- Divergent Carbocatalytic Routes in Oxidative Coupling of Benzofused Heteroaryl Dimers: A Mechanistic Update
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Mildly thermal air or HNO3 oxidized activated carbons catalyse oxidative dehydrogenative couplings of benzo[b]fused heteroaryl 2,2’-dimers, e.g., 2-(benzofuran-2-yl)-1H-indole, to chiral 3,3’-coupled cyclooctatetraenes or carbazole-type migrative products under O2 atmosphere. DFT calculations show that the radical cation and the Scholl-type arenium cation mechanisms lead to different products with 2-(benzofuran-2-yl)-1H-indole, being in accord with experimental product distributions.
- Casadio, David S.,Aikonen, Santeri,Lenarda, Anna,Nieger, Martin,Hu, Tao,Taubert, Stefan,Sundholm, Dage,Muuronen, Mikko,Wirtanen, Tom,Helaja, Juho
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p. 5283 - 5291
(2021/02/26)
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- Palladium-catalyzed homo-coupling of heteroarylsulfoniums via borylation/Suzuki-Miyaura coupling sequence
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Palladium-catalyzed homo-coupling of heteroaryldimethylsulfoniums proceeds in the presence of bis(pinacolato)diboron and a base to yield biheteroaryls. The homo-coupling involves palladium-catalyzed borylation and the subsequent Suzuki-Miyaura coupling. As the sulfoniums were able to be prepared in situ from the corresponding heteroaryl sulfides and methyl triflate, one-pot transformations of heteroaryl sulfides into the homo-coupling products were executed. Furthermore, a facile synthesis of a highly substituted 2,2'-bibenzofuran was accomplished with a combination of Pummerer-type synthesis of 2-benzofuryl sulfide and the present homo-coupling.
- Minami, Hiroko,Nogi, Keisuke,Yorimitsu, Hideki
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p. 998 - 1007
(2019/04/26)
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- An Active Palladium Colloidal Catalyst for the Selective Oxidative Heterocoupling of (Hetero)Aryl Boronic Acids
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A highly selective oxidative heterocoupling protocol for (hetero)aryl boronic acids with an active palladium colloidal catalyst was developed. The judicious choice of electronically different aryl boronic acids made possible such couplings under mild conditions, with air as oxidant, while embracing a wide substrate scope. This successful approach further allowed the development of a unique one-pot sequential oxidative heterocoupling/Suzuki–Miyaura cross-coupling tandem process for accessing substituted terphenyls.
- Sable, Vaibhav,Maindan, Karan,Bhilare, Shatrughn,Chrysochos, Nicolas,Schulzke, Carola,Kapdi, Anant R.
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supporting information
p. 2489 - 2498
(2018/09/10)
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- Selective catalytic transfer dehydrogenation of alkanes and heterocycles by an iridium pincer complex
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Catalytic alkane dehydrogenation is a reaction with tremendous potential for application. We describe a highly active PSCOP-pincer iridium catalyst for transfer dehydrogenation of cyclic and linear alkanes. The dehydrogenation of linear alkanes occurs under relatively mild conditions with high regioselectivity for a-olefin formation. In addition, the catalyst system is very effective in the dehydrogenation of heterocycles to form heteroarenes and olefinic products.
