Fischer indolization and its related compounds. XXIV. Fischer indolization of ethyl pyruvate 2-(2-methoxyphenyl)phenylhydrazone.
作者:Hisashi ISHI、Takao SUGIURA、Kimiko KOGUSURI、Toshiko WATANABE、Yasuoki MURAKAMI
DOI:10.1248/cpb.39.572
日期:——
In order to clarify the mechanism of Fischer indolization of 2-methoxyphenylhydrazones, Fischer indolization of ethyl pyruvate 2-(2-methoxyphenyl)phenylhydrazone (2) was carried out with hydrochloric acid in ethanol and zinc chloride in acetic acid. The reactions proceeded smoothly to give N-arylindoles (11-14) and some chlorinated diphenylamine derivatives (8-10) as by-products. Consideration of the indole products revealed that the Fischer indolization proceeded mainly at the unsubstitued phenyl nucleus rather than at the 2-methoxyphenyl nucleus. This result is inconsistent with the previous result that Fischer indolization of diarylhydrazones proceeded at the electron-richer nucleus. The structures of the diphenylamines were determined by chemical means and the mechanism of their formation is discussed.
为了阐明2-甲氧基苯基肼的Fischer吲哚化反应机理,用盐酸-乙醇和氯化锌-乙酸对乙基丙酮酸2-(2-甲氧基苯基)苯基肼(2)进行了Fischer吲哚化反应。反应顺利进行,生成N-芳基吲哚(11-14)和一些氯代二苯胺衍生物(8-10)作为副产物。对吲哚产物的分析表明,Fischer吲哚化主要发生在未取代的苯环上,而不是在2-甲氧基苯环上。这一结果与之前二芳基肼Fischer吲哚化反应发生在电子较富集的环上的结果不一致。通过化学方法确定了二苯胺的结构,并对其生成机理进行了讨论。