Development of New Photochemical Reactions of Phenols Promoted by Lewis Acid and its Synthetic Application

我们发现了路易斯酸促进的苯酚衍生物的新的光化学反应，并开发了从现成的芳香族化合物开始构筑碳环的新方法。我们发现在溴化铝存在下，3-甲氧基苯酚(1)以较高的产率得到4-甲氧基双环[3.1.0]己烯酮(2)。我们发现，在卤化铝存在下，1-萘酚(3)以较高的产率得到环缩的卤代甲基林丹酮(4)。吲哚4经碱处理后定量转化为环丙烷类化合物5。我们已经报道了在Lewis酸存在下，2-萘酚(6)通过辐射与乙烯生成[2+2]环加合物。为了阐明这一新反应的反应机理，我们考察了烯烃和路易斯酸在该反应中的作用。我们发现1-萘酚(3)及其衍生物的反应活性是发散的，并且与取代基的位置密切相关。因此，3和它的3-甲基衍生物以良好的产率得到了[2+2]环加合物7。另一方面，2-烷基和6-甲氧基衍生物生成的环状加合物8的主要产物是吲哚核。

We have found new photochemical reactions of phenol derivatives promoted by Lewis acid and have developed new method for carbocyclic ring construction starting from readily available aromatic compounds.1. We found that irradiation of 3-methoxyphenol (1) in the presence of aluminum bromide gave 4-methoxybicyclo [3.1.0] hexenone (2) in a good yield.2. We found that irradiation of 1-naphthol (3) in the presence of aluminum halides afforded ringcontracted halomethylindanone (4) in a good yield. indanone 4 was converted to the cyclopropane-containing compound 5 quantitatively by treatment with a base.3. We have already reported that 2-naphthol (6) produced the [2+2] cycloadduct with ethylene by irradiation in the presence of Lewis acid. In order to clarify the mechanism of this novel reaction, we investigated the effect of olefins and Lewis acids in this reaction.4. We found that the reactivity of 1-naphthol (3) and its derivatives was divergent and it was critically dependent on the position of the substituent. Thus 3 and its 3-methyl derivative gave [2+2] cycloadducts 7 in good yields. On the other hand, 2-alkyl and 6-methoxy derivatives yielded ringcontracted adducts 8 having an indenone core as the major products.