Alumina as a Support and Catalyst for the Synthesis of Benzothiazoles in Solvent-free Condition
作者:Mei-Fang Ding、Chia-Pei Chen、Shaw-Tao Lin
DOI:10.1002/jccs.201200413
日期:2013.6
and benzothiazolylcoumarins (5) were prepared by the condensation of 2‐aminothiophenol (1) and hydroxybenzaldehydes (2) and 3‐ethoxycarbonylcoumarinnin (3), respectively, in solvent‐free condition. Of the solid support used, γ‐Al2O3 demonstrated the best activity. A linear regression line obtained from correlation between relative formation rate and Hammett constants with slope of 0.653 suggested that
Arylbenzothiazole(4)和benzothiazolylcoumarins(5)通过2-氨基苯硫酚(的缩合制备1)和羟基苯甲醛(2)和3- ethoxycarbonylcoumarinnin(3),分别在无溶剂的条件。所用的固体支持物,在γ-Al 2 ö 3展示了最佳活性。由相对形成速率和具有0.653斜率的Hammett常数之间的相关性获得的线性回归线表明,由于固态极化效率低,该缩合过程对苯环上的取代基较不敏感。通常,形成4可获得良好的收率(> 80%的收率)。相反,产量5很差,因为γ-Al系的2 ö 3的催化分解3,以形成2(不含P 2 ö 5)和香豆素(以P 2 ö 5)。