共查询到20条相似文献,搜索用时 15 毫秒
1.
Dr. Jie Wang Dr. Tian Qin Dr. Tie‐Gen Chen Dr. Laurin Wimmer Jacob T. Edwards Dr. Josep Cornella Benjamin Vokits Dr. Scott A. Shaw Prof. Phil S. Baran 《Angewandte Chemie (International ed. in English)》2016,55(33):9676-9679
A transformation analogous in simplicity and functional group tolerance to the venerable Suzuki cross‐coupling between alkyl‐carboxylic acids and boronic acids is described. This Ni‐catalyzed reaction relies upon the activation of alkyl carboxylic acids as their redox‐active ester derivatives, specifically N‐hydroxy‐tetrachlorophthalimide (TCNHPI), and proceeds in a practical and scalable fashion. The inexpensive nature of the reaction components (NiCl2?6 H2O—$9.5 mol?1, Et3N) coupled to the virtually unlimited commercial catalog of available starting materials bodes well for its rapid adoption. 相似文献
2.
Nickel‐ and Photoredox‐Catalyzed Cross‐Coupling Reactions of Aryl Halides with 4‐Alkyl‐1,4‐dihydropyridines as Formal Nucleophilic Alkylation Reagents 下载免费PDF全文
Dr. Kazunari Nakajima Sunao Nojima Prof. Dr. Yoshiaki Nishibayashi 《Angewandte Chemie (International ed. in English)》2016,55(45):14106-14110
A combination of nickel and photoredox catalysts promoted novel cross‐coupling reactions of aryl halides with 4‐alkyl‐1,4‐dihydropyridines. 4‐Alkyl‐1,4‐dihydropyridines act as formal nucleophilic alkylation reagents through a photoredox‐catalyzed carbon–carbon (C?C) bond‐cleavage process. The present strategy provides an alternative to classical carbon‐centered nucleophiles, such as organometallic reagents. 相似文献
3.
Dr. Lukiana L. Anka‐Lufford Kierra M. M. Huihui Dr. Nicholas J. Gower Dr. Laura K. G. Ackerman Prof. Dr. Daniel J. Weix 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(33):11564-11567
Cross‐electrophile coupling of aryl halides with alkyl halides has thus far been primarily conducted with stoichiometric metallic reductants in amide solvents. This report demonstrates that the use of tetrakis(dimethylamino)ethylene (TDAE) as an organic reductant enables the use of non‐amide solvents, such as acetonitrile or propylene oxide, for the coupling of benzyl chlorides and alkyl iodides with aryl halides. Furthermore, these conditions work for several electron‐poor heterocycles that are easily reduced by manganese. Finally, we demonstrate that TDAE addition can be used as a control element to ‘hold’ a reaction without diminishing yield or catalyst activity. 相似文献
4.
Rui Sun Yangzhong Qin Daniel G. Nocera 《Angewandte Chemie (International ed. in English)》2020,59(24):9527-9533
Self‐sustained NiI/III cycles are established as a potentially general paradigm in photoredox Ni‐catalyzed carbon–heteroatom cross‐coupling reactions through a strategy that allows us to recapitulate photoredox‐like reactivity in the absence of light across a wide range of substrates in the amination, etherification, and esterification of aryl bromides, the latter of which has remained, hitherto, elusive under thermal Ni catalysis. Moreover, the accessibility of esterification in the absence of light is especially notable because previous mechanistic studies on this transformation under photoredox conditions have unanimously invoked energy‐transfer‐mediated pathways. 相似文献
5.
Dorus Heijnen Dr. Jean‐Baptiste Gualtierotti Dr. Valentín Hornillos Prof. Dr. Ben L. Feringa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(12):3991-3995
Nickel‐catalyzed selective cross‐coupling of aromatic electrophiles (bromides, chlorides, fluorides and methyl ethers) with organolithium reagents is presented. The use of a commercially available nickel N‐heterocyclic carbene (NHC) complex allows the reaction with a variety of (hetero)aryllithium compounds, including those prepared via metal‐halogen exchange or direct metallation, whereas a commercially available electron‐rich nickel‐bisphosphine complex smoothly converts alkyllithium species into the corresponding coupled product. These reactions proceed rapidly (1 h) under mild conditions (room temperature) while avoiding the undesired formation of reduced or homocoupled products. 相似文献
6.
