- One-pot synthesis of 4?-alkyl-4-cyanobiaryls on the basis of the terephthalonitrile dianion and neutral aromatic nitrile cross-coupling
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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
- Peshkov, Roman Yu,Panteleeva, Elena V.,Chunyan, Wang,Tretyakov, Evgeny V.,Shteingarts, Vitalij D.
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- Cyanophenylation of aromatic nitriles by terephthalonitrile dianion: Is the charge-transfer complex a key intermediate?
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The interaction of terephthalonitrile (1) dianion (12-) with benzonitrile (2) or m-tolunitrile (3) provides 4,4′-dicyanobiphenyl (4) or 4,4′-dicyano-2-methylbiphenyl (5), respectively. This result shows that dianion 12- serves as a reagent for p-cyanophenylation of aromatic nitriles. Based on experimental data, such as the chemical trapping of the 4,4′-dicyanobiphenyl precursor 4-cyano-1-(p-cyanophenyl)cyclohexa-2,5-dienyl anion (7) and the failure to obtain biphenyl 4 through the interaction of independently generated radical anions (RAs) 1- and 2-, as well as on the results of quantum-chemical calculations, a mechanism is suggested that includes a charge-transfer complex (CTC) between 12- and the aromatic nitrile as the key intermediate. The formation of this CTC is followed either by an intracomplex electron transfer (ET) and recombination of terephthalonitrile and aromatic nitrile RAs within an unequilibrated RA pair, or by synchronous ET and bonding of the ipso-carbon atom of terephthalonitrile with the p-carbon atom of the aromatic nitrile. The synthetic significance of p-cyanophenylation of arenecarbonitriles by dianion 12- is illustrated by the high yield of biphenyl product 4 (approx. 90%) as well as by the possibility of a one-pot synthesis of 4-butyl-4′-cyanobiphenyl and 4-butyl-4′-cyano-2-methylbiphenyl by successive treatment of dianion 12- with nitrile 2 or 3 and butyl bromide. Wiley-VCH Verlag GmbH & Co, KGaA, 69451 Weinheim, Germany, 2005.
- Panteleeva, Elena V.,Shchegoleva, Lyudmila N.,Vysotsky, Viktor P.,Pokrovsky, Leonid M.,Shteingarts, Vitalij D.
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p. 2558 - 2565
(2007/10/03)
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- Synthesis of Mesogenic Compounds, Catalyzed by Metal Complexes. I. Monoalkylation and Monoarylation of 1,4-Dibromobenzene in the Synthesis of 4-n-Alkyl- and 4-n-Alkoxy-4'-Cyanobiphenyls Catalyzed by Palladium
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New methods of synthesis of mesomorphic 4-n-alkyl- and 4-n-alkoxy-4'-cyanobiphenyls are developed, based on the palladium catalyzed highly selective reactions of 1,4-dibromobenzene with alkyl and aryl Grignard reagents.
- Bumagin, N. A.,Luzikova, E. V.,Beletskaya, I. P.
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p. 1480 - 1486
(2007/10/03)
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- SYNTHESIS OF 4-ALKYL-4'-CYANOBIPHENYLS
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Liquid crystals of the 4-alkyl-4'-cyanobiphenyl group were synthesized without the use of copper cyanide. 4-Alkyl-4'-formylbiphenyls and the 4-formyloximes of 4'-alkylbiphenyl, which possess a liquid-crystalline state, were isolated.Beginning with the pentyl homolog, they form an enantiotropic nematic phase, and beginning with octyl homolog they also form a smectic meso phase.
- Ruolene, Yu. I.,Adomenas, P. V.,Sirutkaitis, R. A.,Denis, G. I.
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p. 1187 - 1191
(2007/10/02)
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