Studies toward the synthesis of 4-(2-R-ethyl)amino-2,2,5,5-tetramethyl-3-imidazoline 1-oxyls: nucleophilic substitution of bromide in the N-alkyl chain of the 1,2,4-oxadiazol-2-one precursor

The synthetic method to access nitroxides with pH-dependent EPR spectra is described. The method can find application in the nonivasive EPR-based method for pH monitoring in biophysical and biomedical studies.