Nurtalya Alandini Luca Buzzetti Gianfranco Favi Tim Schulte Lisa Candish Karl D. Collins Paolo Melchiorre 《Angewandte Chemie (International ed. in English)》2020,59(13):5248-5253
Herein, we report a one‐electron strategy for catalytic amide synthesis that enables the direct carbamoylation of (hetero)aryl bromides. This radical cross‐coupling approach, which is based on the combination of nickel and photoredox catalysis, proceeds at ambient temperature and uses readily available dihydropyridines as precursors of carbamoyl radicals. The method's mild reaction conditions make it tolerant of sensitive‐functional‐group‐containing substrates and allow the installation of an amide scaffold within biologically relevant heterocycles. In addition, we installed amide functionalities bearing electron‐poor and sterically hindered amine moieties, which would be difficult to prepare with classical dehydrative condensation methods. 相似文献
7.
8.
Nickel‐Catalyzed Reductive Cross‐Coupling of Aryl Halides with Monofluoroalkyl Halides for Late‐Stage Monofluoroalkylation 下载免费PDF全文
Hao‐Ran Zhang Kai‐Fan Zhang Yi‐Ning Wang Prof. Dr. Xi‐Sheng Wang 《Angewandte Chemie (International ed. in English)》2018,57(26):7634-7639
A combinatorial nickel‐catalyzed monofluoroalkylation of aryl halides with unactivated fluoroalkyl halides by reductive cross‐coupling has been developed. This method demonstrated high efficiency, mild conditions, and excellent functional‐group tolerance, thus enabling the late‐stage monofluoroalkylation of diverse drugs. The key to success was the combination of diverse readily available bidentate and monodentate pyridine‐type nitrogen ligands with nickel, which in situ generated a variety of readily tunable catalysts to promote fluoroalkylation with broad scope with respect to both coupling partners. This combinatorial catalysis strategy offers a solution for nickel‐catalyzed reductive cross‐coupling reactions and provides an efficient way to synthesize fluoroalkylated druglike molecules for drug discovery. 相似文献
9.
Van T. Tran Zi‐Qi Li Timothy J. Gallagher Joseph Derosa Peng Liu Keary M. Engle 《Angewandte Chemie (International ed. in English)》2020,59(18):7029-7034
Allylation and conjunctive cross‐coupling represent two useful, yet largely distinct, reactivity paradigms in catalysis. The union of these two processes would offer exciting possibilities in organic synthesis but remains largely unknown. Herein, we report the use of allyl electrophiles in nickel‐catalyzed conjunctive cross‐coupling with a non‐conjugated alkene and dimethylzinc. The transformation is enabled by weakly coordinating, monodentate aza‐heterocycle directing groups that are useful building blocks in synthesis, including saccharin, pyridones, pyrazoles, and triazoles. The reaction occurs under mild conditions and is compatible with a wide range of allyl electrophiles. High chemoselectivity through substrate directivity is demonstrated by the facile reactivity of the β‐γ alkene of the starting material, whereas the ?‐ζ alkene of the product is preserved. The generality of this approach is further illustrated through the development of an analogous method with alkyne substrates. Mechanistic studies reveal the importance of the dissociation of the weakly coordinating directing group to allow the allyl moiety to bind and facilitate C(sp3)?C(sp3) reductive elimination. 相似文献
10.
Expedient Synthesis of Chiral α‐Amino Acids through Nickel‐Catalyzed Reductive Cross‐Coupling 下载免费PDF全文
Xi Lu Jun Yi Zhen‐Qi Zhang Jian‐Jun Dai Jing‐Hui Liu Prof. Bin Xiao Prof. Yao Fu Prof. Lei Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(47):15339-15343
A novel method for the synthesis of non‐natural L ‐ and D ‐amino acids by a Ni‐catalyzed reductive cross‐coupling reaction is described. This strategy enables the racemization‐free cross‐coupling of serine/homoserine‐ derived iodides with aryl/acyl/alkyl halides. It provides convenient access to varieties of enantiopure and functionalized amino acids, which are important building blocks in bioactive compounds and pharmaceuticals. 相似文献
11.
