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Cesium and iodine, which are formed during a fission process in a nuclear reactor, are considered as major fission products responsible for the environmental burden in case of a nuclear accident. From the safety point of view, it is thus important to understand their release mechanism when overheating of the reactor core occurs. This work presents an experimental investigation of the behaviour of caesium iodide and caesium fluoride in fluoride based molten salt reactor fuel during high temperature events. It has been demonstrated that CsF will be retained in the fuel salt and thus its volatility will be significantly reduced, while CsI will not dissolve in the fluoride-based fuel matrix and will thus remain more volatile. The influence of the presence of CsI and CsF on the melting behaviour of the fuel has been investigated using calorimetry, revealing their negligible effects.

Methyl carbonate ionic liquids are shown to readily mono-deprotonate p-tert-butylcalix-[4]-arenes initiating the formation of an organic mono-anionic p-tert-butylcalix-[4]-arate salt, methanol and carbon dioxide. These calix-[4]-arate salts have been successfully used in alkylation reactions with dialkyl sulfates and alkyl halides to form a mono-alkylated single product with high yield. This method avoids the common use of alkali metal bases such as caesium fluoride hence providing a safer and more selective synthetic route.

A recently published palladium-catalyzed preparation of fluoroarenes starting from caesium fluoride attracted interest as a new alternative for radiofluorination. To test this method, a suitable protocol for the synthesis of 4-[18F]fluorotoluene and 1-[18F]fluoronaphthalene as model systems has been developed. The possibility to perform the reaction under no-carrier-added condition was of special interest. It was found out, however, that the reaction requires the presence of carrier, thus limiting the method to syntheses of radiotracers with low specific activity. Copyright © 2012 John Wiley & Sons, Ltd.

Simple and efficient protocols for the 10% palladium on carbon (Pd/C)-catalyzed cross-coupling reactions between triarylbismuths and aryl halides have been developed. A variety of iodo- and bromobenzenes possessing an electron-withdrawing group on the aromatic nucleus were smoothly cross-coupled in the presence of 10% Pd/C, sodium phosphate dodecahydrate (Na3PO4⋅12 H2O) and 1,4-diazabicyclo[2.2.2]octane (DABCO) in heated N-methyl-2-pyrrolidone (NMP) as the solvent. For the arylations of iodobenzenes, the reactions effectively proceeded under the combined use of caesium fluoride (CsF) and 2,2′-biquinoline. Furthermore, a ligand-free 10% Pd/C-catalyzed cross-coupling reaction between the aryl iodides and triarylbismuths was also established by the addition of tetra-n-buthylammonium fluoride trihydrate (TBAF⋅3 H2O) in which the palladium metals were hardly leached from the catalyst into the reaction media.

BACKGROUND: The introduction of poly(ether ether ketone)-based carbon-fiber composites accelerated the application of poly(ether ether ketone)s in advanced composite materials. In order to improve the compatibility and processability with reinforced components, polymers with low melt viscosity are preferable. RESULTS: Novel fully aromatic macrocycle-terminated poly(aryl ether ketone)s (MCPAEKs) were prepared by condensation of macrocyclic aryl ether ketone dimers containing hydroxyphenyl groups and fluorine end-capped poly(aryl ether ketone) oligomers. Compared with liner poly(aryl ether ketone)s, MCPAEKs showed much lower melt viscosities at low temperature. In the presence of caesium fluoride, the crosslinking reaction of MCPAEKs afforded fully aromatic thermoset poly(aryl ether ketone)s by ring-opening reaction. CONCLUSION: The MCPAEKs exhibited high thermal stability due to their wholly aromatic structures. After crosslinking, the glass transition temperatures and complex melt viscosities of the polymers were increased greatly. Although there was some residual cesium fluoride or phenoxides produced by ring-opening reaction, the thermoset poly(aryl ether ketone)s obtained had good thermal stability with temperatures at 5% weight loss above 475 °C. Copyright © 2009 Society of Chemical Industry

