S(N)(H) approach in the synthesis of nitronyl nitroxides.
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.
Chupakhin
Oleg N
ON
Urals State Technical University, Mira street, 19, 620002 Ekaterinburg, Russian Federation. chupakhin@ios.uran.ru
Utepova
Irina A
IA
Varaksin
Mikhail V
MV
Tretyakov
Evgeny V
EV
Romanenko
Galina V
GV
Stass
Dmitry V
DV
Ovcharenko
Victor I
VI