Highly fluorinated heterocycles. Part II. Fluorination of tetrahydrofuran over potassium tetrafluorocobaltate(III)

Abstract

Tetrahydrofuran has been fluorinated over potassium tetrafluorocobaltate(III) to give 2,2,5-trifluoro-2,5-dihydrofuran (II) and 2,2,5,5-tetrafluoro-2,5-dihydrofuran (I) as major products. It is suggested that the reaction proceeds mainly via furan which is converted into dihydrofuran (II) and then dihydrofuran (I) by a series of 2,5-additions of fluorine and 2,5-eliminations of hydrogen fluoride.