- Catalyst- and Reagent-Free Electrochemical Azole C?H Amination
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Catalyst- and chemical oxidant-free electrochemical azole C?H aminations were accomplished via cross-dehydrogenative C?H/N?H functionalization. The catalyst-free electrochemical C?H amination proved feasible on azoles with high levels of efficacy and selectivity, avoiding the use of stoichiometric oxidants under ambient conditions. Likewise, the C(sp3)?H nitrogenation proved viable under otherwise identical conditions. The dehydrogenative C?H amination featured ample scope, including cyclic and acyclic aliphatic amines as well as anilines, and employed sustainable electricity as the sole oxidant.
- Qiu, Youai,Struwe, Julia,Meyer, Tjark H.,Oliveira, Jo?o C. A.,Ackermann, Lutz
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supporting information
p. 12784 - 12789
(2018/09/10)
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- Mild direct amination of benzoxazoles using interpenetrating Cobalt(II)-based metal-organic framework as an efficient heterogeneous catalyst
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Based on the acid-base mixed-ligand assembly strategy, a new acid- and base-stable cobalt(II) metal-organic framework {[Co(tcpa)(Fbtx)(H2O)2]·0.5H2O}n (denoted as Co-MOF, Fbtx = 1,4-bis(1,2,4-triazole-1-ylmethyl
- Chen, Sheng-Chun,Li, Nan,Tian, Feng,Chai, Nan-Nan,He, Ming-Yang,Chen, Qun
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p. 104 - 111
(2018/04/06)
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- The synthesis of 2-Aminobenzoxazoles using reusable ionic liquid as a green catalyst under mild conditions
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A facile, green, and efficient method for the direct oxidative amination of benzoxazoles using heterocyclic ionic liquid as catalyst has been developed. The reaction proceeded smoothly at room temperature and gave the desirable 2-Aminobenzoxazoles with good to excellent yields (up to 97%). The catalyst 1-butylpyridinium iodide can be easily recycled and reused with similar efficacies for at least four cycles.
- Zhou, Ya,Liu, Zhiqing,Yuan, Tingting,Huang, Jianbin,Liu, Chenjiang
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supporting information
(2017/04/10)
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- nBu4NI-catalyzed direct amination of benzoxazoles with tertiary amines using TBHP as oxidant under microwave irradiation
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A facile, efficient, and practical method for nBu4NI-catalyzed direct C-H amination of benzoxazoles with tertiary amines has been developed. The system could be performed in the absence of metal catalyst and only requires tert-butyl
- Yuan, Jin-Wei,Jin, Ming,Yin, Qiu-Yue,Mao, Pu,Qu, Ling-Bo
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p. 317 - 325
(2016/04/26)
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- Practical approach for synthesis of 2-amino-benzoxazole in water
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A practical copper-catalyzed amination of benzoxazole with secondary amine in water has been developed. This reaction has proved to be effective to some cyclic amines, and the substituted group of nitrogen has a great impact on the amination reaction. A copper-catalyzed/amine-induced ring opening of the benzoxazole and recyclization/oxidation mechanism was also proposed.
- Cao, Ke,Wang, Jia-Ling,Wang, Lin-Hui
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supporting information
p. 1471 - 1475
(2015/05/20)
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- Amination of benzoxazoles by visible-light photoredox catalysis
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An effective visible-light-promoted 'radical-type' coupling of benzoxazole with secondary amines has been developed. The broad substrate scope and mild reaction conditions make this procedure a practical and environmentally friendly method for the synthesis of 2-aminobenzoxazoles. Georg Thieme Verlag Stuttgart. New York.
- Wang, Jia-Di,Liu, Yu-Xia,Xue, Dong,Wang, Chao,Xiao, Jianliang
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p. 2013 - 2018
(2014/11/08)
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- Electrochemically initiated oxidative amination of benzoxazoles using tetraalkylammonium halides as redox catalysts
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An electrochemically promoted coupling of benzoxazoles and amines has been developed, leading directly to the formation of 2-aminobenzoxazoles. The chemistry utilizes catalytic quantities of a tetraalkylammonium halide redox catalyst and is carried out under constant current conditions in a simple undivided cell. The use of excess chemical oxidant or large amounts of supporting electrolyte is avoided. This greatly simplifies the workup and isolation process and leads to a reduction in waste. (Chemical Equation Presented).
- Gao, Wei-Jing,Li, Wei-Cui,Zeng, Cheng-Chu,Tian, Hong-Yu,Hu, Li-Ming,Little, R. Daniel
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p. 9613 - 9618
(2015/01/09)
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- Heterogeneously porous γ-MnO2-catalyzed direct oxidative amination of benzoxazole through C-H activation in the presence of O2
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Oxidative amination of azoles through catalytic C-H bond activation is a very important reaction due to the presence of 2-aminoazoles in several biologically active compounds. However, most of the reported methods are performed under homogeneous reaction conditions using excess reagents and additives. Herein, we report the heterogeneous, porous γ-MnO 2-catalyzed direct amination of benzoxazole with wide range of primary and secondary amines. The amination was carried under mild reaction conditions and using molecular oxygen as a green oxidant, without any additives. The catalyst can easily be separated by filtration and reused several times without a significant loss of its catalytic performance. Of note, the reaction tolerates a functional group such as alcohol, thus indicating the broad applicability of this reaction.
