Bisindolines from the reaction of 3,5-dimethoxyaniline with vicinal diones
Bisindolines from the reaction of 3,5-dimethoxyaniline with vicinal diones
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3,5-二甲氧基苯胺与邻位二酮反应生成双吲哚啉
DOI：
10.1039/c3ra45350b
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发表时间：
2014
期刊：
影响因子：
3.9
通讯作者：
W. Jones
中科院分区：
文献类型：
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作者：
James Kovach;W. Brennessel;W. Jones
以3，5-二甲氧基苯胺和邻二酮（2，3-丁二酮、苯偶酰和4-甲基苯偶酰）为原料合成了取代双吲哚啉。在极性酸性条件下，3，5-二甲氧基苯胺与2，3-丁二酮的反应进行了意外的双环化反应，形成2，2 ′-二甲基-5，5 ′，7，7 ′-四甲氧基双吲哚，（+/−）-1。3，5-二甲氧基苯胺与苯偶酰在类似条件下的反应没有形成双吲哚啉，而是形成顺式-1，2-二苯基-2-[（3，5-二甲氧基苯基）亚氨基]乙酮，2。当改变溶剂、酸和反应温度以使3，5-二甲氧基苯胺与苯偶酰反应时，分离出3，3-二苯基-4，6-二甲氧基吲哚啉-2-酮3（2的异构体）和2，2 ′-二苯基-5，5 ′，7，7 ′-四甲氧基双吲哚（+/-）-4，分别作为主要和次要产物。类似地，3，5-二甲氧基苯胺与4-甲基苯偶酰的反应产生 顺式-1-（4-甲基苯偶酰-2-基）苯甲酸的1：1混合物。（4-甲基苯基）-2-苯基-2-[（3，5-二甲氧基苯基）-亚氨基]乙酮，6a，和顺式-1-（苯基）-2-（4-甲基苯基）-2-[（3，5-二甲氧基苯基）亚氨基]乙酮，6 b，在极性酸性条件下和3-（4-甲基苯基）-3-苯基-4，6-二甲氧基吲哚啉-2-酮，（+/−）-7和2-（4-甲基苯基）-2′-苯基-5，5 ′，7，7 ′-四甲氧基双吲哚，（+/−）-8，在非极性酸性条件下，在高温下。我们提出的机制bisindoline和indolinone的形成，包括Friedel-Crafts型亲电攻击的富电子的芳基环在闭环C-C键形成的步骤，并进一步提出了一个共同的碳阳离子monocyclized中间体。
Substituted bisindolines were synthesized from the reaction of 3,5-dimethoxyaniline and vicinal diones (2,3-butanedione, benzil, and 4-methylbenzil). The reaction of 3,5-dimethoxyaniline with 2,3-butanedione under polar acidic conditions proceeded with an unanticipated double cyclization reaction forming 2,2′-dimethyl-5,5′,7,7′-tetramethoxybisindole, (+/−)-1. The reaction of 3,5-dimethoxyaniline with benzil under similar conditions did not form a bisindoline, but instead formed cis-1,2-diphenyl-2-[(3,5-dimethoxyphenyl)imino]ethanone, 2. When the solvent, acid, and reaction temperature were changed for the reaction of 3,5-dimethoxyaniline with benzil, 3,3-diphenyl-4,6-dimethoxyindolin-2-one, 3 (an isomer of 2), and 2,2′-diphenyl-5,5′,7,7′-tetramethoxybisindole, (+/−)-4, were isolated as major and minor products, respectively. Similarly, the reaction of 3,5-dimethoxyaniline with 4-methylbenzil produced a 1 : 1 mixture of cis-1-(4-methylphenyl)-2-phenyl-2-[(3,5-dimethoxyphenyl)-imino]ethanone, 6a, and cis-1-(phenyl)-2-(4-methylphenyl)-2-[(3,5-dimethoxyphenyl)imino]ethanone, 6b, under polar acidic conditions and 3-(4-methylphenyl)-3-phenyl-4,6-dimethoxyindolin-2-one, (+/−)-7 and 2-(4-methylphenyl)-2′-phenyl-5,5′,7,7′-tetramethoxybisindole, (+/−)-8, under apolar acidic conditions at elevated temperature. We propose the mechanism of bisindoline and indolinone formation to include a Friedel–Crafts type electrophilic attack on the electron rich aryl ring at the ring closing C–C bond forming steps, and further propose a common carbocationic monocyclized intermediate.