Solid-state Nuclear magnetic resonance (NMR) was used here to explore structural characteristics of samples to be subjected to matrix-assisted laser desorption/ionization (MALDI) and prepared without the use of any solvent. The analytical systems scrutinized in NMR were mixtures of a 2,5-dihydroxybenzoic acid (2,5-DHB) matrix and caesium fluoride (CsF), used as the cationization agent in synthetic polymer MALDI mass analysis, at different molar ratios (1:1, 5:1, and 10:1). Complementary information could be obtained from 13C, 133Cs, and 19F NMR spectra. Grinding the matrix together with the salt in the solid state was shown to induce a strong modification in the molecular organization within the MALDI sample. The evidenced mechano-induced reactions allow strong interactions between the matrix and the cation, up to the formation of a salt, and only occur in the presence of some water molecules. Addition of a poly(ethylene oxide) polymer as the analyte did not further modify the observed molecular organizations. Although relative matrix and salt concentrations in the scrutinized samples were unusual for MALDI analysis, mass spectra of good quality could be obtained and revealed that cation attachment on polymers during the MALDI process is not a matrix-independent event since a lower ionization efficiency was obtained from highly organized solid samples, mostly consisting of 2,5-DHB caesium salt species.

CsY2F7: 78% Y3+, 20% Yb3+, 2% Er3+nanocrystals with a mean diameter of approximately 8 nm were synthesized at 185°Cin the high boiling organic solventN-(2-hydroxyethyl)-ethylenediamine (HEEDA) using ammonium fluoride, the rare earth chlorides and a solution of caesium alkoxide ofN-(2-hydroxyethyl)-ethylenediamine in HEEDA. In parallel with this approach, a microwave assisted synthesis was carried out which forms nanocrystals of the same material, about 50 nm in size, in aqueous solution at200∘C/8 bar starting from ammonium fluoride, the rare earth chlorides, and caesium fluoride. In case of the nanocrystals, derived from the HEEDA synthesis, TEM images reveal that the particles are separated but have a broad size distribution. Also an occurred heat-treatment of these nanocrystals (600∘Cfor 45 minutes) led to bulk material which shows highly efficient light emission upon continuous wave (CW) excitation at 978 nm. Besides the optical properties, the structure and the morphology of the three products were investigated by means of powder XRD and Rietveld method.

A series of mono-O-alkylated calix [4] arenes derivatives, with alkyl chain lengths of between 1 and 12 carbon atoms are reported. Monoalkylation is best achieved using potassium carbonate as the weak base and the respective alkyl iodide for chain lengths of one to three carbon atoms and using caesium fluoride as the base and the respective alkyl iodide for longer chain lengths. The mono-alkylated derivatives were converted into the tri-para-dimethylaminomethylene derivatives by the para-quinonemethide reaction in good yields. Surface tension measurements showed that at pH 2, 4, 6 and 8 all the tri-dimethylaminomethylene derivatives showed surfactant behaviour, and at pH 2 all show a Critical Micellar Concentration values. No correlation between Critical Micellar Concentration values and chain length is observed. Dynamic Light Scattering measurements showed that the CMC behaviour may be correlated with the observed aggregate sizes. The solid state structure of mono-O-ethoxy-calix[4]arene is described, in this structure a 1-D inclusion polymer is observed.A series of mono-O-alkylated calix [4] arenes derivatives, with alkyl chain lengths of between 1 and 12 carbon atoms are reported. Monoalkylation is best achieved using potassium carbonate as the weak base and the respective alkyl iodide for chain lengths of one to three carbon atoms and using caesium fluoride as the base and the respective alkyl iodide for longer chain lengths. The mono-alkylated derivatives were converted into the tri-para-dimethylaminomethylene derivatives by the para-quinonemethide reaction in good yields. Surface tension measurements showed that at pH 2, 4, 6 and 8 all the tri-dimethylaminomethylene derivatives showed surfactant behaviour, and at pH 2 all show a Critical Micellar Concentration values. No correlation between Critical Micellar Concentration values and chain length is observed. Dynamic Light Scattering measurements showed that the CMC behaviour may be correlated with the observed aggregate sizes. The solid state structure of mono-O-ethoxy-calix[4]arene is described, in this structure a 1-D inclusion polymer is observed.

A mild method for the generation of benzynes from 2-(trimethylsilyl)iodobenzene derivatives is reported. The employment of silver fluoride in conjunction with caesium fluoride is key for promoting useful levels of elimination and providing benzyne derived products in good yields. Moreover, the substrates are accessed by a novel alkynyl iodide cycloaddition.

