Tetrafluorophthalic anhydride

The pyrolysis of a number of compounds at temperatures around 600— 800° and at pressures of the order of 10 2 mm. has been shown to give rise to benzyne. These compounds include for example indanetrione 29>, and phthalic anhydride 30 38>. The dimerisation of benzyne to yield biphenylene has been used preparatively 31 33>, an(j the pyrolysis of tetrafluorophthalic anhydride 34>, and tetrachlorophthalic anhydride 3i-33) gave the corresponding octahalobiphenylenes. In the case of the pyrolysis of tetrachlorophthalic anhydride some hexachlorobenzene is also formed, while the pyrolysis of tetrabromophthalic anhydride results in the formation of hexabromobenzene but no octabromobiphenylene. The disproportionation of tetrabromobenzyne to form carbon and bromine is a function of the high temperature involved and, as we shall see later, both tetrabromo- and tetraiodo-benzyne behave normally in solution. 

Bifunctionally tagged Mitsunobu reagents 21 and 22, quaternary ammonium carbonate resin 65, tetrafluorophthalic anhydride (as a solution-phase linking reagent), and amine-functionalized resin 2 were used in a three-step solution-phase synthesis of a series of substituted hydroxypiperidines.39 No further purification (e.g., liquid-phase extraction or chromatography) was required, and products were isolated in good yields and purities. 

Parlow, J. J. Naing, W. South, M. S. Flynn, D. L. In Situ Chemical Tagging Tetrafluorophthalic Anhydride as a Sequestration Enabling Reagent (SER) in the Purification of Solution-Phase Combinatorial Libraries, Tetrahedron Lett. 1997, 38, 7959. 

Parlow JJ, Naing W, South MS, Flynn DL, In situ chemical tagging tetrafluorophthalic anhydride as a sequestration enabling reagent (SER) in the purification of solution-phase combinatorial libraries, Tetrahedron Lett., 38 7959-7962, 1997. 

R CONHR2 —> R COOH. This conversion can be effected in 70-90% yield by tetrachloro- or tetrafluorophthalic anhydride in the absence of water or of a solvent in a melt at 135-170°. This reaction does not affect esters. Conversion of nitriles to carboxylic acids can be effected by a similar reaction with tetrafluoro-or tetrachlorophthalic acid at 135-180° for 4-6 days in 60-85% yield. 

Copyrolysis (ca. 650 °C) of tetrafluorophthalic anhydride with tetrafluoro-ethylene or hexafluoropropene provides a route to perfluorobenzocyclobutenes (50 X = F, Y = F or CFs) (some perfluoroindane is also formed in the former reaction) and an analogous reaction occurs with phthalic anhydride itself [to give (50 X = H, Y = F)]. Perfluoro(methylnaphthalenes) are the main products from octafluoronaphthalene and polytetrafluoroethylene at elevated temperatures, but the reaction of octafluoronaphthalene with potassium fluoride at ca. 500 °C gives a mixture containing perfluoro(methylnaphthalenes, indane, and methyl-indanes). Such reactions are believed to involve difluorocarbene, and some... 

An extension of the approach to additional chemical reactions has been reported by other groups. Flynn and co-workers [21] have developed some protocols for the Moffatt oxidation of secondary alcohol to ketones (Figure 8) and the addition of organometallic reagents to aldehydes. The same group has also developed the use of tetrafluorophthalic anhydride to assist in the purification of reaction mixtures [22]. 

Retention of ester groups. Equimolar amounts of startg. nitrile and tetrafluorophthalic acid heated at 135° for 4 days in a heavy-walled glass pressure tube product. Y 56%. Work-up is simple since no solvent is required. F.e.s. W.D. Rounds, G.W. Gribble, Tetrahedron Letters 29, 6557-60 (1988) from carboxylic acid amides with tetrachloro-or tetrafluoro-phthalic anhydride s. ibid. 6553-6. 

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