- Electrochemical oxidation synergizing with Br?nsted-acid catalysis leads to [4 + 2] annulation for the synthesis of pyrazines
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An electrochemical dehydrogenative [4 + 2] annulation for the synthesis of pyrazines has been developed under undivided electrolytic conditions. In this protocol, neither external chemical oxidants nor transition-metal catalysts are needed, and a wide range of substituted pyrazines could be obtained from simple ketones and diamines in high efficiencies. Of note is that this electrolysis could also be extended for the construction of biheteroarenes and large π systems with good yields.
- Liu, Kun,Song, Chunlan,Wu, Jiarong,Deng, Yuqi,Tang, Shan,Lei, Aiwen
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supporting information
p. 765 - 769
(2019/02/27)
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- The Highly Efficient Suzuki–Miyaura Cross-Coupling of (Hetero)aryl Chlorides and (Hetero)arylboronic Acids Catalyzed by “Bulky-yet-Flexible” Palladium–PEPPSI Complexes in Air
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A series of Pd–PEPPSI complexes were designed and synthesized. The relationship between catalyst structure and properties was systematically investigated. It was revealed that “bulky-yet-flexible” C3 bearing ancenaphthyl backbone was a highly efficient precatalyst and could be successfully employed in Suzuki–Miyaura reactions of (hetero)aryl chlorides with (hetero)arylboronic acids at a low palladium loading in the presence of a weak inorganic base in air.
- Ouyang, Jia-Sheng,Li, Yan-Fang,Huang, Fei-Dong,Lu, Dong-Dong,Liu, Feng-Shou
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p. 371 - 375
(2017/12/15)
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- Copper-Catalyzed Coupling of Triaryl- and Trialkylindium Reagents with Aryl Iodides and Bromides through Consecutive Transmetalations
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An efficient copper(I)-catalyzed coupling of triaryl and trialkylindium reagents with aryl iodides and bromides is reported. The reaction proceeds at low catalyst loadings (2 mol %) and generally only requires 0.33 equivalents of the triorganoindium reagent with respect to the aryl halide as all three organic nucleophilic moieties of the reagent are transferred to the products through consecutive transmetalations. The reaction tolerates a variety of functional groups and sterically hindered substrates. Furthermore, preliminary mechanistic studies that entailed the synthesis and characterization of potential reaction intermediates offered a glimpse of the elementary steps that constitute the catalytic cycle.
- Thapa, Surendra,Gurung, Santosh K.,Dickie, Diane A.,Giri, Ramesh
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supporting information
p. 11620 - 11624
(2016/02/19)
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- Copper-catalysed cross-coupling of arylzirconium reagents with aryl and heteroaryl iodides
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An unprecedented CuI-catalysed cross-coupling of arylzirconium reagents with aryl and heteroaryl iodides is reported. Mechanistic studies with a Cp2ZrAr2 complex revealed that Cp2Zr(Ar)(Cl) is the reactive species that undergoes transmetalation with (PN-1)CuI. In addition, experiments with radical probes indicated that the reaction proceeds via a non-radical pathway. This journal is
- Thapa, Surendra,Basnet, Prakash,Gurung, Santosh K.,Giri, Ramesh
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supporting information
p. 4009 - 4012
(2015/03/30)
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- A general catalyst for Suzuki-Miyaura and Sonogashira reactions of aryl and heteroaryl chlorides in water
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We report the synthesis of 2-(3-sulfonatomesityl)-5-sulfonatoindenyl) dicyclohexylphosphine hydrate sodium salt and its use in palladium-catalyzed Suzuki-Miyaura and Sonogashira coupling reactions in water (and biphasic water-organic solvent mixtures) to prepare a variety of functionalized biaryls and aryl alkynes in excellent yield. This journal is the Partner Organisations 2014.
- Peng, Hui,Chen, Ya-Qin,Mao, Shu-Lan,Pi, Yun-Xiao,Chen, You,Lian, Ze-Yu,Meng, Tong,Liu, Sheng-Hua,Yu, Guang-Ao
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supporting information
p. 6944 - 6952
(2014/09/29)
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- Gold(I)-catalyzed direct C-H arylation of pyrazine and pyridine with aryl bromides
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An efficient procedure for the direct C-H arylation of electron-poor aromatics such as pyrazine and pyridine with aryl bomides is described. In the presence of catalytic amount of Cy3PAuCl and with the use of t-BuOK as base, pyrazine undergoes the direct C-H arylation with aryl bromides at 100 °C, and the yields of the arylated products depend on the nature of aryl bromides. In the cases of electron-rich aryl bromides used, the arylated pyrazines can be obtained in good to high yields. For electron-poor aryl bromides, the addition of AgBF4 is the crucial point to accelerate the coupling reaction to give the arylated products in moderate yields. Pyridine also reacts with electron-rich aryl bromides catalyzed by Cy3PAuCl to give a mixture of arylated regioisomers in moderate yield. However, in order to realize the direct C-H arylation of pyridine with electron-poor aryl bromides, the addition of silver salt as additive and a milder reaction temperature (60 °C) are required.
- Li, Ming,Hua, Ruimao
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supporting information; experimental part
p. 1478 - 1481
(2009/06/08)
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- Aryl-aryl bonds formation in pyridine and diazine series. Diazines part 41
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The synthesis of several symmetrical polyaromatic compounds with pyridine or diazine units has been achieved by homocoupling of aryl halides with Pd(OAc)2 as catalyst. Cross-coupling reactions of aryl Grignard reagents with Fe(acac)3 as catalyst allowed the synthesis of various unsymmetrical polyaryl- or polyheteroaryl compounds with π-deficient rings.
- Boully, Ludovic,Darabantu, Mircea,Turck, Alain,Ple, Nelly
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p. 1423 - 1428
(2007/10/03)
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- THERMAL DEHYDROCYCLIZATION OF α-BENZYL(o-TOLYL)AZINES AND ELECTROPHILIC SUBSTITUTION OF BENZOINDOLIZINE
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At 500-700 deg C, as the result of dehydrocyclization, benzoindolizines are formed from α-benzyl-substituted pyridine, quinoline, and isoquinoline derivatives.Under the same conditions, 1,4-diazafluorene was obtained from 2-(o-tolyl)pyrazine, while 4-azafluorene was obtained from the analogously substituted pyridine.On the example of the acylation reaction it was shown that derivatives of the the five-membered ring are formed during the electrophilic substitution of benzoindolizine.
- Soldatenkov, A. T.,Bagdadi, M. V.,Radzhan, P. K.,Brindkha, O. S.,Edogiaverie, S. L.,et al.
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p. 1184 - 1190
(2007/10/02)
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