- Copper- And ligand-free heteroannulation of o-halohydroxypyridine with terminal alkynes using Pd/C catalyst: One-pot synthesis of 2-substituted furopyridines and their functionalization
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Three types of isomeric 2-substituted furo[3,2-b]pyridine, furo[2,3-b]pyridine and furo[3,2-c]pyridine were prepared using Pd/C-catalyzed heteroannulation of o-halopyridinols and terminal alkynes under copperand ligand-free conditions. We also demonstrated that double functionalization yielding 2,3-disubstituted furopyridines could be achieved through heteroannulation followed by bromination and Suzuki/Heck reactions. In addition, the use of recoverable Pd/C in the absence of a cocatalyst and ligand can aid in the development of greener chemical processes.
- Park, Hee Jung,Kim, Ji-Eun,Yum, Eul Kgun,Kim, Young Hoon,Han, And Chang-Woo
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- One-pot Tandem Heck alkynylation/cyclization reactions catalyzed by Bis(Pyrrolyl)pyridine based palladium pincer complexes
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Ligand assisted palladium catalyzed one-pot tandem Heck alkynylation/cyclization reactions for the synthesis of benzofurans was reported in this paper. Well-defined palladium-pincer complexes exhibited excellent catalytic activities for the one-pot tandem Heck alkynylation/cyclization reactions yielding benzofuran derivatives using 0.1 molpercent catalyst. All the catalytic reactions are performed in air. The effects of variables such as solvents, the temperature on the catalytic activity are also reported. High product conversion was obtained for differently substituted 2-iodophenol at 120 °C in 10 h.
- Yadav, Seema,Dash, Chandrakanta
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- Facile synthesis of 2-substituted benzo[: B] furans and indoles by copper-catalyzed intramolecular cyclization of 2-alkynyl phenols and tosylanilines
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A catalytic amount of CuCl and Cs2CO3 was employed to synthesize a variety of 2-substituted benzo[b]furans and indoles by an intramolecular cyclization of 2-alkynyl phenols and tosylanilines. This protocol features mild conditions, h
- Rong, Zhouting,Gao, Kexin,Zhou, Lei,Lin, Jianyuan,Qian, Guoying
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p. 17975 - 17978
(2019/06/24)
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- CuI catalyzed domino coupling–cyclization of 2-iodo-phenols and 1-alkynes to the synthesis of 2-substituted benzo[b]furans/furo-pyridines
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CuI/proline-catalyzed coupling reaction of 2-iodo-phenols with terminal alkynes and the following cyclization process is carried out successively in DMSO at 80 °C. Under this tandem process, 2-substituted benzo[b]furans/furo-pyridines were synthesized in good to excellent yields with a great diversity.
- Chen, Ze-Pin,Zhou, Yi,Shui, Meng-Zhu,Liu, Feng
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supporting information
p. 133 - 136
(2018/12/11)
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- Synthesis of benzofurans from terminal alkynes and iodophenols catalyzed by recyclable palladium nanoparticles supported on N,O-dual doped hierarchical porous carbon under copper- and ligand-free conditions
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We herein report that a stable and recyclable heterogeneous catalyst, consisting of Pd nanoparticles supported on N,O-dual doped hierarchical porous carbon derived from naturally available and renewable biomass-bamboo shoots, which allows for highly efficient one-pot tandem reaction of o-iodophenols with terminal alkynes to synthesize biologically active 2-benzofuran derivatives under copper- and ligand-free conditions. The catalyst performed superior catalytic performance compared with the analogous Pd/C and supported on other metal oxides under otherwise identical conditions. A broad set of aryl and alkyl terminal alkynes can be effectively coupled /cyclized with various o-iodophenols to afford their corresponding 2-benzofurans in good to high yields with good tolerance of multiple functional groups. Moreover, the catalyst showed good stability and could be reused several times without significant loss of activity.
