Gas-phase F-atom migration reaction of deprotonated N-fluoroarenesulfonamides.

Rationale: Recently N-Fluoroarenesulfonamides (ArSO2NHF) were found to be promising precursors for the preparation of N-fluorobenzenesulfonimide derivatives without applying F2. However, very few studies have discussed the mass spectrometric behaviors of ArSO2NHF with N-F structure. Methods: In this article, we applied high-resolution electrospray ionization tandem mass spectrometry (HR-ESI-MS/MS) to study the effect on the mass spectrometric behaviors of ArSO2NHF after the introduction of the F-atom to the N-atom of ArSO2NH2. Results: High-resolution electrospray ionization mass spectrometry (HR-ESI-MS) experiments showed that ArSO2NHF produced only good signals in negative ion mode, and the dominating product ion SO2F- at m/z 83 was observed in all HR-ESIMS/MS of ArSO2NF- with different substituents in the Ar group. The formation of the product ion SO2F- was proof of the gas-phase F-atom migration rearrangement from the N-atom to the S-atom in ESI-MS/MS of ArSO2NF-. Conclusion: To fully explain the gas-phase reaction mechanism from ArSO2NF- to SO2F-, we studied the HR-ESI-MS/MS of deprotonated ArSO2NHF and also performed theoretical calculations. Both results confirmed that ArSO2NF- first underwent Smiles rearrangement to yield intermediate I (INT1) ArNFSO2-, and then the F-atom of ArNFSO2- migrated from the N-atom to the S-atom to form intermediate II (INT2) ArN-SO2F, which finally dissociated to SO2F- at m/z 83 with loss of a neutral nitrene (ArN). All these results showed that the formation of the product ion SO2F- from ArSO2NF- was a common and intrinsic gas-phase reactivity of ArSO2NF-. [ABSTRACT FROM AUTHOR]