2-Substituted-3H-indol-3-one-1-oxides: Preparation and Radical Trapping Properties

Abstract

A series of 2-alkyl and 2-aryl substituted-3H-indol-3-one-1-oxides was prepared and evaluated for its radical trapping properties. Spin trapping and electron paramagnetic resonance experiments demonstrate the ability of these indolone-1-oxides to trap hetero- and carbon-centered radicals. The most stable spin adducts (lifetime of several hours) are obtained with 2-alkyl substituted nitrones, the 2-ethyl-5,6-dioxolo-3H-indolone-1-oxide, 5e and the 2-secbutyl-3H-indolone-1-oxide, 5f. These two nitrones are also sensitive to redox reactions in solution. Therefore this indolone-1-oxide series lacking a β-hydrogen atom gives rise to highly stable adducts with free radicals.

• Indolone-1-oxide
• Nitrones
• Free radicals
• Spin trapping
• EPR
• EPR, electron paramagnetic resonance
• -BPN, --butylphenylnitrone
• DMPO, 5,5-dimethyl-1pyrroline--oxide
• HFS, hyperfine splitting