Synthesis of Tricyclic Fused 3-Aminopyridines through Intramolecular Co<sup>I</sup>-Catalyzed [2+2+2] Cycloaddition between Ynamides, Nitriles, and Alkynes
Three‐ring circus: An expedient route to tricyclicfused2‐trimethylsilyl‐3‐aminopyridines exhibiting unprecedented skeletons is described. The key step is a very efficient cobalt‐catalyzed [2+2+2] cycloaddition of a polyunsaturated compound displaying an ynamide, an alkyne, and a nitrile functionality (see picture).