One-Step Synthesis of Spiropyridines, a Novel Class of C2-Symmetric Chiral Ligands, by Cobalt(I)-Catalyzed [2 + 2 + 2] Cycloadditions between Bis-Alkynenitriles and Alkynes

Spiropyridines, a novel series of C2-symmetric ligands, can be obtained in moderate yields by means of Co(I)-catalyzed double cocyclization between bis-alkynenitriles and alkynes. This one-step method allowed the first synthesis of the interesting 7,7‘- and 8,8‘-spyropyridines from acyclic precursors.