Pentafluorophenyl acetonitrile

The formation of ethyl cyano(pentafluorophenyl)acetate illustrates the intermolecular nucleophilic displacement of fluoride ion from an aromatic ring by a stabilized carbanion. The reaction proceeds readily as a result of the activation imparted by the electron-withdrawing fluorine atoms. The selective hydrolysis of a cyano ester to a nitrile has been described. (Pentafluorophenyl)acetonitrile has also been prepared by cyanide displacement on (pentafluorophenyl)methyl halides. However, this direct displacement is always aecompanied by an undesirable side reaetion to yield 15-20% of 2,3-bis(pentafluoro-phenyl)propionitrile. 

The low-temperature method was then applied to the resolution of ( )-2-hydroxy-2-(pentafluorophenyl)acetonitrile (7) (Fig. which is usahle for the syntheses of a variety of ethane diols, amino alcohols containing CgFj groups as novel chiral ligands. After screening lipases such as Amano PS and AK, lipase LIP Pseudomonas aeruginosa lipase immobilized on Hyflo Super-Cel, Toyobo,... 

Diethyl malonatc13 gives four products upon reaction with perchloryl fluoride diethyl difluoro-malonate, diethyl ethylmalonate, diethyl ethylfluoromalonate and diethyl fluoromalonate the product distribution depends on the reaction conditions. A number of esters are fluo-rinated,14 15 while (pentafluorophenyl)acetonitrile is converted into mono- and disubstituted products in the presence of cesium fluoride.16... 

The Pseudomonas aeruginosa lipase (immobilised on hyflo Super-Cel) catalysed kinetic resolution of (rac)-2-(acetyloxy)-2-(pentafluorophenyl)acetonitrile gave en-antiomerically pure cyanohydrin and its antipodal ester [142-144l... 

A new one-step synthesis of (pentafluorophenyl)acetonitrile, the precursor of 2-(pentafluorophenyl)ethylamine, provides the key to the much improved route to 4,5,6,7-tetrafluoroindole shown in Scheme 45 [apparently the reaction of penta-... 

Byeon et al. [23] described a fluorimetric method for (z>)-penicillamine using 9-fluorenylmethyl pentafluorophenyl carbonate and acetonitrile. Capsules containing penicillamine were extracted with water and then filtered. The solution was incubated at 70 °C for 40 min with borate buffer solution. After cooling, the mixture was extracted with diethyl ether and the fluorescence of the aqueous phase measured at (excitation = 260 nm, emission = 313 nm). The calibration graph was linear for 0.4-5.0 pM of penicillamine with a coefficient of variation of 0.4%. 

The reaction of pentafluorophenyl isocyanate with thiadiazole 8 in acetonitrile at room temperature gave 5-penta-fluorophenylureido-l,3,4-thiadiazole-2-sulfonamide 105 (Equation 31) <2004JME2796>. Similarly, 2-amino-l,3,4-thia-diazole 37 reacts with benzyl isocyanate in dry THF to afford the l,3,4-thiadiazol-2-yl urea 106 in 94% yield (Equation 32) <1999JME1525>. 

Solution-phase DPV of Au144-C6S dispersed in 10 mM [bis(triphenylpho-sphoranylidene)-ammoniumtetrakis-(pentafluorophenyl)-borate (BTPPATPFB)/ toluene] [acetonitrile] 2 1 revealed well-behaved, equally spaced and symmetric quantized double-layer charging peaks with AE - 0.270 0.010 V. Applying the classical concentric spheres capacitor model (8) reveals an individual cluster capacitance of 0.6 aF [334, 335]. 

Although these two methods have found widespread application for the synthesis of free carbenes, they failed for selected saturated imidazolidin-2-ylidenes and especially in the preparation of triazolin-5-ylidenes. In these cases the free carbene species 7 can be obtained from 2-alkoxyimidazolidines 6 [44] or 5-aUcoxytriazoles [36] by thermally induced ot-elimination of an alcohol (Fig. 5). In addition to 2-aUcoxyimidazolidmes, 2-(pentafluorophenyl)imidazolidines [45, 46] have also been used for the generation of NHCs by cx-elimination. The adduct 8 eliminates acetonitrile upon heating [47] to yield the benzimidazolin-2-ylidene 9. In a more exotic procedure, imidazolium salts have been reduced electrochemically to give the free imidazolin-2-ylidenes [48]. 

Iodine pentafluoride reacts quantitatively with perfluoro(trifluorOsilyl)benzene in acetonitrile at 20"C in the absence of pyridine to yield (pentafluorophenyl)iodine tetrafluoride.133 Alk-oxysilanes were used to replace fluorine atoms in iodine pentafluoride with alkoxy groups.135136... 

The use of iodoacetic acid as an aryl radical trapping agent has confirmed the intermediacy of aryl radicals in some hydrodediazoniation reactions, whether these are initiated or not.4 Spontaneous hydrodediazoniation of aryldiazonium fluoroborates occurs in warm dimethylformamide (DMF). Detailed study5 of the conversion of the 4-nitro derivative into nitrobenzene indicates a homolytic mechanism in which H-atom abstraction occurs from both sites in DMF with a formyl methyl preference of 3.5 1.0. High yields of mixed perfluorinated biaryls may be obtained by the catalytic dediazoniation of pentafluorobenzenediazonium ions in acetonitrile containing aromatic substrates and small amounts of iodide salts. The catalytic role of iodide and the isomeric product distributions indicate that arylation proceeds through the pentafluorophenyl radical in an efficient homolytic chain process.6... 

Pentafluorophenyl Tellurium Trifluoride1 A solution of 0.191 g (0.324mmol) bis[pentafluorophenyl] ditellurium in 5 ml acetonitrile is cooled to — 20. A solution of 0.172 g (1.016 mmol) of xenon difluoride is added in small portions. Acetonitrile is distilled from the reaction mixture. Excess xenon difluoride is removed by sublimation. 

Bis[pentafluorophenyl] tellurium tetrafluoride is very reactive and fluori nates organic solvents such as diethyl ether, methanol, acetonitrile, dimethyl sulfoxide, and nitromethane4.The products obtained by the addition of iodine or iodine halides to... 

Bis[pentafluorophenyl] tellurium and pentafluorophenyl xenon fluorotrisfpentafluorophe-nyljborate reacted in acetonitrile to give the tris[pentafluorophenyl] telluronium salt1. 

Pentafluorophenyl tellurium trifluoride was similarly obtained from the ditellurium compound and xenon difluoride in acetonitrile ... 

HPLC analysis of taxanes is achieved almost exclusively in reversed phase mode on various stationary phases. The normal-phase HPLC mode has been applied in very limited cases and resulted in broad peaks and long analysis times (retention times of 45 min for paclitaxel and 38 min for cephalomannine). The namre of the sample is the main criterion for the choice of the stationary phase. Analysis of plant material is performed mostly on phenyl, biphenyl, and pentafluorophenyl materials, but silica-based cyano, Cig, and Cg materials have been used as well. C18 phases are the most common material utilized in pharmacokinetic studies. Mobile phases typically consist of mixtures of methanol, acetonitrile, and water or buffer (mostly ammonium acetate). Detection is performed by UV, mostly in the low region of 225 -230 nm. Taxanes give similar UV spectra with a minimum at 210-215 nm and a maximum at 225-232 nm. Therefore, detection is performed, preferably at 227-228 nm. Dual/multiple UV detection is performed in both low and upper regions, e.g. 227 and 273 nm 230 and 280 nm 227, 254, and 270 nm, etc. (Fig. 2). 

---