FLASH-PHOTOLYSIS OBSERVATION AND LIFETIMES OF THE CATION INTERMEDIATES IN THE INTRAMOLECULAR PHOTOPROTONATION OF TRYPTAMINE, TRYPTOPHAN AND THEIR N-METHYL DERIVATIVES

Photolysis of the four title compounds in trifluoroethanol results in transient cyclohexadienyl-type cations (lambda(max) approximately 350 nm, 420 nm) arising from photoprotonation at H-4. Lifetimes are 300 - 500 ns, and are considerably shortened by the addition of water and acetate base. For the two parent compounds there is evidence in acetate buffered solutions for N-H deprotonation resulting in the tautomeric form of the parent compound.