First Synthesis of C-Phenyl N-tert-Buty\ [15N]nitrone (PBN-15N) for the EPR Spin Trapping Methodology

C-Phenyl N-tert-Butyl [15N]nitrone, Nitrone, Spin Trap, EPR Spin Trapping, Aminoxyl (Nitroxide) As compared to normal PBN, about fifty percent increase of electron paramagnetic reso­ nance (EPR) spin trapping sensitivity has been gained by using a new 100% 1:>N-enriched spin trap, C-phenyl /V-rm-butyl[15N]nitrone (PBN-15N). PBN-15N has been prepared by a convenient four-step route using ammonium-15N chloride as the starting material. This syn­ thetic method produces 2-methyl-2-[15N]nitropropane which is useful for the synthesis of many other PBN-15N type spin traps for the purpose of increasing spin trapping sensitivity. EPR spin trapping with PBN-15N in benzene and in phosphate buffer has been investigated. The 15N hyperfine splitting constant (15N-hfsc) is larger than 14N-hfsc by 40%. The larger 15N-hfsc gives more opportunity to identify different radical addends within the same system.