2,2-Difluoro-1,3-Dimethylimidazolidine (DFI) Deoxofluorination
2,2-Difluoro-1,3-dimethylimidazolidine (DFI) was first reported as a novel deoxofluorination reagent by Hayashi and coworkers in 2002 . It is a clear liquid with boiling point of 47 °C at 37 mmHg and melting point of −8.7 °C . In terms of the chemical structure, DFI is similar to other α,α-difluoroalkylamine agents such as Yarovenko  and Ishikawa  agent. Accelerating rate calorimetry (ARC) analysis showed that thermal decomposition of DFI begins at 150 °C , while diethylaminosulfur trifluoride (DAST) decomposes at about 90 °C , indicating that DFI is much more thermally stable.
Deoxofluorination with DFI
Regeneration of DFI
Deoxofluorination with DFI Analogues
Conclusion and Future Directions
In conclusion, DFI is a thermally stable and economical deoxofluorination reagent, and the byproduct DMI can be reused to prepare DFI, which makes it practical for industry application. However, the substrate scope is limited owing to ready elimination reactions induced by DFI . The development of PhenoFluor with a more complex structure has largely extended the synthetic application of this kind of “-NCF2N-” reagents, although the cost is still much greater.
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