Several new β-aminopyrroles, 3-aminoindoles, pyrido [3, 4-b] indoles, and pyrrolo-[3, 2-b] pyridines have been synthesized by a sequence of reactions involving intramolecular addition of an enamine to a cyano group. Enamine (1), prepared from tert-butyl aminocyanoacetate and cyclohexane-1, 3-dione, cyclized after substitution of the methine by ethyl bromoacetate in the presence of sodium ethoxide to afford 2-tert-butoxycarbonyl-2-ethoxycarbonylmethyl-3-imino-4-oxo-4, 5, 6, 7-tetrahydroindoline (2). Reaction of 1 with methyl vinyl ketone-sodium ethoxide furnished 3-amino-2-tert-butoxycarbonyl-4-oxo-4, 5, 6, 7-tetrahydroindole (7). Similarly, certain 3-aminopyrroles (44 and 45) and pyrrolo [3, 2-b] pyridines (51 and 52) have been synthesized from the enamine (41) prepared from acetoacetate and tert-butyl aminocyanoacetate. Enamines (70-72) obtained by condensation of ethyl acetoacetate with aminocyanoacetamides underwent cyclizations to 3-amino-2-carbamoylpyrroles (73-75) upon treatment with base. Several new 3-aminopyrroles thus prepared have been derived into new pyrrolo [3, 2-d]-(78-81) and pyrrolo-[3, 4-d] pyrimidines (90 and 91). A steric effect of the neighbouring butoxycarbonyl group in 41 has also been briefly discussed.
几种新的β-
氨基
吡咯、3-
氨基
吲哚、
吡啶[3, 4-b]
吲哚和
吡咯啉[3, 2-b]
吡啶通过一系列反应合成,涉及到烯胺与
氰基的分子内加成反应。烯胺(1)是由叔丁基
氨基
氰乙酸酯和
环己烯-1,3-二酮制备的,在存在
乙醇钠的条件下,经过乙基
溴乙酸酯取代甲烯后环化,得到2-叔丁氧羰基-2-乙氧羰基甲基-3-亚
氨基-4-氧基-4, 5, 6, 7-四氢
吲哚(2)。烯胺1与
乙烯基甲酮-
乙醇钠反应生成3-
氨基-2-叔丁氧羰基-4-氧基-4, 5, 6, 7-四氢
吲哚(7)。类似地,某些3-
氨基
吡咯(44和45)和
吡咯啉[3, 2-b]
吡啶(51和52)也是通过与叔丁基
氨基
氰乙酸酯反应得到的烯胺(41)合成的。通过将乙基
乙酰乙酸酯与
氨基
氰乙酰酰胺缩合得到的烯胺(70-72)在碱的处理下经历环化反应,形成3-
氨基-2-
氨甲酰
吡咯(73-75)。因此,几种新制备的3-
氨基
吡咯进一步衍生为新的
吡咯啉[3, 2-d](78-81)和
吡咯啉-[3, 4-d]
嘧啶(90和91)。文中还简要讨论了邻近的丁氧羰基在41中的空间效应。