- Ji, Guijie,Duan, Yanan,Zhang, Shaochun,Yang, Yong
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p. 101 - 108
(2018/05/05)
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- Strategy for Overcoming Full Reversibility of Intermolecular Radical Addition to Aldehydes: Tandem C-H and C-O Bonds Cleaving Cyclization of (Phenoxymethyl)arenes with Carbonyls to Benzofurans
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An intermolecular addition of carbon radicals enabled by a cascade radical coupling strategy is developed. It includes an intermolecular alkyl radical addition to a carbonyl group followed by an intramolecular alkoxy radical addition to haloarenes and produces substituted benzofurans in high yields. The radical nature of this reaction is explored by radical trapping experiments and EPR analysis. The mechanism is investigated by KIE experiments and control experiments. This method could provide rapid and practical access to the key intermediate of TAM-16, a safe and potent antibacterial agent for treating tuberculosis, and, therefore, is of great importance for organic synthesis and the pharmaceutical industry.
- Zheng, Hong-Xing,Shan, Xiang-Huan,Qu, Jian-Ping,Kang, Yan-Biao
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supporting information
p. 3310 - 3313
(2018/06/11)
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- Chelation-assisted C-S activation/cascade heteroannulation of pyridine-2-thione derivatives in Pd-catalyzed cross-coupling reaction with alkynes
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Ortho-chelation assistance was proved to be crucial for the success of the desulfitative Sonogashira cross-coupling reaction of thioamide-type pyridine derivatives and alkynes. Corresponding alkynylated products were obtained with moderate to excellent yields. Thanks to this reaction, furo[3,2-b]pyridine and 1H-pyrrolo[3,2-b]pyridine derivatives were synthesized through a one-pot cross-coupling reaction/heteroannulation sequence.
- Zou, Wenxing,Huang, Zongze,Jiang, Kang,Wu, You,Xue, Yuqing,Suzenet, Franck,Sun, Qi,Guillaumet, Gérald
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p. 5485 - 5492
(2017/08/22)
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- Tandem Sonogashira-Hagihara coupling/cycloisomerization reactions of ethynylboronic acid MIDA ester to afford 2-heterocyclic boronic acid MIDA esters: A concise route to benzofurans, indoles, furopyridines and pyrrolopyridines
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A one-pot process that provides direct access to 2-heterocyclic MIDA (N-methyliminodiacetic acid) boronates has been developed. The reaction of 2-iodophenols or 2-iodoanilines with ethynylboronic acid MIDA ester readily afforded 2-substituted heterocyclic compounds. Amidine and phosphazene bases, especially TMG (1,1,3,3-tetramethylguanidine) assumed an important role in the tandem Sonogashira-Hagihara coupling/cycloisomerization reactions.
- Sakurai, Yohji
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p. 1322 - 1336
(2017/07/18)
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- Synthesis of Benzofurans and Indoles from Terminal Alkynes and Iodoaromatics Catalyzed by Recyclable Palladium Nanoparticles Immobilized on Siliceous Mesocellular Foam
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Herein, we report on the utilization of a heterogeneous catalyst, consisting of Pd nanoparticles supported on a siliceous mesocellular foam (Pd0-AmP-MCF), for the synthesis of heterocycles. Reaction of o-iodophenols and protected o-iodoanilines with acetylenes in the presence of a Pd nanocatalyst produced 2-substituted benzofurans and indoles, respectively. In general, the catalytic protocol afforded the desired products in good to excellent yields under mild reaction conditions without the addition of ligands. Moreover, the structure of the reported Pd nanocatalyst was further elucidated with extended X-ray absorption fine-structure spectroscopy, and it was proven that the catalyst could be recycled multiple times without significant loss of activity.
- Bruneau, Alexandre,Gustafson, Karl P. J.,Yuan, Ning,Tai, Cheuk-Wai,Persson, Ingmar,Zou, Xiaodong,B?ckvall, Jan-E.
