- Selective C-C bonds formation, N-alkylation and benzo[d]imidazoles synthesis by a recyclable zinc composite
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Earth abundant metals are much less expensive, promising, valuable metals and could be served as catalysts for the borrowing hydrogen reaction, dehydrogenation and heterocycles synthesis, instead of noble metals. The uniformly dispersed zinc composites were designed, synthesized and carefully characterized by means of XPS, EDS, TEM and XRD. The resulting zinc composite showed good catalytic activity for the N-alkylation of amines with amines, ketones with alcohols in water under base-free conditions, while unsaturated carbonyl compounds could also be synthesized by tuning the reaction conditions. Importantly, it was the first time to realize the synthesis of 2-aryl-1H-benzo[d]imidazole derivatives by using this zinc composite under green conditions. Meanwhile, this zinc catalyst could be easily recovered and reused for at least five times.
- Zhu, Guanxin,Duan, Zheng-Chao,Zhu, Haiyan,Ye, Dongdong,Wang, Dawei
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supporting information
p. 266 - 270
(2021/08/06)
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- ARYL HYDROCARBON RECEPTOR ACTIVATORS
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Small molecule AhR ligands are disclosed. The ligands can induce the differentiation of Tr1 cells to suppress pathogenic immune responses without inducing nonspecific immune suppression. Methods of treatment of autoimmune diseases using the AhR ligands are also disclosed.
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Page/Page column 36
(2021/02/05)
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- Graphene oxide-catalyzed CSp3–H activation of methylarenes in aqueous medium: A unified metal-free access to amides and benzimidazoles
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Graphene oxide (GO)-catalyzed selective synthesis of amides via CSp3–H activation of methylarenes and consequent C–N bond formation with anilines under aqueous medium has been described. Oxygen functionality allied with GO surface played a dual role both as acid catalyst and oxidizing agent to some extent. However, GO has a copious effect on the reaction, shown by a high TOF value with TBHP as co-oxidant. The decisive role of carboxylic acid functional groups on GO nanosheets in this metal-free strategy has been confirmed and was monitored by various analytic techniques viz. Fourier transform-infrared, UV–Vis, Raman and XPS. A plausible mechanism was proposed by control experiments and by the isolation of the intermediate. Over-oxidation of methylarenes was not detected, and high recyclability of the carbocatalyst with its heterogeneous behavior facilitated the isolation and purification of the desired products. We have further explored the utility of this process for the chemoselective synthesis of benzimidazoles.
- Dandia, Anshu,Mahawar, Dinesh Kumar,Sharma, Ruchi,Badgoti, Ranveer Singh,Rathore, Kuldeep S.,Parewa, Vijay
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- Tunable Triazole-Phosphine-Copper Catalysts for the Synthesis of 2-Aryl-1H-benzo[d]imidazoles from Benzyl Alcohols and Diamines by Acceptorless Dehydrogenation and Borrowing Hydrogen Reactions
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Triazole-phosphine-copper complexes (TAP?Cu) have been synthesized and applied as tunable and efficient catalysts for the selective synthesis of fluoro-substituted 2-aryl-1H-benzo[d]imidazole and 1-benzyl-2-aryl-1H-benzo[d]imidazole derivatives from simple alcohols in only one step. TAP?Cu exhibited excellent and tunable catalytic activity for both dehydrogenation and borrowing hydrogen reactions with more than 80 examples being demonstrated for the first time. It was observed that the ligand played a critical role in catalyst activity. Mechanistic studies and deuterium labeling experiments indicated that the reactions proceeded by an initial and reversible alcohol dehydrogenation resulting in a copper hydride intermediate. This was also supported by the direct observation of a diagnostic copper hydride signal by solid-state infrared spectroscopy. The TAP?Cu-H complex showed absorptions at 912 cm?1 that could be assigned to copper?hydride stretches. Furthermore, the direct trapping of an intermediate bisimine was also successfully performed. (Figure presented.).
- Xu, Zhaojun,Wang, Duo-Sheng,Yu, Xiaoli,Yang, Yongchun,Wang, Dawei
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supporting information
p. 3332 - 3340
(2017/10/06)
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- Magnetically separable MnFe2O4 nano-material: An efficient and reusable heterogeneous catalyst for the synthesis of 2-substituted benzimidazoles and the extended synthesis of quinoxalines at room temperature under aerobic conditions
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A simple and efficient protocol has been developed for the synthesis of biologically relevant 2-substituted benzimidazoles and quinoxalines using magnetically separable manganese ferrite (MnFe2O4) nanopowder for the first time as a reusable heterogeneous catalyst at room temperature under aerobic conditions. MnFe2O4 nanoparticles were prepared by a simple sol-gel method using starch as a bio-polymeric matrix, and characterized by XRD, TEM, EDAX and VSM analyses. The Royal Society of Chemistry 2013.
- Brahmachari, Goutam,Laskar, Sujay,Barik, Puspendu
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p. 14245 - 14253
(2013/09/02)
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