- Pal, Provas,Giri, Arnab Kanti,Singh, Harshvardhan,Ghosh, Subhash Chandra,Panda, Asit Baran
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supporting information
p. 2392 - 2396
(2014/10/15)
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- Merging the ring opening of benzoxazoles with secondary amines and an iron-catalyzed oxidative cyclization towards the environmentally friendly synthesis of 2-aminobenzoxazoles
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A facile and environmentally friendly method was developed through merging the ring opening of benzoxazoles with secondary amines and an iron-catalyzed oxidative cyclization towards the synthesis of 2-aminobenzoxazoles. In the oxidative cyclization step, with catalytic amounts of FeCl and aqueous H 2O2 as a green oxidant, highly desirable 2-aminobenzoxazoles were isolated in excellent yields of up to 97%. A plausible radical process is proposed for the oxidative cyclization on the basis of mechanistic studies.
- Xu, Daqian,Wang, Wenfang,Miao, Chengxia,Zhang, Qiaohong,Xia, Chungu,Sun, Wei
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p. 2975 - 2980
(2013/10/08)
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- Cooperative catalysis with aldehydes and copper: Development and application in aerobic oxidative C-H amination at room temperature
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A conceptually new cooperative catalytic system via a synergistic combination of aldehyde and copper catalysis has been established based on systemic mechanistic studies. This new cooperative catalysis has been successfully applied in the direct aerobic oxidative C-H amination of azoles at room temperature, which was previously realized under harsh conditions. Mechanistic studies including isotopic labeling experiments and kinetic isotope effect (KIE) experiments support a reaction pathway that involves formation of an aminal, hydrolysis of the aminal to generate the copper-amide species, subsequent C-H amination and re-oxidation of copper(I) to copper(II) by oxygen. It not only provides an efficient method to realize the oxidative C-H amination of benzoxazoles with free amines at room temperature, but also paves the way for establishing new C-N bond formation reactions by using this efficient cooperative catalysis. Copyright
- Xie, Yinjun,Qian, Bo,Xie, Pan,Huang, Hanmin
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supporting information
p. 1315 - 1322
(2013/06/27)
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- A metal-free amination of benzoxazoles - The first example of an iodide-catalyzed oxidative amination of heteroarenes
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An efficient transition-metal-free amination of benzoxazoles has been developed. With catalytic amounts of tetrabutylammoniumiodide (TBAI), aqueous solutions of H2O2 or TBHP as co-oxidant and under mild reaction conditions, highly desirable 2-aminobenzoxazoles were isolated in excellent yields of up to 93%. First mechanistic experiments indicate the in situ iodination of the secondary amine as the putative mode of activation.
- Froehr, Tanja,Sindlinger, Christian P.,Kloeckner, Ulrich,Finkbeiner, Peter,Nachtsheim, Boris J.
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supporting information; experimental part
p. 3754 - 3757
(2011/10/08)
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- Cobalt- and manganese-catalyzed direct amination of azoles under mild reaction conditions and the mechanistic details
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A bonding moment: A new cobalt- or manganese-catalyzed amination of azoles has been developed using peroxide and an acid additive to couple various types of azoles with ammonia, and primary or secondary amines (see scheme). The catalyst loadings are low, the optimal reaction conditions are mild, and the substrate scope is broad. The product azoles are an important pharmacophore of high biological activity. Copyright
- Kim, Ji Young,Cho, Seung Hwan,Joseph, Jomy,Chang, Sukbok
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experimental part
p. 9899 - 9903
(2011/02/25)
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- A new entry of amination reagents for heteroaromatic C-H bonds: Copper-catalyzed direct amination of azoles with chloroamines at room temperature
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Chloroamine serves as an efficient amination reagent to the heteroaromatic C-H bond of azole under copper catalysis even at room temperature. This catalysis enables a rapid and concise construction of aminoazoles of great interest in biological and medicinal chemistry.
- Kawano, Tsuyoshi,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
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supporting information; experimental part
p. 6900 - 6901
(2010/07/05)
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- Silver-mediated direct amination of benzoxazoles: Tuning the amino group source from formamides to parent amines
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Formamides or parent amines were used as an amino group source for the silver-mediated amination of benzoxazoles. Although reactions with formamides proceeded at high temperatures, the direct amination with amines took place under much milder conditions (
- Cho, Seung Hwan,Kim, Ji Young,Lee, S. Yunmi,Chang, Sukbok
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supporting information; experimental part
p. 9127 - 9130
(2010/03/04)
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