The enthalpy of solution of CsF in water at 25.00°C has been carefully measured with an adiabatic calorimeter. The value at infinite dilution is: ΔH°sol = −36.08 ± 0.17 kj/mole.

A new regioselective route to 2-ethoxycarbonylmethyl-1,2-dihydro-N-methylquinolines and 1-ethoxycarbonylmethyl-1,2-dihydro-N-methylisoquinolines is described starting from methylquinolinium or -isoquinolinium iodides and commercially available ethyltrimethylsilyl acetate (ETSA). The methylene carbanion was generated by fluorodesilylation using caesium fluoride. On exposure to air, the ethoxycarbonylmethyl adducts were oxidised, leading to the corresponding alkylidene derivatives 4 and 5, whereas 2a in solution led slowly to its regioisomer 6a.

The haloalkylation of polyfluorothiophenols with CHal 3 R compounds (Hal=Cl, F; R=Cl, H, C 6 H 5 , C 6 F 5 ) in the presence of AlCl 3 has been investigated. The reactions of polyfluorothiophenols 4-XC 6 F 4 SH (X=F, H, CH 3 ) with CCl 4 and AlCl 3 lead to dichloromethane derivatives (4-XC 6 F 4 S) 2 CCl 2 . The reaction of pentafluorothiophenol with CHCl 3 in the presence of AlCl 3 gave (C 6 F 5 S) 2 CHCl and (C 6 F 5 S) 3 CH (ratio by GLC 8:1). In the reaction of pentafluorothiophenol with ArCX 3 (Ar=C 6 H 5 , C 6 F 5 ; X=Cl, F) compounds (C 6 F 5 S) 2 CClAr (Ar=C 6 H 5 , C 6 F 5 ) together with C 6 F 5 SCCl 2 Ar (Ar=C 6 H 5 , C 6 F 5 ) are formed. Peculiarities of these processes are considered. The hydrolysis of (C 6 F 5 S) 2 CCl 2 and C 6 F 5 SCCl 2 C 6 H 5 leads to bis(pentafluorophenyl)dithiocarbonate and the S -(pentafluorophenyl) ester of thiobenzoic acid, respectively. Compounds (C 6 F 5 S) 2 CF 2 and (C 6 F 5 S) 2 CClF were obtained from (C 6 F 5 S) 2 CCl 2 by the action of caesium fluoride. An attempt to produce these compounds through the action of antimony fluorides was unsuccessful. The compounds (C 6 F 5 S) 2 CCl 2 , (C 6 F 5 S) 2 CClF and (C 6 F 5 S) 2 CF 2 are stable to oxidation. The reactions of (C 6 F 5 S) 2 CF 2 and (C 6 F 5 S) 2 CClF with CrO 3 in acetic acid proceeded only with the formation of mono-sulphoxide. The conversion is low in the former case.

Perfluoro-(2,2,6,6-tetramethyl- N -fluoropiperidine) ( 1 ) has been synthesized via direct fluorination (with F 2 –N 2 ) of caesium perfluoro-(2,2,6,6-tetramethylpiperidide) ( 10 ) in cold (−30°C) acetonitrile, the piperidide ( 10 ) being produced via treatment of perfluoro-(2,6-dimethyl-1-azacyclohexene) ( 6 ) with an excess of (trifluoromethyl)trimethylsilane in the presence of caesium fluoride. Methylation of perfluoro-(2,6-dimethyl-1-azacyclohexene) ( 6 ) with methyl-lithium in diethyl ether, followed by the addition of aqueous sulphuric acid provided 3,3,4,4,5,5-hexafluoro-2( a ),6( a )-dimethyl-2( e ),6( e )-bis(trifluoromethyl)piperidine ( 13 ); fluorination (with F 2 –N 2 ) of 13 in trichlorofluoromethane containing anhydrous potassium fluoride provided 3,3,4,4,5,5-hexafluoro-2( a ),6( a )-dimethyl-2( e ),6( e )-bis(trifluoromethyl)- N -fluoropiperidine ( 14 ), the stereochemistry of which was established by X-ray crystallographic analysis. Site-specific electrophilic fluorination of the sodium enolate of ethyl 2-oxocyclopentanecarboxylate ( 15 ) proceeded more efficiently with the new NF reagents 1 and 14 than with their analogues perfluoro- N -fluoropiperidine and perfluoro-(2,6-dimethyl- N -fluoropiperidine), which contain α-fluorine substituents.

