共查询到20条相似文献,搜索用时 31 毫秒
1.
Lin Yu Leiyang Lv Zihang Qiu Zhangpei Chen Ze Tan Yu‐Feng Liang Chao‐Jun Li 《Angewandte Chemie (International ed. in English)》2020,59(33):14009-14013
We have developed an unprecedented Pd‐catalyzed formal hydroalkylation of alkynes with hydrazones, which are generated in situ from naturally abundant aldehydes, as both alkylation reagents and hydrogen donors. The hydroalkylation proceeds with high regio‐ and stereoselectivity to form (Z)‐alkenes, which are more difficult to generate compared to (E)‐alkenes. The reaction is compatible with a wide range of functional groups, including hydroxy, ester, ketone, nitrile, boronic ester, amine, and halide groups. Furthermore, late‐stage modifications of natural products and pharmaceutical derivatives exemplify its unique chemoselectivity, regioselectivity, and synthetic applicability. Mechanistic studies indicate the possible involvement of Pd‐hydride intermediates. 相似文献
2.
Reaction between Azidyl Radicals and Alkynes: A Straightforward Approach to NH‐1,2,3‐Triazoles 下载免费PDF全文
Long Hu Dr. Christian Mück‐Lichtenfeld Prof. Dr. Tao Wang Guifeng He Dr. Meng Gao Prof. Dr. Junfeng Zhao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(3):911-915
Reaction between nitrogen‐centered radicals and unsaturated C?C bonds is an effective synthetic strategy for the construction of nitrogen‐containing molecules. Although the reactions between nitrogen‐centered radicals and alkenes have been studied extensively, their counterpart reactions with alkynes are extremely rare. Herein, the first example of reactions between azidyl radicals and alkynes is described. This reaction initiated an efficient cascade reaction involving inter‐/intramolecular radical homolytic addition toward a C?C triple bond and a hydrogen‐atom transfer step to offer a straightforward approach to NH‐1,2,3‐triazoles under mild reaction conditions. Both the internal and terminal alkynes work well for this transformation and some heterocyclic substituents on alkynes are compatible. This mechanistically distinct strategy overcomes the inherent limitations associated with azide anion chemistry and represents a rare example of reactions between a nitrogen‐centered radicals and alkynes. 相似文献
3.
Etienne Crochet Dr. Lucile Anthore-Dalion Dr. Thibault Cantat 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(1):e202214069
Easily accessible via a simple esterification of alcohols with formic acid, alkyl formates are used as a novel class of transfer hydroalkylation reagents, CO2 acting as a traceless linker. As a proof-of-concept, their reactivity in the transfer hydroalkylation of imines is investigated, using a ruthenium-based catalyst and LiI as promoter to cleave the C−O σ-bond of the formate scaffold. Providing tertiary amines, the reaction displays a divergent regioselectivity compared to previously reported transfer hydroalkylation strategies. 相似文献
4.
The first direct intermolecular hydroamination/hydroalkylation of terminal alkynes catalyzed by In(OTf)(3) under one-pot conditions leading to the formation of conjugated ketimines in good yields is described. 相似文献
5.
The on‐surface coupling reactions of terminal alkynes catalyzed by exogenous cupric ions on chemically inert highly oriented pyrolytic graphite (HOPG) surface have been investigated by scanning tunnelling microscopy. In the presence of exogenous cupric ions, diyne‐linked nanostructures generated via homocoupling of terminal alkynes are the exclusive products, whereas no coupling reaction occurs for the terminal alkynes on the surface in the absence of the cupric ions, suggesting that exogenous cupric ions are efficient to catalyze the highly chemoselective on‐surface reaction of terminal alkynes. The HOPG surface displays a template effect to the growth and alignment of the products on the surface. As a result, 2D arrays of diyne‐linked zigzag polymers and 2D diyne‐linked porous polymers are fabricated from ditopic monomer 3,6‐diethynylcarbazole and tritopic monomer 1,3,5‐tris‐(4‐ethynylphenyl) benzene, respectively. This synthetic strategy combining the high selectivity of cupric ion catalyst as well as the template effect of on‐surface synthesis approach could be a general strategy to fabricate diyne‐linked nanostructures and nanomaterials on solid surfaces. 相似文献
6.
Yulin Zhang Dr. Yoshiaki Tanabe Dr. Shogo Kuriyama Prof. Yoshiaki Nishibayashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(36):e202200727
Dual photoredox- and nickel-catalyzed hydroalkylation of terminal alkynes with 4-alkyl-1,4-dihydropyridines under visible light irradiation to afford Markovnikov- or anti-Markovnikov-type alkylated alkenes in good-to-high yields has been achieved, in which the regioselectivity of the products was effectively controlled by coordination ligands for nickel species. Using [NiCl2(dtbbpy)] as a catalyst led to the formation of Markovnikov-type products, whereas using NiCl2 ⋅ 6 H2O led to the formation of anti-Markovnikov-type products. 相似文献
7.
