Highly fluorinated heterocycles. Part VI. Fluorination and rearrangement of 1,4-dithian

Abstract

1,4-Dithian has been fluorinated over potassium tetrafluorocobaltate(III) to give mainly the rearrangement products, polyfluoro(2-methyl-1,3-dithiolans)(five compounds, 59% of the fluorination mixture), together with the polyfluoro-1,4-dithians (seven compounds, 27% of the mixture). The rearrangements are believed to proceed via carbonium ions. The degree of fluorination is high compared to 1,4-dioxan; this is attributed to better co-ordination by ring sulphur than by ring oxygen to the fluorinating agent. The fluorination path is discussed.