Abstract When appropriately substituted amides are treated with PIFA in a non-nucleophilic solvent like trifluoroethanol, a stable N-acylnitrenium ion is generated. If under such conditions a C= C double bond is present in the molecule, an intramolecular cyclization process takes place in an exo mode with additional generation of a hydroxy group at the terminal position of the original olefin moiety to render a series of pyrrolidine and ...
