Radical scavenging by N-aminoazaaromatics.

N-Aminoazaaromatics were found to react with nitric oxide in the presence of oxygen to afford deaminated products in high yields. The reaction proceeded almost instantaneously in various solvents including water, and one to two equivalent of NO was consumed depending upon the amount of oxygen coexisted, and 1 equivalent of N2O was released in the reaction. In addition, N-aminoazoles were deaminated by potassium superoxide to give parent azoles in good yields. Two equivalents of superoxide was consumed, and about half equivalents of both nitrite and nitrate ion were released. The results demonstrated that N-aminoazoles have ability to protect the biological system against the oxidation promoted by radicals such as nitrogen oxides and superoxide.