A simple Cu（OAc）2 catalyzed Sonogashira coupling protocol is presented. It was found that the couplings of a variety of aryl halides with terminal alkynes were conducted smoothly to afford the corresponding desired ...A simple Cu（OAc）2 catalyzed Sonogashira coupling protocol is presented. It was found that the couplings of a variety of aryl halides with terminal alkynes were conducted smoothly to afford the corresponding desired products in moderate to excellent yields, using Cu（OAc）2 as the catalyst and Et3N as the solvent.展开更多
The mechanism of palladium-catalyzed Sonogashira cross-coupling reaction has been studied theoretically by DFT （density functional theory） calculations. The model system studied consists of Pd（PH3）2 as the startin...The mechanism of palladium-catalyzed Sonogashira cross-coupling reaction has been studied theoretically by DFT （density functional theory） calculations. The model system studied consists of Pd（PH3）2 as the starting catalyst complex, phenyl bromide as the substrate and acetylene as the terminal alkyne, without regarding to the co-catalyst and base. Mechanistically and energetically plausible catalytic cycles for the cross-coupling have been identified. The DFT analysis shows that the catalytic cycle occurs in three stages： oxidative addition of phenyl bromide to the palladium center, alkynylation of palladium（Ⅱ） intermediate, and reductive elimination to phenylacetylene. In the oxidative addition, the neutral and anionic pathways have been investigated, which could both give rise to cis-configured palladium（Ⅱ） diphosphine intermediate. Starting from the palladium（Ⅱ） diphosphine intermediate, the only identifiable pathway in alkynylation involves the dissociation of Br group and the formation of square-planar palladium（Ⅱ） intermediate, in which the phenyl and alkynyl groups are oriented cis to each other. Due to the close proximity of phenyl and alkynyl groups, the reductive elimination of phenylacetylene proceeds smoothly.展开更多
Palladium-catalyzed the Sonogashira coupling reaction of 3-halogen-2-aminopyridines 1 with terminal alkynes 2 afforded the corresponding 21 target products 3a-3u in the presence of palladium catalyst. The structure of...Palladium-catalyzed the Sonogashira coupling reaction of 3-halogen-2-aminopyridines 1 with terminal alkynes 2 afforded the corresponding 21 target products 3a-3u in the presence of palladium catalyst. The structure of target products 3a-3u was confirmed and characterized by 1H NMR, 13C NMR, and HRMS. The influences of different kinds of catalyst loading, bases, substrates and temperature were also investigated. Under the optimized conditions, including 2.5 mol% Pd?(CF3COO)2, 5 mol% PPh3 and 5 mol% CuI as additive, 1 mL Et3N, substrate 1 with terminal alkynes 2 for the cross-coupling reactions at 100°C for 3 h in DMF afforded the corresponding products of 2-amino-3-alkynylpyridines 3 in moderate to excellent yields (72%?-?96%). The present methodology has provided an effective synthetic method including operational convenience, high efficiency and wide-application.展开更多
CuI/ethylene diamine/K2CO3/dioxane is shown to be a useful system for the cross coupling reactions of various aryl iodides and bromides with aryl and alkyl alkynes. Compared to the conventional Sonogashira reactions, ...CuI/ethylene diamine/K2CO3/dioxane is shown to be a useful system for the cross coupling reactions of various aryl iodides and bromides with aryl and alkyl alkynes. Compared to the conventional Sonogashira reactions, the new procedure is free of palladium and phosphines.展开更多
A series of 2-arylamino-1,3,5-triazine derivatives(4a–4g),which were designed and synthesized via Sonogashira coupling reaction,were evaluated using two-electrode voltage clamp(TEVC)recordings of humanα7 nAChR expre...A series of 2-arylamino-1,3,5-triazine derivatives(4a–4g),which were designed and synthesized via Sonogashira coupling reaction,were evaluated using two-electrode voltage clamp(TEVC)recordings of humanα7 nAChR expressed in Xenopus ooctyes.Compound 4g as a positive allosteric modulator(PAM)showed better efficacy than lead compound 3(HZZ-A-11)with an EC50 value of 1.23±0.41μM.Further pharmacological evaluation of compound 4g might lead to the developmental potential for therapy of cognitive deficits commonly shared by neuropsychiatric disorders,such as schizophrenia and Alzheimer’s disease.展开更多
An oxime-derived palladacycle was synthesized using 4-bromobenzoxime and pyridine in CHCl3, and characterized by FT-IR and 1H NMR spectroscopy. This Pd complex was supported on Fe3O4/oleic acid and shown to be an effi...An oxime-derived palladacycle was synthesized using 4-bromobenzoxime and pyridine in CHCl3, and characterized by FT-IR and 1H NMR spectroscopy. This Pd complex was supported on Fe3O4/oleic acid and shown to be an efficient catalyst for the copper-free Sonogashira cross-coupling reaction of various aryl halides with phenylacetylene in air and in ethanol or mixed aqueous medium. The oxime- derived palladacycle gave highly active palladium nanoparticles for the organic synthesis. The coupling products were obtained in high yields with low Pd loading and the heterogeneous catalyst can be separated by an external magnet and reused six times without loss of its activity. The characterization of the catalyst was carried out by XRD, SEM and TEM. Both TEM and XRD revealed that the palladium nanoparticles were well dispersed with diameters from 5 to 10 nm and average size 9.97 nm.展开更多
Excellent results have been achieved in the Cu（OAc）2-catalyzed Sonogashira cross-couplings of aryl iodides and activated aryl bromides utilizing TBAF （tetrabutylammonium fluoride） as the base and 4,6-dimethoxypyri...Excellent results have been achieved in the Cu（OAc）2-catalyzed Sonogashira cross-couplings of aryl iodides and activated aryl bromides utilizing TBAF （tetrabutylammonium fluoride） as the base and 4,6-dimethoxypyrimidin-2-amine as the ligand. It is noteworthy that the reaction is conducted under aerobic, solvent-free and palladium-free conditions.展开更多
文摘A simple Cu（OAc）2 catalyzed Sonogashira coupling protocol is presented. It was found that the couplings of a variety of aryl halides with terminal alkynes were conducted smoothly to afford the corresponding desired products in moderate to excellent yields, using Cu（OAc）2 as the catalyst and Et3N as the solvent.
