Currently, the chemistry of organofluorine compounds is a leading and rapidly developing area of organic chemistry. Fluorine present in a molecule largely determines its specific chemical and biological properties. This thematic issue covers the trends of organofluorine chemistry that have been actively developed in Russia the last 15 – 20 years. The review describes nucleophilic substitution and heterocyclization reactions involving fluorinated arenes and quinones and skeletal cationoid rearrangements in the polyfluoroarene series. The transformations involving CF3-substituted carbocations and radical cations are considered. Heterocyclization and oxidative addition reactions of trifluoroacetamide derivatives and transformations of the organic moiety in polyfluorinated organoboranes and borates with retention of the carbon – boron bond are discussed. Particular attention is devoted to catalytic olefination using freons as an efficient synthetic route to fluorinated compounds. The application of unsymmetrical fluorine-containing N-heterocyclic carbene ligands as catalysts for olefin metathesis is demonstrated. A variety of classes of organofluorine compounds are considered, in particular, polyfluorinated arenes and 1,2-diaminobenzenes, 1-halo-2-trifluoroacetylacetylenes, α-fluoronitro compounds, fluorinated heterocycles, 2-hydrazinylidene-1,3-dicarbonyl derivatives, imines and silanes. The potential practical applications of organofluorine compounds in fundamental organic chemistry, materials science and biomedicine are outlined. The bibliography includes 1019 references.

The reduction of Bcyanonnthracene by two equivalents of potassium in liquid ammonia was shown to yield the 9cyanoanthracene dianion, whereas 1-naphtho-and benzonitrile gave the cyanodihydroaryl anions corresponding to the protonation of nitrile dianions at a position para to the cyano group. The 9-cyanoanthracene dianion underwent the same transformation in the presence of a stronger protonating agent, methanol. According to I3C NMR spectral data of the generated species, the cyano group extracts the negative charge from the *-electronic system: ca 0.20:0*25 e in the case of the 9-cyanoanthracene dianion and ca 0-140.17 e in the case of cyanodihydroaryl anions. These estimations and the general NMR pattern of r-charge distribution in all the anionic species under investigation are in accordance with data from quantum molecular orbital calculations at the PM3 and INDO levels, being reflected by the fairly good linear relationships between the changes of ring carbon chemical shifts on going to the anionic species from the respective neutral precursors on the one hand and the calculated nsharges on the other. The para-orienting effect of the cyano group in the protonation of nitrile dinnions is discussed in terms of the r-charge distribution in the starting dianion and the tendency to form a most stable cyanodihydroaryl anion isomer. RESULTSThe reduction was performed just before recording NMR spectra by adding two equivalents of potassium 'Part5 of the series 'Reductive Alkylation of Arenes.' For Parts 1-4, see Refs 1 and 2. t Present address:

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.

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)

A concise noncatalytic synthetic approach to 2‐ and 3‐substituted 4,4′‐dicyanobiphenyls by applying terephthalonitrile dianion 12– as para‐cyanophenylating reagent for neutral benzonitriles is described. Neutral participants are varied to reveal the scope of applicable substrates and to evaluate the electronic and structural factors governing the regioselectivity and efficiency of the cross‐coupling. Benzonitriles substituted with Me, OMe and F provide the corresponding dicyanobiphenyls in good yields. The regularities in the reactivities are interpreted in terms of a reaction scheme involving the intermediacy of a charge‐transfer complex between 12– and benzonitrile, which transforms into a dimeric dianion either through a heterolytic pathway and/or by successive single electron transfer and recombination of the primary generated radical anions. Quantum chemical calculations of the structure and energy of the principal reaction intermediates match the experimental data. CV measurements of the new dicyanobiphenyls are also included.

The interaction of octafluorotoluene (1a), as well as pentafluorobenzonitrile (1b) with tert-butylamine, followed by the oxidation of thus formed tert-butylanilines (2a,b) with meta-chloroperoxybenzoic acid led to functionalized perfluorinated phenyl tert-butyl nitroxides [namely, 4-(N-tert-butyl(oxyl)amino)heptafluorotoluene (3a) and 4-(N-tert-butyl(oxyl)amino)tetrafluorobenzonitrile (3b)] with nearly quantitative total yields. The molecular and crystal structures of nitroxide 3a were proved by single crystal X-ray diffraction analysis. The radical nature of both nitroxides was confirmed by ESR data. The interaction of Cu(hfac)2 with the obtained nitroxides 3a,b gave corresponding trans-bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato-κ2O,O′)bis{4-(N-tert-butyl(oxyl)amino)perfluoroarene-κO}copper (II) complexes ([Cu(hfac)2(3a)2] and [Cu(hfac)2(3b)2]). X-ray crystal structure analysis showed square bipyramid coordination of a centrally symmetric Cu polyhedron with the axial positions occupied by oxygen atoms of the nitroxide groups. Magnetic measurements revealed intramolecular ferromagnetic exchange interactions between unpaired electrons of Cu(II) ions and paramagnetic ligands, with exchange interaction parameters JCu–R reaching 53 cm−1.

