N. N. Vorozhtsov Institute of Organic Chemistry , 9 Ac. Lavrentiev Avenue, Novosibirsk 630090, Russia.
Novosibirsk State University , 2 Pirogova Str., Novosibirsk 630090, Russia.
J Org Chem. 2017 Apr 21;82(8):4179-4185. doi: 10.1021/acs.joc.7b00144. Epub 2017 Apr 6.
A 4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (1) lithium derivative was found to react with perfluorobenzonitrile (2) substituting its para-fluorine atom to form 2-(4-cyanotetrafluorophenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-3-oxide-1-oxyl (3), a new nitronyl nitroxide containing a multifunctional framework of strong electron-withdrawing nature. This result shows the possibility of obtaining multifunctional nitronyl nitroxides via the interaction of paramagnetic lithium derivatives as C-nucleophiles with polyfluoroarenes activated for nucleophilic substitution. The reaction regioselectivity is supported by the data of quantum-chemical calculations, which also show that the reaction follows a concerted pathway without formation of an intermediate. Reduction of nitronyl nitroxide 3 in system NaNO-AcOH yielded corresponding iminonitroxide 4. Characterization of persistent radicals 3 and 4 obtained by the S synthetic strategy includes X-ray crystal structures, electron spin resonance data, and static magnetic-susceptibility measurements. X-ray diffraction analysis of both nitronyl nitroxide and iminonitroxide revealed a complete match of the parameters of their crystal lattices.
发现 4,4,5,5-四甲基-4,5-二氢-1H-咪唑-3-氧化物-1-氧基（1）的锂衍生物与全氟苯甲腈（2）反应，取代其对位氟原子，形成 2-（4-氰基四氟苯基）-4,4,5,5-四甲基-4,5-二氢-1H-咪唑-3-氧化物-1-氧基（3），这是一种含有强吸电子性质的多功能框架的新型硝酮氮氧自由基。这一结果表明，通过作为 C-亲核试剂的顺磁锂衍生物与多氟芳烃之间的相互作用，有可能获得多功能硝酮氮氧自由基。反应的区域选择性得到量子化学计算数据的支持，该数据还表明反应遵循协同途径，而不形成中间体。在 NaNO-AcOH 体系中还原硝酮氮氧自由基 3 得到相应的亚硝酮氮氧自由基 4。通过 S 合成策略获得的持久自由基 3 和 4 的特征包括 X 射线晶体结构、电子自旋共振数据和静态磁化率测量。两种硝酮氮氧自由基和亚硝酮氮氧自由基的 X 射线衍射分析都显示出其晶格参数的完全匹配。
