Photoinduced oxygenation of tryptamines by aromatic amine N-oxides

Irradiation (1) (253-7 nm) of N_a,N_b-dimethyltryptaimne with pyridine N-oxide or benzo[c]cinnoline N-oxide in CH₂Cl₂ yielded 1,8-dimethyl-3a-hydroxy-1,2,3,3a,8-8a,- hexahydropyrrolo[2,3-b]indole (19), while with visible light N_b-(4-cyanobutadienyl)-N_a,N_b,- dimethyltryptamine (21) was obtained. This method was applied to trimethyltryptamine and the corresponding oxindole (34) and the N-formyl derivative (20) were obtained.