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1.
Huifeng Yue Chen Zhu Rajesh Kancherla Fangying Liu Magnus Rueping 《Angewandte Chemie (International ed. in English)》2020,59(14):5738-5746
Alkynes are an important class of organic molecules due to their utility as versatile building blocks in synthesis. Although efforts have been devoted to the difunctionalization of alkynes, general and practical strategies for the direct hydroalkylation and alkylarylation of terminal alkynes under mild reaction conditions are less explored. Herein, we report a photoredox/nickel dual‐catalyzed anti‐Markovnikov‐type hydroalkylation of terminal alkynes as well as a one‐pot arylalkylation of alkynes with alkyl carboxylic acids and aryl bromides via a three‐component cross‐coupling. The results indicate that the transformations proceed via a new mechanism involving a single‐electron transfer with subsequent energy‐transfer activation pathways. Moreover, steady‐state and time‐resolved fluorescence‐spectroscopy measurements, density functional theory (DFT) calculations, and wavefunction analysis have been performed to give an insight into the catalytic cycle. 相似文献
2.
Metal-free anti-Markovnikov hydroalkylation of unactivated alkenes with cyanoacetate has been developed,featuring the use of a dual-component initiator containing an organic photocatalyst and a radical precursor.When combined,the two components can undergo visible light-induced singleelectron transfer,and serve as a versatile and effective alkyl radical generator. 相似文献
3.
A general method for the hydroalkylation of electron-rich terminal and non-terminal alkenes such as enol esters, alkenyl sulfides, enol ethers, silyl enol ethers, enamides and enecarbamates has been developed. The reactions are carried out at room temperature under air initiation in the presence of triethylborane acting as a chain transfer reagent and 4-tert-butylcatechol (TBC) as a source of hydrogen atom. The efficacy of the reaction is best explained by very favorable polar effects supporting the chain process and minimizing undesired polar reactions. The stereoselective hydroalkylation of chiral N-(alk-1-en-1-yl)oxazolidin-2-ones takes place with good to excellent diastereocontrol.Giese reaction not anymore limited to electron poor alkenes! A general method for the radical mediated hydroalkylation of electron rich alkenes including enol ethers, silylenolethers, enamides, and enecarbamates has been developed. 相似文献
4.
Copper‐Catalyzed Regioselective Hydroalkylation of 1,3‐Dienes with Alkyl Fluorides and Grignard Reagents
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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
5.
Synthesis of Polysubstituted α‐Pyrones Using Zinc‐Catalyzed Addition–Cyclization Reactions
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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
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.
Zhi-Lin Zhang Zhen Li Yuan-Tai Xu Dr. Lu Yu Jian Kuang Yan Li Dr. Jia-Wang Wang Prof. Changlin Tian Prof. Xi Lu Prof. Yao Fu 《Angewandte Chemie (International ed. in English)》2023,62(30):e202306381
Cyclopropene hydrofunctionalization has been a promising strategy for accessing multi-substituted cyclopropanes; however, cyclopropene hydroalkylation remains underdeveloped. Herein, we report a low-valent CoH-catalyzed facial-selective cyclopropene hydroalkylation to access multi-substituted cyclopropanes. This reaction exhibits a broad substrate scope of alkyl halides and cyclopropenes and tolerates many functional groups. Moderate-to-good facial-selectivity is obtained without any directing groups. Mechanism studies provide evidence that alkyl radicals are generated from alkyl halides and irreversible CoH insertion is responsible for the facial-selectivity. Our preliminary exploration demonstrates that asymmetric cyclopropene hydroalkylation can be realized without conspicuous auxiliary groups. 相似文献
8.
Ramazanov I. R. Djyachenko L. I. Ibragimov A. G. Dzhemilev U. M. 《Russian Chemical Bulletin》2002,51(5):833-835
The reactions of olefins with alkyl halides and Et3Al in the presence of catalytic amounts of Cp2TiCl2 were studied. Unbranched -olefins of the aliphatic series underwent hydroalkylation under the action of tert-butyl bromide to form 2,3-dimethylalkanes. 相似文献
9.
A practical method for the intramolecular hydroalkylation of electron-deficient olefins has been developed. The direct transformation of benzylic, tertiary, and sterically hindered secondary sp3 C-H bonds into C-C bonds under the action of a catalytic amount of a variety of Lewis acids is described. The mechanism of these transformations is proposed to involve a tandem hydride transfer/cyclization sequence. 相似文献
10.
Deyun Qian Xile Hu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(51):18690-18694
Nickel hydride (NiH) catalyzed hydrocarbonation has emerged as an efficient approach to construct new C?C bonds containing at least one C(sp3) center. However, the regioselectivity of this reaction is by far dictated by substrates. Described here is a strategy to achieve two different regioselectivites of hydroalkylation of the same substrates by using ligand control. This strategy enables the first regiodivergent hydroalkylation of 3‐pyrrolines, yielding both 2‐ and 3‐alkylated pyrrolidines, valuable synthetic intermediates and common motifs in many bioactive molecules. This method demonstrates broad scope and high functional‐group tolerance, and can be applied in late‐stage functionalizations. 相似文献
11.
