Vicinal bromofluoroalkanes: Their regioselective formation and their conversion to fluoroolefins

Article abstract of DOI:10.1016/S0040-4020(01)86762-4

The reaction of alkenes with N-bromosuccinimide and triethylamine tris(hydrofluoride) produces vic-bromofluoroalkanes (1) with high yields. As long as the addition to the double bond is sterically unhindered, bromine and fluorine get attached with very high regioselectivity, the latter halogen occupying the more substituted, carbocation stabilizing position. 2-Fluoro-1-alkenes give 1-bromo-2,2-di-fluoroalkanes (4). The heavier halogen may be removed by base promoted dehydro-fluorination, to afford fluoroolefins (2), or by reduction with tributyltin hydride, leading to mono- or difluoroalkanes (e.g., 5).