V. F. Starichenko

Highly efficient cross-coupling reactions with the perfluoroorganotrifluoroborate salts K [RFBF3] (RF=C6F5, CF2CF)

Potassium pentafluorophenyl- and trifluorovinyltrifluoroborates, both containing electron-poor organo groups, reacted with iodobenzene and p-substituted iodobenzenes in the presence of palladium compounds and stoichiometric amounts of silveroxide to the fluorinated cross-coupling products in very good yields. Substituted bromobenzenes were less efficient substrates.

A new application of (polyfluoroorgano)trifluoroborate salts: the palladium-catalysed cross-coupling reaction with substituted benzenediazonium tetrafluoroborates

Abstract For the first time (polyfluoroorgano)trifluoroborate salts, namely K[C 6 F 5 BF 3 ], K[C 6 HF 4 BF 3 ] (all three isomers), K[3,4,5-C 6 H 2 F 3 BF 3 ], and K[CF 2 CFBF 3 ] were principally applied as reagents to Pd-catalysed cross-coupling reactions. A series of polyfluorinated biphenyls C 6 H 5− n F n –C 6 H 4 X-4′ were obtained from K[C 6 H 5− n F n BF 3 ] and the substrates [4-XC 6 H 4 N 2 ][BF 4 ] in the presence of Pd catalysts. The influence of the number and the position of the fluorine atoms in the (polyfluorophenyl)trifluoroborate salts on the reactivity in the coupling reaction was elucidated. In addition to (polyfluorophenyl)trifluoroborate salts, the cross-coupling was expanded to a first example of a perfluoroalkenyl reagent. K[CF 2 CFBF 3 ] reacted with [4-FC 6 H 4 N 2 ][BF 4 ] and formed CF 2 CF–C 6 H 4 F-4.

Regioselective ortho-hydrodefluorination of pentafluorobenzoic acid by low-valent nickel complexes

Abstract 2,3,4,5-Tetrafluorobenzoic and 3,4,5-trifluorobenzoic acids were prepared in high yields by reaction of C 6 F 5 COOH with zinc in the presence of NiCl 2 –2′-bipyridine (or 1,10-phenanthroline) complexes.

Polyfluoroorganoboron-Oxygen Compounds. 2 [1] Base-catalysed Hydrodeboration of Polyfluorophenyl(dihydroxy)boranes†

Polyfluorinated phenyl(dihydroxy)boranes C6H5-nFnB(OH)2 (n = 3 — 5) underwent hydrodeboration (formal replacement of the (dihydroxy)boryl group by hydrogen) in the presence of bases (MeOH, 33 % H2O—MeOH, KOH (1 equiv.)/33 % H2O—MeOH, pyridine and 9 % D2O—pyridine) and formed the fluoroaromatic compounds ArH or ArD, respectively. The rate of reaction depends on the number of fluorine atoms in the phenyl group and on the position of the fluorine atoms, relative to the B(OH)2 substituent. Polyfluororganische Bor-Sauerstoff Verbindungen. 2 [1] Die Hydrodeborierung von Polyfluorphenyl(dihydroxy)boranen unter basischen Bedingungen Polyfluorierte Phenyl(dihydroxy)borane C6H5-nFnB(OH)2 (n = 3 — 5) unterliegen in Gegenwart von Basen (MeOH, 33 % H2O—MeOH, KOH (1 Aquiv.)/33 % H2O—MeOH, Pyridin und 9 % D2O—Pyridin) einer Hydrodeborierungsreaktion (formaler Ersatz der (Dihydroxy)borylgruppe durch Wasserstoff) und bilden die entsprechenden Fluoraromaten ArH oder ArD. Die Reaktionsgeschwindigkeit hangt dabei von der Anzahl der Fluoratome in der Arylgruppe und der relativen Stellung der Fluoratome zum B(OH)2-Substituenten ab.