Linear oligomers of alternating 2,6-disubstituted pyridine (P) and N,N′-disubstituted imidazolidine-2-one (I) units have been made rapidly and in high yield with up to nine repeating units, terminating in either pyridine or imidazolidin-2-one units, or one of each. Synthetic methods include: (1) the sodium hydride-mediated condensation of N-(tert-butyl)imidazolidin-2-one with 2,6-difluoropyridine (F-P-F) or with higher analogues such as F-PIP-F, to give IPI, IPIPI and IPIPIPI. (The tert-butyl protection is readily and quantitatively removed with acid.) (2) The caesium fluoride catalysed interaction of N,N′-[dimethyl-(1,1,3-trimethylpropyl)]-protected IPI with But-IP-F sequentially leads firstly to IPIPIPI which by the same method reacts with F-P-F to give F-PIPIPIPIP-F. (3) F-P-F also reacts with 1,2-ethylenediamine (E) sequentially to give F-PEP-F, EPEPE and F-PEPEPEP-F while similar reactions starting from F-PIP-F give EPIPE and F-PEPIPEP-F in sequence. Alternative routes examined include: (1) the interaction of F-P-F with imidazole to give 2,6-bis(imidazol-1-yl)pyridine and salts therefrom followed by (unsuccessful) oxidation. (2) The reaction of 2,6-diaminopyridine with 2-chloroethyl isocyanate followed by cyclisation to give IPI. (3) The interaction of 2,6-diaminopyridine with oxalate esters (O) to give OPO or H2N-POP-NH2, the latter of which was reduced to H2N-PEP-NH2.Cyclisation of the linear assemblies was not successful. However macrocyclic systems were made by linking two IPI units with two ethoxyethyl or with two ethoxyethoxyethyl units. Also two F-PIP-F units were similarly reacted to give polyether-linked macrocycles. Mono- and bis-prop-2-ynylated IPI derivatives were made but could not be cyclised. Attempts to cyclise ethylenediamine and oxamide based systems were also unsuccessful. The linear and macrocyclic ligands showed calcium selectivity in a study of their metal complexing abilities.

The atomic metal anions Rb-, Cs-, Cu-, Ag- and Fe- have been generated in the gas phase and reacted with various neutral reactants in a triple quadrupole mass spectrometer. The metal anions were formed via electrospray ionization of the metal-oxalate solutions and form in gas phase between the capillary and the first quadrupole. Neutral gas phase reactants investigated include NO, NO2, SO2, C6F5OH, C6F5NH2, C6F6, E-octafluoro-butene and 1,2,3/1,2,4/1,3,5 trifluoro-benzene. When possible, CBS-4M methods were used to suggest the lowest energy products based on relative energy. Observed reactions of atomic metal anions with the aforementioned neutral species include electron transfer and dissociative electron transfer to the neutral gas phase reactants. In addition, hydrogen abstraction and fluorine abstraction forming a neutral metal hydride or fluoride as well as the formation of multiply substituted metal-oxide/fluoride anions was also observed. Metal-complex anions observed from the gas phase reactions include CuF-,CuF2-,CuO-,CuO2-, FeO-, FeO2-, FeO3-, FeF-, FeF2-, FeF3-, CsF- and CsF2-.

Substituted 3,4,6,7-tetrahydro-1H-5,2-benzoxathionines 4 have been synthesized by the base-assisted aromatization of [2,3] sigmatropic rearrangement products 7 (substituted 1,3,4,11a-tetrahydro-6H-5,2-benzoxathionines) of the S-ylides 3, which were generated by the reaction of trans-3-(substituted phenyl)-4-(trimethylsilyl)methyl-1,4-oxathianium perchlorate 2 with caesium fluoride in dimethyl sulfoxide (DMSO) at room temperature.

