共查询到20条相似文献,搜索用时 31 毫秒
1.
Direct C(sp2)C(sp3) Cross‐Coupling of Diaryl Zinc Reagents with Benzylic,Primary, Secondary,and Tertiary Alkyl Halides
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Jay J. Dunsford Dr. Ewan R. Clark Dr. Michael J. Ingleson 《Angewandte Chemie (International ed. in English)》2015,54(19):5688-5692
The direct C(sp2)? C(sp3) cross‐coupling of diaryl zinc reagents with benzylic, primary, secondary, and tertiary alkyl halides proceeded in the absence of coordinating ethereal solvents at ambient temperature without the addition of a catalyst. The C(sp2)? C(sp3) cross‐coupling showed excellent functional‐group tolerance, and products were isolated in high yields, generally without the requirement for purification by chromatography. This process represents an expedient, operationally simple method for the construction of new C(sp2)? C(sp3) bonds. 相似文献
2.
William G. Whitehurst J. Henry Blackwell Gary N. Hermann Matthew J. Gaunt 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(27):9152-9157
Reported is the discovery of an approach to functionalize secondary alkylamines using 2‐halobenzoic acids as aryl‐transfer reagents. These reagents promote an unusually mild carboxylate‐assisted oxidative addition to alkylamine‐derived palladacycles. In the presence of AgI salts, a decarboxylative C(sp3)?C(sp2) bond reductive elimination leads to γ‐aryl secondary alkylamines and renders the carboxylate motif a traceless directing group. Stoichiometric mechanistic studies were effectively translated to a Pd‐catalyzed γ‐C(sp3)?H arylation process for secondary alkylamines. 相似文献
3.
Robert Szpera Daniel F. J. Moseley Lewis B. Smith Alistair J. Sterling Vronique Gouverneur 《Angewandte Chemie (International ed. in English)》2019,58(42):14824-14848
This Review summarizes advances in fluorination by C(sp2)?H and C(sp3)?H activation. Transition‐metal‐catalyzed approaches championed by palladium have allowed the installation of a fluorine substituent at C(sp2) and C(sp3) sites, exploiting the reactivity of high‐oxidation‐state transition‐metal fluoride complexes combined with the use of directing groups (some transient) to control site and stereoselectivity. The large majority of known methods employ electrophilic fluorination reagents, but methods combining a nucleophilic fluoride source with an oxidant have appeared. External ligands have proven to be effective for C(sp3)?H fluorination directed by weakly coordinating auxiliaries, thereby enabling control over reactivity. Methods relying on the formation of radical intermediates are complementary to transition‐metal‐catalyzed processes as they allow for undirected C(sp3)?H fluorination. To date, radical C?H fluorinations mainly employ electrophilic N?F fluorination reagents but a unique MnIII‐catalyzed oxidative C?H fluorination using fluoride has been developed. Overall, the field of late‐stage nucleophilic C?H fluorination has progressed much more slowly, a state of play explaining why C?H 18F‐fluorination is still in its infancy. 相似文献
4.
Stereospecific Nickel‐Catalyzed Cross‐Coupling Reactions of Alkyl Grignard Reagents and Identification of Selective Anti‐Breast‐Cancer Agents
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ivelina M. Yonova A. George Johnson Charlotte A. Osborne Dr. Curtis E. Moore Prof. Naomi S. Morrissette Prof. Elizabeth R. Jarvo 《Angewandte Chemie (International ed. in English)》2014,53(9):2422-2427
Alkyl Grignard reagents that contain β‐hydrogen atoms were used in a stereospecific nickel‐catalyzed cross‐coupling reaction to form C(sp3)? C(sp3) bonds. Aryl Grignard reagents were also utilized to synthesize 1,1‐diarylalkanes. Several compounds synthesized by this method exhibited selective inhibition of proliferation of MCF‐7 breast cancer cells. 相似文献
5.
Jay J. Dunsford Ewan R. Clark Michael J. Ingleson 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(19):5780-5784
The direct C(sp2) C(sp3) cross‐coupling of diaryl zinc reagents with benzylic, primary, secondary, and tertiary alkyl halides proceeded in the absence of coordinating ethereal solvents at ambient temperature without the addition of a catalyst. The C(sp2) C(sp3) cross‐coupling showed excellent functional‐group tolerance, and products were isolated in high yields, generally without the requirement for purification by chromatography. This process represents an expedient, operationally simple method for the construction of new C(sp2) C(sp3) bonds. 相似文献
6.
