463336-62-1Relevant academic research and scientific papers
Pyridine-bridged bifunctional organocatalysts for the synthesis of cyclic carbonates from carbon dioxide
Liu, Quan-Yao,Shi, Lei,Liu, Ning
, p. 248 - 256 (2019/07/15)
Hydroxyl- and carboxyl-functionalized imidazolium halides are used as efficient bifunctional organocatalysts for the synthesis of cyclic carbonates from CO2 and epoxides under mild reaction conditions. Control experiments suggest that the cycloaddition reaction is realized by the combination of the nucleophilic halide anions with hydroxyl and carboxyl groups as hydrogen bond donors. Moreover, the bifunctional organocatalysts can be easily recycled five times by simple filtration; however, a loss of activity was observed.
Counteranion-Controlled Ag2O-Mediated Benzimidazolium Ring Opening and Its Application in the Synthesis of Palladium Pincer-Type Complexes
Tao, Sheng,Guo, Cheng,Liu, Ning,Dai, Bin
, p. 4432 - 4442 (2017/12/05)
We report a new approach to synthesize palladium complexes through Ag2O-promoted hydrolytic ring opening followed by palladium coordination. The novelty of Ag2O-promoted hydrolysis in comparison with the commonly used base-mediated hydrolysis lies in the anion-controlled product selectivity in the synthesis of pincer-type palladium complexes. Moreover, these palladium complexes have been tested in the Suzuki reaction using aryl bromides in methanol and H2O, respectively. In comparison with palladium complexes with normal coordination, the palladium complexes generated from the hydrolytic ring-opening coordination demonstrate excellent catalytic activity.
Metal-free site-selective C-N bond-forming reaction of polyhalogenated pyridines and pyrimidines
Wang, Lei,Liu, Ning,Dai, Bin
, p. 82097 - 82111 (2015/10/12)
This paper presents a metal-free method for highly site-selective C-N bond-forming reaction of polyhalogenated pyridines and pyrimidines. The preferred coupling site can be tuned from the fluorine group bearing the N-heterocyclic ring to the chlorine group when changing from the pyridine ring to the pyrimidine ring. A wide array of halogenated pyridines preferentially reacted with amines at the fluorine group of the pyridine ring to generate monosubstituted halogenated pyridines with high selectivities. Different halogen atoms at various positions were produced by the pyridine ring that performed well under mild conditions. Halogenated pyrimidines underwent highly selective coupling at the chloride group with a wide range of amines having broad substrate applicability and moderate to good yields. The selectivity of the polyfluoropyridines in the developed reaction system was also tested, and the result indicated that the reaction occurred site-selectively at the ortho-position of the nitrogen ring. This reaction accommodated a wide range of halogenated groups. Thus, a wide range of chloro-, bromo-, iodo-, and fluoropyridines were generated, which have a wide utility for organic synthesis.
Selective C-N bond-forming reaction of 2,6-dibromopyridine with amines
Wang, Lei,Liu, Ning,Dai, Bin,Hu, Hengcai
, p. 6493 - 6500 (2016/02/18)
A practical and efficient protocol for the syntheses of 6-substituted 2-bromopyridine compounds has been developed by using a selective copper-catalyzed C-N bond-forming reaction between 2,6-dibromopyridine and a range of amines. The major advantage of this protocol is the complete control of selectivity of the pyridine bromine atom for the C-N cross-coupling reaction. There are few reported syntheses of unsymmetrical 2,6-disubstituted pyridine-bridged compounds because of their complicated preparations. Although this is the case, a new series of these unsymmetrical compounds have been successfully prepared in two steps by using this copper-catalyzed coupling approach. A practical protocol for the syntheses of 6-substituted 2-bromopyridine compounds has been developed by using a selective copper-catalyzed coupling reaction of 2,6-dibromopyridine with a range of amines.
Role of copper in catalyzing aryl and heteroaryl-nitrogen (or -oxygen) bond formation under ligand-free and solvent-free conditions
Basu, Basudeb,Das, Sajal,Mandal, Bablee
experimental part, p. 1701 - 1706 (2009/07/04)
Formation of aryl- or heteroaryl-nitrogen (or -oxygen) bonds under ligand and solvent-free conditions are highly selective to the presence of copper. While bromoarenes undergo C-N (or -O) coupling in stoichiometric presence of copper, heteroaryl bromides require only catalytic amounts of copper(I) salts depending on the position of bromo substituents. Such selectivity coupled with ligand and solvent-free protocols appear promising from the viewpoint of ecology and economy and are more attractive as compared to the existing protocols.
