Kinetics and Mechanism of the Base-Catalysed Cyclisation of 2-(Substituted benzoylamino)benzamides Giving Quinazolin-4-one and Quinazolin-4-thione Derivatives
作者:Jiří Hanusek、Miloš Sedlák、Petr Šimůnek、Vojeslav Štěrba
DOI:10.1002/1099-0690(200206)2002:11<1855::aid-ejoc1855>3.0.co;2-a
日期:2002.6
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
2-氨基苯甲酰胺和 2-(甲氨基)苯甲酰胺在丙酮中用取代的苯甲酰氯酰化已被用于制备各自的 2-(取代的苯甲酰氨基)苯甲酰胺 1a-i,然后将其进行甲醇钠催化的闭环以得到各自的2-(取代苯基)quinazolin-4-ones 2a-i。在甲醇钠的甲醇溶液中,在 25°C 下通过紫外/可见光谱监测环化反应的动力学。在 2-(取代苯甲酰氨基)苯甲酰胺 1a-i 和 2-(取代苯甲酰氨基)硫代苯甲酰胺 3a-j 的情况下,观察到的速率常数 kobs 对甲醇钠浓度的非线性依赖性得到了,它们的形状是典型的具有快速预平衡的反应。所有环化反应均符合哈米特相关性。在 2-[(苯甲酰基)(甲基)氨基]苯甲酰胺 1e-i 的情况下,增加甲醇钠浓度导致 kobs 值逐渐增加,这可能是由于形成二价阴离子。在 2-(取代苯甲酰氨基)硫代苯甲酰胺 3b 和 3h 的情况下,由于氮原子上存在甲基,活化吉布斯能 ΔG‡25