Miles H. Aukland Fabien J. T. Talbot Dr. José A. Fernández‐Salas Dr. Matthew Ball Dr. Alexander P. Pulis Prof. Dr. David J. Procter 《Angewandte Chemie (International ed. in English)》2018,57(31):9785-9789
An interrupted Pummerer/nickel‐catalysed cross‐coupling strategy has been developed and used in the elaboration of styrenes. The operationally simple method can be carried out as a one‐pot process, involves the direct formation of stable alkenyl sulfonium salt intermediates, utilises a commercially available sulfoxide, catalyst, and ligand, operates at ambient temperature, accommodates sp‐, sp2‐, and sp3‐hybridised organozinc coupling partners, and delivers functionalised styrene products in high yields over two steps. An interrupted Pummerer/cyclisation approach has also been used to access carbo‐ and heterocyclic alkenyl sulfonium salts for cross‐coupling. 相似文献
12.
This report presents the first example of nickel‐catalyzed mild decarboxylative cross‐coupling reaction for the regioselective formation of C–Si bond. An easily accessible and significantly stable Ni (dmg)2 owes the role of key promoter. This reaction is highly functional group tolerant and offers α,β‐unsaturated silanes in synthetically useful yields. The reaction gives access to the successful utilization of otherwise difficult trialkyl silanes as coupling partners and operates at a moderate temperature, which is beneficial to deal with highly volatile silanes. 相似文献
13.
Jiang Wang Brian P. Cary Peyton D. Beyer Samuel H. Gellman Daniel J. Weix 《Angewandte Chemie (International ed. in English)》2019,58(35):12081-12085
Synthesis of the C?C bonds of ketones relies upon one high‐availability reagent (carboxylic acids) and one low‐availability reagent (organometallic reagents or alkyl iodides). We demonstrate here a ketone synthesis that couples two different carboxylic acid esters, N‐hydroxyphthalimide esters and S‐2‐pyridyl thioesters, to form aryl alkyl and dialkyl ketones in high yields. The keys to this approach are the use of a nickel catalyst with an electron‐poor bipyridine or terpyridine ligand, a THF/DMA mixed solvent system, and ZnCl2 to enhance the reactivity of the NHP ester. The resulting reaction can be used to form ketones that have previously been difficult to access, such as hindered tertiary/tertiary ketones with strained rings and ketones with α‐heteroatoms. The conditions can be employed in the coupling of complex fragments, including a 20‐mer peptide fragment analog of Exendin(9–39) on solid support. 相似文献
14.
Ryan T. McGuire Connor M. Simon Arun A. Yadav Michael J. Ferguson Mark Stradiotto 《Angewandte Chemie (International ed. in English)》2020,59(23):8952-8956
The development of Ni‐catalyzed C?N cross‐couplings of sulfonamides with (hetero)aryl chlorides is reported. These transformations, which were previously achievable only with Pd catalysis, are enabled by use of air‐stable ( L )NiCl(o‐tol) pre‐catalysts (L= PhPAd‐DalPhos and PAd2‐DalPhos ), without photocatalysis. The collective scope of (pseudo)halide electrophiles (X=Cl, Br, I, OTs, and OC(O)NEt2) demonstrated herein is unprecedented for any reported catalyst system for sulfonamide C?N cross‐coupling (Pd, Cu, Ni, or other). Preliminary competition experiments and relevant coordination chemistry studies are also presented. 相似文献
15.
Ke‐Jin Jiao Dong Liu Hong‐Xing Ma Hui Qiu Ping Fang Tian‐Sheng Mei 《Angewandte Chemie (International ed. in English)》2020,59(16):6520-6524
A highly regioselective Ni‐catalyzed electrochemical reductive relay cross‐coupling between an aryl halide and an alkyl halide has been developed in an undivided cell. Various functional groups are tolerated under these mild reaction conditions, which provides an alternative approach for the synthesis of 1,1‐diarylalkanes. 相似文献
16.
