1079-95-4Relevant articles and documents
Hantzsch reaction in urea-formaldehyde resins
Kotova,Maslosh,Pekhtereva,Chervinskii
, p. 901 - 903 (2008)
The effect of acetylacetone and ammonia in urea-formaldehyde resins on the reactions occurring in their presence was examined. The formation of 2,6-dimethyl-3,5-diacetyl-l,4-dihydropyridine in urea-formaldehyde resins was confirmed by 1H NMR spectroscopy.
Artificial Z-scheme constructed with a supramolecular metal complex and semiconductor for the photocatalytic reduction of CO2
Sekizawa, Keita,Maeda, Kazuhiko,Domen, Kazunari,Koike, Kazuhide,Ishitani, Osamu
, p. 4596 - 4599 (2013)
A hybrid for the visible-light-driven photocatalytic reduction of CO 2 using methanol as a reducing agent was developed by combining two different types of photocatalysts: a Ru(II) dinuclear complex (RuBLRu′) used for CO2 reduction is adsorbed onto Ag-loaded TaON (Ag/TaON) for methanol oxidation. Isotope experiments clearly showed that this hybrid photocatalyst mainly produced HCOOH (TN = 41 for 9 h irradiation) from CO 2 and HCHO from methanol. Therefore, it converted light energy into chemical energy (ΔG = +83.0 kJ/mol). Photocatalytic reaction proceeds by the stepwise excitation of Ag/TaON and the Ru dinuclear complex on Ag/TaON, similar to the photosynthesis Z-scheme.
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)
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).
Azachalcone derivatives and their bis substituted analogs as novel antimycobacterial agents
Kozmik, Vaclav,Lhotak, Pavel,Odlerova, Zelmira,Palecek, Jaroslav
, p. 698 - 712 (1998)
Fifteen novel substituted azachalcone derivatives and their bis substituted analogs were prepared from 3,5-diacetyl-2,6-dimethylpyridine by the Claisen-Schmidt condensation. The influence of the reaction conditions on the yield of mono- and bischalcones was studied to optimize the reaction. Spectral characteristics along with preliminary results of antimycobacterial activity of selected compounds are given.
Chemical aromatization of 19-hydroxyandrosta-1,4-diene-3,17-dione with acid or alkaline: Elimination of the 19-hydroxymethyl group as formaldehyde
Numazawa, Mitsuteru,Yamashita, Kouwa,Kimura, Nao,Takahashi, Madoka
, p. 208 - 211 (2009)
In order to determine whether or not a 19-hydroxymethyl group of 19-hydroxyandrosta-1,4-diene-3,17-dione (2, 19-hydroxy ADD), an intermediate of aromatase-catalyzed estrone formation from ADD, a suicide substrate of aromatase, is eliminated as formaldehyde, we examine chemical nature of removal of the 19-hydroxymethyl group. 19-Acetate 3 and 19-tert-butyldimethylsiloxy compound 4 are known to convert rapidly to estrone with treatment of NaOH or n-Bu4NF. Since compound 2 was unstable and unobtainable under these conditions, compounds 3 and 4 as equivalents to compound 2 were used in this study. The acetate 3 with 5 mol/l HCl in acetone and 10% KOH in MeOH along with the silyl ether 4 with 5 mol/l HCl in acetone and 1 mol/l n-Bu4NF in THF gave formaldehyde and estrone in which a ratio of the aldehyde to estrone was near 1. This result indicates that the 19-hydroxymethyl groups of compound 3 and 4 are eliminated as formaldehyde along with estrone derived from the steroid skeleton under the acid or base treatment. The findings suggest that a single hydroxylation at the 19 carbon of ADD (1) would be, chemically, all that was required for estrone formation.
Laccase-catalyzed oxidation of Hantzsch 1,4-dihydropyridines to pyridines and a new one pot synthesis of pyridines
Abdel-Mohsen, Heba T.,Conrad, Juergen,Beifuss, Uwe
, p. 2686 - 2690,5 (2012)
The laccase-catalyzed oxidation of 1,4-dihydropyridines to pyridines using aerial O2 as the oxidant exclusively delivers pyridines with yields up to 95% under mild reaction conditions. Combination of the Hantzsch 1,4-dihydropyridine synthesis with the newly developed laccase-catalyzed oxidation forms the basis of a facile and environmentally benign method for the synthesis of pyridines in one pot.
Application of ammonium acetate as a dual rule reagent-catalyst in synthesis of new symmetrical terpyridines
Gu, Yanlong,Torabi, Morteza,Yarie, Meysam,Zolfigol, Mohammad Ali
, (2021/11/02)
Herein, we present a green, efficient and simple synthetic route to the new symmetrical terpyridines by using ammonium acetate (NH4OAc) as catalytically active reagent. Various techniques including Fourier transform infrared (FT‐IR) spectroscop
