Oxygen replacement by fluorine in carbonyl derivatives of perfluoroaromatic compounds and isomerization of perfluoroindan-1,3-dione to perfluoro-3-methylenephthalide under the action of HF/SbF5

When acted upon by HF/SbF5 at 95 degrees C, carbonyl groups of perfluorinated acetophenone (10), 3,4-dihydronaphthalen-1(2H)-one (8), 2,3-dihydronaphthalene-1,4-dione (9), benzocyclobutenone (6), benzocyclobutenedione (7) and indan-l-one (1) are converted into difluoromethylene groups to give the corresponding perfluoroaromatic products. Perfluoroindan-2-one (5), under the same conditions, is transformed to bis(perfluoroindan-2-yl) ether (21). On heating with HF/SbF5, perfluoroindan-1,3-dione (2) isomerizes into perfluoro-3-methylenephthalide (4) at 95 degrees C, and gives 4,5,6,7-tetrafluoro-3-trifluoromethyl-phthalide (14) at 130 degrees C. Compound 4 in the absence of a solvent dimerizes giving perfluorodispiro[phthalide-3,1 '-cyclobutane-2 ',3 ''-phthalide] (18), and when heated with SbF5 at 130 degrees C, it is converted into perfluoro-3-methylphthalide (3). When acted upon by HF/SbF5 at 95 degrees C, perfluorinated benzoic acid (12) and phthalic anhydride (13) give the corresponding products with trifluoromethyl groups. (c) 2006 Elsevier B.V. All rights reserved.