Trifluoracetic acid, reduction

Methylation analysis was run by the method of Hakomori ( ), followed by hydrolysis with trifluoracetic acid, sodium borohydride reduction, and acetylation. 6LC was performed on a Hewlett-Packard 5970, used as an inlet for a mass spectrometer. Molecular weight was determined on a Sephacryl S-500 column (2.6 x 70 cm), using deionized water as solvent, upward flow, 2.75 ml/min, and detection by refractive index monitor. Model R-401 (Waters Associates). 

Redox processes involving 178 have also been studied.Anodic oxidation of thianthrene has been eifected in a wide variety of solvents. Use of trifluoracetic acid gives stable solutions of 178 and, if perchloric acid is included, the solid perchlorate salt may be isolated on evaporation of the solvent after electrolysis. Dichloromethane at low temperatures has been used and, at the opposite extreme, fused aluminum chloride-sodium chloride mixtures. " Propylene carbonate permits the ready formation of 178, whereas the inclusion of water in solvent mixtures gives an electrochemical means of sulfoxidizing thianthrene. Reversible oxidation of 178 to thianthrenium dication may be brought about in customary solvents such as nitriles, nitro compounds, and dichloromethane if the solvent is treated with neutral alumina immediately before voltammetry addition of trifluoracetic anhydride to trifluoracetic acid equally ensures a water-free medium. The availability of anhydrous solvent systems which permit the reversible oxidation and reduction of 178 has enabled the determination of the equilibrium constants for the disproportionation of the radical and for its equilibria with other aromatic materials. ... 

Polarographic reduction of aromatic cation radicals (e.g. perylene, naphthacene, anthracene, pyrene and others) in trifluoracetic acid-boron trifluoride leads to the formation of the radical ArH2 [eqns (5)-(7)] and has shown that reduction of the cation radical (5) is... 

Selective reduction to 128 was achieved in much improved yield (56%). The A ring modification to 129 was then accomplished by Eschenmoser cleavage of the derived epoxide, addition of methyllithium, and trifluoracetic acid mediated cyclization to 130. 

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