A range of unsaturated amines and sulfonamides were converted to β-fluoro nitrogen analogues after hydrofluorination in superacidHFâSbF5, based on the formation of highly reactive electrophilic intermediates.
This paper describes the scope and limitations of the hydrofluorination reaction in superacid HF/SbF5. On the basis of experimental studies of polyfunctional substrates’ behaviour, the dramatic effect of substitution on the superelectrophilic character of ammonium–carbenium dications was emphasized. This reaction was applied to the synthesis of novel fluorinated key building blocks. Furthermore, the hydrofluorination reaction and the discovered homodimerization/fluorination reaction were applied to the synthesis of highly valued fluorinated diamines.
The superacid-promoted electrophilic Csp3–H bond activation of aliphaticamines generates superelectrophilic species that can be subsequently fluorinated. Demonstrated by low-temperature in situ NMR experiments, the ammonium–carbenium dications, crucial for this reaction, can also react with C–H bonds opening future synthesis perspectives for this mode of activation.
Anti-Markovnikov additions to non-conjugated unsaturated amines in superacid are reported. In situ NMR studies, DFT calculations and labelled substrates reactions support the involvement of new ammoniumâcarbenium superelectrophiles in this original process.