Nickel‐Catalyzed Alkoxy–Alkyl Interconversion with Alkylborane Reagents through C−O Bond Activation of Aryl and Enol Ethers
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
M. Sc. Lin Guo Dr. Xiangqian Liu Christoph Baumann Prof. Dr. Magnus Rueping 《Angewandte Chemie (International ed. in English)》2016,55(49):15415-15419
A nickel‐catalyzed alkylation of polycyclic aromatic methyl ethers as well as methyl enol ethers with B‐alkyl 9‐BBN and trialkylborane reagents that involves the cleavage of stable C(sp2)?OMe bonds is described. The transformation has a wide substrate scope and good chemoselectivity profile while proceeding under mild reaction conditions; it provides a versatile way to form C(sp2)?C(sp3) bonds that does not suffer from β‐hydride elimination. Furthermore, a selective and sequential alkylation process by cleavage of inert C?O bonds is presented to demonstrate the advantage of this method. 相似文献
7.
Visible Light Activation of Boronic Esters Enables Efficient Photoredox C(sp2)–C(sp3) Cross‐Couplings in Flow
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Fabio Lima Dr. Mikhail A. Kabeshov Dr. Duc N. Tran Dr. Claudio Battilocchio Dr. Joerg Sedelmeier Dr. Gottfried Sedelmeier Dr. Berthold Schenkel Prof. Steven V. Ley 《Angewandte Chemie (International ed. in English)》2016,55(45):14085-14089
We report herein a new method for the photoredox activation of boronic esters. Using these reagents, an efficient and high‐throughput continuous flow process was developed to perform a dual iridium‐ and nickel‐catalyzed C(sp2)–C(sp3) coupling by circumventing solubility issues associated with potassium trifluoroborate salts. Formation of an adduct with a pyridine‐derived Lewis base was found to be essential for the photoredox activation of the boronic esters. Based on these results we were able to develop a further simplified visible light mediated C(sp2)–C(sp3) coupling method using boronic esters and cyano heteroarenes under flow conditions. 相似文献
8.
A Highly Efficient Gold‐Catalyzed Photoredox α‐C(sp3)H Alkynylation of Tertiary Aliphatic Amines with Sunlight
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Jin Xie Dr. Shuai Shi M. Sc. Tuo Zhang M. Sc. Nina Mehrkens Dr. Matthias Rudolph Prof. Dr. A. Stephen K. Hashmi 《Angewandte Chemie (International ed. in English)》2015,54(20):6046-6050
A new α‐C(sp3)? H alkynylation of unactivated tertiary aliphatic amines with 1‐iodoalkynes as radical alkynylating reagents in the presence of [Au2(μ‐dppm)2]2+ in sunlight provides propargylic amines. Based on mechanistic studies, a C? C coupling of an α‐aminoalkyl radical and an alkynyl radical is proposed for the C(sp3)? C(sp) bond formation. The mild, convenient, efficient, and highly selective C(sp3)? H alkynylation reaction shows excellent regioselectivity and good functional‐group compatibility. A scale‐up to gram quantities is possible with sunlight used as a clean and sustainable energy source. 相似文献
9.
Giuseppe Dilauro Andrea FrancescaQuivelli Paola Vitale Vito Capriati Filippo Maria Perna 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(6):1813-1816
Direct palladium‐catalysed cross‐couplings between organolithium reagents and (hetero)aryl halides (Br, Cl) proceed fast, cleanly and selectively at room temperature in air, with water as the only reaction medium and in the presence of NaCl as a cheap additive. Under optimised reaction conditions, a water‐accelerated catalysis is responsible for furnishing C(sp3)–C(sp2), C(sp2)–C(sp2), and C(sp)–C(sp2) cross‐coupled products, in competition with protonolysis, within a reaction time of 20 s, in yields of up to 99 %, and in the absence of undesired dehalogenated/homocoupling side products even when challenging secondary organolithiums serve as the starting material. It is worth noting that the proposed protocol is scalable and the catalyst and water can easily and successfully be recycled up to 10 times, with an E‐factor as low as 7.35. 相似文献
10.
