Vadim V. Bardin

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.

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.

Trifluoropropynylxenon(II) tetrafluoroborate [CF3CCXe][BF4] – isolation of an alkynylxenon(II) compound for the first time

The salt [CF3CCXe] [BF4] was prepared as neat compound by the reaction of the hitherto unknown alkynyldifluoroborane CF3CCBF2 with XeF2 in 1,1,1,3,3-pentafluoropropane (PFP) at −45 °C in 59% yield. [CF3CCXe] [BF4] was unambiguously characterised by multinuclear NMR spectroscopy in anhydrous HF (aHF) solution.

A Convenient and General Approach to Alkyl-, Alk-1-enyl-, and Aryldifluoroboranes

A simple and general procedure, especially useful for the small scale preparation of alkyl-, alk-1-enyl-, and aryldifluoroboranes RBF2 was elaborated. Suspensions of the easily available and storable K [RBF3] salts undergo fluoride abstraction when treated with boron trifluoride to form solutions of the corresponding difluoroboranes RBF2.

Fluorination of tetrafluorobenzenes C6HF4R with XeF2

Abstract Replacement of hydrogen by fluorine and addition of fluorine atoms to the aromatic ring were found in the reaction of XeF2 with 1,2,3,4,5-tetrafluorobenzene (RH, F, Br, NO2) or 1-R-2,3,4,6-tetrafluorobenzene (RH, CF3) in HF or CH2Cl2BF3·OEt2. Only flourine addition took place in the case of 1-R-2,3,5,6-tetrafluorobenzenes (RH, Br, CF3) or 1-Br-2,3,4,6-tetrafluorobenzene. The role of cation radicals as reactive intermediates is discussed.

(Heptafluoro-1,4-cyclohexadien-1-yl)xenon(II) and (nonafluorocyclohexen-l-yl)xenon(II) hexafluoroarsenates: synthesis, spectroscopic characterization and reactivity of the first alkenylxenon(II) compounds

The first alkenylxenon(II) compounds: (heptafluoro-1,4-cyclohexadien-1-yl)xenon(II) hexafluoroarsenate [1-Xe+-1,4-C6F7][AsF6]- and (nonafluorocyclohexen-l-yl)xenon(II) hexafluoroarsenate [1-Xe+-C6F9][AsF6]– were obtained by fluorination of [C6F5Xe]+[AsF6]– with XeF2 in HF.

New approach to the synthesis of tris(perfluoroalkyl)borane adducts with dialkylamines

A convenient synthetic approach to the adducts (CnF2n+1)3BNHR2 (n = 2–4, 6; R = Me, Et) was developed, based on the reaction of lithium perfluoroalkyls with dichloro(dialkylamino)boranes at temperatures below −90°C. The target products can be synthesized with preparative yields of 50–90%.

Synthesis and Properties of Perfluoroalkenylboronic Acids and some of their Derivatives

Lithium perfluoroalkenyltrimethoxyborates were prepared and characterised by NMR spectroscopy. These compounds possess the properties inherent in both organic and inorganic boron-containing compounds. Li[XCF=CFB(OMe)3] (X = F, c«-CF3, Irans-CF^) react with I2 to give corresponding 1iodopolyfluoroalkenes in 30-50 % yields. Interaction of Li[XCF=CFB(OMe)3] with ClSiMe3, followed by working up with XCF=CFLi leads to formation of lithium bis(perfluoroalkenyl)dimethoxyborates. Reaction of Li[(XCF=CF)„B(OMe)4-n] with K[HF2] in aqueous HF gives corresponding potassium perfluoroalkenylfluoroborates, K[(XCF=CF)nBF4.n].