共查询到20条相似文献,搜索用时 390 毫秒
1.
Dr. Youai Qiu Cong Tian Leonardo Massignan Torben Rogge Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2018,57(20):5818-5822
Electrocatalysis has been identified as a powerful strategy for organometallic catalysis, and yet electrocatalytic C?H activation is restricted to strongly N‐coordinating directing groups. The first example of electrocatalytic C?H activation by weak O‐coordination is presented, in which a versatile ruthenium(II) carboxylate catalyst enables electrooxidative C?H/O?H functionalization for alkyne annulations in the absence of metal oxidants; thereby exploiting sustainable electricity as the sole oxidant. Mechanistic insights provide strong support for a facile organometallic C?H ruthenation and an effective electrochemical reoxidation of the key ruthenium(0) intermediate. 相似文献
2.
Korkit Korvorapun Julia Struwe Rositha Kuniyil Agnese Zangarelli Anna Casnati Marjo Waeterschoot Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2020,59(41):18103-18109
Ambient temperature ruthenium‐catalyzed C?H arylations were accomplished by visible light without additional photocatalysts. The robustness of the ruthenium‐catalyzed C?H functionalization protocol was reflected by a broad range of sensitive functional groups and synthetically useful pyrazoles, triazoles and sensitive nucleosides and nucleotides, as well as multifold C?H functionalizations. Biscyclometalated ruthenium complexes were identified as the key intermediates in the photoredox ruthenium catalysis by detailed computational and experimental mechanistic analysis. Calculations suggested that the in situ formed photoactive ruthenium species preferably underwent an inner‐sphere electron transfer. 相似文献
3.
Herein, we developed a Ru(II)(BPGA) complex that could be used to catalyze chemo‐ and site‐selective C?H oxidation. The described ruthenium complex was designed by replacing one pyridyl group on tris(2‐pyridylmethyl)amine with an electron‐donating amide ligand that was critical for promoting this type of reaction. More importantly, higher reactivities and better chemo‐, and site‐selectivities were observed for reactions using the cis‐ruthenium complex rather than the trans‐one. This reaction could be used to convert sterically less hindered methyne and/or methylene C?H bonds of a various organic substrates, including natural products, into valuable alcohol or ketone products. 相似文献
4.
1,4‐Iron Migration for Expedient Allene Annulations through Iron‐Catalyzed C−H/N−H/C−O/C−H Functionalizations 下载免费PDF全文
Jiayu Mo Thomas Müller Dr. João C. A. Oliveira Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2018,57(26):7719-7723
C?H activation bears great potential for enabling sustainable molecular syntheses in a step‐ and atom‐economical manner, with major advances having been realized with precious 4d and 5d transition metals. In contrast, we employed earth abundant, nontoxic iron catalysts for versatile allene annulations through a unique C?H/N?H/C?O/C?H functionalization sequence. The powerful iron catalysis occurred under external‐oxidant‐free conditions even at room temperature, while detailed mechanistic studies revealed an unprecedented 1,4‐iron migration regime for facile C?H activations. 相似文献
5.
Santhivardhana Reddy Yetra Torben Rogge Svenja Warratz Julia Struwe Wentao Peng Philipp Vana Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2019,58(22):7490-7494
Chemoselective C?H arylations were accomplished through micellar catalysis by a versatile single‐component ruthenium catalyst. The strategy provided expedient access to C?H‐arylated ferrocenes with wide functional‐group tolerance and ample scope through weak chelation assistance. The sustainability of the C?H arylation was demonstrated by outstanding atom‐economy and recycling studies. Detailed computational studies provided support for a facile C?H activation through thioketone assistance. 相似文献
6.
Distal Weak Coordination of Acetamides in Ruthenium(II)‐Catalyzed C−H Activation Processes 下载免费PDF全文
Qingqing Bu Torben Rogge Dr. Vladislav Kotek Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2018,57(3):765-768
C?H activations with challenging arylacetamides were accomplished by versatile ruthenium(II) biscarboxylate catalysis. The distal C?H functionalization offers ample scope—including twofold oxidative C?H functionalizations and alkyne hydroarylations—through facile base‐assisted internal electrophilic‐type substitution (BIES) C?H ruthenation by weak O‐coordination. 相似文献
7.
