Simple Synthesis of a 4a-hydroperoxy Adduct of a 1,5-dihydroflavine: Preliminary Studies of a Model for Bacterial Luciferase

The solution chemistry of N(5)-alkyl flavinium cations and radical species formed by their le- reduction are discussed. Previously unknown, the 4a-flavine hydroperoxides are established to be formed on reaction of N(5)-alkyl flavinium cations with H2O2 or on reaction of N(5)-alkyl-1, 5-dihydroflavines with 3O2. The stability of the 4a-flavine hydroperoxide species is exemplified in the isolation and characterization of 4a-hydroperoxy-N(5)-ethyl-3-methyl-lumiflavine. 4a-Flavine hydroperoxide compounds are shown to be stronger oxidants than H2O2, and to undergo a chemiluminescent reaction in the presence of an aldehyde. Preliminary observations on the chemiluminescent reaction of 4a-flavine hydroperoxides + RCHO are provided, and these are compared to those in the literature dealing with the bioluminescence of bacterial luciferase in the presence of 3O2 and RCHO.