22686-83-5Relevant academic research and scientific papers
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 (2002)
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).
Mechanism of alkaline cyclization of 2-(substituted benzamido)benzamides to 4-quinazolinones
Gardner,Kanagasooriam,Smyth,Williams
, p. 6245 - 6250 (2007/10/02)
The title amides cyclize rapidly to the corresponding quinazolin-4-ones in aqueous alkaline solution at 25°C; the pseudo-first-order rate constants fit the empirical equation k(obs) = k(max) [OH-]/(K(m) + [OH-] + [OH-]sup
