Dye-Sensitized Photooxygenations of 1,3-Isoquinolinediones
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文摘
Singlet oxygen reactions of 1,3-isoquinolinediones 1a-1e could be sensitized by the anionic sensitizer Rose Bengal (RB) in methanol or by tetraphenylporphin (TPP) in the presence of pyridine as a base and a cosolvent in benzene. The products are the corresponding 1,3,4-isoquinolinetriones 2a-2e and methyl 1-hydroxy-3-oxoisoindole-1-carboxylates 3b-3e in methanol and the triketones 2a-2e and the 3-hydroxy-3-alkyl (aryl)aminocarbonylbenzoisofuran-1-ones 4b-4e in benzene-pyridine. TPP sensitized photooxygenations of the 4-alkylated 1,3-isoquinolinediones 5a-5c yielded the 4-alkyl-4-hydroxy-1,3-isoquinolinediones 6a-6c, the 4-alkyl-4-hydroperoxy-1,3-isoquinolinediones 7a-7c and the 3-alkyl-3-hydroxybenzoisofuran-1-ones 8a-8b. Reaction mechanisms have been proposed.