Nitroxide radicals. Part 20. Formation and reactions of t-butyl p-formylphenyl nitroxide and its derivatives

Abstract

Preparation of the parent hydroxylamine of the title nitroxide and its conversion into several hydroxylamine derivatives and the corresponding nitroxides has been achieved with a view to using functionalised aryl nitroxides as spin labels. The aN values of the derived aryl nitroxides vary with the nature of their para-substituents, thus providing a potential method for identifying the site of attachment of aryl nitroxide spin labels.Reactions of a nitrone-nitroxide, derived from the title radical, with cyanoisopropyl, phenyl, benzoyloxyb and t-butoxyl radicals were investigated. In no case was a bisnitroxide formed. Bu t , N

Design, Synthesis, and Characterization of Polyphosphazene Bearing Stable Nitroxide Radicals as Cathode-Active Materials in Li-Ion Batteries

“…The most extensively used method for the synthesis of linear poly(organophosphazenes) (PDCP) is a two‐step reaction sequence, in which the first step involves preparation of polydichlorophosphazene and the second one requires the replacement of the chlorine atoms by reactions with the desired nucleophiles . Initially, we have been trying to synthesize the 4‐( N ‐ tert ‐butyl‐ N ‐nitroxide)phenol as the desired nucleophile according to the literature report, Nevertheless, 4‐( N ‐ tert ‐butyl‐ N ‐nitroxide)phenol was not stable enough to be reacted with PDCP under nucleophilic conditions. A similar result was found by Yamauchi and co‐workers who reported that t ‐butyl nitroxide cyclophosphazene derivatives were too labile to be isolated .…”

“…Nevertheless, reactive nucleophilic group carrying aromatic nitroxide radical derivatives, such as OH, NH, or SH, in the various position of aromatic ring, are instable under nucleophilic conditions both in solution and solid state due to the unpaired electron of the nitroxide radicals which can go into a self‐condensation. Thus, preparation of aromatic nitroxide radical carrying phosphazene groups via nucleophilic replacement reaction of halophosphazenes have some synthetic challenge . For example, it was reported that the reaction of a cyclotriphosphazene derivative with 4‐( N ‐ tert ‐butyl‐ N ‐nitroxide)phenoxy produced a product which was too labile to be isolated that necessity to develop different reaction routes such as postmodification of the substituted group on the phosphazene chain.…”

“…Thus, preparation of aromatic nitroxide radical carrying phosphazene groups via nucleophilic replacement reaction of halophosphazenes have some synthetic challenge. [23][24][25] For example, it was reported that the reaction of a cyclotriphosphazene derivative with 4-(N-tert-butyl-N-nitroxide)phenoxy produced a product which was too labile to be isolated [24] that necessity to develop different reaction routes such as postmodification of the substituted group on the phosphazene chain. As a whole, we have successfully developed a new and facile synthetic strategy to overcome the abovementioned synthetic difficulties, which employ a two-step macromolecular substitution process followed by an oxidation of the hydroxyl amine derivative to the stable nitroxide radical with Ag 2 O to prepare the required polyphosphazene derivative.…”

Nitroxide radicals. Part 21. Spontaneous decomposition of N-aryl 1- and 2-naphthyl nitroxides

“…Preparation of N-Naphthyl-N-phenylhydroxylamines (1 ) and Nitroxides (2).-The naphthylmagnesium bromide, prepared from the corresponding bromonaphthalene (1 mol), 1,2dibromoethane (0.2 ml), and magnesium (2.2 g-atom) in a 1 : 1 mixture of benzene and tetrahydrofuran, was treated with nitrosoarene (0.45 mol) in tetrahydrofuran dropwise with stirring at -45 "C under nitrogen. The mixture was stirred for 15 min while the temperature rose to room temperature.…”

Some regio- and stereochemical aspects of the Diels-Alder reaction of nitrosocarbonyl compounds with N-substituted 1,2-dihydropyridines

“…N-Substituted 1,2dihydropyridines (1) are useful synthons for use in heterodiene condensation reactions and they have played a significant role in the synthesis of various alkaloids3 and bicycloheterocycles of pharmacological interest. [4][5][6][7] In some earlier studies we reported the reactions of 1,2-dihydropyridines 1 with azides,4 nitrosobenzene,5 oxyamination reagents,6 and phenylsulfonyl cyanide JV-oxide. 7 We now report the Diels-Alder reaction of 1,2-dihydropyridines 1 with nitrosocarbonyl compounds of varied dienophilicity, the electronic effect of substituents upon regiochemistry, the stereochemistry of the cycloadducts formed, and the structures of rearrangement products.…”