Phenyltrimethylammonium Salts as Methylation Reagents in the Nickel‐Catalyzed Methylation of C−H Bonds
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Takeshi Uemura Mao Yamaguchi Prof. Dr. Naoto Chatani 《Angewandte Chemie (International ed. in English)》2016,55(9):3162-3165
Methylation of C(sp2)?H bonds was achieved through the NiII‐catalyzed reaction of benzamides with phenyltrimethylammonium bromide or iodide as the source of the methyl group. The reaction has a broad scope and shows high functional‐group compatibility. The reaction is also applicable to the methylation of C(sp3)?H bonds in aliphatic amides. 相似文献
11.
Veronica V. Angeles‐Dunham Dr. David M. Nickerson Devin M. Ray Prof. Dr. Anita E. Mattson 《Angewandte Chemie (International ed. in English)》2014,53(52):14538-14541
Nitrimines are employed as powerful reagents for metal‐free formal C(sp2)–C(sp2) cross‐coupling reactions. The new chemical process is tolerant of a wide array of nitrimine and heterocyclic coupling partners giving rise to the corresponding di‐ or trisubstituted alkenes, typically in high yield and with high stereoselectivity. This method is ideal for the metal‐free construction of heterocycle‐containing drug targets, such as phenprocoumon. 相似文献
12.
C?C triple bonds are amongst the most versatile functional groups in synthetic chemistry. Complementary to the Sonogashira coupling the direct metal‐catalyzed alkynylation of C?H bonds has emerged as a highly promising approach in recent years. To guarantee a high regioselectivity suitable directing groups (DGs) are necessary to guide the transition metal (TM) into the right place. In this Focus Review we present the current developments in DG‐mediated C(sp2)?H and C(sp3)?H modifications with terminal alkynes under oxidative conditions and with electrophilic alkynylation reagents. We will discuss further modifications of the alkyne, in particular subsequent cyclizations to carbo‐ and heterocycles and modifications of the DG in the presence of the alkyne. 相似文献
13.
《中国化学》2018,36(10):950-954
Organoboron is well‐developed and broadly utilized organometallic reagents in organic synthesis due to its extraordinary performances in transition‐metal catalyzed C‐C and C‐X bonds construction. Catalytic C—H borylation and further transformations catalyzed by transition metal catalysts in the absence of oxidants were well studied in decades. However, as known, transition metal catalyzed oxidative C—H borylations were not reviewed up to date. In this article the oxidative borylation of C(sp2)‐H and C(sp3)‐H bonds were summarized and their mechanisms were also accounted. 相似文献
14.
Wenbin Mao Weichao Xue Elisabeth Irran Martin Oestreich 《Angewandte Chemie (International ed. in English)》2019,58(31):10723-10726
A new application of silicon Grignard reagents in C(sp3)?Si bond formation is reported. With the aid of BF3?OEt2, these silicon nucleophiles add across alkenes activated by various azaaryl groups under copper catalysis. An enantioselective version employing benzoxazole‐activated alkenes as substrates and a CuI‐josiphos complex as catalyst has been developed, forming the C(sp3)?Si bond with good to high enantiomeric ratios (up to 97:3). The method expands the toolbox for “conjugate addition” type C(sp3)?Si bond formation. 相似文献
15.
Exploiting Synergistic Effects in Organozinc Chemistry for Direct Stereoselective C‐Glycosylation Reactions at Room Temperature
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Alberto Hernán‐Gómez Dr. Samantha A. Orr Dr. Marina Uzelac Dr. Alan R. Kennedy Dr. Santiago Barroso Dr. Xavier Jusseau Dr. Sébastien Lemaire Dr. Vittorio Farina Prof. Eva Hevia 《Angewandte Chemie (International ed. in English)》2018,57(33):10630-10634
Pairing a range of bis(aryl) zinc reagents ZnAr2 with the stronger Lewis acidic [(ZnArF2)] (ArF=C6F5), enables highly stereoselective cross‐coupling between glycosyl bromides and ZnAr2 without the use of a transition metal. Reactions occur at room temperature with excellent levels of stereoselectivity, where ZnArF2 acts as a non‐coupling partner although its presence is crucial for the execution of the C(sp2)–C(sp3) bond formation process. Mechanistic studies have uncovered a unique synergistic partnership between the two zinc reagents, which circumvents the need for transition‐metal catalysis or forcing reaction conditions. Key to the success of the coupling is the avoidance of solvents that act as Lewis bases versus diarylzinc compounds (e.g. THF). 相似文献
16.
