Gas‐phase F‐atom migration reaction of deprotonated N‐fluoroarenesulfonamides

Rationale Recently N ‐Fluoroarenesulfonamides (ArSO 2 NHF) were found to be promising precursors for the preparation of N ‐fluorobenzenesulfonimide derivatives without applying F 2 . However, very few studies have discussed the mass spectrometric behaviors of ArSO 2 NHF 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 ArSO 2 NHF after the introduction of the F‐atom to the N‐atom of ArSO 2 NH 2 . Results High‐resolution electrospray ionization mass spectrometry (HR‐ESI‐MS) experiments showed that ArSO 2 NHF produced only good signals in negative ion mode, and the dominating product ion SO 2 F − at m/z 83 was observed in all HR‐ESI‐MS/MS of ArSO 2 NF − with different substituents in the Ar group. The formation of the product ion SO 2 F − was proof of the gas‐phase F‐atom migration rearrangement from the N‐atom to the S‐atom in ESI‐MS/MS of ArSO 2 NF − . Conclusion To fully explain the gas‐phase reaction mechanism from ArSO 2 NF − to SO 2 F − , we studied the HR‐ESI‐MS/MS of deprotonated ArSO 2 NHF and also performed theoretical calculations. Both results confirmed that ArSO 2 NF − first underwent Smiles rearrangement to yield intermediate I ( INT1 ) ArNFSO 2 − , and then the F‐atom of ArNFSO 2 − migrated from the N‐atom to the S‐atom to form intermediate II ( INT2 ) ArN − SO 2 F, which finally dissociated to SO 2 F − at m/z 83 with loss of a neutral nitrene (ArN). All these results showed that the formation of the product ion SO 2 F − from ArSO 2 NF − was a common and intrinsic gas‐phase reactivity of ArSO 2 NF − .