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1.
Cuiju Zhu Rositha Kuniyil Lutz Ackermann 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(16):5392-5396
Complexity‐increasing Domino reactions comprising C?H allenylation, a Diels–Alder reaction, and a retro‐Diels–Alder reaction were realized by a versatile catalyst derived from earth‐abundant, non‐toxic manganese. The C?H activation/Diels–Alder/retro‐Diels–Alder alkyne annulation sequence provided step‐economical access to valuable indolone alkaloid derivatives through a facile organometallic C?H activation manifold with transformable pyridines. 相似文献
2.
Palladium‐Catalyzed Construction of Heteroatom‐Containing π‐Conjugated Systems by Intramolecular Oxidative CH/CH Coupling Reaction
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Kenta Saito Dr. Prasanna Kumara Chikkade Prof. Dr. Motomu Kanai Prof. Dr. Yoichiro Kuninobu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(23):8365-8368
Synthesis of heteroatom‐containing ladder‐type π‐conjugated molecules was successfully achieved via a palladium‐catalyzed intramolecular oxidative C?H/C?H cross‐coupling reaction. This reaction provides a variety of π‐conjugated molecules bearing heteroatoms, such as nitrogen, oxygen, phosphorus, and sulfur atoms, and a carbonyl group. The π‐conjugated molecules were synthesized efficiently, even in gram scale, and larger π‐conjugated molecules were also obtained by a double C?H/C?H cross‐coupling reaction and successive oxidative cycloaromatization. 相似文献
3.
Cobalt‐Catalyzed Tandem C−H Activation/C−C Cleavage/C−H Cyclization of Aromatic Amides with Alkylidenecyclopropanes
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Dr. Mingliang Li Prof. Dr. Fuk Yee Kwong 《Angewandte Chemie (International ed. in English)》2018,57(22):6512-6516
A cobalt‐catalyzed chelation‐assisted tandem C?H activation/C?C cleavage/C?H cyclization of aromatic amides with alkylidenecyclopropanes is reported. This process allows the sequential formation of two C?C bonds, which is in sharp contrast to previous reports on using rhodium catalysts for the formation of C?N bonds. Here the inexpensive catalyst system exhibits good functional‐group compatibility and relatively broad substrate scope. The desired products can be easily transformed into polycyclic lactones with m‐CPBA. Mechanistic studies revealed that the tandem reaction proceeds through a C?H cobaltation, β‐carbon elimination, and intramolecular C?H cobaltation sequence. 相似文献
4.
Direct Synthesis of Benzofuro[2,3‐b]pyrroles through a Radical Addition/[3,3]‐Sigmatropic Rearrangement/Cyclization/Lactamization Cascade
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Dr. Masafumi Ueda Yuta Ito Yuki Ichii Maiko Kakiuchi Hiroko Shono Prof. Dr. Okiko Miyata 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(22):6763-6770
A straightforward synthetic method for the construction of benzofuro[2,3‐b]pyrrol‐2‐ones by a novel domino reaction through a radical addition/[3,3]‐sigmatropic rearrangement/cyclization/lactamization cascade has been developed. The domino reaction of O‐phenyl‐conjugated oxime ether with an alkyl radical allows the construction of two heterocycles with three stereogenic centers as a result of the formation of two C?C bonds, a C?O bond, and a C?N bond in a single operation, leading to pyrrolidine‐fused dihydrobenzofurans, which are not easily accessible by existing synthetic methods. Furthermore, asymmetric synthesis of benzofuro[2,3‐b]pyrrol‐2‐one derivatives through a diastereoselective radical addition reaction to a chiral oxime ether was also developed. 相似文献
5.
Tjark H. Meyer Joo C. A. Oliveira Debasish Ghorai Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2020,59(27):10955-10960
The merger of cobalt‐catalyzed C?H activation and electrosynthesis provides new avenues for resource‐economical molecular syntheses, unfortunately their reaction mechanisms remain poorly understood. Herein, we report the identification and full characterization of electrochemically generated high‐valent cobalt(III/IV) complexes as crucial intermediates in electrochemical cobalt‐catalyzed C?H oxygenations. Detailed mechanistic studies provided support for an oxidatively‐induced reductive elimination via highly‐reactive cobalt(IV) intermediates. These key insights set the stage for unprecedented cobaltaelectro two‐fold C?H/C?H activation. 相似文献
6.