Cobalt‐Catalyzed Tandem C−H Activation/C−C Cleavage/C−H Cyclization of Aromatic Amides with Alkylidenecyclopropanes 下载免费PDF全文
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
8.
Zhong‐Jian Cai Chen‐Xu Liu Qing Gu Chao Zheng Shu‐Li You 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(7):2171-2175
Asymmetric C?H bond functionalization reaction is one of the most efficient and straightforward methods for the synthesis of optically active molecules. Herein we disclose an asymmetric C?H/C?H cross‐coupling reaction of ferrocenes with azoles such as oxazoles and thiazoles. Palladium(II)/monoprotected amino acid (MPAA) catalytic system which exhibits excellent reactivity and regioselectivity for oxazoles and thiazoles. This method offers a powerful strategy for constructing planar chiral ferrocenes. Mechanistic studies suggest that the C?H bond cleavage of azoles is likely proceeding through a SEAr process and may not be a turnover limiting step. 相似文献
9.
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
10.
Daniel Zell Qingqing Bu Dr. Milica Feldt Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2016,55(26):7408-7412
Cationic cobalt complexes enable unprecedented cobalt‐catalyzed C?H/C?C functionalizations with unique selectivity features. The versatile cobalt catalyst proved broadly applicable, enabled efficient C?H/C?C cleavage at room temperature, and delivered Z‐alkenes with excellent diastereocontrol. 相似文献
11.
Single‐Component Phosphinous Acid Ruthenium(II) Catalysts for Versatile C−H Activation by Metal–Ligand Cooperation 下载免费PDF全文
Prof. Dr. Dmitri Gelman Prof. Dr. Simon J. Garden Prof. Dr. Lutz Ackermann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(4):1248-1252
Well‐defined ruthenium(II) phosphinous acid (PA) complexes enabled chemo‐, site‐, and diastereoselective C?H functionalization of arenes and alkenes with ample scope. The outstanding catalytic activity was reflected by catalyst loadings as low as 0.75 mol %, and the most step‐economical access reported to date to angiotensin II receptor antagonist blockbuster drugs. Mechanistic studies indicated a kinetically relevant C?X cleavage by a single‐electron transfer (SET)‐type elementary process, and provided evidence for a PA‐assisted C?H ruthenation step. 相似文献
12.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(32):9543-9547
C−H/C−C functionalizations with methylenecyclopropanes (MCPs) were accomplished with a versatile base‐metal catalyst. A robust manganese(I) complex enabled the expedient annulation of MCPs by synthetically meaningful ketimines to deliver, upon one‐pot hydroarylation, densely substituted polycylic anilines in a step‐economical fashion. Mechanistic studies provided strong support for a facile organometallic C−H manganation, while typical cobalt, ruthenium, rhodium, and palladium catalysts were found completely ineffective. 相似文献
13.
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
14.
Parthasarathy Gandeepan Julian Koeller Korkit Korvorapun Jens Mohr Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2019,58(29):9820-9825
Visible‐light‐induced ruthenium catalysis has enabled remote C?H alkylations with excellent levels of position control under exceedingly mild conditions at room temperature. The metallaphotocatalysis occurred under exogenous‐photosensitizer‐free conditions and features an ample substrate scope. The robust nature of the photo‐induced mild meta‐C?H functionalization is reflected by the broad functional group tolerance, and the reaction can be carried out in an operationally simple manner, setting the stage for challenging secondary and tertiary meta‐C?H alkylations by ruthenaphotoredox catalysis. 相似文献
15.
