Alkene nitrofluorination

A process known as alkene nitrofluorination has been extensively used for the synthesis of /3-nitroalkyl fluorides. Reagents used generate the nitronium cation in the presence of... 

The first examples of nitrofluorination of alkenes were demonstrated by the reaction in a solution of 10% nitric acid in hydrogen fluoride at — 10 C.204 Further investigation has shown that the rate of this conjugate addition is determined predominantly by the nature of the tr-bond (electron density, polarity).205 As a rule, the reaction is carried out at temperatures between - 60 C (i.e., 1,1-dichloro-or 1,1-difluoroethene) and + 20 C. However, nitrofluorination of hexafluoropropene is only successful at higher pressure and temperature, i.e. if the alkene rc-bond is less polar the regioselectivity of the addition is also unsatisfactory,205 e.g. reaction of 1 and 2.206... 

Table 13. Nitrofluorination of Alkenes Using 70% Hydrogen Fluoride/Pyridine, Nitronium Tetrafluoro-boratc31...

Nitrofluorination of alkenes to give 1 (simultaneous addition of fluorine and a nitro group) can be accomplished by a mixture of anhydrous hydrogen fluoride and concentrated nitric jjcid 32i.323 -.t.u.34o.34t,345 jy itronium fluoridc, by nitronium tetrafluorobor-yle 2. .332 338 yj. ijy nitronium fluorosulfatc. ... 

Examples of nitrofluorination reactions of alkenes, cycloalkencs, halogenated and other substituted alkenes are shown in Tables 28 and 29. It should be mentioned that the yield of the fluoro nitro product is higher if the starting alkene is substituted by electron-withdrawing substituents. 

Olah and Nojima have shown [85] that when alkenes are allowed to react with equimolar nitronium tetrafluoroborate in 70% hydrogen fluoride-pyridine, nitrofluorination takes place. 

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