- Efficient symmetrical bidentate dioxime ligand-accelerated homogeneous palladium-catalyzed Suzuki-Miyaura coupling reactions of aryl chlorides
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A series of N,O-bidentate ligands were synthesized using the Vilsmeier-Haack reaction and oximation. 2,5-Dihydroxyterephthalaldehyde dioxime (L8) as an efficient N,O-symmetrical bidentate ligand was prepared from hydroquinone. It was studied as a high activity ligand for palladium-catalyzed Suzuki-Miyaura cross-coupling reactions of aryl chlorides with arylboronic acids under mild conditions. The coupling reactions were performed in the presence of PdCl2 as the catalyst, L8 as the ligand, Na2CO3 as the base, PEG-400 as the PTC and in ethanol/water (1?:?1) as an environmentally benign solvent at 85 °C. Plentiful biaryls were obtained by the optimized reaction with good yields at a low palladium loading of 0.20 mol%.
- Song, Jinyi,Zhao, Hongyan,Liu, Yang,Han, Huatao,Li, Zhuofei,Chu, Wenyi,Sun, Zhizhong
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- One-pot synthesis preparation 4,6-diaminoresorcinol method of hydrochloride
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The invention discloses a method for preparing 4,6-diaminoresorcinol dihydrochloride through one-pot synthesis. The method mainly comprises the steps of: by taking Bronsted acid such as polyphosphoric acid, concentrated sulfuric acid or methanesulfonic acid as the catalyst and the solvent, realizing oximation, Beckmann rearrangement, hydrolysis and hydrocchlorination of 4,6-diacetylresorcinol, and thus obtaining the 4,6-diaminoresorcinol dihydrochloride (DAR.2HCl), wherein the mol ratio of hydroxylamine hydrochloride, the Bronsted acid catalyst and the 4,6-diacetylresorcinol is (2.0-2.5)/(1-10)/1, and the reaction temperature ranges from 65 to 125 DEG C. The method provided by the invention is simple in process steps and efficient in preparation; therefore, the industrialization of the 4,6-diaminoresorcinol dihydrochloride is greatly promoted.
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Paragraph 0050; 0051; 0052
(2016/10/08)
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- Synthesis of isoxazoline N -oxides via [hydroxy(tosyloxy)iodo]benzene (HTIB)-mediated oxidative N-O coupling
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An HTIB mediated oxidative N-O coupling strategy for the synthesis of some isoxazoline N-oxide derivatives from β-hydroxyketoximes is described, along with a comparative study of the efficiency of N-O coupling in two different solvents. A plausible mechanism for the conversion is proposed.
- Raihan, Mustafa J.,Kavala, Veerababurao,Habib, Pateliya Mujjamil,Guan, Qiao-Zhi,Kuo, Chun-Wei,Yao, Ching-Fa
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supporting information; experimental part
p. 424 - 434
(2011/04/17)
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