5,6-Dihydroxyindole is prepared by the catalytic reductive cyclization of 4,5-dihydroxy-2,.beta.-dinitrostyrene in a single step using hydrogen with a palladium, platinum or rhodium catalyst in a polar hydroxylic reaction system. No reaction byproducts or only a single reaction byproduct are produced. The 4,5-dihydroxy-2,.beta.-dinitrostyrene intermediate can be prepared by the chemoselective debenzylation of 4,5-dibenzyloxy-2,.beta.-dinitrostyrene using trifluoroacetic acid. 5,6-Dihydroxyindole is a useful component in hair dye formulations and as an intermediate in the synthesis of melanin.
5,6-二羟基吲哚是通过在极性羟基反应体系中使用
氢气和
钯、
铂或
铑催化剂,通过一步催化还原环化反应制备的4,5-二羟基-2,β-
二硝基苯乙烯。不产生任何反应副产物或仅产生单一反应副产物。4,5-二羟基-2,β-
二硝基苯乙烯中间体可以通过使用
三氟乙酸对4,5-二苄氧基-2,β-
二硝基苯乙烯进行
化学选择性去苄基化来制备。
5,6-二羟基吲哚是头发
染料配方中的有用成分,也是
黑色素合成中间体。