The Ruthenium‐Catalyzed Domino Cross Enyne Metathesis/Ring‐Closing Metathesis in the Synthesis of Enantioenriched Nitrogen‐Containing Heterocycles

The tetrahydropyridine structure is present in a wide variety of natural and synthetic compounds with interesting pharmacological properties. Therefore, the search for new chemical routes capable of yielding this valuable nitrogen-containing heterocycle is of utmost interest. Herein, we report the use of the ruthenium-catalyzed ring-closing enyne metathesis (RCEYM) and cross enyne metathesis/ring-closing metathesis (CEYM/RCM) reactions of chiral nitrogen-containing 1,7-enynes as an efficient route to synthesize a variety of enantioenriched tetrahydropyridine-based conjugated 1,3-dienes. The RCEYM presented wide functional group tolerance and took place in moderate to high yields, with no significant differences when carried out on gram scale. These 1,3-dienes were suitable for further transformations, such as the Diels-Alder reaction, effectively yielding more complex enantioenriched bicyclic structures.