Cobalt-Catalyzed Intramolecular [2 + 2 + 2] Cocyclotrimerization of Nitrilediynes: An Efficient Route to Tetra- and Pentacyclic Pyridine Derivatives

Abstract

In this paper, we wish to report the intramolecular [2 + 2 + 2] cocyclotrimerization of nitrilediynes catalyzed by the CoI₂(dppe)/Zn system at 80 °C in CH₃CN. Under these reaction conditions, various highly substituted nitrilediynes having steric conjunction at the α and β positions to a nitrile group and a bulkier substitution at the terminal carbon of alkyne undergo [2 + 2 + 2] cocylotrimerization to afford tetra- and pentacyclic pyridine derivatives in good to excellent yields.