A One-Pot Synthesis of 1,3-Dihydro-1,3,3-tris(perfluoroalkyl)isobenzofuran-1-olates and Their Complete NMR Spectroscopic Analysis on the Basis of 1D and 2D Experiments

A convenient synthesis of the 1,3-dihydro-1,3,3-tris(perfluoroalkyl)isobenzofuran-1-ols 3a,b was elaborated starting from commercially available phthaloyl dichloride and trimethyl(perfluoroalkyl)silanes (Me3SiRf) 1a,b (Rf=CF3, C2F5) in the presence of a fluoride source (Schemes 1 and 3). In a reaction analogous to alkyl Grignard reagents, double chloride substitution by two perfluoroalkyl groups and subsequent addition of one perfluoroalkyl group with concomitant ring closure led to this new class of compounds (Scheme 2). The syntheses of the alcohols and some alcoholates, as well as of the corresponding trimethylsilyl ethers are described. A combination of special 1D and 2D NMR experiments allowed the assignment of all atoms of the new compounds. The solid-state structure of 1,3-dihydro-1,3,3-tris(trifluoromethyl)isobenzofuran-1-ol (3a) was elucidated by X-ray diffraction methods.