient Synthesis of Indoles and Benzofurans 下载免费PDF全文
Jayanta Ghorai Angula Chandra Shekar Reddy Prof. Dr. Pazhamalai Anbarasan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(45):16042-16046
An efficient cobalt(III)‐catalyzed intramolecular cross‐dehydrogenative C?H/N?H coupling of ortho‐alkenylanilines has been developed utilizing O2 as a terminal oxidant. The developed reaction tolerates various reactive functional groups and allows the synthesis of diverse indole derivatives in good to excellent yields. The method was successfully extended to the synthesis of benzofurans through the intramolecular cross‐dehydrogenative C?H/O?H coupling of ortho‐alkenylphenols. 相似文献
12.
Highly Stereoselective β‐Mannopyranosylation via the 1‐α‐Glycosyloxy‐isochromenylium‐4‐gold(I) Intermediates 下载免费PDF全文
While the gold(I)‐catalyzed glycosylation reaction with 4,6‐O‐benzylidene tethered mannosyl ortho‐alkynylbenzoates as donors falls squarely into the category of the Crich‐type β‐selective mannosylation when Ph3PAuOTf is used as the catalyst, in that the mannosyl α‐triflates are invoked, replacement of the ?OTf in the gold(I) complex with less nucleophilic counter anions (i.e., ?NTf2, ?SbF6, ?BF4, and ?BAr4F) leads to complete loss of β‐selectivity with the mannosyl ortho‐alkynylbenzoate β‐donors. Nevertheless, with the α‐donors, the mannosylation reactions under the catalysis of Ph3PAuBAr4F (BAr4F=tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate) are especially highly β‐selective and accommodate a broad scope of substrates; these include glycosylation with mannosyl donors installed with a bulky TBS group at O3, donors bearing 4,6‐di‐O‐benzoyl groups, and acceptors known as sterically unmatched or hindered. For the ortho‐alkynylbenzoate β‐donors, an anomerization and glycosylation sequence can also ensure the highly β‐selective mannosylation. The 1‐α‐mannosyloxy‐isochromenylium‐4‐gold(I) complex ( Cα ), readily generated upon activation of the α‐mannosyl ortho‐alkynylbenzoate ( 1 α ) with Ph3PAuBAr4F at ?35 °C, was well characterized by NMR spectroscopy; the occurrence of this species accounts for the high β‐selectivity in the present mannosylation. 相似文献
13.
Shao‐Tao Bai Charles B. Bheeter Joost N. H. Reek 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(37):13173-13177
Reported is an iridium catalyst for ortho‐selective C?H borylation of challenging secondary aromatic amide substrates, and the regioselectivity is controlled by hydrogen‐bond interactions. The BAIPy ‐Ir catalyst forms three hydrogen bonds with the substrate during the crucial activation step, and allows ortho‐C?H borylation with high selectivity. The catalyst displays unprecedented ortho selectivities for a wide variety of substrates that differ in electronic and steric properties, and the catalyst tolerates various functional groups. The regioselective C?H borylation catalyst is readily accessible and converts substrates on gram scale with high selectivity and conversion. 相似文献
14.
Ortho‐Functionalized Aryltetrazines by Direct Palladium‐Catalyzed C−H Halogenation: Application to Fast Electrophilic Fluorination Reactions 下载免费PDF全文
Christelle Testa Élodie Gigot Semra Genc Dr. Richard Decréau Dr. Julien Roger Prof. Dr. Jean‐Cyrille Hierso 《Angewandte Chemie (International ed. in English)》2016,55(18):5555-5559
A general catalyzed direct C?H functionalization of s‐tetrazines is reported. Under mild reaction conditions, N‐directed ortho‐C?H activation of tetrazines allows the introduction of various functional groups, thus forming carbon–heteroatom bonds: C?X (X=I, Br, Cl) and C?O. Based on this methodology, we developed electrophilic mono‐ and poly‐ortho‐fluorination of tetrazines. Microwave irradiation was optimized to afford fluorinated s‐aryltetrazines, with satisfactory selectivity, within only ten minutes. This work provides an efficient and practical entry for further accessing highly substituted tetrazine derivatives (iodo, bromo, chloro, fluoro, and acetate precursors). It gives access to ortho‐functionalized aryltetrazines which are difficult to obtain by classical Pinner‐like syntheses. 相似文献
15.