Hong Yi Wenbin Mao Martin Oestreich 《Angewandte Chemie (International ed. in English)》2019,58(11):3575-3578
An enantioselective C(sp3)?C(sp3) cross‐coupling of racemic α‐silylated alkyl iodides and alkylzinc reagents is reported. The reaction is catalyzed by NiCl2/(S,S)‐Bn‐Pybox and yields α‐chiral silanes with high enantiocontrol. The catalyst system does not promote the cross‐coupling of the corresponding carbon analogue, corroborating the stabilizing effect of the silyl group on the alkyl radical intermediate (α‐silicon effect). Both coupling partners can be, but do not need to be, functionalized, and hence, even α‐chiral silanes with no functional group in direct proximity of the asymmetrically substituted carbon atom become accessible. This distinguishes the new method from established approaches for the synthesis of α‐chiral silanes. 相似文献
17.
Simon L. Rssler Benson J. Jelier Pascal F. Tripet Andrej Shemet Gunnar Jeschke Antonio Togni Erick M. Carreira 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(2):536-541
Electron‐transfer photocatalysis provides access to the elusive and unprecedented N‐pyridyl radical cation from selected N‐substituted pyridinium reagents. The resulting C(sp2)?H functionalization of (hetero)arenes furnishes versatile intermediates for the development of valuable aminated aryl scaffolds. Mechanistic studies that include the first spectroscopic evidence of a spin‐trapped N‐pyridyl radical adduct implicate SET‐triggered, pseudo‐mesolytic cleavage of the N?X pyridinium reagents mediated by visible light. 相似文献
18.
Yan‐Shang Kang Ping Zhang Min‐Yan Li You‐Ke Chen Hua‐Jin Xu Jing Zhao Wei‐Yin Sun Jin‐Quan Yu Yi Lu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(27):9197-9201
A ligand‐promoted RhIII‐catalyzed C(sp2)?H activation/thiolation of benzamides has been developed. Using bidentate mono‐N‐protected amino acid ligands led to the first example of RhIII‐catalyzed aryl thiolation reactions directed by weakly coordinating directing amide groups. The reaction tolerates a broad range of amides and disulfide reagents. 相似文献
19.
Xuesong Liu Linqian Yu Mupeng Luo Prof. Jidong Zhu Prof. Wanguo Wei 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(24):8745-8749
A direct C(sp2)?H alkynylation of aldehyde C(O)?H bonds with hypervalent iodine alkynylation reagents provides ynones under metal‐free conditions. In this method, 1‐[(triisopropylsilyl)ethynyl]‐1,2‐benziodoxol‐3(1H)‐one (TIPS‐EBX) constitutes an efficient alkynylation reagent for the introduction of the triple bond. The substrate scope is extended to a variety of (hetero)aromatic, aliphatic, and α,β‐unsaturated aldehydes. 相似文献
20.
Intramolecular Metal‐Free Oxidative Aryl–Aryl Coupling: An Unusual Hypervalent‐Iodine‐Mediated Rearrangement of 2‐Substituted N‐Phenylbenzamides
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Siyun Shang Dr. Daisy Zhang‐Negrerie Prof. Dr. Yunfei Du Prof. Dr. Kang Zhao 《Angewandte Chemie (International ed. in English)》2014,53(24):6216-6219
Hypervalent‐iodine‐mediated oxidative coupling of the two aryl groups in either 2‐acylamino‐N‐phenyl‐benzamides or 2‐hydroxy‐N‐phenylbenzamides, with concomitant insertion of the ortho‐substituted N or O atom into the tether, has been described for the first time. This unusual metal‐free rearrangement reaction involves an oxidative C(sp2)? C(sp2) aryl–aryl bond formation, cleavage of a C(sp2)? C(O) bond, and a lactamization/lactonization. Furthermore, unsymmetrical diaryl compounds can be easily obtained by removing the tether within the cyclized product. 相似文献