Elena V. Panteleeva

Substitution of a Fluorine Atom in Perfluorobenzonitrile by a Lithiated Nitronyl Nitroxide

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 NaNO2-AcOH yielded corresponding iminonitroxide 4. Characterization of persistent radicals 3 and 4 obtained by the SNF 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.

Evidence for the transition from SN to ET mechanism in the reaction of arene radical anion with alkyl halide evoked by the introduction of an electron withdrawing substituent into radical anion

The interaction of potassium salts of benzonitrile and 1.4-dicyanobenzene radical anions with cyclopropylmethyl bromide provides benzylcyclopropane, in the first case, and 4-alkyl- benzonitriles together with 2-alkyl-1,4-dicyanobenzenes containing both cyclopropylmethyl and its isomeric 3-butenyl fragment, in the second case. These results provide evidence for the change of reaction mechanism from SN to ET.

Reductive activation of arenes. VII. Alkylation of 9-cyanoanthracene two-electron reduction products in liquid ammonia.

Abstract The reactions of the 9-cyanoanthracene dianion generated by the action of two equivalents of potassium in liquid ammonia with primary alkyl iodides and bromides gave 9-cyano-9,10-dialkyl-9,10-dihydroanthracenes. The alkylation of the 9-cyano-9,10-dihydro-9-anthryl anion generated by the two-electron reduction of 9-cyanoanthracene in liquid ammonia in the presence of ammonium chloride gave 9-cyano-9-alkyl-9,10-dihydroanthracene. The results obtained by using cyclopropylmethyl bromide as model reagent suggest these reactions to proceed through SN mechanism. The spatial structure of 9,10-dihydroanthracene derivatives obtained is discussed.

Synthesis of 4-(ω-X-alkyl)benzonitriles (X = 1,3-dioxan-2-yl, CN, CO2Et) by the reaction of terephthalonitrile dianion with ω-X-alkyl bromides in liquid ammonia

The main products of the reaction of terephthalonitrile dianion disodium salt with ω-X-alkyl bromides (2-(2-bromoethyl)-1,3-dioxane, 5-bromovaleronitrile, ethyl 6-bromohexanoate) in liquid ammonia are the corresponding 4-(ω-X-alkyl)benzonitriles. Similar reactions of benzonitrile radical anion sodium salt lead to ω-X-alkylbenzenes. In both cases the formation of products is due to selective ipso-alkylation of anionic forms that indicates the nucleophilic activity of terephthalonitrile dianion and benzonitrile radical anion in these reactions and the realization of alkylation via SN2 mechanism.

One-pot synthesis of 4′-alkyl-4-cyanobiaryls on the basis of the terephthalonitrile dianion and neutral aromatic nitrile cross-coupling

Summary A convenient one-pot approach to alkylcyanobiaryls is described. The method is based on biaryl cross-coupling between the sodium salt of the terephthalonitrile dianion and a neutral aromatic nitrile in liquid ammonia, and successive alkylation of the long-lived anionic intermediate with alkyl bromides. The reaction is compatible with benzonitriles that contain methyl, methoxy and phenyl groups, fluorine atoms, and a 1-cyanonaphthalene residue. The variety of ω-substituted alkyl bromides, including an extra bromine atom, a double bond, cyano and ester groups, as well as a 1,3-dioxane fragment are suitable as alkylation reagents.