1-甲基-2-苯基吲哚的琥红敏化单重态氧反应

1-甲基-2-苯基吲哚(1)在甲醇中的琥红(RB)敏化单重态氧反应生成1-甲基-2-甲基氧-2-苯基-1, 2-二氢-3H-吲哚-3-酮(4)和1-甲基-2-羟基-2-苯基-1, 2-二氢-3H-吲哚-3-酮(6), 后者在强碱性介质下发生苯乙醇酸型重排生成1-甲基-3-羟基-3-苯基氧化吲哚(14)。研究了6的溶剂分解反应以及外加碱对光氧化反应的影响。探讨了光氧化产物的形成途径。结果表明: 4系两性离子中间体2的溶剂捕获、脱水产物, 而6则系二氧杂环丁烷中间体7的裂解、抽氢产物。

Rose bengal sensitized singlet oxygenation of 1-methyl-2- phenylindole

Rose bengal sensitized singlet oxygenation of 1 - methyl - 2 - phenylindole (1) in methanol yielded 1 - methyl - 2 - methoxy - 2 - phenyl -1,2- dihydro - 3H - indol - 3 - one(4) and 1 - methyl - 2 - hydroxy - 2 - phenyl -1,2- dihydro - 3H - indol - 3 - one(6), the latter underwent benzilic acid - type rearrangement in alkline medium to give 1 - methyl - 3 - hydroxy - 3 -phenyloxindole(14). The solvolysis of 6 and the influence of added base on photooxygenation reaction were studied and the forrnation pathways of photooxygenation products were also discussed. A possible mechanism involving interception of the initially generated zwitterionic intermediate 2 by methanol, followed by dehydration leading to 4, as well as the O - O homolysis of 1,2 - dioxetane 7, followed by hydrogen abstraction to give 6 was proposed.