Photochemical Reactions of Aromatic 1,3-Diketones having a Functional Group on beta-carbon in the Side Chain.

研究了侧链β-碳上带有羰基、羟基、烷氧基或乙酰氧基等官能团的邻甲基、邻乙基和邻异丙基芳基酮的光化学反应。研究了光产物的化学行为，发现带有β-酮基或β-酯基的邻位烷基芳基酮经光照射后，可高产率地得到相应的苯并环丁烯醇。苯并环丁烯醇热解得到苯并环丁烯酮，带有β-羟基或β-烷氧基的邻烷基芳基酮通过β-或γ-夺氢进行光环化得到苯并环丁烯醇和环丙烷-1，2-二醇或2-烷氧基环丙醇，带有β-羟基或β-乙酰氧基的邻烷基芳基酮经辐照得到两种非对映体苯并环丁烯醇，其经历热互变。由α-碳上具有β-羟基或β-乙酰氧基和两个甲基的邻烷基芳基酮形成的苯并环丁烯醇经酸处理得到亚异丙基苯并环丁烯。β-碳上具有羟基的邻异丙基芳基酮经辐照得到2，2-二甲基苯并环丁烯醇在热条件下发生C-2甲基到C-1碳的立体定向氢转移，生成邻异亚丙基芳基醇。1-（2 '，4'，6 '-三烷基苯基）-2-甲基-1，3-二酮存在于烯醇中。单重态氧与这些烯醇式1，3-二酮的反应受溶剂极性的影响，并通过两种不同构象的同分异构过氧环氧化物进行。

Photochemical reactions of ortho-methyl, -ethyl, and -isopropylaryl ketones having a functional group such as carbonyl, hydroxyl, alkoxyl, or acetoxy group on beta-carbon in their side chain have been investigated. The chemical behavior of the photoproducts have also been investigated.Irradiation of ortho-alkylarylketones with a beta-keto or beta-ester group gave the corresponding benzocyclobutenols in good yields. The pyrolysis of the benzocyclobutenols thus obtained gave benzocyclobutenones.Ortho-alkylarylketones with a beta-hydroxyl or beta-alkoxyl group underwent photocyclization via beta- or gamma-hydrogen abstraction to give benzocyclobutenols and cyclopropane-1,2-diols or 2-alkoxyclopropanols.Irradiation of ortho-alkylarylketones with a beta-hydroxyl or beta-acetoxy group gave two diastereomeric benzocyclobutenols, which underwent thermal interconversion.The acid treatment of benzocyclobutenols formed from ortho-alkylarylketones with a beta-hydroxyl or beta-acetoxy group and two methyl groups on alpha-carbon gave isopropylidenebenzocyclobutenes.Irradiation of ortho-isopropylarylketones with a hydroxyl group on beta-carbon gave 2,2-dimethylbenzocyclobutenols which underwent stereospecific hydrogen shift from C-2 methyl group to C-1 carbon on thermal conditions to give arylalcohols with ortho-isopropylidene group.1- (2', 4', 6'-Trialkylphenyl) -2-methyl-1,3-diketones exists in the enol from in solution. The reaction of singlet oxygen with these enolic 1,3-diketones were affected by solvent polarity, and proceeded through two different conformational isomeric perepoxide.