Simple and efficient protocols for the 10% palladium on carbon (Pd/C)-catalyzed cross-coupling reactions between triarylbismuths and aryl halides have been developed. A variety of iodo- and bromobenzenes possessing an electron-withdrawing group on the aromatic nucleus were smoothly cross-coupled in the presence of 10% Pd/C, sodium phosphate dodecahydrate (Na3PO4⋅12 H2O) and 1,4-diazabicyclo[2.2.2]octane (DABCO) in heated N-methyl-2-pyrrolidone (NMP) as the solvent. For the arylations of iodobenzenes, the reactions effectively proceeded under the combined use of caesium fluoride (CsF) and 2,2′-biquinoline. Furthermore, a ligand-free 10% Pd/C-catalyzed cross-coupling reaction between the aryl iodides and triarylbismuths was also established by the addition of tetra-n-buthylammonium fluoride trihydrate (TBAF⋅3 H2O) in which the palladium metals were hardly leached from the catalyst into the reaction media.

Hexamethyldisilazane and 1,1,1-trimethyl- N , N -bis(trimethylsilyl) stannaneamine aminate pentafluoropyridine, octafluorotoluene, pentafluorobenzonitrile, pentafluoronitrobenzene and pentafluorobenzene sulphonyl fluoride in the presence of caesium fluoride with formation of the corresponding perfluorinated aryl amines (ArNH 2 ), diarylamines (Ar 2 NH) and triarylamines (Ar 3 N) (where the amine functions are in positions 4 relative to the arene substituent).

The effect of intracellular fluoride ions on voltage-dependent calcium currents was tested during whole-cell voltage-clamp recordings in thalamic neurones acutely dissociated from young adult rats. It is demonstrated that 5-30 mM intracellular fluoride selectively and reversibly suppresses the high voltage-activated, dihydropyridine-sensitive calcium current, without affecting the transient, low voltage-activated calcium current. Intracellular diffusion of a fluoride-free solution restores the blocking effect on the slow inactivating current induced by a transitory fluoride perfusion obtained by filling the patch microelectrode tip with caesium fluoride.

One pot asymmetrical double allylations of sodium sulfide catalyzed by an iridium complex along with a combination of caesium fluoride and water in dichloromethane have been realized and the double allylation products with two C–S bond chiral centers were obtained in 67–99% yields with b/l 81/19–99/1, dr 85/15–99/1, and 96–99% ee.

Hexafluoroisopropyl groups were introduced into fluorinated aromatic systems using 2H-pentafluoropropene and caesium fluoride. Reaction with pentafluoronitrobenzene gave a fluorinated isoxazole and a mechanism is advanced for this reaction. Direct observation of fluorinated benzyl anion derivatives has been possible and effects on fluorine chemical shifts are discussed.

Hexamethyldisilazane and 1,1,1-trimethyl- N , N -bis(trimethylsilyl) stannaneamine aminate pentafluoropyridine, octafluorotoluene, pentafluorobenzonitrile, pentafluoronitrobenzene and pentafluorobenzene sulphonyl fluoride in the presence of caesium fluoride with formation of the corresponding perfluorinated aryl amines (ArNH 2 ), diarylamines (Ar 2 NH) and triarylamines (Ar 3 N) (where the amine functions are in positions 4 relative to the arene substituent).

Aziridination of vinylsilanes PhCHCHSiR3 (R = Me, Et, Ph) with enantiopure 3-acetoxyaminoquinazolinone 11 gives the corresponding aziridines 12 [diastereoisomer ratio (dr) 10∶1], 18 (dr 13∶1) and 20 (dr 2∶1). Desilylative elimination of the quinazolinone from these aziridines by caesium fluoride in the presence of cyanide gives aziridine 14 by cyanide addition to the 3-unsubstituted azirine 13, produced in situ. Acylation of aziridine 14 with (S)-acetoxypropionyl chloride gives N-acylaziridine 16; the good correlation between the diastereoisomer ratios of aziridines 12, 18 and 20 and those of the N-acylaziridine 16 produced in each case suggests that intermediate azirine 13 is configurationally stable.

Inden-2-one and some simple derivatives are smoothly generated by reaction of caesium fluoride with 1-bromo-2-tert-butyldimethylsilyloxyindenes and they can be efficiently trapped in both intra- and inter-molecular additions; the intramolecular additions proceed with exo-addition of the tether, in contrast to the intermolecular additions and intramolecular additions to 2-benzopyran-3-ones.