Polyfluoroorganoboron-Oxygen Compounds. 1 Polyfluorinated Aryl(dihydroxy)boranes and Tri(aryl)boroxins†

A general preparative procedure for polyfluorinated aryl(dihydroxy)boranes C6H5-nFnB(OH)2 (n = 3 — 5) is described. Polyfluorinated aryl(dihydroxy)boranes are easily dehydrated to the corresponding tri(aryl)boroxins (C6H5-nFnBO)3 by thermal or chemical treatment. The property of the acids C6H5-nFnB(OH)2 to condensate depends on the number and on the position of the fluorine atoms in the aryl group. Examples of both classes of boron compounds were isolated as pure individuals and characterized by multinuclear NMR spectroscopy. Polyfluororganische Bor-Sauerstoff Verbindungen. 1 Polyfluorierte Aryl(dihydroxy)borane und Tri(aryl)boroxine Es wird ein allgemeiner Weg fur die Darstellung polyfluorierter Aryl(dihydroxy)borane beschrieben. Polyfluorierte Aryl(dihydroxy)borane lassen sich thermisch und chemisch leicht dehydratisieren und gehen dabei in die entsprechenden Tri(aryl)boroxine uber. Die Neigung zur Kondensation hangt sowohl von der Anzahl als auch von der Stellung der Fluoratome in der Arylgruppe ab. Es werden Beispiele fur beide Klassen von Borverbindungen vorgestellt, die in Reinsubstanz isoliert und durch Multikern-NMR-Spektroskopie charakterisiert wurden.

The palladium-catalysed cross-coupling reaction of lithium polyfluorophenyltrimethoxyborates with 4-fluoroiodobenzene

Abstract Li[C 6 F 5 B(OMe) 3 ], Li[C 6 HF 4 B(OMe) 3 ] (all three isomers) and Li[3,4,5-C 6 H 2 F 3 B(OMe) 3 ] are the first examples of polyfluorophenyltrimethoxyborate salts which have been applied as reagents to Pd-catalysed cross-coupling reactions. A series of polyfluorinated biphenyls C 6 H 5− n F n -C 6 H 4 F-4′ were obtained from Li[C 6 H 5− n F n B(OMe) 3 ] and the model substrate 4-FC 6 H 4 I in the presence of Pd catalysts. The influence of the number and the position of fluorine atoms in the polyfluorophenyltrimethoxyborate salts on the reactivity in the coupling reaction was elucidated.

Preparative Electrochemical Reduction of Fluorinated Benzonitriles

Electrochemical reduction of fluorinated benzonitriles in aprotic media is accompanied by concurrent processes of dimerization and fragmentation of the corresponding anion-radicals. With 2-fluoro- and 3,4,5-trifluorobenzonitriles the defluorinated products can be obtained at direct electrochemical reduction; for the other compounds studied have been found mediators providing a possibility to obtain in high yield defluorinated products at preparative electrochemical reduction. A fundamental possibility was demonstrated of providing products by nucleophilic fluorine substitution by SBN mechanism at electrochemical reduction of fluorinated benzonitriles in aprotic solvents in the presence of mediators.

Perylene derivatives formation in reaction of 3-bromobenzanthrone and 4-bromonaphthalic acid derivatives with a reduction system NiCl2-2,2′bipyridyl (or 1,10-phenathroline)-Zn

The reaction of 3-bromobenzanthrone and 4-bromonaphthalic acid derivatives with a reduction system NiCl2-2,2′bipyridyl (or l,10-phenathroline)-Zn gives rise to compounds containing perylene fragment. Under similar conditions was established a possibility to transform substituted l.l′-binaphthyls into the corresponding perylene derivatives.

Preparative Electrochemical Reduction of Decafluorobenzil

Preparative electrochemical reduction of decafluorobenzil in DMF on a platinum electrode at the potential of the first peak afforded decafluorobenzophenone as the principal product. The reaction mixture lacked products of hydrodefluorination of the decafluorobenzil or of its reduction at the C=O group.