Triflic Anhydride‐Mediated Beckmann Rearrangement Reaction of β‐Oximyl Amides: Access to 5‐Iminooxazolines.

Facile and efficient synthesis of 5-iminooxazolines from α,α-disubstituted β-oximyl amides mediated by triflic anhydride (Tf2O) in the presence of 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU) in dichloromethane at room temperature is developed, and a mechanism involving tandem Beckmann rearrangement and intramolecular cyclization reaction is proposed.