Making endo-cyclizations favorable again: a conceptually new synthetic approach to benzotriazoles <i>via</i> azide group directed lithiation/cyclization of 2-azidoaryl bromides
作者:Alexandra A. Ageshina、Gleb A. Chesnokov、Maxim A. Topchiy、Igor V. Alabugin、Mikhail S. Nechaev、Andrey F. Asachenko
DOI:10.1039/c9ob00615j
日期:——
in aryl azides containing several bromine atoms. Furthermore, (2-bromophenyl)diazomethane undergoes similar cyclization to give an indazole. Thus, cyclizations of aryl lithiums containing an ortho–X = Y = Z group emerge as a new general approach for the synthesis of aromatic heterocycles. DFT computations suggested that the observed endo-selectivity applies to the anionic cyclizations of other functionalities
尽管苯并三唑是重要的且无处不在,但目前仅有一种概念上的合成方法:将两个邻氨基与亲电氮原子桥连。在此,我们公开了新的可行的选择-将内获得2 azidoaryl lithiums -cyclization原位从2 azidoaryl溴化物。使用二十四个带有各种烷基,烷氧基,全氟烷基和卤素取代基的实例来说明反应的范围。我们发现叠氮化物基团的导向作用允许在含有几个溴原子的芳基叠氮化物中进行选择性的金属-卤素交换。此外,(2-溴苯基)重氮甲烷经历类似的环化以生成吲唑。因此,芳基锂的环化包含邻-X = Y = Z基团是合成芳族杂环的一种新的通用方法。DFT计算表明,观察到的内选择性适用于经历“ 1,1-加成”(即叠氮化物,重氮化合物和异腈)的其他官能团的阴离子环化反应。与此相反,与遵循“1,2-加成”图案(氰酸酯,硫氰酸酯,异氰酸酯,异硫氰酸酯,和腈)的杂原子官能团的环化反应倾向于外-cyclizat