A designed
Tf<sub>2</sub>O-promoted intramolecular Schmidt reaction
of 2-substituted ω-azido carboxylic acids was demonstrated.
Tf<sub>2</sub>O was used as an activation reagent for the carboxylic
acid, and ω-azido anhydride was in situ generated, releasing
a molecular TfOH, which acted as an acid promoter for the Schmidt
process. A series of 2-substituted pyrrolidines was produced and acetylated
for better purification. The strategy was also efficient for conversion
of a 4-substituted ω-azido carboxylic acid to the tricyclic
lactam
