Amidinoquinoxaline N-oxides as novel spin trapsElectronic supplementary information (ESI) available: Experimental details and spectral data for all the new compounds. See DOI: 10.1039/c4ra14335c

• Main Authors: Gruber, Nadia, Piehl, Lidia L, Rubin de Celis, Emilio, Díaz, Jimena E, García, María B, Stipa, Pierluigi, Orelli, Liliana R
• Format: Article
• Language: English
• ISSN: 2046-2069
• DOI: 10.1039/c4ra14335c

A novel type of spin traps 1 derived from the pyrimidoquinoxaline N-oxide heterocyclic core is reported. EPR technique was used to evaluate their ability to trap methyl radicals generated in a Fenton reaction in the presence of DMSO. All the synthesized nitrones showed spin trapping properties and the corresponding nitroxides 2 were characterized by EPR. The novel spin traps showed remarkably persistent signals, as confirmed in a competition experiment with DMPO. The addition rate constants leading to the spin adducts ( k add ) were determined, and very good correlations were found with steric and electronic parameters of the parent nitrones. The spin adducts decomposition rate constants ( k dec ) and the corresponding half-life times ( t 1/2 ) were also determined. DFT and MP2 calculations were used in order to rationalize the adducts hfcc and the structural factors influencing their addition and decomposition rates. A series of nitrones were synthesized and tested as novel spin traps. The adducts generated by CH 3 addition showed remarkably persistent signals. Their EPR features and kinetics were rationalised by DFT and MP2 calculations.