Synthesis of Regioselectively Functionalized Benzo[<i>b</i>]thiophenes by Combined <i>ortho</i>-Lithiation−Halocyclization Strategies
作者:Roberto Sanz、Verónica Guilarte、Elsa Hernando、Ana M. Sanjuán
DOI:10.1021/jo101436f
日期:2010.11.5
An efficient synthesis of 3-halo-7-oxygen-functionalized benzo[b]thiophenes bearing different substituents at C-2 has been developed from N,N-diethyl O-3-halophenylcarbamates. The key steps are an ortho-lithiation reaction, which gives rise to 3-halo-2-sulfanylphenol derivatives, and a electrophilic cyclization. The subsequent functionalization of the prepared halobenzothiophenes allows the access
由N,N-二乙基O -3-卤代苯基氨基甲酸酯开发了一种有效合成在C-2处带有不同取代基的3-卤代-7-氧官能化的苯并[ b ]噻吩的方法。关键步骤是邻位锂化反应和亲电环化反应,该反应可生成3-卤代-2-硫烷基苯酚衍生物。所制备的卤代苯并噻吩的随后官能化使得能够以良好的总产率获得各种各样的2,3,7-区域选择性官能化的苯并[ b ]噻吩。
Application of directed metalation in synthesis. Part 6: A novel anionic rearrangement under directed metalation conditions leading to heteroannulation
作者:Tarun Kanti Pradhan、Chandrani Mukherjee、Sukanta Kamila、Asish De
DOI:10.1016/j.tet.2004.04.033
日期:2004.6
from easily available phenols is described. The key step in this synthesis is a hitherto unreported anionic rearrangement under directed metalation conditions. The rearrangement occurs after side chain deprotonation of a methyl sulfanyl group by an O-carbamate directed metalating group and the reaction mixture is kept at room temperature for 8–12 h. Acid-mediated cyclisation of the rearranged product