Co-catalyzed [2+2+2] cycloaddition of two alkynes to one nitrile. They exhibit two nitrogen-containing rings fused in an angular fashion to one pyridine unit. Several relative positions of the nitrogen atoms have been studied, giving rise to eight different new scaffolds. In order to allow selective functionalization of the two amino groups, orthogonalprotectinggroups (PG' and PG 2 ) were introduced prior
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).