SYNTHESIS OF A NOVEL NITRONE, 2-PHENYL-5,5-DIMETHYL-1-PYRROLINE N-OXIDE (NITRONYL-C-13), FOR ENHANCED RADICAL ADDEND RECOGNITION AND SPIN ADDUCT PERSISTENCE

Synthesis and spin trapping chemistry of the new C-13-labeled cyclic n itrone, 2-phenyl-5,5-dimethyl-1-pyrroline N-oxide (nitronyl-C-13), is described. A total of 15 carbon- and oxygen-centered radical adducts w ere prepared and their electron paramagnetic resonance (EPR) spectral parameters examined in organic as well as aqueous solutions. All the r adical spin adducts derived from the novel nitrone displayed a well-re solved triplet of doublets in the EPR spectra. The alpha-C-13 hyperfin e splitting is a good indicator for the chemical structure of the adde d radical and varies from around 3.2 to 6.2 G. Free radicals are spin trapped at rates that are quite comparable to those observed with C-ph enyl-N-tert-butylnitrone (PBN). The main advantage, however, is the en hanced persistence of its radical spin adducts. For this reason the ti tle nitrone holds promise as a biological spin trapping agent because spin adduct decay during metabolism or isolation often governs the suc cess or failure of a given experiment.