A proton and 13C NMR study of keto-enol tautomerism of some β-ketoamides (2023)

bKetoamides possess multiple nucleophilic and electrophilic reaction sites within their molecular structures, which makes them excellent building blocks for the construction of various heterocyclic compounds. In this review, we summarize the applications of structurally diverse structuresb-ketoamides for the synthesis of (1) Five-membered heterocycles, including furans, thiophenes, pyrroles, indoles, pyrazoles, triazoles and their derivatives; (2) six-membered nitrogen and oxygen-containing heterocycles such as pyridones, dihydropyridines, pyridines, quinolones, quinolines, pyranones and the like; (3) several lactams and some aza-aliphatic rings. The focus is on multicomponent reactions that take advantage of the unique and versatile reactivities ofb-ketoamide.

Plant β-diketone derivatives exhibit biological activity due to tautomerism and extended conjugation with the aromatic ring system. β-diketone derivatives; (Z)-3-(4-(4-aminophenoxy)phenylamino)-1,3-diphenylprop-2-en-1-one(L1) and (2Z,2$\prime$Z)-3,3${}^{\prime }$-(4,4${}^{\prime }$-oxybis(4,1-phenylene)bis(azanediyl)bis(1,3-diphenylprop-2-en-1-one(L2) were synthesized and characterized by spectral and single crystal analysis XRD illustrate the compounds are in the form of Ketamine The study evaluated the cytotoxicity and apoptotic effect of L1 and L2 and similar ketamines against human breast cancer cell lines (MCF 7). O-linkage exhibits greater anticancer activity with inhibitory concentration (IC) values₅₀) comparable to the standard drug (tamoxifen). Further investigations using DCFH-DA and DAPI staining assay revealed that the compounds induce cellular apoptosis through intracellular production of Reactive Oxygen Species (ROS). To investigate further, the binding attribute of L1-L4 with CT DNA was evaluated, and the compounds were coupled with sequence DNA duplex, d(CGCGAATTCGCG)₂and breast cancer protease (3EU7).

Journal of Molecular Structure, Volume 1089, 2015, pp. 216-221

By a combined IV and theoretical study, it was found that oxygen basicity decreased markedly from mono- and di-functional alkoxysilanes to tri- and tetra-functional alkoxysilanes. An analysis of the natural bonding orbital interactions in Me_4-nYes (OMe)_n(n=1–4) and its 1:1 hydrogen bonding complex with chloroform indicate that the basicity properties of the Si–O–C unit can be determined by the competitive hyperconjugation of adjacent silicon and the carbon center. The increased contribution of oxygen lone pair delocalization to adjacent Si-R antibonding orbitals may be the main origin for the decrease in Si(OEt) basicity.₄compared to me₃SiOEt.

Inorganica Chimica Acta, Volume 405, 2013, pp. 437-443

A series of trestle-type tetracarbonyl diruthenium complexes containing pyrenyl groups at the equatorial positions of the diruthenium skeleton were synthesized and characterized. The reaction between dodecacarbonyltriruthenium Ru₃(CO)₁₂and pyrene carboxylic acids, 1-pyrene carboxylic acid (C₁₆H₉COOH), 1-pyreneacetic acid (C₁₆H₉CH₂COOH) and 1-pyrenebutyric acid (C₁₆H₉(CH₂)₃COOH), followed by the addition of axial ligands (L), pyridine (a) and triphenylphosphine (b), provides the stable diruthenium tetracarbonyl complexes, Ru₂(CO)₄(m₂-o²-OOCC₁₆H₉)₂(EU)₂(1), ru₂(CO)₄(m₂-o²-OOCCH₂C₁₆H₉)₂(EU)₂(2) e Ru₂(CO)₄(m₂-o²-OOC(CH₂)₃C₁₆H₉)₂(EU)₂(3), respectively. The molecular structure of triphenylphosphine Ru derivatives₂(CO)₄(m₂-o²-OOCC₁₆H₉)₂(PPh₃)₂(1b), ru₂(CO)₄(m₂-o²-OOCCH₂C₁₆H₉)₂(PPh₃)₂(2b) e Ru₂(CO)₄(m₂-o²-OOC(CH₂)₃C₁₆H₉)₂(PPh₃)₂(3b) was determined by single-crystal X-ray structure analysis and showed a typical tetracarbonyl diruthenium skeleton bound by pyrene-carboxylate linkers and completed with PPh₃axial linkers. The molecular structure of complexes2e3reveals that the pyrenyl moieties are properly positioned to potentially allow these bis-pyrenyl systems to act as molecular tweezers. However, these systems did not show interaction with fullerene in solution, despite having, as suggested by molecular modeling, adequate structural characteristics.

