3-polyfluoroacylmethylenephthalides: Synthesis and structure

3-Polyfluoroacylmethylenephthalides (R-F = CF3, CF2CF2H, C2F5) can be synth esized conveniently by cyclodehydration of 1-(2-carboxyphenyl)-3-polyfluoro alkylpropane-1,3-diones, obtained from o-acetylbenzoic acid and polyfluorin ated esters, as a separable mixture of Z- and E-isomers. In solution, the Z - and E-isomers of 3-polyfluoroacylmethylenephthalides are interconvertable . For CD3CN and (CD3)(2)SO solutions of 1-(2-carboxyphenyl)-3-polyfluoroalk ylpropane- 1,3-diones a ring-chain tautomerism is observed. The structures of the new compounds have been determined by heteronuclear nuclear magnetic resonance (NMR) spectroscopy and nuclear Overhauser effect (NOE) experimen ts.