Palladium‐Catalyzed/Norbornene‐Mediated CH Activation/ N‐Tosylhydrazone Insertion Reaction: A Route to Highly Functionalized Vinylarenes
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Dr. Ping‐Xin Zhou Lan Zheng Jun‐Wei Ma Yu‐Ying Ye Xue‐Yuan Liu Prof. Dr. Peng‐Fei Xu Prof. Dr. Yong‐Min Liang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(22):6745-6751
A straightforward method for the synthesis of highly functionalized vinylarenes through palladium‐catalyzed, norbornene‐mediated C?H activation/carbene migratory insertion is described. Extension to a one‐pot procedure is also developed. Furthermore, this method can also be used to generate polysubstituted bicyclic molecules. The reaction proceeds under mild conditions to give the products in satisfactory yields using readily available starting materials. This is a Catellani–Lautens reaction that incorporates different types of coupling partners. Additionally, this reaction is the first to demonstrate the possibility of combining Pd‐catalyzed insertion of diazo compounds and Pd‐catalyzed C?H activation. 相似文献
7.
Jiangliang Yin Jingsong You 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(1):308-312
Disclosed herein is the merging of C?H activation and radical chemistry, enabling rapid access to a structurally diverse family of fused carbohelicenes through the fusion of α‐acetylnaphthalenes with alkynes under oxidative conditions. This cascade process exhibits exquisite chemoselectivity and regioselectivity. The reaction pathway was analyzed by intermediate separations, control experiments, radical trapping, EPR, MALDI‐TOF‐MS, and ESI‐HRMS experiments, and shown to involve a C2?H activation/radical reaction/C8?H activation relay. 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.
Cong Liu Qi Zhang Hongbo Li Shuangxi Guo Bin Xiao Prof. Dr. Wei Deng Prof. Dr. Lei Liu Prof. Dr. Wei He 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(18):6208-6212
We report a Cu/Fe co‐catalyzed Ritter‐type C?H activation/amination reaction that allows efficient and selective intermolecular functionalization of benzylic C?H bonds. This new reaction is featured by simple reaction conditions, readily available reagents and general substrate scope, allowing facile synthesis of biologically interesting nitrogen containing heterocycles. The Cu and Fe salts were found to play distinct roles in this cooperative catalysis. 相似文献
10.
Mechanistic Study on Rh‐Catalyzed Stereoselective CC/CH Activation of tert‐Cyclobutanols
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Dr. Haizhu Yu Dr. Chen Wang Yimeng Yang Prof. Zhi‐Min Dang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(13):3839-3848
A mechanistic study was performed on the Rh‐catalyzed stereoselective C?C/C?H activation of tert‐cyclobutanols. The present study corroborated the previous proposal that the reaction occurs by metalation, β‐C elimination, 1,4‐Rh transfer, C?O insertion, and a final catalyst‐regeneration step. The rate‐determining step was found to be the 1,4‐Rh transfer step, whereas the stereoselectivity‐determining step did not correspond to any of the aforementioned steps. It was found that both the thermodynamic stability of the product of the β‐C elimination and the kinetic feasibility of the 1,4‐Rh transfer and C?O insertion steps made important contributions. In other words, three steps (i.e., β‐C elimination, 1,4‐Rh transfer, and C?O insertion) were found to be important in determining the configurations of the two quaternary stereocenters. 相似文献
11.