- Yao, Wubing,Zhang, Yuxuan,Jia, Xiangqing,Huang, Zheng
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supporting information
p. 1390 - 1394
(2014/03/21)
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- Pd-catalyzed tandem chemoselective synthesis of 2-arylbenzofurans using threefold arylating triarylbismuth reagents
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A tandem chemoselective synthesis of 2-arylbenzofurans was accomplished from o-hydroxy-gem-(dibromovinyl)benzenes and BiAr3 reagents under palladium-catalyzed conditions. This unique and synthetically valuable strategy proceeds through three consecutive coupling reactions involving triarylbismuth reagents and provides 2-arylbenzofuran products in high yields. A tandem chemoselective synthesis of 2-arylbenzofurans was accomplished from o-hydroxy-gem-(dibromovinyl)benzenes and BiAr3 reagents under palladium-catalyzed conditions. This unique and synthetically valuable strategy proceeds through three consecutive coupling reactions involving triarylbismuth reagents and provides 2-arylbenzofuran products in high yields. Copyright
- Rao, Maddali L. N.,Jadhav, Deepak N.,Dasgupta, Priyabrata
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p. 781 - 788
(2013/03/13)
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- One-pot synthesis of 2,2′-bisbenzofurans using cuprous chloride as a catalyst
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A variety of novel 5,5′-disubstituted-2,2′-bisbenzofuran derivatives were synthesized by treatment of 4-substituted-2-(2- trimethylsilylethynyl)phenyl tert-butyldimethylsilyl ether analogues with CuCl as a catalyst in 62-82% isolated yields. This novel st
- Pan, Wen-Bin,Chen, Chin-Chau,Wei, Li-Lan,Wei, Li-Mei,Wu, Ming-Jung
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p. 2655 - 2657
(2013/06/05)
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- The first general and selective palladium(II)-catalyzed alkoxycarbonylation of arylboronates: Interplay among benzoquinone-ligated palladium(0) complex, organoboron, and alcohol solvent
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Methoxycarbonylation of aryl- and alken-ylboron compounds was performed using the palladium (II) acetate/triphenylphosphine [PdACHTUNGTRENNUNG(OAc) 2/PPh3] catalyst with p-benzoquinone as a stoichiometric oxidant in methanol at ambient temperature to obtain the corresponding methyl esters in good yields. A wide variety of functional groups including various carbonyl functionalities, nitrile, nitro, sulfone, and unprotected pyrrole rings were tolerated in the methoxycarbonlation, while the use of higher alcohols except for tert-butanol afforded various pchlorobenzoates in moderate to high yields. The catalytic alkoxycarbonylation proceeded without any acid or base additive, and an oxidative transmetalation step is proposed to explain the exceptional efficacy of this protocol. DFT and MP2 calculations support the proposed mechanism.
- Yamamoto, Yoshihiko
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supporting information; experimental part
p. 478 - 492
(2010/07/03)
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- Deprotonative metalation of functionalized aromatics using mixed lithium-cadmium, lithium-indium, and lithium-zinc species
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In situ mixtures of CdCl2TMEDA (0.5 equiv; TMEDA = N,N,N',N'-tetramethylethylenediamine) or InCl3 (0.33 equiv) with [Li(tmp)] (tmp = 2,2,6,6-tetramethylpiperidino; 1.5 or 1.3 equiv, respectively) were compared with the previously described mixture of ZnCl2-TMEDA (0.5 equiv) and [Li(tmp)] (1.5 equiv) for their ability to deprotonate anisole, benzothiazole, and pyrimidine. [(tmp)3CdLi] proved to be the best base when used in tetrahydrofuran at room temperature, as demonstrated by subsequent trapping with iodine. The Cd-Li base then proved suitable for the metalation of a large range of aromatics including benzenes bearing reactive functional groups (CONEt2, CO2Me, CN, COPh) or heavy halogens (Br, I), and heterocycles (from the furan, thiophene, pyrrole, oxazole, thiazole, pyridine, and diazine series). Fivemembered heterocycles benefiting from doubly activated positions were similarly dideprotonated at room temperature. The aromatic lithium cadmates thus obtained were involved in palladium-catalyzed cross-coupling reactions or simply quenched with acid chlorides.
- Snegaroff, Katia,L'Helgoual'ch, Jean-Martial,Bentabed-Ababsa, Ghenia,Nguyen, Tan Tai,Chevallier, Floris,Yonehara, Mitsuhiro,Uchiyama, Masanobu,Derdour, Aicha,Mongin, Florence
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experimental part
p. 10280 - 10290
(2010/04/24)
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- New synthesis of benzo[b]furan and indole derivatives from 1,1-dibromo-1-alkenes using a tandem Pd-assisted cyclization-coupling reaction
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We report a new flexible method for the synthesis of 2-functionalized benzo[b]furans and indoles from readily available o-(2,2-dibromovinyl)-phenol, -aniline or -acetanilide using a tandem Pd-assisted cyclization-coupling reaction.
- Thielges, Sabine,Meddah, Emilie,Bisseret, Philippe,Eustache, Jacques
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p. 907 - 910
(2007/10/03)
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