A novel route to 2-imidazolin-5-one derivatives via oxidative cyclization of aryl-substituted (Z)-N-acetyl-α-dehydroalanines having a dialkylamino group

It was found that the reaction of the title compounds [] with oxygen in methanol proceeds according to the first-order kinetics to give (Z)-2-imidazolin-5-one derivatives and hydrogen peroxide in quantitative yields. Analysis of substituent and solvent effects on the rate constant for this oxidative cyclization led us to propose that electron transfer from the dialkylamino nitrogen in to oxygen, amide-proton abstraction by superoxide and the subsequent intramolecular electron transfer are all rate-determining steps. The synthetic utility of the novel cyclization reaction of aryl-substituted (Z)-N-acetyl-α-dehydroalanine derivatives was discussed.