AMINE FLAVIN ELECTRON-TRANSFER PHOTOCHEMISTRY - POTENTIAL MODELS FOR MONOAMINE-OXIDASE CATALYSIS AND INHIBITION

The photoreactions of 3-methyllumiflavin (3MLF) and a variety of amines have been explored. These studies have demonstrated that 3MLF undergoes efficient photoreactions with alpha-silyl tertiary benzylamines to generate 4a-adducts by pathways involving sequential SET and desilylation followed by radical coupling. These adducts are unstable substances that react rapidly with nucleophiles (e.g., MeOH, H2O, and NaBH4) and oxygen. They are also photolabile, providing the corresponding 4a-benzyldihydroflavin upon irradiation. Non-silicon-containing primary and secondary amines also participate in SET-promoted photoreactions with 3MLF. The amine cation radicals formed in these processes undergo further transformations to produce radical intermediates by either alpha-CH or NH deprotonation pathways. The potential relevance of these findings to the area of monoamine oxidase chemistry is considered.