- An Unexpected Formation of 2-Arylbenzimidazoles from α,α-Diiodo-α’-acetoxyketones and o-Phenylenediamines
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An unusual reactivity of the α,α-diiodo-α’-acetoxyketones with o-phenylenediamines is reported through the formation of 2-arylbenzimidazoles. A systematic study through a series of fruitful control experiments and isolation of key intermediates unravelled the unprecedented domino mechanism. This process involves a stepwise two-carbon fragmentation pathway through domino and sequential amidation–aziridination–decarbonylation–I2-mediated aminative cyclization–oxidation reactions. This strategy employs no additives like oxidant, metal catalyst, bases, and represents yet another novel reactivity profile of the building blocks α,α-diiodo-α’-acetoxyketones.
- Sadhukhan, Santu,Mondal, Swagata,Baire, Beeraiah
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- Aromatic C-H Methylation and Other Functionalizations via the Rh(III)-Catalyzed Migratory Insertion of Bis(phenylsulfonyl)carbene and Subsequent Transformations
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The Rh(III)-catalyzed migratory insertion of bis(phenylsulfonyl)carbene into aromatic C-H bonds has been developed. A variety of bis(phenylsulfonyl)methyl derivatives were prepared with good yields under mild conditions. The methylated products were readily obtained after reductive desulfonylation. Furthermore, the diverse transformations of bis(phenylsulfonyl)methyl to trideuteriomethyl, aldehyde, and other functional groups were demonstrated.
- Chen, Lei,Peng, Rui-Jun,Zhang, Xue-Jing,Yan, Ming,Chan, Albert S. C.
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p. 10177 - 10189
(2021/07/28)
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- Electrochemical Synthesis of Benzimidazoles via Dehydrogenative Cyclization of Amidines
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The development of efficient and sustainable methodologies for the synthesis of N-heterocycles is a constant focus of organic synthesis. Herein an electrochemical method is reported for the synthesis of benzimidazoles through dehydrogenative cyclization of easily available N-aryl amidines. The reactions were conducted under simple constant current conditions in an undivided cell without need for catalysts, chemical oxidants, or additives, and produced H2 as the only theoretical byproduct.
- Zhao, Huai-Bo,Zhuang, Jin-Liang,Xu, Hai-Chao
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p. 1692 - 1695
(2021/03/01)
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- Nickel-Catalyzed Heteroarenes Cross Coupling via Tandem C-H/C-O Activation
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Inert aryl methyl ethers as coupling components via C-O activation have been established with a Ni catalyst for C-H activation of heteroarene. The key to simultaneous C-H/C-O bond activation is the use of sterically demanding o-tolylMgBr. The protocol is effective for a wide scope of substrates including naphthyl methyl ethers, anisoles, and a variety of other heteroarene derivatives. Detailed mechanistic studies indicated that the C-O cleavage is assisted via synergistic effect of nickel and Grignard reagent in this C-H/C-O reaction, which is supported by DFT calculation. At this stage, single-electron transfer can be ruled out as a main operative process for this tandem strategy.
- Wang, Ting-Hsuan,Ambre, Ram,Wang, Qing,Lee, Wei-Chih,Wang, Pen-Cheng,Liu, Yuhua,Zhao, Lili,Ong, Tiow-Gan
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p. 11368 - 11376
(2018/11/23)
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- N-Heterocyclic Carbene (NHC)-Catalyzed One-Pot Aerobic Oxidative Synthesis of 2-Substituted Benzo[ d ]oxazoles, Benzo[ d ]thiazoles and 1,2-Disubstituted Benzo[ d ]imidazoles
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N-Heterocyclic carbene (NHC), generated in situ from easily available N-heterocyclic imidazolium salt with air as terminal oxidant, has successfully been utilized as a cheap and efficient catalyst for one-pot aerobic oxidative synthesis of 2-arylbenzo[ d ]oxazoles, 2-substituted benzo[ d ]thiazoles, and 1,2-disubstituted benzo[ d ]imidazoles.