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supporting information
p. 12886 - 12891
(2017/09/25)
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- One-pot synthesis of 2-substituted benzo[b]furans via Pd-tetraphosphine catalyzed coupling of 2-halophenols with alkynes
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A catalyst composed of [Pd(η3-C3H 5)Cl]2 and N,N,N',N'-tetra(diphenylphosphinomethyl) pyridine-2,6-diamine (L) was found to be effective for one-pot synthesis of 2-substituted benzo[b]furans from 2-halophenols and alkynes. For 2-bromo-3-hydroxypyridine, the catalyst loading could be as low as 1 ppm and the turnover number (TON) was up to 870000. the Partner Organisations 2014.
- Zhou, Rong,Wang, Wei,Jiang, Zhi-Jie,Wang, Kun,Zheng, Xue-Li,Fu, Hai-Yan,Chen, Hua,Li, Rui-Xiang
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supporting information
p. 6023 - 6026
(2014/05/20)
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- Copper pincer complexes as advantageous catalysts for the heteroannulation of ortho-halophenols and alkynes
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A new, non-symmetrical copper(II) pincer complex catalyzes much more efficiently the formation of benzofuran by the reaction between ortho-iodophenols and alkynes. The lowest catalyst loadings are realized for this reaction, and bromo- and chlorophenols are heteroannulated for the first time. Strong evidence for hydrophenoxylation and intramolecular halogen atom-transfer steps catalyzed by this remarkably active, recyclable homogeneous catalyst is provided.
- Moure, Maria Jesus,Sanmartin, Raul,Dominguez, Esther
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p. 2070 - 2080
(2014/07/07)
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- Copper-free palladium-catalyzed sonogashira-type coupling of aryl halides and 1-aryl-2-(trimethylsilyl)acetylenes
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A one-pot procedure for the direct coupling of 1-aryl-2- trimethylsilylacetylenes with aryl halides to give diaryl acetylenes is reported. The procedure does not involve the use of copper(I) iodide. Improvement in reaction yields has been obtained by replacing conventional oil bath heating with the use of microwave dielectric heating.
- S?rensen, Ulrik S.,Pombo-Villar, Esteban
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p. 2697 - 2703
(2007/10/03)
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- Electrophilic cyclization of o-acetoxy- and o-benzyloxyalkynylpyridines: An easy entry into 2,3-disubstituted furopyridines
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(Matrix Presented) 2,3-Disubstituted furo[3,2-b]pyridines, 2,3-disubstituted furo[2,3-to]pyridines, and 2,3-disubstituted furo[2,3-c]pyridines are readily prepared under mild conditions via the palladium-catalyzed cross-coupling of 1-alkynes with o-iodoac
- Arcadi, Antonio,Cacchi, Sandro,Di Giuseppe, Sabrina,Fabrizi, Giancarlo,Marinelli, Fabio
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p. 2409 - 2412
(2007/10/03)
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- A CONVENIENT ACCESS TO FUROQUINOLINES AND TO FUROPYRIDINES VIA SRN1 REACTIONS
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The two steps route to furoquinolines 4 or to furopyridines 17 involves an SRN1 reaction between 5-chloro-7-iodo-8-isopropoxyquinoline 1a or 2-bromo-3-isopropoxypyridine 15 and enolates derived from ketones.The substitution produc
- Beugelmans, Rene,Bois-Choussy, Michele
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p. 1863 - 1871
(2007/10/02)
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- CONDENSED HETEROAROMATIC RING SYSTEMS. VII. SYNTHESIS OF THIENOPYRIDINES, THIENOPYRIMIDINES, AND FUROPYRIDINES FROM o-SUBSTITUTED N-HETEROARYLACETYLENES
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The cross-coupling reaction of 2-chloro-3-iodo- and 4-chloro-3iodopyridines with phenylacetylene in the presence of dichlorobis(triphenylphosphine)palladium occured at the 3-position.The 3-ethynylpyridines containing an adjacent chloro group were converti
- Sakamoto, Takao,Kondo, Yoshinori,Watanabe, Ryo,Yamanaka, Hiroshi
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p. 2719 - 2724
(2007/10/02)
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