Rhodium(III)‐Catalyzed ortho Alkenylation of N‐Phenoxyacetamides with N‐Tosylhydrazones or Diazoesters through CH Activation 下载免费PDF全文
Fangdong Hu Ying Xia Fei Ye Zhenxing Liu Prof. Dr. Chen Ma Prof. Dr. Yan Zhang Prof. Dr. Jianbo Wang 《Angewandte Chemie (International ed. in English)》2014,53(5):1364-1367
A coupling reaction of N‐phenoxyacetamides with N‐tosylhydrazones or diazoesters through RhIII‐catalyzed C? H activation is reported. In this reaction, ortho‐alkenyl phenols were obtained in good yields and with excellent regio‐ and stereoselectivity. Rh–carbene migratory insertion is proposed as the key step in the reaction mechanism. 相似文献
16.
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
17.
Alkali‐Metal Trichloroacetates for Dichloromethylenation of Fullerenes: Nucleophilic Addition‐Substitution Route 下载免费PDF全文
Marina G. Apenova Vladimir A. Akhmetov Nikita M. Belov Dr. Alexey A. Goryunkov Dr. Ilya N. Ioffe Dr. Natalia S. Lukonina Dr. Vitaliy Yu. Markov Prof. Dr. Lev N. Sidorov 《化学:亚洲杂志》2014,9(3):915-923
The first experimental evidence that fullerenes react with alkali‐metal trichloroacetates through a nucleophilic addition‐substitution route, yielding dichloromethylenefullerenes as the final products, is reported. The intermediates, C60(CCl3)? and C70(CCl3)? anions, have been isolated in their protonated forms as ortho‐C60(CCl3)H, as well as three ortho and one para isomer of C70(CCl3)H. The structures were unambiguously determined by means of 1H, 13C, and 1H–13C HMBC NMR spectroscopy along with UV/Vis spectroscopy. The observed regiochemistry was analyzed with the aid of quantum chemical calculations. Conversion of the protonated compounds into the [6,6]‐closed C60/70(CCl2) cycloadducts under basic conditions can be effected only for the ortho isomers, whereas para‐C70(CCl3)H decomposes back into pristine C70. 相似文献
18.
《Journal of heterocyclic chemistry》2017,54(2):1287-1297
ortho‐Aryl phenols, synthesized via protecting group free Suzuki–Miyaura coupling of ortho‐halophenols and arene boronic acids, undergo a cyclization to dibenzofurans via oxidative C–H activation. The reaction proceeds under microwave irradiation in short reaction times using catalytic amounts of Pd(OAc)2 without additional ligands. 相似文献
19.
Ruthenium‐Catalyzed Oxidant‐Free Allylation of Aromatic Ketoximes with Allylic Acetates at Room Temperature 下载免费PDF全文
Rajendran Manikandan Padmaja Madasamy Dr. Masilamani Jeganmohan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(40):13934-13938
Substituted aromatic ketoximes reacted efficiently with allylic acetates in the presence of {[RuCl2(p‐cymene)]2} and AgSbF6 in 1,2‐dichloroethane at ambient temperature, providing ortho‐allyl aromatic ketoximes in a highly regioselective manner without an oxidant. In the reaction, the acetate group of allyl acetate acts as a base to activate the C?H bond of aromatics. Later, ortho‐allyl aromatic ketoximes were converted into ortho‐allyl aromatic ketones in the presence of HCl. 相似文献
20.
Shangda Li Hang Wang Yunxiang Weng Gang Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(51):18673-18678
The first example of carboxy group assisted, remote‐selective C(sp2)?H activation with a PdII catalyst has been developed and proceeds through a possible κ2 coordination of the carboxy group, thus suppressing the ortho‐C?H activation through κ1 coordination. Besides meta‐C?H olefination, direct meta‐arylation of hydrocinnamic acid derivatives with low‐cost aryl iodides has been achieved for the first time. These findings may motivate the exploration of novel reactivities of the carboxy assisted C?H activation reactions with intriguing selectivities. 相似文献