Preparation of N-aryl-ketonitrone spin traps

Abstract

Abstract:The syntheses of seven N -aryl-C,C-dialkoxycarbonylnitrones 1-7, six of which were original, were achieved from the appropriate aryl-nitroso compounds. These ketonitrones were found to trap efficiently carbon-centred free radicals in aqueous media, yielding stable aminoxyl radicals whose EPR spectra lasted several days. The two penta-deuterated compounds 6 and 7 were also found to be efficient at trapping methoxyl radical. Their various spin adducts showed simple three line signals, very sensitive to the polarity of the environment. This study represents the very first use of linear ketonitrones as spin traps.

Detection and identification of various carbon-centred free radicals using N-arylketonitrones: a spin trapping/EPR/MS study

“…The first synthesis of 1 was described in 2003, 3 while 2 and 3 were prepared three years later, 7 and none of these ketonitrones has ever been studied by mass spectrometry. The analysis of the fragmentation pathway of 1-3 was thus an essential step preceeding the MS/MS identification of their various spin adducts.…”

“…In the case of 1-CH 2 OH for instance, a N varies from 1.20 mT in water to 1.10 mT in CH 2 Cl 2 . 7 However, the hfccs listed in Table 1 are not characteristic of the radical trapped. Whatever the nitrone, the different spin adducts of carbon-centred free radicals exhibited almost identical spectra.…”

“…The nitrones 1-3 were synthesised, purified and identified in our laboratory after procedures extensively described pre-viously. 7 All chemicals, including the 2-methyl-2-nitrosopropane (MNP), were purchased from Sigma-Aldrich (St. Louis, MO) and used without further purification. The solvents were of the highest purity commercially available and used as received.…”

“…Recently, we described the synthesis of seven N-arylketonitrones. 7 Among them, three N-aryl-C,C-methoxycarbonyl-nitrones, namely the dimethyl [oxido(phenyl)imino]malonate 1, the dimethyl [oxido(phenyl)imino]malonate-d 5 2 and the dimethyl { [4-(methoxycarbonyl)phenyl](oxido)imino}malonate 3, showed the most interesting performances in spin trapping chemistry (see Scheme 1). Compound 1 is very easily obtained from nitrosobenzene: its low cost synthesis allows its use in large amounts generally necessary for biological applications.…”

Synthetic Studies of Azulenyl and Pseudoazulenyl Nitrones

“…Thus, nitroso compounds are toxic, thermally and photochemically unstable, and the lifetime of their oxygen-centered radical adducts are exceedingly short. 114 For these reasons, researchers prefer nitrones over nitroso compounds, especially in biological systems, despite the fact that the EPR spectra of their nitroxide spin adducts provide less structural information.…”