Fluorine atoms, reactive intermediate generation

A number of synthetic methodologies involving fluorosubstituted carbocations have been developed. The reports have shown that these are viable reactive intermediates, as the fluorine atoms impart a measure of stability to the carbocation center by n-i p donation. While most of these synthetic methods utilize Br0nsted superacids, a recent report described the use of InBr3 as a catalytic reagent in the chemistry (Scheme 7). Thus, the difluoroallene (20) generates the zwitterionic species (21),... 

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