Synthetic and mechanistic aspects of the developed approach to the activation of aromatic nitriles are considered. The approach is based on the transformation of aromatic nitriles into stable anionic reduced forms. The latter, as shown for the reactions with alkyl halides and cyanoarenes, are promising reactants for the reactions with carbon centered electrophiles.Numerous methods for the modification of basic com pounds of the aromatic series aimed at obtaining various practically important substances and materials are based on electrophilic substitution. For electron deficient are nes, this reaction is hindered and limited to a narrow range of the most reactive electrophiles with the reaction center on an atom different from carbon, and their interaction with carbon centered electrophiles is virtually impossible. The reductive activation of the substrate provides a basic possibility for overcoming this restriction. The essence of the approach is that one or two electron reduction of electron withdrawing arenes in aprotic media makes it possible to generate relatively stable anionic reduced forms (ARFs), viz., radical anions, dianions, and cyclohexadie nyl anions retaining, as a whole, the structure of precur sors and used in syntheses as reactants.In our opinion, arenecarbonitriles are especially valu able as substrates in the framework of this approach. These compounds are prone, to a considerable extent, to the formation of ARFs combining stability in aprotic media with high reactivity toward electrophiles. A possi bility to generate ARFs of arenecarbonitriles in concen trations significant for preparative syntheses allows their use as highly reactive nucleophilic and radical (in the case of radical anions) synthons. In addition, they are valuable models for studying the structure and reactivity of the ARFs, first of all, from the viewpoint of a general theoretical problem of the competition between the prop erties of a nucleophile/base (S N mechanism) and a one electron reducing agent (ET mechanism). It is also im portant to know the factors that determine this competi tion for planning the synthesis on the basis of reductive activation, because the mechanism of the interaction of the ARFs with the electrophile determines the nature of the products formed.The results of recent studies generalized in the present review show that the specific features of the electronic structure of the ARFs of basic arenecarbonitriles, name ly, benzonitrile (1), o (2), m (3), and p tolunitrile (4), 1 naphthonitrile (5), 9 cyanoanthracene (6), phthaloni trile (7), terephthalonitrile (8), and 9,10 dicyanoan thracene (9), predetermine products of their interaction with carbon centered electrophiles. These products are valuable from the synthetic point of view. First, the reac tions proceed exclusively at the aromatic moiety and, second, the products containing the readily and variably modifiable cyano group provide wide possibilities of their further use for preparing practically important substan ces and materials. Nature and el...

A systematic study of the direction of nucleophilic attack of the nucleophiles Me 3 MEMe 2 (M ϭ Si, Sn; E ϭ P, As), NaOMe, LiR (R ϭ Me, nBu, Ph) and PhMgBr on 5,6,7,8-tetrafluoroquinoline (1), 6-CF 3 -5,7,8-trifluoroquinoline (2) and 5,7,8-trifluoroquinoline (3) was performed with the aim to develop synthetic routes to specific functional derivatives and to gain a deeper insight into the mechanisms governing the regioselectivity. With the fairly "soft" nucleophiles Me 3 MEMe 2 in general mixtures of 7-Me 2 EC-(main product) and 6-Me 2 EC-derivatives (side product) are formed (Schemes 1, 2, 4). Sulfuration of the isomer mixtures with E ϭ P yields mixtures of the corresponding thiophosphano derivatives. The observed regioselectivity is explained by a concerted action of two factors: (i) The influence of the heteroatom N on the stabilization of the σ-complex type transition states and (ii) the collective effect of four fluorine substituents favouring 6-and 7-substitution.Ϫ The reaction of 1 with sodium methoxide (Scheme 3) was carried out to test the early conclusion on the exclusive formation of 7methoxy-5,6,8-trifluoroquinoline (14) [2], made on the basis of a GC-analysis. For that purpose the molar ratio 1 : MeO Ϫ was varied from 1 : 1.25 over 1 : 1 to 1 : 0.5. Ϫ In the reactions of the quinoline Regioselektivität von 5,6,7,8-Tetrafluorchinolin und der 6-X-Trifluorchinoline mit X ‫؍‬ CF 3 , H in Reaktionen mit Nucleophilen Inhaltsübersicht. Die Nucleophile Me 3 MEMe 2 (M ϭ Si, Sn; E ϭ P, As), NaOMe, LiR (R ϭ Me, nBu, Ph) und PhMgBr wurden hinsichtlich der Richtung des nucleophilen Angriffs auf 5,6,7,8-Tetrafluorchinolin (1), 6-CF 3 -5,7,8-trifluorchinolin (2) und 5,7,8-trifluorchinolin (3) untersucht mit dem Ziel, Synthesewege zu bestimmten funktionalisierten Derivaten zu entwickeln und einen tieferen Einblick in die Mechanismen der Regioselektivität zu gewinnen. Bei Verwendung der relativ "weichen" Nucleophile Me 3 MEMe 2 werden generell Gemische des 7-Me 2 EC-(Hauptprodukt) und 6-Me 2 EC-Derivats (Nebenprodukt) (Schemes 1, 2, 4) gebildet. Durch Sulfurierung der Isomerenmischungen mit E ϭ P entstehen Gemische der entsprechenden Thiophosphan-Verbindungen. Die beobachtete Regioselektivität wird mit einer konzertierten Aktion zweier Faktoren erklärt: 1) Dem Einfluss des Heteroatoms N auf die Stabilität der möglichen σ-Komplex-Intermediate und 2) der kollektiven Wirkung von vier Fluorsubstituenten, die 6-und 7-Substitution favorisieren. Ϫ Die Umsetzung von 1 mit Natriummethoxid (Scheme 3) wurde durchgeführt, um die früher [2] aus einer GC-Analyse des Reaktionsgemisches gefolgerte ausschließliche 71 precursors 1Ϫ3 with the organometallic reagents LiR (R ϭ Me, nBu, Ph) and PhMgBr (Scheme 5) products of the nucleophileaddition at position 2 were obtained in high yields, which with hydrochloric acid led to 2-R-1,2-dihydro-5,6,7,8-tetrafluoroquinolines. In contact with air or by reaction with MnO 2 , oxidation to aromatic 2-R-5,6,7,8-tetrafluoroquinolines occurred. To rationalize the observed differences between the "sof...