Preparation of halogenated derivatives of thiazolo[5,4-<i>d</i>]thiazole<i>via</i>direct electrophilic aromatic substitution
作者:Vladimir Benin、Alan T. Yeates、Douglas Dudis
DOI:10.1002/jhet.5570450328
日期:2008.5
Chlorination and bromination reactions of thiazolo[5,4-d]thiazole led to the generation of its mono- and dihalogenated derivatives. These are the first instances of successful direct electrophilic aromatic substitution in the thiazolo[5,4-d]thiazole ring system. X-ray analysis demonstrates that both 2-bromothiazolo[5,4-d]-thiazole and 2,5-dibromothiazolo[5,4-d]thiazole are planar structures, with strongly
噻唑并[5,4- d ]噻唑的氯化和溴化反应导致其单卤代和二卤代衍生物的产生。这些是噻唑并[5,4- d ]噻唑环系统中成功的直接亲电子芳族取代的首次实例。X射线分析表明2-溴噻唑并[5,4- d ]-噻唑和2,5-二溴噻唑并[5,4- d ]-噻唑均为平面结构,在固态下强烈表现出π-堆积。吡啶催化卤化反应的理论分析(MP2 / 6-31 + G(d)和B3LYP / 6-31 + G(d)计算结果表明,引入一种卤素实际上会导致对进一步卤化的反应性稍微增强。已经研究了几种卤化机理:1)以N-卤代吡啶为亲电体直接进行C-卤代反应;2)通过中间的N-卤化作用进行C-卤化反应,以及3)加成-消除途径后的C-卤化反应,中间形成环状ha离子。理论研究表明,直接的C卤化是有利的机制。