70677-66-6Relevant academic research and scientific papers
Aqueous CO2fixation: construction of pyridine skeletons in cooperation with ammonium cations
Fan, Weibin,Guo, Shiwei,Huang, Deguang,Li, Yinghua,Xiang, Shiqun,Zhang, Wei
supporting information, p. 7950 - 7955 (2021/10/29)
A simple and green method is explored for the synthesis of fused pyridines by [2 + 2 + 1 + 1] the cycloaddition of ketones with an ammonium cation under a CO2atmosphere. The reactions employed ammonium cation as a nitrogen source and CO2gas as a carbon source in an aqueous solution. Monoethanolamine (MEA) was used as an additive to increase the solubility of CO2in an aqueous solution. The scope and versatility of the method are demonstrated with 38 examples. Products are found to be photosensitive and show potential applications as organic optoelectronic materials. A selectfluor-promoted reaction mechanism is proposed based on the experimental studies. Our work is superior as it is a metal-free system, uses CO2as a carbon source and MEA as an additive in aqueous synthesis.
Photoinduced proton transfer promoted by peripheral subunits for some Hantzsch esters
Azizi, Sbastien,Ulrich, Gilles,Guglielmino, Maud,Le Calv, Stphane,Hagon, Jerry P.,Harriman, Anthony,Ziessel, Raymond
, p. 39 - 49 (2015/01/30)
It is noted that, for a small series of 3,5-diacetyl-1,4-dihydrolutidine (DDL) derivatives and the corresponding Hantzsch esters, the presence of methyl groups at the 2,6-positions serves to extinguish fluorescence in solution but not in the solid state. Emission is weakly activated and affected by changes in solvent polarity. The latter situation arises because the optical transition involves intramolecular charge transfer. Calculations, both semiempirical and DFT, indicate that, in all cases, rotation of the carbonyl function is facile and that the dihydropyridine ring is planar. These calculations also indicate that the 2,6-methyl groups do not affect the generic structure of the molecule. It is proposed that illumination increases the molecular dipole moment and pushes electron density toward the carbonyl oxygen atom. Proton transfer can now occur from one of the methyl groups, leading to formation of a relatively low-energy, neutral intermediate, followed by a second proton transfer step that forms the enol. Reaction profiles computed for the ground-state species indicate that this route is highly favored relative to hydrogen transfer from the 4-position. The barriers for light-induced proton transfer are greatly reduced relative to the ground-state process but such large-scale structural transformations are hindered in the solid state. A rigid analogue that cannot form an enol is highly emissive in solution, supporting the conclusion that proton transfer is in competition to fluorescence in solution. (Figure Presented).
Iron-catalyzed selective oxidation of N-methyl amines: highly efficient synthesis of methylene-bridged bis-1,3-dicarbonyl compounds
Li, Haijun,He, Zhiheng,Guo, Xingwel,Li, Wenjuan,Zhao, Xuhul,Ll, Zhlplng
supporting information; experimental part, p. 4176 - 4179 (2009/12/30)
Methylene-bridged bis-1,3-dicarbonyl derivatives were synthesized efficiently by Iron-catalyzed oxidative reactions of 1,3-dicarbonyl compounds and N,N-dimethylaniline. Blpyrazoles and substituted 1,4-dlhydropyridlne were obtained by the reactions of bis-1,3-dicarbonyl compounds with hydrazines and ammonium acetate, respectively.
