- Pentafluoropropionyl and trifluoroacetyl groups for temporary hydroxyl group protection in oligomannoside synthesis
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Pentafluoropropionyl (PFP) and trifluoroacetyl (TFA) esters were demonstrated to be useful in facile oligosaccharide synthesis. These were well compatible with glycosylation conditions and removable by treatment with pyridine-EtOH, with complete preservation of acetyl groups. Analytically pure products were obtained quantitatively, simply by evaporating the reaction mixtures. Using O-PFP and O-TFA carrying glycosyl halides, trisaccharide (Manα1→2Manα1→2Man) and tetrasaccharide (Glcα1→3Manα1→2Manα1→2Man) portions of monoglucosylated high-mannose type dodecasaccharide (Glc1Man9GlcNAc2), a putative ligand for the ER chaperon, calnexin and calreticulin, were synthesized.
- Takatani, Maki,Matsuo, Ichiro,Ito, Yukishige
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p. 1073 - 1081
(2007/10/03)
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- Perfluoroalcohols
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Perfluorinated primary alcohol adducts with triethylamine were prepared from lower perfluorinated acid fluorides and triethylamine monohydrofluoride. They are stable compounds and may be used as a source of RFO groups in organic syntheses.
- Cheburkov, Yuri,Lillquist, Gerald J.
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p. 123 - 126
(2007/10/03)
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- High-yield, radical-initiated oxidative functionalization of ethane by perfluorocarboxylic acid anhydrides. Role of metal ions in catalytic alkane oxidations in the presence of perfluorocarboxylic acid anhydrides
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Hydrogen peroxide and a trace of either ethene or propene initiated the conversion of ethane to propionic acid and its mixed anhydride (CH3CH2CO2H + CH3CH2COOCOCF3) and trifluoromethyl ethyl ketone, CH3CH2COCF3, by trifluoroacetic anhydride at 80 °C. For a fixed amount of H2O2, the amount of products formed increased with increasing amount of trifluoroacetic anhydride employed and was always higher than the amount of H2O2 added. These products were also obtained when H2O2 was replaced by other radical initiators: m-chloroperbenzoic acid, azobisisobutyronitrile, and PbEt4. With PbEt4, ethene or propene was not required for product formation and close to 500 equiv of products was formed for every equivalent of PbEt4 employed! Longer chain perfluorocarboxylic acid anhydrides reacted analogously; however, as the R(f) group increased in length, a corresponding increase in mixed anhydride to ketone selectivity was observed. Methane gave very little product under the reaction conditions whereas propane underwent simple stoichiometric oxidation to 2-propanol and acetone by H2O2. The addition of (CF3CO2)2Pd to the ethane reaction resulted in simple oxidation to ethanol and acetaldehyde in amounts lower than that corresponding to the H2O2 present. In complete contrast to the ethane reaction, the yield of products from methane increased significantly (although less than the H2O2 added) upon the addition of (CF3CO2)2Pd, with methanol being the principal product.
- Hogan, Terrence,Sen, Ayusman
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p. 2642 - 2646
(2007/10/03)
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- New reactions of fluoroepoxides. Cleavage by trialkyl phosphites
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Mono-, di- and tri-substituted fluorine-containing α-oxides have been shown to enter into reactions with trialkyl phosphites which proceed through cleavage of the C-C and C-O bonds in the epoxide ring.The trialkoxyphosphorus ylides II, V, VII and VIII were obtained from the epoxides I, IV, VII and XVI.Triethoxyfluorocarbonylfluorophosphorane (IIIb) has been isolated and characterized.Further conversions of IIIb have been studied and the formation of trialkoxyphosphorus ylides XXIV containing a fluorine atom in the position α to the phosphorus atom has been noted.It has been shown that when propylene oxide reacts with triethyl phosphite, vinyl ethers are obtained through the intermediate formation of tetrafluoroethylidenetriethoxyphosphorane (XX).
- Kadyrov, A. A.,Bargamov, G. G.,Rokhlin, E. M.
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p. 195 - 202
(2007/10/02)
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- ETHYL PENTAFLUOROPROPANETHIOATE: A USEFUL PENTAFLUOROPROPIONYLATING AGENT FOR AMINES AND ALCOHOLS
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Ethyl pentafluoropropanethioate, prepared by treating ethanethiol with hexafluoro-1,2-epoxypropane in the presence of triethylamine, was found to be a convenient pentafluoropropionylating agent for amines and alcohols.
- Kawa, Hajimu,Ishikawa, Nobuo
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p. 365 - 372
(2007/10/02)
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