Fischer Indolization of Variously ortho-Substituted Phenylhydrazones. Fischer Indolization and Its Related Compounds. XXV.
作者:Yasuoki MURAKAMI、Toshiko WATANABE、Yuusaku YOKOYAMA、Junko NAOMACHI、Haruo IWASE、Noriko WATANABE、Michiyo MORIHATA、Naomi OKUYAMA、Hiroyuki KAMAKURA、Tomoko TAKAHASHI、Hideko ATODA、Toshiaki TOJO、Kenji MORITA、Hisashi ISHII
DOI:10.1248/cpb.41.1910
日期:——
Various kinds of ethyl pyruvate 2-(2-substituted phenyl)hydrazones (1) were subjected to Fischer indolization with acid catalysts. All the phenylhydrazones gave corresponding normal 7-substituted indoles (2). In addition, phenyl-hydrazones whose ortho-substituent is electron-donative or has a central atom with an unshared electron pair tended to give the 4- or 5-substituted indole (3), which was produced by migration of the ortho-substituent during cyclization, whereas those whose ortho-substituent is electron-attractive tended to give little or no such abnormal product. The kind of acid catalyst used had some effect on the yield ratio of products but not on the kind of products.
各种丙酮酸乙酯 2-(2-取代苯基)酰肼(1)在酸催化剂作用下进行费歇尔吲哚化反应。所有的苯肼都得到了相应的 7-取代吲哚(2)。此外,如果苯肼的正位取代基是电子疏导型的,或者其中心原子上有一个未共享的电子对,则往往会产生 4 或 5 取代的吲哚(3),这是由正位取代基在环化过程中发生迁移而产生的;而如果苯肼的正位取代基是电子吸引型的,则往往很少或根本不会产生这种异常产物。所使用的酸催化剂对产物的产率有一定影响,但对产物的种类没有影响。