A NEW SYNTHESIS OF FLUORINATED OXETANES

Polyfluorinated oxetanes are prepared in high yields by an electrophil ic [2 + 2] cycloaddition reaction between hexafluoroacetone and fluori nated ethylenes that is catalyzed by an anhydrous aluminum chlorofluor ide Lewis acid. The reaction is regiospecific with hydrofluoroethylene s CHX=CF2(X=H, F, Cl, Br), whereas halotrifluoroethylenes CFX=CF2 (X=C l, Br) give nearly equal amounts of the isomeric oxetanes. Hexafluorop ropylene oxide, which rapidly rearranges under the reaction conditions , can be substituted for hexafluoroacetone in this new oxetane synthes is.