On the reactivity of 3-bromo-2-nitrobenzo[ b ]thiophene with nucleophiles: elucidation of the base-catalysed mechanism with rearrangement
作者:Barbara Cosimelli、Liliana Lamartina、Domenico Spinelli
DOI:10.1016/s0040-4020(01)00875-4
日期:2001.10
The reactivity of 3-bromo-2-nitrobenzo[b]thiophene (1) with several (anionic and neutral) nucleophiles has been examined. Only with neutral, weak nucleophiles (as anilines) 1 gives, in the presence of non-nucleophilic bases (triethylamine or potassium carbonate), together with the ‘expected’ 3-amino-2-nitrobenzo[b]thiophenes (3) also the ‘unexpected’ 2-amino-3-nitrobenzo[b]thiophenes (4). The composition
考察了3-溴-2-硝基苯并[ b ]噻吩(1)与几种(阴离子和中性)亲核试剂的反应性。只有在存在非亲核碱(三乙胺或碳酸钾)的情况下,只有中性,弱亲核试剂(如苯胺)1才能与“预期的” 3-氨基-2-硝基苯并[ b ]噻吩(3)一起提供。 “意外的” 2-氨基-3-硝基苯并[ b ]噻吩(4)。最终异构体混合物的组成取决于所添加的碱(性质和数量)以及所使用的溶剂。结果证明了碱催化的相关性并支持涉及阴离子中间体(B),其经历第二个亲核分子的加成,得到(C),其中硝基的迁移通过由溴离子损失形成的三元环(D或E)发生。