Koltunov Konstantin Yuryevich, Chernov Aleksey Nikolaevich, Surya Prakash Gubbi Krishnamurthy, Olah George Andrew
Boreskov Institute of Catalysis, Novosibirsk, Russia.
Chem Pharm Bull (Tokyo). 2012;60(6):722-7. doi: 10.1248/cpb.60.722.
It is known that 1-naphthol, as a result of superelectrophilic (dicationic) activation in superacid media, is able to react with such deactivated aromatic compound as o-dichlorobenzene to give 4-(3,4-dichlorophenyl)-1-tetralone (2), which is a highly valuable intermediate in the synthesis of the antidepressant, sertraline (1) and other useful derivatives. However, the analogous reactivity of 2-naphthol and a variety of naphthalenediols towards o-dichlorobenzene has not been investigated thus far, although the corresponding tetralones, bearing dichlorophenyl moiety, could be of great pharmacochemical interest. In present work, we disclose that 1,5-, 1,6-, and 1,7- naphthalenediols (6a-c) react smoothly with o-dichlorobenzene in the presence of an excess of aluminum chloride or aluminum bromide to give the pairs of isomeric 4-(3,4-dichlorophenyl)- and 4-(2,3-dichlorophenyl)- 5-, 6-, and 7-hydroxy-1-tetralones (10a-c and 11a-c) in high overall yields. 2-Naphthol and 2,7-naphthalenediol (6d) exhibited comparatively lower reactivity, which however was sufficient to obtain the corresponding dichlorophenyl-2-tetralones in moderate yields. The mechanism of these reactions involving superelectrophilic dicationic or even tricationic intermediates, is discussed.
已知1-萘酚在超强酸介质中由于超亲电（双阳离子）活化作用，能够与诸如邻二氯苯这种钝化的芳香化合物反应，生成4-(3,4-二氯苯基)-1-四氢萘酮（2），它是合成抗抑郁药舍曲林（1）及其他有用衍生物的一种非常有价值的中间体。然而，尽管带有二氯苯基部分的相应四氢萘酮可能具有很大的药物化学研究价值，但迄今为止，2-萘酚和多种萘二醇对邻二氯苯的类似反应活性尚未得到研究。在本工作中，我们揭示了1,5-、1,6-和1,7-萘二醇（6a - c）在过量氯化铝或溴化铝存在下能与邻二氯苯顺利反应，以高总收率得到成对的异构体4-(3,4-二氯苯基)-和4-(2,3-二氯苯基)-5-、6-和7-羟基-1-四氢萘酮（10a - c和11a - c）。2-萘酚和2,7-萘二醇（6d）表现出相对较低的反应活性，不过这足以以中等收率得到相应的二氯苯基-2-四氢萘酮。本文讨论了这些涉及超亲电双阳离子甚至三阳离子中间体的反应机理。