基金Supported by the NNSFC (No. 20464001 and 20674034)
文摘The mechanism of palladium-catalyzed Sonogashira cross-coupling reaction has been studied theoretically by DFT （density functional theory） calculations. The model system studied consists of Pd（PH3）2 as the starting catalyst complex, phenyl bromide as the substrate and acetylene as the terminal alkyne, without regarding to the co-catalyst and base. Mechanistically and energetically plausible catalytic cycles for the cross-coupling have been identified. The DFT analysis shows that the catalytic cycle occurs in three stages： oxidative addition of phenyl bromide to the palladium center, alkynylation of palladium（Ⅱ） intermediate, and reductive elimination to phenylacetylene. In the oxidative addition, the neutral and anionic pathways have been investigated, which could both give rise to cis-configured palladium（Ⅱ） diphosphine intermediate. Starting from the palladium（Ⅱ） diphosphine intermediate, the only identifiable pathway in alkynylation involves the dissociation of Br group and the formation of square-planar palladium（Ⅱ） intermediate, in which the phenyl and alkynyl groups are oriented cis to each other. Due to the close proximity of phenyl and alkynyl groups, the reductive elimination of phenylacetylene proceeds smoothly.
文摘Palladium-catalyzed the Sonogashira coupling reaction of 3-halogen-2-aminopyridines 1 with terminal alkynes 2 afforded the corresponding 21 target products 3a-3u in the presence of palladium catalyst. The structure of target products 3a-3u was confirmed and characterized by 1H NMR, 13C NMR, and HRMS. The influences of different kinds of catalyst loading, bases, substrates and temperature were also investigated. Under the optimized conditions, including 2.5 mol% Pd?(CF3COO)2, 5 mol% PPh3 and 5 mol% CuI as additive, 1 mL Et3N, substrate 1 with terminal alkynes 2 for the cross-coupling reactions at 100°C for 3 h in DMF afforded the corresponding products of 2-amino-3-alkynylpyridines 3 in moderate to excellent yields (72%?-?96%). The present methodology has provided an effective synthetic method including operational convenience, high efficiency and wide-application.
文摘CuI/ethylene diamine/K2CO3/dioxane is shown to be a useful system for the cross coupling reactions of various aryl iodides and bromides with aryl and alkyl alkynes. Compared to the conventional Sonogashira reactions, the new procedure is free of palladium and phosphines.
基金National Natural Science Foundation of China aw arded to Q.Sun(NSFC,Grant No.81973169,21572011)and K.W.Wang(NSFC,Grant No.81537410)the Ministry of Science and Technology of China to K.W.Wang(Grant No.2014ZX09507003-006-004)。
文摘A series of 2-arylamino-1,3,5-triazine derivatives(4a–4g),which were designed and synthesized via Sonogashira coupling reaction,were evaluated using two-electrode voltage clamp(TEVC)recordings of humanα7 nAChR expressed in Xenopus ooctyes.Compound 4g as a positive allosteric modulator(PAM)showed better efficacy than lead compound 3(HZZ-A-11)with an EC50 value of 1.23±0.41μM.Further pharmacological evaluation of compound 4g might lead to the developmental potential for therapy of cognitive deficits commonly shared by neuropsychiatric disorders,such as schizophrenia and Alzheimer’s disease.
基金supported by the Department of Chemistry,Isfahan University of Technology and the Iranian Nano Technology Initiative Council
文摘An oxime-derived palladacycle was synthesized using 4-bromobenzoxime and pyridine in CHCl3, and characterized by FT-IR and 1H NMR spectroscopy. This Pd complex was supported on Fe3O4/oleic acid and shown to be an efficient catalyst for the copper-free Sonogashira cross-coupling reaction of various aryl halides with phenylacetylene in air and in ethanol or mixed aqueous medium. The oxime- derived palladacycle gave highly active palladium nanoparticles for the organic synthesis. The coupling products were obtained in high yields with low Pd loading and the heterogeneous catalyst can be separated by an external magnet and reused six times without loss of its activity. The characterization of the catalyst was carried out by XRD, SEM and TEM. Both TEM and XRD revealed that the palladium nanoparticles were well dispersed with diameters from 5 to 10 nm and average size 9.97 nm.
基金Project supported by the Key Project of Chinese Ministry of Education （No. 206102）, Fok Ying Dong Education Foundation （No. 101012）, Scientific Research Fund of Hunan Provincial Education Department （No. 05B038）, Hunan Provincial Natural Science Foundation of China （No. 05JJ1002） and the National Natural Science Foundation of China （Nos. 20572020 and 20202002）
文摘Excellent results have been achieved in the Cu（OAc）2-catalyzed Sonogashira cross-couplings of aryl iodides and activated aryl bromides utilizing TBAF （tetrabutylammonium fluoride） as the base and 4,6-dimethoxypyrimidin-2-amine as the ligand. It is noteworthy that the reaction is conducted under aerobic, solvent-free and palladium-free conditions.
