Synthesis of selectively fluorinated cyclohexanes:the observation of phenonium rearrangements during deoxyfluorination reactions on cyclohexane rings with a vicinal phenyl substituent

A study focused on the synthesis of a derivative of all-cis phenyl-2,3,5,6-tetrafluorocyclohexane, incorporating a methyl group at the benzylic position, found that the fluorination reactions of diepoxide and diol precursors, were susceptible to rearrangement and unexpected products. The origin of these rearranged products can be rationalised by aryl migrations occurring via phenonium ion intermediates, in adventitious pathways occurring during deoxofluorination reactions with hydrogen fluoride reagents.