Bromination of indazoles enhanced by organic-dye, visible-light photoredox catalysis
作者:Lauren F. Hornbrook、Connor D. Reed、Angus A. Lamar
DOI:10.1016/j.tet.2023.133523
日期:2023.8
electrophilicity of the bromine atom, thus leading to enhanced reactivity as a brominating reagent. Differing intermediate indazole species have been observed depending upon the electronic nature of the indazole substituents. The indazole-containing pharmaceutical Benzydamine has been brominated in good yield using the optimized reaction conditions as a demonstration of the bromination method.
在可见光激活条件下,使用 N-溴代琥珀酰亚胺 (NBS) 可以以中等至优异的产率对各种官能化吲唑进行溴化。对有机染料催化剂的筛选结果表明,玫瑰红是与 NBS 一起使用以生成吲唑的最有效催化剂。根据机理研究,推测该反应是通过NBS 的单电子氧化进行的,该氧化放大了溴原子的亲电性,从而增强了作为溴化试剂的反应性。根据吲唑取代基的电子性质,已经观察到不同的中间体吲唑种类。含吲唑的药物使用优化的反应条件作为溴化方法的示范,以良好的产率对苯甲胺进行溴化。