Cyclization reactions of propargylic amides: mild access to N-heterocycles

Cyclization reactions of propargylic amides, due to their rapid assembly of structural complexity and good functional group compatibility, have gained considerable attention in recent years. These transformations have been successfully achieved with transition metals, halogen sources, Bronsted acids, and strong bases. Generally, the cyclizations proceed through a 5-exo-dig or 6-endo-dig fashion to furnish heterocycles. (C) 2014 Published by Elsevier Ltd.