Intra‐ and Intermolecular Nickel‐Catalyzed Reductive Cross‐Electrophile Coupling Reactions of Benzylic Esters with Aryl Halides 下载免费PDF全文
Mikhail O. Konev Luke E. Hanna Prof. Dr. Elizabeth R. Jarvo 《Angewandte Chemie (International ed. in English)》2016,55(23):6730-6733
Nickel‐catalyzed cross‐electrophile coupling reactions of benzylic esters and aryl halides have been developed. Both inter‐ and intramolecular variants proceed under mild reaction conditions. A range of heterocycles and functional groups are tolerated under the reaction conditions. Additionally, the first example of a stereospecific cross‐electrophile coupling of a secondary benzylic ester is described. 相似文献
17.
Liana Hie Emma L. Baker Sarah M. Anthony Dr. Jean‐Nicolas Desrosiers Dr. Chris Senanayake Prof. Dr. Neil K. Garg 《Angewandte Chemie (International ed. in English)》2016,55(48):15129-15132
Recent studies have demonstrated that amides can be used in nickel‐catalyzed reactions that lead to cleavage of the amide C?N bond, with formation of a C?C or C?heteroatom bond. However, the general scope of these methodologies has been restricted to amides where the carbonyl is directly attached to an arene or heteroarene. We now report the nickel‐catalyzed esterification of amides derived from aliphatic carboxylic acids. The transformation requires only a slight excess of the alcohol nucleophile and is tolerant of heterocycles, substrates with epimerizable stereocenters, and sterically congested coupling partners. Moreover, a series of amide competition experiments establish selectivity principles that will aid future synthetic design. These studies overcome a critical limitation of current Ni‐catalyzed amide couplings and are expected to further stimulate the use of amides as synthetic building blocks in C?N bond cleavage processes. 相似文献
18.
M. Sc. Congjun Yu Prof. Dr. Frederic W. Patureau 《Angewandte Chemie (International ed. in English)》2018,57(36):11807-11811
A highly selective CuII‐catalyzed cross‐dehydrogenative ortho‐aminomethylation of phenols with aniline derivatives is described. The corresponding C(sp2)?C(sp3) coupling products were obtained in moderate to excellent yields under mild reaction conditions and with a broad substrate scope. A radical mechanism is proposed. 相似文献
19.
Visible light‐mediated radical alkenylation of benzylsulfonium salts was achieved by means of fac‐Ir(ppy)3 as a photocatalyst, giving allylbenzenes as products. A variety of functional groups, such as halogen, ester, and cyano, were well tolerated in this transformation. Starting benzylsulfonium salts could be readily prepared from benzyl alcohols by an acid‐mediated substitution, increasing the synthetic utility of this transformation. 相似文献
20.
A General Strategy for the Synthesis of Enantiomerically Pure Azetidines and Aziridines through Nickel‐Catalyzed Cross‐Coupling 下载免费PDF全文
Dr. Kim L. Jensen Dennis U. Nielsen Prof. Dr. Timothy F. Jamison 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(20):7379-7383
In this communication, we report a straightforward synthesis of enantiomerically pure 2‐alkyl azetidines. The protocol is based on a highly regioselective nickel‐catalyzed cross‐coupling of aliphatic organozinc reagents with an aziridine that features a tethered thiophenyl group. Activation by methylation transforms the sulfide into an excellent leaving group and triggers the formation of the 2‐substituted azetidine core structure by cyclization. In addition, we have expanded this concept to the synthesis of enantiomerically pure, terminal alkyl aziridines. Coupling of a TMS‐protected aziridine alcohol, followed by acidic work‐up to remove the silyl group, provides 1,2‐amino alcohol products that are readily cyclized to aziridines. Both of these sequences display excellent functional group tolerance and deliver the desired azetidine and aziridine products in good to excellent yields. 相似文献