Mixed Directing‐Group Strategy: Oxidative C−H/C−H Bond Arylation of Unactivated Arenes by Cobalt Catalysis 下载免费PDF全文
Cong Du Peng‐Xiang Li Dr. Xinju Zhu Jian‐Feng Suo Dr. Jun‐Long Niu Prof. Mao‐Ping Song 《Angewandte Chemie (International ed. in English)》2016,55(43):13571-13575
A mixed directing‐group strategy for inexpensive [Co(acac)3]‐catalyzed oxidative C?H/C?H bond arylation of unactivated arenes has been disclosed. This strategy enables the arylation of a wide range of benzamide and arylpyridines effectively to afford novel bifunctionalized biaryls, which are difficult to achieve by common synthetic routes. Two different pathways, namely, a single‐electron‐transmetalation process (8‐aminoquinoline‐directed) and a concerted metalation–deprotonation process (pyridine‐directed), were involved to activate two different inert aromatic C?H bonds. Moreover, the aryl radicals have been trapped by 2,6‐di‐tert‐butyl‐4‐methylphenol to form benzylated products. This unique strategy should be useful in the design of other arene C?H/C?H cross‐couplings as well. 相似文献
16.
Electrooxidative Rhodium‐Catalyzed C−H/C−H Activation: Electricity as Oxidant for Cross‐Dehydrogenative Alkenylation 下载免费PDF全文
Dr. Youai Qiu Dr. Wei‐Jun Kong Julia Struwe Nicolas Sauermann Torben Rogge Alexej Scheremetjew Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2018,57(20):5828-5832
Rhodium(III) catalysis has enabled a plethora of oxidative C?H functionalizations, which predominantly employ stoichiometric amounts of toxic and/or expensive metal oxidants. In contrast, we herein describe the first electrochemical rhodium‐catalyzed C?H activation that avoids hazardous chemical oxidants. Environmentally benign twofold C?H/C?H functionalizations were accomplished with weakly coordinating benzoic acids and benzamides, employing electricity as the terminal oxidant and generating H2 as the sole byproduct. 相似文献
17.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(47):15327-15331
The para ‐selective C−H alkylation of aniline derivatives furnished with a pyrimidine auxiliary is herein reported. This reaction is proposed to take place via an N−H‐activated cyclometalate formed in situ. Experimental and DFT mechanistic studies elucidate a dual role of the ruthenium catalyst. Here the ruthenium catalyst can undergo cyclometalation by N−H metalation (as opposed to C−H metalation in meta ‐selective processes) and form a redox active ruthenium species, to enable site‐selective radical addition at the para position. 相似文献
18.
Metal‐ and Oxidant‐Free Alkenyl C−H/Aromatic C−H Cross‐Coupling Using Electrochemically Generated Iodosulfonium Ions 下载免费PDF全文
Dr. Ryutaro Hayashi Dr. Akihiro Shimizu Jonathan A. Davies Yu Ishizaki Prof. Dr. Chris Willis Prof. Dr. Jun‐ichi Yoshida 《Angewandte Chemie (International ed. in English)》2018,57(39):12891-12895
A three‐step transformation consisting of 1) addition of electrochemically generated iodosulfonium ions to vinylarenes to give (1‐aryl‐2‐iodoethoxy)sulfonium ions, 2) nucleophilic substitution by subsequently added aromatic compounds to give 1,1‐diaryl‐2‐iodoethane, and 3) elimination of HI with a base to give 1,1‐diarylethenes was developed. The transformation serves as a powerful metal‐ and chemical‐oxidant‐free method for alkenyl C?H/aromatic C?H cross‐coupling. 相似文献
19.
Ramesh C. Samanta Julia Struwe Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2020,59(33):14154-14159
Direct alkylations of carboxylic acid derivatives are challenging and particularly nickel catalysis commonly requires high reaction temperatures and strong bases, translating into limited substrate scope. Herein, nickel‐catalyzed C?H alkylations of unactivated 8‐aminoquinoline amides have been realized under exceedingly mild conditions, namely at room temperature, with a mild base and a user‐friendly electrochemical setup. This electrocatalyzed C?H alkylation displays high functional group tolerance and is applicable to both the primary and secondary alkylation. Based on detailed mechanistic studies, a nickel(II/III/I) catalytic manifold has been proposed. 相似文献
20.
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