Formation of Linear Tetramers of Diarylalkynes by the Zr/Cr System

Abstract

The reaction of diarylalkynes with Cp2ZrBu2 and successive treatment with CrCl3 afforded linear tetramers of diarylalkynes, (1E,3E,5E,7E)-octatetraenes. On the other hand, dialkylalkynes did not give the corresponding octatetraenes but cyclized products, such as pyridines and pyridones, by the reaction with nitriles and isocyanates.