Palladium/Norbornene‐Catalyzed C−H Alkylation/Alkyne Insertion/Indole Dearomatization Domino Reaction: Assembly of Spiroindolenine‐Containing Pentacyclic Frameworks
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Lu Bai Jingjing Liu Wenjie Hu Kunyu Li Prof. Dr. Yaoyu Wang Prof. Dr. Xinjun Luan 《Angewandte Chemie (International ed. in English)》2018,57(18):5151-5155
Reported is a highly chemoselective intermolecular annulation of indole‐based biaryls with bromoalkyl alkynes by using palladium/norbornene (Pd/NBE) cooperative catalysis. This reaction is realized through a sequence of Catellani‐type C?H alkylation, alkyne insertion, and indole dearomatization, by forming two C(sp2)?C(sp3) and one C(sp2)?C(sp2) bonds in a single chemical operation, thus providing a diverse range of pentacyclic molecules, containing a spiroindolenine fragment, in good yields with excellent functional‐group tolerance. Preliminary mechanistic studies reveal that C?H bond cleavage is likely involved in the rate‐determining step, and the indole dearomatization might take place through an olefin coordination/insertion and β‐hydride elimination Heck‐type pathway. 相似文献
12.
Gold‐Catalyzed C(sp3)H/C(sp)H Coupling/Cyclization/Oxidative Alkynylation Sequence: A Powerful Strategy for the Synthesis of 3‐Alkynyl Polysubstituted Furans
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Yuanhong Ma Shuai Zhang Shiping Yang Dr. Feijie Song Prof. Dr. Jingsong You 《Angewandte Chemie (International ed. in English)》2014,53(30):7870-7874
In sharp contrast to the gold‐catalyzed reactions of alkynes/allenes with nucleophiles, gold‐catalyzed oxidative cross‐couplings and especially C? H/C? H cross‐coupling have been under represented. By taking advantage of the unique redox property and carbophilic π acidity of gold, this work realizes the first gold‐catalyzed direct C(sp3)? H alkynylation of 1,3‐dicarbonyl compounds with terminal alkynes under mild reaction conditions, with subsequent cyclization and in situ oxidative alkynylation. A variety of terminal alkynes including aryl, heteroaryl, alkenyl, alkynyl, alkyl, and cyclopropyl alkynes all successfully participate in the domino reaction. The protocol offers a simple and region‐defined approach to 3‐alkynyl polysubstituted furans. 相似文献
13.
Tomohiro Tsuda Yuka Kawakami Seung‐Min Choi Ryo Shintani 《Angewandte Chemie (International ed. in English)》2020,59(21):8057-8061
A new and efficient synthesis of 8H‐benzo[e]phenanthro[1,10‐bc]silines from 2‐((2‐(arylethynyl)aryl)silyl)aryl triflates under palladium catalysis has been developed. The reaction mechanism was experimentally investigated and a catalytic cycle involving C?H/C?H coupling through a new mode of 1,4‐palladium migration with concomitant alkene stereoisomerization is proposed. 相似文献
14.
Cobalt(III)‐Catalyzed Intramolecular Cross‐Dehydrogenative C−H/X−H Coupling: Efficient Synthesis of Indoles and Benzofurans
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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
15.
Gaowen Zhai Xueting Liu Wentao Ma Guoqiang Wang Liu Yang Shuhua Li Youting Wu Xingbang Hu 《化学:亚洲杂志》2020,15(19):3082-3086
Tandem Friedel‐Crafts (FC) and C?H/C?O coupling reactions catalyzed by tris(pentafluorophenyl) borane (B(C6F5)3) were achieved without using any other additive in the absence of solvent. This process can be used for the reactions between a series of dialkylanilines and vinyl ethers with good isolated yields of bis(4‐dialkylaminophenyl) compounds. Based on combined theoretical and experimental studies, the possible reaction mechanism was proposed. B(C6F5)3 can activate the C=C and C?O bond for FC and C?H/C?O coupling reactions respectively. The FC reaction is slow, which is followed by a fast C?H/C?O coupling. 相似文献
16.
