Lewis Acid Catalyzed Reaction of Cinnamanilides: Competition of Intramolecular and Intermolecular Friedel-Crafts Reaction
作者:Tai-Chi Wang、Yeh-Long Chen、Kuan-Han Lee、Cherng-Chyi Tzeng
DOI:10.1055/s-1997-1505
日期:1997.1
The first intermolecular Friedel-Crafts reaction of benzene leading to the formation of 3,3-diphenylpropionanilide 7 is described. 4-Methoxyaniline was reacted with cinnamoyl chloride to give 4-methoxycinnamanilide (5a), the treatment of which with aluminum(III) chloride in chlorobenzene at 120°C or in benzene at 80°C afforded exclusively 6-hyddroxyquinolin-2(1H)-one (3a) or 4‘-hydroxy-3,3-diphenylpropionanilide (7a), respectively. The formation of 7a rather than 3a in benzene indicated that an intermolecular Friedel-Crafts reaction occurred prior to the relatively more facile intramolecular ring cyclization. This intermolecular Friedel-Crafts reaction was observed during the attempted ring cyclization of cinnamanilide and its methoxy derivatives in aluminum(III) chloride/benzene. Preparation of 3a can also be achieved in 17% overall yield via the N-oxidation of 6-hydroxyquinoline followed by acetylation and hydrolysis.
本文介绍了苯分子间的第一个弗里德尔-卡夫斯反应,该反应导致生成 3,3-二苯基丙酰亚胺 7。4-甲氧基苯胺与肉桂酰氯反应生成 4-甲氧基肉桂酰苯胺(5a),将其与氯化铝(III)在氯苯中于 120°C 或在苯中于 80°C 进行处理,可分别得到 6-羟基喹啉-2(1H)-酮(3a)或 4'-羟基-3,3-二苯基丙酰苯胺(7a)。在苯中形成的是 7a 而不是 3a,这表明在相对更容易的分子内环化之前发生了分子间弗里德尔-卡夫斯反应。在尝试肉桂苯胺及其甲氧基衍生物在氯化铝(III)/苯中的环化过程中,也观察到了这种分子间 Friedel-Crafts 反应。通过 6-羟基喹啉的 N-氧化反应,然后进行乙酰化和水解,也可以制备 3a,总产率为 17%。