Perfluoro-(2,2,6,6-tetramethyl- N -fluoropiperidine) ( 1 ) has been synthesized via direct fluorination (with F 2 –N 2 ) of caesium perfluoro-(2,2,6,6-tetramethylpiperidide) ( 10 ) in cold (−30°C) acetonitrile, the piperidide ( 10 ) being produced via treatment of perfluoro-(2,6-dimethyl-1-azacyclohexene) ( 6 ) with an excess of (trifluoromethyl)trimethylsilane in the presence of caesium fluoride. Methylation of perfluoro-(2,6-dimethyl-1-azacyclohexene) ( 6 ) with methyl-lithium in diethyl ether, followed by the addition of aqueous sulphuric acid provided 3,3,4,4,5,5-hexafluoro-2( a ),6( a )-dimethyl-2( e ),6( e )-bis(trifluoromethyl)piperidine ( 13 ); fluorination (with F 2 –N 2 ) of 13 in trichlorofluoromethane containing anhydrous potassium fluoride provided 3,3,4,4,5,5-hexafluoro-2( a ),6( a )-dimethyl-2( e ),6( e )-bis(trifluoromethyl)- N -fluoropiperidine ( 14 ), the stereochemistry of which was established by X-ray crystallographic analysis. Site-specific electrophilic fluorination of the sodium enolate of ethyl 2-oxocyclopentanecarboxylate ( 15 ) proceeded more efficiently with the new NF reagents 1 and 14 than with their analogues perfluoro- N -fluoropiperidine and perfluoro-(2,6-dimethyl- N -fluoropiperidine), which contain α-fluorine substituents.

Treatment of a benzyl substituted meso-ditriflate with boronic acids in the presence of palladium acetate, triphenylphosphine and caesium fluoride results in intermolecular Suzuki coupling followed by vinyl triflate–arene cyclisation to provide, in high yields, single regioisomers of tricyclic-carbocycles.

Reactions of (CH3)3SiRf (Rf = CF3, C2F5) with NOCl, NO/NO2, SO2, CO2, in the presence of caesium fluoride provide a one step synthetic route to perfluoroalkylated compounds in very good yields.

[Na(15-crown-5)][NbF 5 (NPPh 3 )] (1) has been prepared by the reaction of [NbCl 4 (NPPh 3 )] 2 with excess sodium fluoride in acetonitrile in the presence of 15-crown-5. Partial hydrolysis of (1) leads to (PPh 3 NH 2 )[NbF 5 (NPPh 3 )] (2). According to the crystal structure determinations both phosphorane-iminato complexes form ion pairs. The anions contain nearly linear N − N + PPh 3 groups. [Cs(15-crown-5) 2 ](WOF 5 ) (3) was obtained by hydrolysis through the reaction of WCl 5 (NPPh 3 ) with caesium fluoride in acetonitrile solution in the presence of 15-crown-5. The crystal structure analysis shows that each Cs + ion is coordinated sandwich-like by two crown ether molecules. The (WOF 5 ) − ions are disordered; the unit cell shows similarities to that of CsCl and of KOsF 6 . 1. (1) Space group Pbca ; Z =8; 2253 observed independent reflections; R =0.054. Lattice dimensions at 20 °C: a =1909.3(7) pm; b =1700.4(8) pm; c =1932.3(7) pm. 2. (2) Space group P 1 ; Z =2; 5128 observed independent reflections; R =0.034. Lattice dimensions at −50 °C: a =1293.4(1) pm; b =1632.1(1) pm; c =877.8(1) pm; α =104.101(7)°; β =104.000(8)°; γ =70.438(7)°. 3. (3) Space group P 1 ; Z =1; 2746 observed independent reflections; R =0.037. Lattice dimensions at 20 °C: a =863.5(1) pm; b =894.9(1) pm; c =1003.7(1) pm; α =96.03(1)°; β =92.84(1)°; γ =98.62(1)°.

Treatment of bromodeoxyaldonolactones with a nonaqueous base, such as potassium fluoride, caesium fluoride or potassium carbonate in acetone, yields 2,3-anhydro-, 5,6-anhydro-, and 2,3:5,6-dianhydrohexonolactones, or 2,3-anhydro- and 2,3:6,7-dianhydroheptonolactones in good yields

An efficient reagent-controlled methodology for generating highly substituted diverse scaffolds from a common substrate has been developed; thus, treatment of a common precursor with different desilylating reagents, such as ammonium fluoride, caesium fluoride and PPTS, triggers different domino reaction sequences, yielding highly substituted pyridines, phenols and benzopyrans, respectively; the substituent patterns of these scaffolds provide further opportunities for library development.