An intriguing C?N transformation involving a catalyst‐free N‐alkylation/N′‐arylation process in a multicomponent reaction with secondary amines, cyclic tertiary amines and electron‐deficient aryl halides has been described. In this case, the N‐alkylation of secondary amines, utilizing cyclic tertiary amines as alkyl group sources, is enabled by a facile C?N cleavage. Such an operationally simple method could facilitate access to aromatic aminoalkyl amines, nitrogen‐containing bioactive molecules, in good to excellent yields. 相似文献
17.
Cu/Fe‐Cocatalyzed Formation of β‐Ketophosphonates by a Domino Knoevenagel–Decarboxylation–Oxyphosphorylation Sequence from Aromatic Aldehydes and H‐Phosphonates
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Mingxin Zhou Yao Zhou Prof. Qiuling Song 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(30):10654-10659
A domino Knoevenagel–decarboxylation–alkene difunctionalization sequence has been developed for the conversion of benzaldehydes into β‐ketophosphonates, catalyzed by a cooperative Cu/Fe system, whereby C?P and C?O bonds are formed simultaneously in a one‐pot reaction. The reaction proceeds in good yields and with a broad substrate scope and environmentally benign conditions. 相似文献
18.
Palladium‐Catalyzed CS Activation/Aryne Insertion/Coupling Sequence: Synthesis of Functionalized 2‐Quinolinones
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Ying Dong Bangyu Liu Peng Chen Prof. Qun Liu Prof. Mang Wang 《Angewandte Chemie (International ed. in English)》2014,53(13):3442-3446
The insertion of an aryne into a C? S bond can suppress the addition of an S nucleophile to the aryne in the presence of palladium. Catalyzed by Pd(OAc)2, a wide range of α‐carbamoyl ketene dithioacetals readily react with arynes to selectively afford functionalized 2‐quinolinones in high yields under neutral reaction conditions by a C? S activation/aryne insertion/intramolecular coupling sequence. The attractive feature of the new strategy also lies in the versatile transformations of the alkythio‐substituted quinolinone products. 相似文献
19.
The development of ecofriendly methods for carbon–carbon (C?C) and carbon–heteroatom (C?Het) bond formation is of great significance in modern‐day research. Metal‐free cross‐dehydrogenative coupling (CDC) has emerged as an important tool for organic and medicinal chemists as a means to form C?C and C?Het bonds, as it is atom economical and more efficient and greener than transition‐metal catalyzed CDC reactions. Molecular iodine (I2) is recognized as an inexpensive, environmentally benign, and easy‐to‐handle catalyst or reagent to pursue CDCs under mild reaction conditions, with good regioselectivities and broad substrate compatibility. This review presents the recent developments of I2‐catalyzed C?C, C?N, C?O, and C?S/C?Se bond‐forming reactions for the synthesis of various important organic molecules by cross‐dehydrogenative coupling. 相似文献
20.
Oxidative C−H/C−H Cross‐Coupling Reactions between N‐Acylanilines and Benzamides Enabled by a Cp*‐Free RhCl3/TFA Catalytic System
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Yang Shi Luoqiang Zhang Prof. Dr. Jingbo Lan Min Zhang Fulin Zhou Wenlong Wei Prof. Dr. Jingsong You 《Angewandte Chemie (International ed. in English)》2018,57(29):9108-9112
By making use of a dual‐chelation‐assisted strategy, a completely regiocontrolled oxidative C?H/C?H cross‐coupling reaction between an N‐acylaniline and a benzamide has been accomplished for the first time. This process constitutes a step‐economic and highly efficient pathway to 2‐amino‐2′‐carboxybiaryl scaffolds from readily available substrates. A Cp*‐free RhCl3/TFA catalytic system was developed to replace the [Cp*RhCl2]2/AgSbF6 system generally used in oxidative C?H/C?H cross‐coupling reactions between two (hetero)arenes (Cp*=pentamethylcyclopentadienyl, TFA=trifluoroacetic acid). The RhCl3/TFA system avoids the use of the expensive Cp* ligand and AgSbF6. As an illustrative example, the procedure developed herein greatly streamlines the total synthesis of the naturally occurring benzo[c]phenanthridine alkaloid oxynitidine, which was accomplished in excellent overall yield. 相似文献