Highly regioselective cyclotrimerization of terminal alkynes catalyzed by Fe(II) complexes bearing 2-(benzimidazolyl)-6-(1-(arylimino)ethyl)pyridines

FeCl2 ligated with 2-(benzimidazolyl)-6-(1-(arylimino)ethyl)pyridine in the presence of zinc powder and zinc iodide could effectively catalyze cyclotrimerization of intermolecular alkynes to afford benzene derivatives in high regioselectivity. The synthetic usefulness of this catalytic system consisting of Fe(II) complex C1, Zn and Znl(2) in acetonitrile was tested with various terminal alkynes. In the cases of using aryl substituted alkynes, the 1,2,4-trisubstituted benzenes 2 were found to be the major products. (C) 2010 Elsevier B.V. All rights reserved.