- Transition Metal-Free Synthesis of Halobenzo[b]furans from O-Aryl Carbamates via o-Lithiation Reactions
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A straightforward and transition metal-free one-pot protocol to synthesize halobenzo[b]furans has been developed employing simple and easily available starting materials such as O-aryl carbamates and alkynylsulfones. The fine-tuning of the different steps involved was key to achieving a successful one-pot procedure. Initially, a directed ortho-lithiation process, which uses the carbamate as the directed metalation group, was crucial in providing access to O-2-alkynylaryl N,N-diethyl carbamates by a direct alkynylation of the o-lithiated carbamate, with arylsulfonylalkynes as electrophilic reagents. Cyclization of the generated o-alkynylaryl carbamates was successfully accomplished through a strategy involving in situ carbamate alkaline hydrolysis under conventional heating or microwave irradiation, coupled with a subsequent heterocyclization step delivering the desired benzo[b]furans. A wide variety of new halobenzo[b]furans has been synthesized and their utility has been demonstrated by their further transformation.
- Feberero, Claudia,Renedo, Lorena,Sanz, Roberto,Sedano, Carlos,Suárez-Pantiga, Samuel,Virumbrales, Cintia
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- Highly Efficient Synthesis of 2-Substituted Benzo[ b ]furan Derivatives from the Cross-Coupling Reactions of 2-Halobenzo[ b ]furans with Organoalane Reagents
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A highly efficient and simple route for the synthesis of 2-substituted benzo[ b ]furans has been developed by palladium-catalyzed cross-coupling reaction of 2-halobenzo[ b ]furans with aryl, alkynyl, and alkylaluminum reagents. Various 2-aryl-, 2-alkynyl-, and 2-alkyl-substituted benzo[ b ]furan derivatives can be obtained in 23-97% isolated yields using 2-3 mol% PdCl 2/4-6 mol% XantPhos as the catalyst under mild reaction conditions. The aryls bearing electron-donating or electron-withdrawing groups in 2-halobenzo[ b ]furans gave products in 40-97% isolated yields. In addition, aluminum reagents containing thienyl, furanyl, trimethylsilanyl, and benzyl groups worked efficiently with 2-halobenzo[ b ]furans as well, and three bioactive molecules with 2-substituted benzo[ b ]furan skeleton were synthesized. Furthermore, the broad substrates scope and the typical maintenance of vigorous efficiency on gram scale make this protocol a potentially practical method to synthesize 2-substituted benzo[ b ]furan derivatives. On the basis of the experimental results, a possible catalytic cycle has been proposed.
- Wen, Chang,Wu, Chuan,Luo, Ruiqiang,Li, Qinghan,Chen, Feng
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supporting information
p. 3847 - 3861
(2021/07/02)
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- Acid-promoted selective synthesis of trifluoromethylselenolated benzofurans with Se-(trifluoromethyl) 4-methylbenzenesulfonoselenoate
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A Br?nsted acid-promoted trifluoromethylselenolation of benzofurans was disclosed by using Se-(trifluoromethyl) 4-methylbenzenesulfonoselenoate as a stable and easily prepared electrophilic trifluoromethylselenolating reagent. A wide range of SeCF3-substituted benzofuran derivatives were obtained in moderate to good yields with excellent regioselectivity. The tandem cyclization/trifluoromethylselenolation procedure of 1-methoxy-2-(arylethynyl)benzenes were also realized by engaging FeCl3 as the catalyst.
- Liu, Juyan,Tian, Miaomiao,Li, Ankun,Ji, Liangshuo,Qiu, Di,Zhao, Xia
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supporting information
(2021/02/01)
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- Aerobic, Metal-Free, and Catalytic Dehydrogenative Coupling of Heterocycles: En Route to Hedgehog Signaling Pathway Inhibitors
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The nitrosonium ion-catalyzed dehydrogenative coupling of heteroarenes under mild reaction conditions is reported. The developed method utilizes ambient molecular oxygen as a terminal oxidant, and only water is produced as byproduct. Dehydrogenative coupl
- Bering, Luis,Paulussen, Felix M.,Antonchick, Andrey P.
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supporting information
p. 1978 - 1981
(2018/04/16)
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- N-Heterocyclic Carbene-Palladium(II)-1-Methylimidazole Complex Catalyzed Direct C-H Bond Arylation of Benzo[b]furans with Aryl Chlorides
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The first example of sole direct C-H bond arylation of benzo[b]furans with aryl chlorides was achieved catalyzed by a well-defined NHC-Pd(II)-Im complex. Under the suitable conditions, all reactions involving kinds of benzo[b]furans and (hetero)aryl chlor
- Yin, Shun-Chao,Zhou, Quan,Zhao, Xiao-Yun,Shao, Li-Xiong
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p. 8916 - 8921
(2015/09/15)
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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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- Iron-catalyzed synthesis of 2-arylbenzo[b]furans
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An iron-catalyzed procedure was employed to achieve both the Sonogashira cross-coupling and intramolecular o-arylation of o-iodophenols and aryl acetylenes/1-substituted-2-trimethylsilyl acetylenes. A variety of 2-arylbenzo[b]furans were synthesized in mo
- Yang, Jianguo,Shen, Guodong,Chen, Dingben
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p. 837 - 847
(2013/02/23)
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- Highly asymmetric synthesis of (+)-corsifuran A. Elucidation of the electronic requirements in the Ruthenium-NHC catalyzed hydrogenation of benzofurans
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A short and efficient synthesis of ent-corsifuran A by a highly asymmetric hydrogenation of a benzofuran precursor is reported. In addition, the electronic influence of the substituents on the asymmetric hydrogenation of benzofurans is provided. Whereas the hydrogenation of electron-deficient benzofurans was achieved under very mild conditions, the presence of electron-donating groups in the benzofuran required harsher reaction conditions for achieving full conversion to the 2,3-dihydrobenzofuran.
- Ortega, Nuria,Beiring, Bernhard,Urban, Slawomir,Glorius, Frank
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p. 5185 - 5192
(2012/07/31)
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- Cationic palladium(II)-catalyzed synthesis of 2-substituted 3-hydroxymethylbenzo[b]furans
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A tandem reaction involving an intramolecular oxypalladation of an alkyne and an addition to the carbonyl group to quench the carbon-palladium bond to complete the catalytic cycle was developed. The reaction was catalyzed with the cationic palladium(II) species without the necessity of a redox system. Georg Thieme Verlag Stuttgart · New York.
- Wang, Huan,Han, Xiuling,Lu, Xiyan
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p. 2590 - 2594
(2011/11/29)
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