A Quick Access to 1‐(2‐Pyridyl)indoles <i>via</i> Solvent‐Free Ruthenium(II)‐Catalyzed Chemo‐ and Regioselective [2+2+2] Cycloaddition of α,ω‐Diynes and <i>N</i>‐Cyanoindoles

Abstract

Abstract A new route to synthesize 1‐(2‐pyridyl)indole scaffolds via the solvent‐free, ruthenium(II)‐catalyzed, chemo‐ and regioselective [2+2+2] cycloaddition reaction of diynes with N ‐cyanoindoles has been developed with good to excellent yields. Among the various transition metal‐based catalysts known for cycloaddition reaction to synthesize pyridine derivatives, chloro(pentamethylcyclopentadienyl)(cyclooctadiene)ruthenium(II) was established to be the best catalyst for this system. This efficient methodology provides 3‐substituted 1‐(2‐pyridyl)indole scaffolds having very close structural similarity with biological drug molecules. magnified image