Low-Valent Niobium-Catalyzed Intermolecular [2 + 2 + 2] Cycloaddition of <i>tert</i>-Butylacetylene and Arylnitriles to Form 2,3,6-Trisubstituted Pyridine Derivatives

Abstract

A catalytic system based on low-valent niobium has been developed, consisting of NbCl5, Zn, and an alkoxysilane. This combination has been shown to be an efficient catalyst for the synthesis of pyridine derivatives from the intermolecular cycloaddition of alkynes and nitriles via a niobacyclopentadiene intermediate.