Theoretical evidence on O–N type smiles rearrangement mechanism: a computational study on the intramolecular cyclization of N ‐methyl‐2‐(2‐chloropyridin‐3‐yloxy)‐acetamide anion

Smiles rearrangement (SR) falls under a broad category of organic synthesis for many important compounds. A complete understanding toward SR process appeals to the assistance of theoretical research. Herein, by performing quantum chemistry calculations, we give a theoretical evidence for the mechanism of a representative O–N type SR, the intramolecular cyclization of N ‐methyl‐2‐(2‐chloropyridin‐3‐yloxy)acetamide anion. It is found that the SR to the ipso ‐position involves a two‐step mechanism and is energetically more favorable than the direct nucleophilic attack by N atom on the ortho ‐position. The present result rationalizes well the experimentally observed ipso ‐SR product and provides a consistent picture of the O–N SR process. Copyright © 2008 John Wiley & Sons, Ltd.