Additions of terminal alkynes to electrophiles are important transformations in organic chemistry. Generally, activated terminal alkynes react with epoxides in an S(N)2 fashion to form homopropargylic alcohols. We have developed a new synthetic method to form propargylic alcohols from epoxides and terminal alkynes via 1,2-shifts. This method involves cationic zirconium acetylides as both the activator of epoxides and nucleophiles. Due to the mild conditions to pre-activate alkynes with silver nitrate, this synthetic method is useful for both electron-rich and electron-deficient alkynes with other acid- and base-sensitive functional groups. 相似文献
8.
Oxidant-dependent Cu-catalyzed alkynylation and aminomethylation reactions have been achieved under facile and mild conditions. TMEDA coupled with various terminal alkynes via C–H bond cleavage in good yields using atmospheric oxygen as an oxidant. Switching from air to TBHP afforded aminomethylation products of terminal alkynes through C–C bond cleavage of TMEDA. The protocol provided a novel strategy to prepare bi/tridentate N-ligand. 相似文献
9.
Lin Yu Dr. Leiyang Lv Dr. Zihang Qiu Dr. Zhangpei Chen Prof. Dr. Ze Tan Dr. Yu-Feng Liang Prof. Dr. Chao-Jun Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(33):14113-14117
We have developed an unprecedented Pd-catalyzed formal hydroalkylation of alkynes with hydrazones, which are generated in situ from naturally abundant aldehydes, as both alkylation reagents and hydrogen donors. The hydroalkylation proceeds with high regio- and stereoselectivity to form (Z)-alkenes, which are more difficult to generate compared to (E)-alkenes. The reaction is compatible with a wide range of functional groups, including hydroxy, ester, ketone, nitrile, boronic ester, amine, and halide groups. Furthermore, late-stage modifications of natural products and pharmaceutical derivatives exemplify its unique chemoselectivity, regioselectivity, and synthetic applicability. Mechanistic studies indicate the possible involvement of Pd-hydride intermediates. 相似文献
10.
A facile and practical synthetic route of unsymmetrical 1,3‐diynes via the PdCl/CuI catalyzed oxidative coupling of two different terminal alkynes has been developed by using 3‐(diphenylphosphino)propanoic acid as a ligand in the presence of oxygen. This system is suitable for not only aromatic alkynes but also heteroaromatic and aliphatic alkynes which were transformed into the corresponding unsymmetrical 1,3‐diynes in moderate to good yields at room temperature. Moreover, the unsymmetrical 1,3‐diynes were also obtained on a multi‐gram scale. Mechanistic studies suggest that oxygen plays a key role in the catalytic cycles. 相似文献
11.
Iron‐Induced Regio‐ and Stereoselective Addition of Sulfenyl Chlorides to Alkynes by a Radical Pathway 下载免费PDF全文
Dr. Masayuki Iwasaki Tomoya Fujii Prof. Dr. Kiyohiko Nakajima Prof. Dr. Yasushi Nishihara 《Angewandte Chemie (International ed. in English)》2014,53(50):13880-13884
The radical addition of the Cl? S σ‐bond in sulfenyl chlorides to various C? C triple bonds has been achieved with excellent regio‐ and stereoselectivity in the presence of a catalytic amount of a common iron salt. The reaction is compatible with a variety of functional groups and can be scaled up to the gram‐scale with no loss in yield. As well as terminal alkynes, internal alkynes underwent stereodefined chlorothiolation to provide tetrasubstituted alkynes. Preliminary mechanistic investigations revealed a plausible radical process involving a sulfur‐centered radical intermediate via iron‐mediated homolysis of the Cl? S bond. The resulting chlorothiolation adducts can be readily transformed to the structurally complex alkenyl sulfides by cross‐coupling reactions. The present reaction can also be applied to the complementary synthesis of the potentially useful bis‐sulfoxide ligands for transition‐metal‐catalyzed reactions. 相似文献
12.
A novel NiH-catalyzed decarboxylative hydroalkylation of internal alkynes has been developed. Trisubstituted olefins were obtained in moderate to good yields with good regioselectivities. The reaction involves cis addition of NiH to the internal alkyne. The reaction shows good functional-group tolerance. 相似文献
13.
Copper‐Catalyzed Regioselective Hydroalkylation of 1,3‐Dienes with Alkyl Fluorides and Grignard Reagents 下载免费PDF全文
Dr. Takanori Iwasaki Ryohei Shimizu Reiko Imanishi Prof. Dr. Hitoshi Kuniyasu Prof. Dr. Nobuaki Kambe 《Angewandte Chemie (International ed. in English)》2015,54(32):9347-9350
Copper complexes generated in situ from CuCl2, alkyl Grignard reagents, and 1,3‐dienes play important roles as catalytic active species for the 1,2‐hydroalkylation of 1,3‐dienes by alkyl fluorides through C? F bond cleavage. The alkyl group is introduced to an internal carbon atom of the 1,3‐diene regioselectively, thus giving rise to the branched terminal alkene product. 相似文献
14.
