A series of 6,7-disubstituted 2-hydroxy-3-nitronaphthazarins were prepared by treatment of 2,3-dichloronaphthazarins with sodium nitrite. Acid-catalyzed hydrolysis of a mixture of two isomeric 6(7)-ethoxy-7(6)-ethyl-substituted 2-hydroxy-3-nitronaphthazarins followed by chromatographic separation led to the individually precursors of echinamines A and B. Further reduction of nitroquinones using various reducing agents gave echinamines and related 3-amino-2-hydroxynaphthazarins in good yields.
                                    一系列6,7-取代的2-羟基-3-
硝基萘唑被制备,方法是将
2,3-二氯萘唑与
亚硝酸钠反应。通过酸催化
水解一混合的两个异构体6(7)-乙氧基-7(6)-乙基取代的2-羟基-3-
硝基萘唑,随后进行色谱分离,得到了引物独立的艾奇胺A和B。进一步使用各种还原剂对硝基喹酮进行还原,良好产率地得到了艾奇胺及相关的3-
氨基-2-羟基
萘唑。