Han X Wang X Pei T Widenhoefer RA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(24):6333-6342
Reaction of 3-butenyl beta-keto esters or 3-butenyl alpha-aryl ketones with a catalytic amount of [PdCl2(CH3CN)2] (2) and a stoichiometric amount of Me3SiCl or Me3SiCl/CuCl2 in dioxane at 25-70 degrees C formed 2-substituted cyclohexanones in good yield with high regioselectivity. This protocol tolerated a number of ester and aryl groups and tolerated substitution at the allylic, enolic, and cis and trans terminal olefinic positions. In situ NMR experiments indicated that the chlorosilane was not directly involved in palladium-catalyzed hydroalkylation, but rather served as a source of HCl, which presumably catalyzes enolization of the ketone. Identification of HCl as the active promoter of palladium-catalyzed hydroalkylation led to the development of an effective protocol for the hydroalkylation of alkyl 3-butenyl ketones that employed sub-stoichiometric amounts of 2, HCl, and CuCl2 in a sealed tube at 70 degrees C. 相似文献
12.
Ziyauddin S. Qureshi 《Tetrahedron letters》2010,51(4):724-11188
Benzylation and hydroalkylation of 1,3-dicarbonyl compounds using Amberlyst-15 immobilized in ionic liquid [Bmim][PF6] as an efficient reusable reagent was studied. The reagent was compared with other solid acid reagents along with role of the ionic liquid. The effect of various reaction parameters like type of reagent, solvent, substrate molar ratio, reaction time, and temperature were studied. Present protocol is advantageous due to the ease in handling of reagent, simple work-up procedure, economical and environmentally benign process. The products were obtained in good to excellent yield and applicable to wide variety of substrates. 相似文献
13.
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
14.
Xinyu Duan Dong Cui Zhiguo Wang Dannan Zheng Linye Jiang Wen-Yu Huang Yi-Xia Jia Jian Xu 《Angewandte Chemie (International ed. in English)》2023,62(5):e202214135
Carbene insertion reactions initiated with diazo compounds have been widely used to develop unnatural enzymatic reactions. However, alternative functionalization of diazo compounds in enzymatic processes has been unexploited. Herein, we describe a photoenzymatic strategy for radical-mediated stereoselective hydroalkylation with diazo compounds. This method generates carbon-centered radicals through an ene reductase catalyzed photoinduced electron transfer process from diazo compounds, enabling the synthesis of γ-stereogenic carbonyl compounds in good yields and stereoselectivities. This study further expands the possible reaction patterns in photo-biocatalysis and offers a new approach to solving the selectivity challenges of radical-mediated reactions. 相似文献
15.
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
16.
Ai-Fang Wang Jin-Miao Tian Xiao-Jing Zhao Zi-Hao Li Ye Zhang Ka Lu Hong Wang Shu-Yu Zhang Yong-Qiang Tu Tong-Mei Ding Yu-Yang Xie 《Angewandte Chemie (International ed. in English)》2023,62(39):e202308858
An asymmetric intramolecular hydroalkylation of unactivated internal olefins with tethered cyclic ketones was realized by the cooperative catalysis of a newly designed chiral amine (SPD-NH2) and PdII complex, providing straightforward access to either bridged or fused bicyclic systems containing three stereogenic centers with excellent enantioselectivity (up to 99 % ee) and diastereoselectivity (up to >20 : 1 dr). Notably, the bicyclic products could be conveniently transformed into a diverse range of key structures frequently found in bioactive terpenes, such as Δ6-protoilludene, cracroson D, and vulgarisins. The steric hindrance between the Ar group of the SPD-NH2 catalyst and the branched chain of the substrate, hydrogen-bonding interactions between the N−H of the enamine motif and the C=O of the directing group MQ, and the counterion of the PdII complex were identified as key factors for excellent stereoinduction in this dual catalytic process by density functional theory calculations. 相似文献
17.
Cong Liu 《Tetrahedron letters》2005,46(2):285-287
Reaction of 5,5-dimethyl-8-nonene-2,4-dione with a catalytic mixture of [PtCl2(CH2CH2)]2 (2) (1 mol %), and EuCl3 (2 mol %) in dioxane that contained HCl (1.0 equiv) at 90 °C for 18 h led to the isolation of 2-acetyl-3,6,6-trimethyl-2-cyclohexanone in 85% yield. A number of 4-pentenyl β-dicarbonyl compounds underwent intramolecular hydroalkylation to form cyclohexanones in moderate to excellent yield. 相似文献
18.
Jia Hao Pang Bin Wang Kohei Watanabe Ryo Takita Shunsuke Chiba 《Helvetica chimica acta》2021,104(10):e2100120
A method for the synthesis of 1,3-diarylpropylamines through hydroalkylation of styrenes with benzylamines by potassium hydride has been developed. The protocol is initiated by solvothermal treatment of benzylamines with KH at 100 °C to generate deprotonated anionic species, which undergo selective C-alkylation with arylalkenes at 0 °C to ambient temperature to afford 1,3-diarylpropylamines as the major product. 相似文献
19.
Jinzhong Yao Zhangpei Chen Lin Yu Leiyang Lv Dawei Cao Chao-Jun Li 《Chemical science》2020,11(39):10759
A palladium-catalyzed hydroalkylation reaction of methylenecyclopropanes via highly selective C–C σ-bond scission was achieved under mild conditions, in which simple hydrazones served as carbanion equivalents. This method featured good functional group compatibility, affording high yields of C-alkylated terminal alkenes.A palladium-catalyzed hydroalkylation of methylenecyclopropanes via selective C–C σ-bond scission was achieved, in which simple hydrazones served as carbanion equivalents. This method affords high yields of C-alkylated terminal alkenes with good functional group compatibility. 相似文献
20.
An efficient and convenient method for the direct hydroalkylation of styrene and norborene with 1,3-diketones has been developed by using 12-phosphotungstic acid as an eco-friendly, and air- and moisture-tolerable catalyst. Reactions proceeded without any solvent, providing a clean access to alkylated 1,3-diketones. 相似文献