119388-39-5Relevant academic research and scientific papers
INFLUENCE OF INTRAMOLECULAR HYDROGEN BONDS ON THE TAUTOMERIC EQUILIBRIUM OF 1,3-DIKETONES
Zheglova, D.,Denkov, N.,Kol'tsov, A. I.
, p. 371 - 374 (1984)
The paper deals with a quantitative characterization of the influence of multiple intramolecular hydrogen bonds on the tautomeric equilibrium of 1,3-diketones by means of NMR-spectroscopy.The contents of the keto- and two enol forms of 1-(o-hydroxyphenyl)-1,3-butandione and 1-(o-methoxyphenyl)-1,3-butandione in tetrachloromethane, deuterochloroforme, acetone-d6 and acetonitrile-d3 are compared.The intramolecular hydrogen bond between the phenolic hydroxyl group and the aromatic carbonyl group in 1-(o-hydroxyphenyl)-1,3-butandione shifts the keto-enol equilibrium toward the keto-tautomer and enol-enol equilibrium toward the tautomer with an enolized aliphatic carbonyl group.
Novel chromone and xanthone derivatives: Synthesis and ROS/RNS scavenging activities
Proen?a, Carina,Albuquerque, Hélio M.T.,Ribeiro, Daniela,Freitas, Marisa,Santos, Clementina M.M.,Silva, Artur M.S.,Fernandes, Eduarda
, p. 381 - 392 (2016/04/06)
Chromones and xanthones are oxygen-containing heterocyclic compounds acknowledged by their antioxidant properties. In an effort to develop novel agents with improved activity, a series of compounds belonging to these chemical classes were prepared. Their syntheses involve the condensation of appropriate 2-methyl-4H-chromen-4-ones, obtained via Baker-Venkataraman rearrangement, with (E)-3-(3,4-dimethoxyphenyl)acrylaldehyde to provide the corresponding 2-[(1E,3E)-4-(3,4-dimethoxyphenyl)buta-1,3-dien-1-yl]-4H-chromen-4-ones. Subsequent electrocyclization and oxidation of these compounds led to the synthesis of 1-aryl-9H-xanthen-9-ones. After cleavage of the protecting groups, hydroxylated chromones and xanthones were assessed as scavenging agents against both reactive oxygen species (ROS) [superoxide radical (O2?-), hydrogen peroxide (H2O2), hypochlorous acid (HOCl), singlet oxygen (1O2), and peroxyl radical (ROO?)] and reactive nitrogen species (RNS) [nitric oxide (?NO) and peroxynitrite anion (ONOO-)]. Generally, all the tested new hydroxylated chromones and xanthones exhibited scavenger effects dependent on the concentration, with IC50 values found in the micromolar range. Some of them were shown to have improved scavenging activity when compared with previously reported analogues, allowing the inference of preliminary conclusions on the structure-activity relationship.
A Baker-Venkataraman retro-Claisen cascade delivers a novel alkyl migration process for the synthesis of amides
Ameen, Dana,Snape, Timothy J.
supporting information, p. 1816 - 1819 (2015/03/30)
A simple extension of the carbamoyl Baker-Venkataraman rearrangement has been developed. If residual water in the reaction is not strictly excluded a Baker-Venkataraman retro-Claisen cascade takes place, giving amide products, in which an alkyl group apparently migrates between two functionalities of the substrate.