Synthesis of Polysubstituted α‐Pyrones Using Zinc‐Catalyzed Addition–Cyclization Reactions 下载免费PDF全文
Various polysubstituted α‐pyrone derivatives have been directly synthesized via a hydroalkylation of Michael additional reaction following a cyclized process catalyzed by the Lewis acid of Zn(OAc)2. This protocol provides a new convenient and step‐economical route to construct heterocycles. Fourteen examples are obtained from easily available materials with moderate to good yields. 相似文献
15.
Beatriz Trastoy M. Eugenia Pérez‐Ojeda Roberto Sastre Prof. Dr. Jose Luis Chiara Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(12):3833-3841
A one‐step synthesis of octakis(3‐azidopropyl)octasilsesquioxane from commercially available octakis(3‐aminopropyl)octasilsesquioxane has been developed through a highly efficient diazo‐transfer reaction under very mild conditions. Nonaflyl azide is shown to be a safer, cheaper, and more efficient reagent for this transformation than the better known and generally used diazo‐transfer reagent triflyl azide. Octakis(3‐azidopropyl)octasilsesquioxane is an excellent nanobuilding block that can be readily octafunctionalized with a range of terminal alkynes by copper(I)‐catalyzed 1,3‐dipolar azide–alkyne cycloaddition to provide new functional nanocages, maintaining a perfect 3D cubic symmetry. The mildness, simplicity, and efficiency of this approach have been demonstrated in the preparation of a glyco‐polyhedral oligosilsesquioxane (POSS) conjugate and a BODIPY–POSS cluster (BODIPY=boron dipyrromethene). 相似文献
16.
Yuanhong Ma Shuai Zhang Shiping Yang Feijie Song Jingsong You 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(30):8004-8008
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
17.
Gold‐Catalyzed C(sp3)H/C(sp)H Coupling/Cyclization/Oxidative Alkynylation Sequence: A Powerful Strategy for the Synthesis of 3‐Alkynyl Polysubstituted Furans 下载免费PDF全文
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
18.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(2):610-614
Direct radical additions to terminal alkynes have been widely employed in organic synthesis, providing credible access to the anti‐Markovnikov products. Because of the Kharasch effect, regioselective control for the formation of Markovnikov products still remains a great challenge. Herein, we develop a transition‐metal‐free, visible light‐mediated radical addition of S‐nucleophiles to terminal alkynes, furnishing a wide array of α‐substituted vinyl sulfones with exclusive Markovnikov regioselectivity. Mechanistic investigations demonstrated that radical/radical cross‐coupling might be the key step in this transformation. This radical Markovnikov addition protocol also provides an opportunity to facilitate the synthesis of other valuable α‐substituted vinyl compounds. 相似文献
19.
Zinc‐Catalyzed Dehydrogenative Cross‐Coupling of Terminal Alkynes with Aldehydes: Access to Ynones 下载免费PDF全文
Shan Tang Li Zeng Yichang Liu Prof. Aiwen Lei 《Angewandte Chemie (International ed. in English)》2015,54(52):15850-15853
Because of the lack of redox ability, zinc has seldom been used as a catalyst in dehydrogenative cross‐coupling reactions. Herein, a novel zinc‐catalyzed dehydrogenative C(sp2)? H/C(sp)? H cross‐coupling of terminal alkynes with aldehydes was developed, and provides a simple way to access ynones from readily available materials under mild reaction conditions. Good reaction selectivity can be achieved with a 1:1 ratio of terminal alkyne and aldehyde. Various terminal alkynes and aldehydes are suitable in this transformation. 相似文献
20.
Synthesis of Triborylalkenes from Terminal Alkynes by Iridium‐Catalyzed Tandem CH Borylation and Diboration 下载免费PDF全文
Dr. Chun‐I Lee Wei‐Chun Shih Prof. Jia Zhou Dr. Joseph H. Reibenspies Prof. Oleg V. Ozerov 《Angewandte Chemie (International ed. in English)》2015,54(47):14003-14007
A two‐step reaction to convert terminal alkynes into triborylalkenes is reported. In the first step, the terminal alkyne and pinacolborane (HBpin) are converted into an alkynylboronate, which is catalyzed by an iridium complex supported by a SiNN pincer ligand. In the second step, treatment of the reaction mixture with CO generates a new catalyst which mediates dehydrogenative diboration of alkynylboronate with pinacolborane. The mechanism of the diboration remains unclear but it does not proceed via intermediacy of hydroboration products or via B2pin2. 相似文献