Direct Hydroheteroarylation of Ynamides with 2H‐Tetrazoles: Regio‐ and Stereoselective Synthesis of (Z)‐α‐Tetrazole Enamides

We herein report the direct reaction of ynamides with 2H‐tetrazoles under metal‐free conditions to provide a variety of functionalized (Z)‐α‐tetrazole enamide products in high yields, including the N‐2 and N‐1 adducts that are easily separated. The reaction proceeds via a key keteniminium ion intermediate, generated in situ from ynamides with acidic 2H‐tetrazoles, leading to the formation of C‐N bonds efficiently. The present reaction features simple experimental operations and mild reaction conditions, high chemo‐, regio‐, and stereoselectivities, and high reaction efficiencies. Without using any catalyst, the reaction protocol should facilitate the modification of tetrazole‐containing molecules for the discovery of new potentially bioactive compounds. Ynamides react with 2H‐tetrazoles in the absence of any catalyst, providing a variety of (Z)‐α‐tetrazole enamides efficiently. The reaction proceeds via a key keteniminium intermediate, leading to the formation of C‐N bonds. It features simple experimental operations and mild reaction conditions, high chemo‐, regio‐ and stereoselectivities, and high reaction efficiencies.