74375-03-4Relevant articles and documents
Kinetics and mechanism of desulfurization reaction of 1-methyl-2- phenylquinazoline-4(1H)-thiones
Hanusek, Jiri,Sedlak, Milos,Keder, Roman,Sterba, Vojeslav
, p. 2212 - 2222 (2007/10/03)
Kinetics and mechanism of desulfurization reaction of 1-methyl-2- (substituted phenyl)-quinazoline-4(1H)-thiones in sodium methoxide solutions have been studied, giving the corresponding 1-methyl-2-(substituted phenyl)quinazolin-4(1H)-ones. The reaction proceeds in two steps. The first step involves splitting off of sulfur in the form of SH- and is much faster than the second step, whose rate is almost independent of the concentration of water in methanol. At lowest concentrations of methoxide, the rate of the first step increases linearly, but at higher concentrations a gradual decrease in the rate takes place. The rate of the second step, i.e. the transformation of the intermediate formed In into 1-methyl-2-(substituted phenyl)quinazolin-4(1H)-one (2a-2e), is independent of the methoxide concentration but increases with increasing concentration of water in methanol. On the basis of the kinetic dependences, the mechanism for both steps of desulfurization and the structure of intermediate In were proposed.
Kinetics and mechanism of the base-catalysed cyclisation of 2-(substituted benzoylamino)benzamides giving quinazolin-4-one and quinazolin-4-thione derivatives
Hanusek, Jiri,Sedlak, Milos,Simunek, Petr,Sterba, Vojeslav
, p. 1855 - 1863 (2007/10/03)
Acylation of 2-aminobenzamide and 2-(methylamino)benzamide with substituted benzoyl chlorides in acetone has been used to prepare the respective 2-(substituted benzoylamino)benzamides 1a-i, which were then subjected to sodium methoxide catalysed ring closure to give the respective 2-(substituted phenyl)quinazolin-4 -ones 2a-i. The kinetics of the cyclisation reactions were monitored by UV/Vis spectroscopy at 25 °C in methanolic solutions of sodium methoxide. In the case of 2-(substituted benzoylamino)benzamides 1a-i and 2-(substituted benzoylamino)thiobenzamides 3a-j, non-linear dependences of observed rate constants κobs on the sodium methoxide concentrations were obtained, the shape of them being typical of a reaction with rapid pre- equilibrium. All the cyclisation reactions satisfactorily obeyed the Hammett correlation. In the case of 2 - [(benzoyl) (methyl) amino] benzamides 1e-i, increasing sodium methoxide concentration resulted in a progressive increase in κobs values which is probably due to formation of dianion. In the case of 2-(substituted benzoylamino)thiobenzamides 3b and 3h, which differ in the presence of a methyl group on the nitrogen atom the values of the activation Gibbs energy ΔG? 25 °C, activation enthalpy ΔH? 25 °C, and activation entropy ΔS? 25 °C for their respective cyclisations to 2-(substituted phenyl)quinazoline-4-thiones 4b and 4h were determined. Whereas the ΔG? 25 °C values were very close for the two substances, the ΔH? 25 °C and ΔS? 25 °C distinctly differed. This was interpreted by the enthalpy and entropy factors operating against each other in the cyclisation. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).
Synthesis of substituted 2-benzoylaminothiobenzamides and their ring closure to substituted 2-phenylquinazoline-4-thiones
Hanusek, Jiri,Hejtmankova, Ludmila,Kubicova, Lenka,Sedlak, Milos
, p. 323 - 337 (2007/10/03)
Acylation of 2-aminothiobenzamide or 2-methylaminothiobenzamide with substituted benzoyl chlorides has been used to synthesise the corresponding 2-benzoyl-aminothiobenzamides whose subsequent sodium methoxide-catalysed ring closure gives the corresponding quinazoline-4-thiones. These compounds were characterised by means of their 1H- and 13C-NMR spectra. The preferred tautomeric form of selected compounds has been discussed on the basis of their 13C-NMR, IR and Raman spectra. It has been found that in the given medium 1-methyl-quinazoline-4-thiones undergo a replacement of the sulphur substituent by oxygen giving 1-methyl-quinazoline-4-ones. In strong acid media, 2-benzoylaminothiobenzamide is cyclised through its sulphur atom to give 2-phenylbenzo[d-1,3]thiazin-4-one.
Microwave induced dry media DDQ oxidation - A one step synthesis of 2-arylquinazolin-4(3H)-ones
Santa Deepthi,Sahadeva Reddy,Reddy,Reddy
, p. 220 - 222 (2007/10/03)
An efficient microwave assisted solvent free DDQ mediated oxidative synthesis of 2-arylquinazolin-4(3H)-ones 3 is reported.