Journal of Environmental Sciences, Volume 26, Issue 1, 2014, pp. 154-159

Fluorine-containing halogenated fluorophenol may have an effect as an intermediate species involved in the formation of dibenzo-p-dioxin/polyfluorinated dibenzofurans (PFDDs/Fs). The mechanism for atomic H-initiated reactions with complete series of nineteen fluorophenol congeners was studied using density functional theory. At the MPWB1K/6-31+G(d,p) level, the geometries and frequencies of the reactants, transition states and products were obtained, and precise energy values ​​were acquired at the MPWB1K/6-311+G(3df, 2p) level. The rate constants were evaluated by canonical variational transition state theory with the contribution of the small curvature tunnel over a wide temperature range of 600–1000 K. The study shows that intramolecular hydrogen bonding in thevegetable gardenThe substituted FPs as well as the inductive effect of electron-withdrawing fluorine and the steric repulsion of multiple substitutions may be responsible for the relative strength of O-H bonds in FPs. The results can be used for further studies on the mechanism of formation of PFDD/Fs.

Tetrahedron Letters, Volume 56, Issue 15, 2015, pp. 1976-1981

Subtilisin lyophilized from its solution in aqueous buffer in the presence of 6M urea showed up to a 50-fold increase (compared to lyophilized subtilisin not subjected to urea treatment) in its initial rate of an anhydrous transesterification reactionn-hexane. Lyophilization time controlling the extent of "drying" was an important parameter. Urea-treated subtilisin had a five-fold shorter half-life when heated to 100°C in hexane. The change in conformation was also reflected in its 92 times greater activity at 15°C compared to only 28 times greater activity at 45°C. The comparative enantioselectivity of urea-treated subtilisin during kinetic resolution of 1-phenylethanol was expected to be lower. Its enantioselectivity during kinetic resolution of a natural substrateN-acetyl-(R,S)-phenylalanine ethyl ester in hexane was higher. Subtilisin treated with urea also showed greater catalytic promiscuity during an aldol condensation. CD studies in the far UV and near UV region were also performed to compare the two structures.

Chinese Journal of Catalysis, Volume 36, Issue 4, 2015, pp. 579-587

Mesoporous TiO oxides₂and ZrO₂, synthesized by surfactant modeling through a neutral C₁₃(EO)₆–Zr(OC₃H₇)₄mounting route and ceria-modified TiO₂and ZrO₂, prepared by a deposition-precipitation (DP) method, with high surface areas and uniform pore size distributions were used as supports for gold catalysts. Supported gold catalysts were evaluated for the catalytic reduction of air pollutants, i.e. CO, CH₃OH, e (CH₃)₂O. Gold was supported on mesoporous oxides by a DP method. The supports and catalysts were characterized by X-ray powder diffraction, high resolution transmission electron microscopy, N₂adsorption-desorption analysis and temperature-programmed reduction technique. A high degree of synergistic interaction between ceria and mesoporous ZrO₂and TiO₂as well as a positive modification of the structural and catalytic properties by ceria was observed. The ceria additive interacts with the mesoporous oxides and induces a strong effect on the reducibility of the supports. The catalytic behavior of the catalysts was discussed to determine the role of the ceria modifying additive and the possible interaction between the gold nanoparticles and the mesoporous ceria oxide supports. Gold catalysts supported on ceria-modified mesoporous ZrO₂showed superior catalytic activity (conversion of approximately 100% of CO at 10 °C and CH₃OH at 60°C). The high catalytic activity can be attributed to the ability of the support to assist in the formation of oxygen vacancies. Studies indicate that ceria-modified mesoporous oxide supports have potential as supports for gold-based catalysts.

Phytochemistry Letters, Volume 13, 2015, pp. 103-107

Two new penterpenoid saponins, hemsloside-Ma4 (1) hemsloside-Ma5 (2) and a novel diterpenoid glycoside, hemsloside-Ma6 (3), were isolated from the rhizomes ofHemsleya chinensis. By detailed analysis of NMR spectra and chemical methods, the structures of new compounds were determined to be 3-O-b-eu-arabinopiranosil-(1→3)-O-(6'-methyl ester)-β-d-glucuropyranosyl-oleanolic acid-28-O-b-d-glucopiranosil-(1→6)-O-b-d-glucopyranoside (1), 3-O-b-eu-arabinopiranosil-(1→3)-O-(6'-methyl ester)-β-d-glucuropyranosyl-oleanolic acid-28-O-b-d-xylopyranosyl-(1→6)-O-b-d-glycopyranoside (2) e 13ϵ-hydroxylabda-8(17), 14-dien-18-oic-18- acidO-a-eu-rhamnopyranosyl-(1→2)-O-b-d-glucopiranosil-(1→4)-O-a-eu-rhamnopyranósido (3). Diterpenoid type compound (3) was isolated fromHemsleyagenre for the first time.