5,6-二羟基吲哚的合成

以3,4-二甲氧基苯乙腈为主要原料,经去甲基、羟基保护、硝化及还原环合四步反应合成了5,6-二羟基吲哚。去甲基反应中,以氯化氢／吡啶为醚键裂解试剂,收率为90．2%;以氯化苄为羟基保护试剂、碳酸钾为缚酸剂,保护羟基的反应收率为87．8％;浓硝酸硝化的收率为86．9％;还原环合时,10％Pd／C是适宜的催化剂,环己稀作为氢供体,环合收率为85．2%。以3,4-二甲氧基苯乙腈计产物5,6-二羟基吲哚的综合收率为58.6％,所得产物结构经1H NMR分析确认。

SYNTHESIS OF 5,6-DIHYDROXYINDOLE

5 ,6-Dihydroxyindole is the precursor for the synthesis of melanin, an effective and safe component used in hair dying. In this work, 5,6-dihydroxyindole was prepared from homoveratronitrile by means of demethylation, hydroxyl protection, nitration and reductive ring closure. For demethyl-ating reaction hydrochloride/pyridine was the proper reagent for breaking the ether bonds, and the yield of the target product was 90. 2%. For hydroxyl protecting reaction benzyl chloride was the proper protective agent and potassium carbonate was the proper acid binding agent, and the yield of the desired product was 87. 8%. The yield of nitration by concentrated nitric acid was 86. 9%. For reductive ring closure 10% pd/C was the proper catalyst and cyclohexene was selected as the hydrogen donor, and the yield of the desired product was 85. 2%. The overall yield of 5,6-dihydroxyindole based on homoveratronitrile was 58. 6%. The structures of the intermediates and the final product Were elucidated by 1H NMR.