- Zhou, Quan,Liu, Shu,Ma, Ming,Cui, He-Zhen,Hong, Xi,Huang, Shuang,Zhang, Jing-Fan,Hou, Xiu-Feng
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supporting information
p. 1315 - 1322
(2018/03/10)
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- Nanoparticle mediated organic synthesis (NAMO-synthesis): CuI-NP catalyzed ligand free amidation of aryl halides
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The first CuI-nanoparticle catalyzed ligand free synthesis of N-aryl amides from aryl halides and arylamides/cyclic amides has been developed. This methodology is further extended for the synthesis of nitrogen heterocycles such as benzimidazole, and quinazolinone via intermolecular amidation reaction followed by cyclization. TEM images of the CuI-NP catalyst showed spherical, well-dispersed particles which provide large surface area for reactivity and have good recyclability. This journal is
- Kumar, Atul,Bishnoi, Ajay Kumar
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p. 41631 - 41635
(2014/12/10)
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- Transition-metal-free synthesis of benzimidazoles mediated by KOH/DMSO
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Benzimidazoles are prepared by intramolecular N-arylations of amidines mediated by potassium hydroxide in DMSO at 120 °C. In this manner, diversely substituted products have been obtained in moderate to very good yields.
- Baars, Hannah,Beyer, Astrid,Kohlhepp, Stefanie V.,Bolm, Carsten
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p. 536 - 539
(2014/04/03)
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- Nanoparticle mediated organic synthesis (NAMO-synthesis): CuI-NP catalyzed ligand free amidation of aryl halides
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The first CuI-nanoparticle catalyzed ligand free synthesis of N-aryl amides from aryl halides and arylamides/cyclic amides has been developed. This methodology is further extended for the synthesis of nitrogen heterocycles such as benzimidazole, and quinazolinone via intermolecular amidation reaction followed by cyclization. TEM images of the CuI-NP catalyst showed spherical, well-dispersed particles which provide large surface area for reactivity and have good recyclability. This journal is
- Kumar, Atul,Bishnoi, Ajay Kumar
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p. 41631 - 41635
(2015/05/20)
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- N -heterocyclic carbene-palladium(II)-1-methylimidazole complex-catalyzed direct C-H bond arylation of (Benz)imidazoles with aryl chlorides
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(Benz)imidazoles can be efficiently functionalized by (hetero)aryl chlorides via direct C-H bond arylation in the presence of a well-defined NHC-Pd(II)-Im complex. Under the optimal conditions, various activated, unactivated, and deactivated (hetero)aryl chlorides were successfully applied as the arylating reagents to achieve the 2-(hetero)aryl (benz)imidazoles in acceptable to high yields, giving a facile and alternative methodology for the direct C-H bond arylation of (benz)imidazoles.
- Gu, Zheng-Song,Chen, Wen-Xin,Shao, Li-Xiong
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p. 5806 - 5811
(2014/07/08)
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- Nickel-catalyzed direct C-H arylation and alkenylation of heteroarenes with organosilicon reagents
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"Chemical Equation Presented" Breaking the Si-lence: The direct crosscoupling of heteroarenes with aryl- or alkenylsilanes proceeds efficiently, in the presence of a nickel catalyst, to create a wide range of aryl- and alkenyl-heteroaryl bonds efficiently (see scheme; DMAc= N.N-dimethylacetamide, bpy = 2,2′-bipyridine). This catalysis represents a new avenue for using organosilanes in the catalytic C-H functionalization chemistry.
- Hachiya, Hitoshi,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
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scheme or table
p. 2202 - 2205
(2010/06/18)
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- C-H functionalization/C-N bond formation: Copper-catalyzed synthesis of benzimidazoles from amidines
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(Chemical Equation Presented) Copper closes the ring: Benzimidazoles are synthesized from amidines through a copper-catalyzed C-H functionalization/ C-N bond-forming process. The method tolerates a broad range of functional groups and provides the benzimidazoles in up to 89% yield. Best results are obtained by using 15 mol% Cu(OAc)2, 2-5 equivalents of HOAc as additive, and oxygen as the stoichiometric reoxidant (see scheme).
- Brasche, Gordon,Buchwald, Stephen L.
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p. 1932 - 1934
(2008/12/22)
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