Novel spin traps in which a methyl group of the tert-butyl of PBN was substituted with a diphenylphosphoryl group, were successfully synthesized. The nitrone precursors were synthesized from diphenylphosphine oxide, acetone, and appropriate amines under microwave irradiation. The obtained amines were converted to the desired nitrones using Oxone. Spin adducts of oxygen-centered radicals such as the superoxide anion radical and the hydroxyl radical, which could not be detected in adducts using PBN, were observed using these nitrones.