First synthesis of nitro-substituted 2,2-diphenyl-2H-1-benzopyrans via the ipso-nitration reaction
作者:Lahoussine Bougdid、Arnault Heynderickx、Stéphanie Delbaere、Corinne Moustrou
DOI:10.1016/j.tet.2007.05.113
日期:2007.8
first synthesis of a series of nitro-substituted 2,2-diphenyl-2H-1-benzopyrans is reported. Our synthetic approach is based on a linear synthesis in two steps from appropriate brominated 2,2-diphenyl-2H-1-benzopyrans 12–17, which requires the preliminary preparation of bromophenols 7–11. These latter were easily obtained by the reaction of phenols 1–5 with a mild and selective brominating agent tetrabutylammonium
报道了一系列硝基取代的2,2-二苯基-2 H -1-苯并吡喃的首次合成。我们的合成方法是基于在从适当的两步线性合成溴化2,2-二苯基-2- ħ -1-苯并吡喃12 - 17,这需要溴苯酚的初步制备7 - 11。后者可以通过使酚1 – 5与温和的溴化剂四丁基三溴化四丁基铵(TBA·Br 3)反应而轻松获得。关键中间体12 – 17通过可商购的1,1-二苯基丙-2-炔-1-醇与溴化酚类之间的单义经典chromenization被有效阐述6 - 11。化合物12 - 17,以便获得被转换成芳基硼酸18 - 23通过一金属化/ boronylation序列,然后进行酸水解。从高级积木18 - 23,引入硝基,这构成我们的策略的最终步骤的,是由一个实现本位使用CRIVELLO试剂-nitration反应。这种高选择性方法仅提供了本位-nitrated产品24 – 29,中等至高产。