Syntheses of benz[f]indoles from 1, 2-disubstituted naphthalene derivatives by means of cyclization reactions were attempted. The Fischer indolization of 1-methyl-(5a), 1-chloro-(5b), or 1-nitro-(5c)-2-naphthylhydrazones gave only benz[e]indole derivative or decomposed products, and the desired 9-substituted benz[f]indole (3) was not produced. On the other hand, the Fischer indolization of 2-methoxy-1-naphthylhydrazone (17) gave ethyl 5-chlorobenz[g]indole-2-carboxylate (19). The hemetsberger reaction of 1-methyoxy-2-naphthylazido acrylate (26a) gave an azirine (28a) and a nitrile (29a), whereas the same reaction of 1-chloro-2-naphthylazido acrylate (26b) gave the desired 4-chlorobenz[f]indole in a poor yield together with large amounts of by-products, the azirine (28b), the nitrile (29b) and the benz[g]indole (20). These results show that cyclization reactions of a 2-substituent toward the 3-position in naphthalene derivative are not suitable for preparing benz[f]indoles.
尝试通过环化反应从1,2-二取代的
萘衍
生物合成苯并[f]
吲哚。1-甲基-(5a)、1-
氯-(5b)或1-硝基-(5c)-2-
萘基苯
肼经Fischer
吲哚合成法只得到苯并[e]
吲哚衍
生物或分解产物,未得到期望的9-取代苯并[f]
吲哚(3)。另一方面,2-甲氧基-1-
萘基苯
肼(17)经Fischer
吲哚合成法得到乙基5-
氯苯并[g]
吲哚-2-羧酸酯(19)。1-甲氧基-2-
萘基
叠氮丙烯酸酯(26a)的Hemetsberger反应得到
氮杂环丙烷(28a)和腈(29a),而同样的反应1-
氯-2-
萘基
叠氮丙烯酸酯(26b)得到产率低的期望4-
氯苯并[f]
吲哚以及大量副产物,
氮杂环丙烷(28b)、腈(29b)和苯并[g]
吲哚(20)。这些结果表明,
萘衍
生物2-取代基向3-位置的环化反应不适合用于制备苯并[f]
吲哚。