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CF3 Groups (cf3 + groups)
Selected AbstractsChemInform Abstract: C,C Coupling Reactions of Superstrong CF3 Groups with C(sp2),H Bonds: Reactivity and Synthetic Utility of Zero-Valent Niobium Catalyst.CHEMINFORM, Issue 27 2008Kohei Fuchibe Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Electrophilic S -Trifluoromethylation of Cysteine Side Chains in , - and , -Peptides: Isolation of Trifluoro-methylated Sandostatin® (Octreotide) DerivativesHELVETICA CHIMICA ACTA, Issue 11 2008Stefania Capone Abstract The new electrophilic trifluoromethylating 1-(trifluoromethyl)-benziodoxole reagents A and B (Scheme,1) have been used to selectively attach CF3 groups to the S-atom of cysteine side chains of , - and , -peptides (up to 13-residues-long; products 7,14). Other functional groups in the substrates (amino, amido, carbamate, carboxylate, hydroxy, phenyl) are not attacked by these soft reagents. Depending on the conditions, the indole ring of a Trp residue may also be trifluoromethylated (in the 2-position). The products are purified by chromatography, and identified by 1H-, 13C-, and 19F-NMR spectroscopy, by CD spectroscopy, and by high-resolution mass spectrometry. The CF3 groups, thus introduced, may be replaced by H (Na/NH3), an overall Cys/Ala conversion. The importance of trifluoromethylations in medicinal chemistry and possible applications of the method (spin-labelling, imaging, PET) are discussed. [source] Effects of diamines and their fluorinated groups on the color lightness and preparation of organosoluble aromatic polyimides from 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]-hexafluoropropaneJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2003Chin-Ping Yang Abstract To investigate the position and amount of the CF3 group affecting the coloration of polyimides (PIs), we prepared 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]hexafluoropropane (2) with four CF3 groups with 2-chloro-5-nitrobenzotrifluoride and 2,2-bis(4-hydroxyphenol)hexafluoropropane. A series of soluble and light-colored fluorinated PIs (5) were synthesized from 2 and various aromatic dianhydrides (3a,3f). 5a,5f had inherent viscosities ranging from 0.80 to 1.19 dL/g and were soluble in amide polar solvents and even in less polar solvents. The glass-transition temperatures of 5 were 221,265 °C, and the 10% weight-loss temperatures were above 493 °C. Their films had cutoff wavelengths between 343 and 390 nm, b* values (a yellowness index) ranging from 5 to 41, dielectric constants of 2.68,3.01 (1 MHz), and moisture absorptions of 0.03,0.29 wt %. In a comparison of the PI series 6,8 based on 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]propane, and 2,2-bis[4-(4-aminophenoxy)phenyl]propane, we found that the CF3 group close to the imide group was more effective in lowering the color; this means that CF3 of 5, 7, and 8f was more effective than that of 6c. The color intensity of the four PI series was lowered in the following order: 5 > 7 > 6 > 8. The PI 5f, synthesized from diamine 2 and 4,4,-hexafluoroisopropylidenediphthalic anhydride, had six CF3 groups in a repeated segment, so it exhibited the lightest color among the four series. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 922,938, 2003 [source] Conformational and substituent effects in the 19F spectra of C7,C10 straight-chain chlorofluoroalkanesMAGNETIC RESONANCE IN CHEMISTRY, Issue 11 2004Wallace S. Brey Abstract One- and two-dimensional fluorine NMR spectra of straight-chain chlorofluoroalkanes having 7,10 carbons were obtained and interpreted. Spectral assignments were based primarily on indirect spin,spin correlations. A scale of chlorine substituent effects was developed. The effects of asymmetric CFCl centers on chemical-shift differences in nearby CF2 groups were analyzed in terms of molecular conformational effects. Spin,spin coupling patterns of CF3 groups were elucidated. Copyright © 2004 John Wiley & Sons, Ltd. [source] 1,3,4-Triphenyl-7-trifluoromethyl-1H -pyrazolo[3,4- b]quinoline at 293 and 100,KACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2010Szlachcic In the structure of the title compound, C29H18F3N3, belonging to the space group P65 (or P61), three symmetry-independent molecules are arranged in two chains, with two molecules alternating along the 32 axes, whereas the remaining molecule forms a chain along [0001] due to the 65 screw axis. The conformation of each of the molecules is stabilized by an intramolecular C,H...N hydrogen bond, with C...N distances in the range 2.964,(6),3.069,(5),Å at room temperature (293,K) and 2.943,(4),3.084,(4),Å at low temperature (100,K). One molecule has its ,CF3 group ordered even at 293,K, which can be explained only by considering its involvement in two weak intermolecular C,H...F interactions, with C...F distances in the range 3.084,(6),3.302,(5),Å at 293,K and 3.070,(3),3.196,(3),Å at 100,K, and also a C,F...N interaction, with a C...N distance of 3.823,(5),Å at 293,K and 3.722,(4),Å at 100,K. The trifluoromethyl groups in the two remaining molecules are disordered at 293,K, whereas at 100,K the continuous (dynamic) positional disorder of one of the ,CF3 groups (of the molecule forming the chain along [0001]) is totally eliminated while the ,CF3 group disorder remains for the third molecule. [source] | ||||||||||