Expedient Synthesis of 5,6-Dihydroxyindole and Derivatives via an Improved Zn(II)-Assisted 2,β-Dinitrostyrene Approach
作者:Luisa Novellino、Marco d'Ischia、Giuseppe Prota
DOI:10.1055/s-1999-3469
日期:1999.5
A facile 3-step synthesis of 5,6-dihydroxyindole (4a) is reported, featuring the Zn(II)-controlled regioselective nitration of 3,4-dihydroxynitrostyrene (2) with tetranitromethane at pH 8.0 and the reductive cyclization of the resulting 4,5-dihydroxy-2,β-dinitrostyrene (3a) with Na2S2O4/Zn(II) at pH 4. The latter procedure was successfully extended to the conversion of the 2,β-dinitrostyrenes 3b and 3c to 5,6-dibenzyloxyindole (4b) and 5,6-diacetoxyindole (4c) in good-to-high yields.
报告了 5,6-二羟基吲哚(4a)的简便三步合成法,其特点是在 pH 值为 8 时,用四硝基甲烷在 Zn(II)控制下对 3,4-二羟基硝基苯乙烯(2)进行区域选择性硝化。在 pH 值为 4 时,用 Na2S2O4/Zn(II)将生成的 4,5-二羟基-2,δ-二硝基苯乙烯(3a)还原环化。后一过程成功地扩展到将 2,δ-二硝基苯乙烯 3b 和 3c 转化为 5,6-二苄氧基吲哚(4b)和 5,6-二乙酰氧基吲哚(4c),收率从好到高。