PHOTOINDUCED REACTIONS. LXVII. PHOTOSENSITIZED OXYGENATION OF N-SUBSTITUTED 1,2,3,4-TETRAHYDROCARBAZOLES
Rose bengal-sensitized photooxygenation of N-methyl- (1a), N-methyl-6-nitro- (1b), and N-acetyl- (1c) 1,2,3,4-tetrahydrocarbazoles was investigated. The N-methyl derivatives underwent oxidative cleavage of the enamine double bond to give exclusively 2, whereas the N-acetyl derivative in water-containing solvents gave predominantly 3, possibly via a zwitterionic peroxide intermediate.