Treatment of (1R)-camphorquinone 2 with (trifluoromethyl)trimethylsilane in the presence of catalytic amounts of caesium fluoride in DME at room temperature yields two pairs of exo/endo isomers of trifluoromethylated silylated alcohols 5 and 6. In this case, nucleophilic addition of the CF3 anion occurs neither regio- nor stereoselectively. On the other hand, the analogous reaction with (1R)-camphorquinone 3-imines 3, followed by hydrolysis with 5 M HCl in ethanol, leads stereoselectively to (1R,2S)-2-hydroxy-2-(trifluoromethyl)bornan-3-one 8. The attempted reductions of the intermediate adducts with NaBH4 in ethanol gave the corresponding (1R,2S)-3-imino-2-(trifluoromethyl)bornan-2-ols 9 as the sole isomers in high yield. The configuration of C(2), that is, the endo course of the nucleophilic CF3 addition, was proven by X-ray crystallography. Furthermore, the reduction of the Cdouble bond; length as m-dashN bond in 9 with DIBAL-H leads stereoselectively to the exo amino derivatives 10, which, by treatment with phosgene, smoothly form the fused 1,3-oxazolidin-2-ones 11. In contrast, the reduction of ketone 8 yields a mixture of the exo,exo- and exo,endo-2,3-diols 12.

Reactions of isomeric pyridinealdehydes and acetylpyridines with dime thylphenylsi lane proceed readily in dichloromethane in the presence of catalytic amounts of CsF and 18-crown-6 to give silyl ethers of the corresponding pyridyl carbinols in good yields (50–70%).

Fluorine-19 NMR of the products of halogen exchange between octachloronaphthalene and caesium fluoride or potassium fluoride is reported. Twelve polychloropolyfluoronaphthalenes, although in complex mixtures and largely inseparable, could be identified by fluorine-19 NMR. One of the easily recognised parts of the fluorine NMR spectra was the ABX of 1,2,3,6,8-pentachloro-4,5,7-trifluoronaphthalene with a peri through-space F,F coupling of 95.8Hz. Initial exchange occurs at the 1-position in octachloronaphthalene and subsequent exchange occurs at the 3-position and/or at the 8-position. After four exchanges the dominant product was found to be 1,3,6,8-tetrachloro-2,4,5,7-tetrafluoronaphthalene in an experiment in aprotic solvent.

Nucleophilic fluoride fluoro-dechlorination of four isoquinolines (5,6,7,8-tetrachloro-,3,5,6,7,8-pentachloro-,3,4,5,6,7,8-hexachloro- and 1,3,4,5,6,7,8-heptachloro-isoquinoline) led to the preparation of 15 new polychloropolyfluoro isoquinolines by reaction with caesium fluoride in DMSO at 100°C. The product from the perchloroisoquinoline was an inseparable mixture of C 9 Cl 7− n F n N where n is 1–3. The order of reactivity in 1,3,4,5,6,7,8-heptachloro-isoquinoline [10] to nucleophilic attack by fluoride was 1⪢6=7=8>3=5>4

A new regioselective route to 2-ethoxycarbonylmethyl-1,2-dihydro-N-methylquinolines and 1-ethoxycarbonylmethyl-1,2-dihydro-N-methylisoquinolines is described starting from methylquinolinium or -isoquinolinium iodides and commercially available ethyltrimethylsilyl acetate (ETSA). The methylene carbanion was generated by fluorodesilylation using caesium fluoride. On exposure to air, the ethoxycarbonylmethyl adducts were oxidised, leading to the corresponding alkylidene derivatives 4 and 5, whereas 2a in solution led slowly to its regioisomer 6a.

Caesium fluoride was shown to afford advantages over caesium iodide as a mass-calibration compound for fast atom bombardment mass spectrometry.

