N1,N10-Ethylene-bridged high-potential flavins: synthesis, characterization, and reactivity

N1,N10-Ethyleneisoalloxazinium chloride and its 8-Cl-, 7-CF3-, and 3-CH3-7-CF3-substituted analogs were synthesized for the purpose of exhibiting thermal reactivity with organic substrates. The new flavins were characterized spectroscopically and electrochemically, and were found to react with amines, thiols, and phenylhydrazine, the latter case exhibiting catalytic aerobic recycling. Reactions of aliphatic benzylic and cyclopropyl amines with the 7-CF3 analog were also compared to their oxidations by tris(phenanthroline)iron(III). All reactions of the flavinium salts appear to occur through heterolytic rather than homolytic mechanisms.