title: S(N)(H) approach in the synthesis of nitronyl nitroxides.
abstract: We show that the S(N)(H) approach opens up new possibilities in the synthesis of hetaryl-substituted nitronyl nitroxides. The reaction of 4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl lithium salt with pyridine-, pyrimidine-, pyrazine-, isoquinoline-, phthalazine-, quinoxaline-, and 1,2,4-triazine-N-oxides readily gives rise to the corresponding paramagnetic hetarenes. The reaction of this salt with quinoxaline-1,4-dioxide enabled the synthesis of the first nitronyl nitroxide biradical with two spin-labeled fragments in the vicinal positions of the heteroaromatic cycle; the persistent biradicals of this type were not known earlier. The characterizations of all persistent radicals obtained by S(N)(H) synthetic strategy include X-ray crystal structures, EPR investigation, and static magnetic susceptibility measurements.
authors.affiliation: Urals State Technical University, Mira street, 19, 620002 Ekaterinburg, Russian Federation. chupakhin@ios.uran.ru
authors.forename: Oleg N
authors.initials: ON
authors.lastname: Chupakhin
authors.forename: Irina A
authors.initials: IA
authors.lastname: Utepova
authors.forename: Mikhail V
authors.initials: MV
authors.lastname: Varaksin
authors.forename: Evgeny V
authors.initials: EV
authors.lastname: Tretyakov
authors.forename: Galina V
authors.initials: GV
authors.lastname: Romanenko
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Stass
authors.forename: Victor I
authors.initials: VI
authors.lastname: Ovcharenko