The work function of indium tin oxide (ITO) was modified using caesium fluoride (CsF). Various concentrations of CsF was spin-coated on top of ITO and baked while the residual CsF was washed away with DI water. The work function of all the ITO samples was measured using ultraviolet photoelectron spectroscopy and it was found that the work function of ITO reaches as high as 5.75 eV. The work function rapidly increases with small concentrations of CsF solution and then decreases for higher concentrations. Using atomic force microscopy and x-ray photoelectron spectroscopy, the cause was determined to be the change in surface roughness and the oxygen concentration, with the former having a much greater influence on the work function than the latter. The current density of ITO/poly(vinylcarbazole)/Al hole-only devices using the modified ITO increases by more than seven orders of magnitude compared with the control device.

Reactions of (CH3)3SiRf (Rf = CF3, C2F5) with NOCl, NO/NO2, SO2, CO2, in the presence of caesium fluoride provide a one step synthetic route to perfluoroalkylated compounds in very good yields.

Treatment of a benzyl substituted meso-ditriflate with boronic acids in the presence of palladium acetate, triphenylphosphine and caesium fluoride results in intermolecular Suzuki coupling followed by vinyl triflate–arene cyclisation to provide, in high yields, single regioisomers of tricyclic-carbocycles.

Ten DNA fragments containing self-complementary alternating sequences of adenine and thymine differing in length and the starting nucleotide were studied by c.d. spectroscopy. It was found that d(TATATATA) but not d(ATATATAT), d(TATATA), d(CTATATAG) or (dT-dA)20 isomerized into the unusual X-DNA double helix at molar concentrations of CsF in solution. But in contrast to poly(dA-dT), the octamer (dT-dA)4, isomerized very slowly, at relatively low CsF concentrations and the isomerization was strongly dependent on the octamer concentration. A model is proposed to account for the observed properties of the B-to-X isomerization on the oligomer level.

(Fluoroarene)tricarbonylchromium(0) complexes were found to undergo Suzuki and Stille cross-coupling reactions to form functionalised biaryl and styrene complexes in up to 87 and 52% yields, respectively. The Suzuki reactions were optimal with dipalladium tris(dibenzylideneacetone)–trimethylphosphine–caesium carbonate in DME at reflux. The Stille reactions were optimal with dipalladium tris(dibenzylideneacetone)–trimethylphosphine–caesium fluoride in DME at reflux and neither was adversely affected by a methoxy group on the complexed ring. The Suzuki reaction tolerated a chloro group on the arylboronic acid ring but not a bromo group.

Inden-2-one and some simple derivatives are smoothly generated by reaction of caesium fluoride with 1-bromo-2-tert-butyldimethylsilyloxyindenes and they can be efficiently trapped in both intra- and inter-molecular additions; the intramolecular additions proceed with exo-addition of the tether, in contrast to the intermolecular additions and intramolecular additions to 2-benzopyran-3-ones.

Treatment of substituted 1-methyl- and 1-trimethylsilylmethyl-1,2,3-triazolium salts with ethoxide and caesium fluoride respectively gave substituted 2,3-dihydro-1,2,4-triazines and 1-aminoimidazoles via 1,2,5-triazahexa-1,3,5-triene intermediates. Expected isomeric 1,2,3-triazolium-1-methanide 1,3-dipoles were not detected and ab initio calculations suggested that they are thermodynamically unfavoured. Ab initio calculations on the equilibrium between the acyclic hetero-1,3,5-triene system and the cyclic forms of 1,2,3-triazolium-1-oxide, -1-imide and -1-methanide are reported. X-Ray crystal structures are described for 2,5,6-triphenyl-2,3-dihydro-1,2,4-triazine 6a and 1-(p-nitro-anilino)-4,5-diphenylimidazole 11c.

Polyfluorinated N-arylhydroxylamines are obtained in the reaction of hydroxylamine or its derivatives with polyfluoroaromatic compounds [1]. The reaction of N-polyfluoroaryl-O-alkylhydroxylamines with polyfluoroaromatic compounds in the presence of caesium fluoride has been studied, which gave N,N-bispolyfluoroaryl -O-alkylhydroxylamines 1 in 80–90% yields. It has been shown that compounds 1 may be obtained in a small yield from O-alkylhydroxylamines and polyfluoroaromatic oompounds in drastic conditions. Some reactions of compounds 1 in acid systems have been studied.