1446212-86-7Relevant academic research and scientific papers
Kinetics and mechanism of the base-catalyzed oxygenation of 1H-2-phenyl-3-hydroxy-4-oxoquinolines in DMSO/H2O
Czaun, Miklós,Speier, Gábor,Kaizer, József,El Bakkali-Taheri, Nadia,Farkas, Etelka
, p. 6666 - 6672 (2013)
The oxygenation of 4′-substituted 1H-2-phenyl-3-hydroxy-4- oxoquinolines (PhquinH2) in a DMSO/H2O (50/50) solution leads to the cleavage products at the C2-C3 bond in about 75% yield at room temperature. The oxygenation, deduced from the product compositions, has two main pathways, one proceeding via an endoperoxide leading to CO-release, and the other through a 1,2-dioxetane intermediate without CO-loss. The reaction is specific base-catalyzed and the kinetic measurements resulted in the rate law -a...?[PhquinH2]/a...?t=kOH - [OH-] [PhquinH2] [O2]. The rate constant, activation enthalpy, and entropy at 303.16 K are as follows: kOH-=(2.42±0.03)×103mol -2L2s-1; ΔG?=73. 13±4.02 kJ mol-1; ΔH?=70.60±4. 04 kJ mol-1; ΔS?=-28±2 J mol -1 K-1. The reaction fits a Hammett linear free energy relationship for 4′-substituted substrates, and electron-releasing groups make the oxygenation reaction faster (ρ=-0.258). The EPR spectrum of the reaction mixtures showed the presence of the organic radical 1H-2-phenyl-3-oxyl-4-oxoquinoline and superoxide ion due to single electron transfer from the carbanion to dioxygen. The pathway via 1,2-dioxetane could be proved by chemiluminescence measurements.
Silver-Mediated Synthesis of 4H-Benzoxazin-4-ones by Intramolecular Decarboxylative O-Acylation Reactions with α-Oxocarboxylic Acid
Bharathimohan, Kuppusamy,Ponpandian, Thanasekaran,Jafar, Ahamed A.
supporting information, p. 2806 - 2813 (2017/05/29)
The first example of an intramolecular decarboxylative acylation reaction for the synthesis of 4H-benzoxazin-4-one derivatives has been described. The silver-mediated reaction has a broad substrate scope and provides a mild and rapid approach to the corre
