2-取代吲哚的染料敏化光氧化反应

Dye-Sensitized Photooxygenation of 2-Substituted Indoles

2-苯基吲哚(1a)在甲醇中的染料敏化光氧化反应给出2-苯基-2-(2’-苯基-3’-吲哚基)二氢吲哚-3-酮(2a)和2-甲氧基-2-苯基二氢吲哚-3-酮(4a),相应N-甲基取代产物由1-甲基-2-苯基吲哚(1b)的类似反应获得。发现反应产物分布随吲哚(1)的浓度和介质酸度的变化而变化。对反应机理进行了推测,其中当1a的反应在乙腈中进行时,分离到了相应的反应中间体:2-苯基-3H-吲哚-3-酮(3a)。

Dye-sensitized photooxygenation of 2-phenylindole (1a) in methanol gave 2-phenyl-2-(2'-phenyl-3'-indolyl) indoxyl (2a) and 2-methoxy-2-phenylindoxyl (4a). The N-methyl products (2b, 4b) were obtained from 1-methyl-2-phenylindole (1b) similarly. The product distribution of the reaction varied with the concentration of indoles (1) and the acidity of the reaction medium. A mechanism for the reaction was proposed. In the case of la, the proposed reaction intermediate, 2-phenyl-3H-indol-3-one (3a) has been isolated in the same reaction carried out in acetonitrile.