The Formation of 1‐Aryl‐Substituted Naphthalenes by an Unusual Cyclization of Arylethynes Catalyzed by Ruthenium and Rhodium Porphyrins

Abstract

AbstractThe dimerization of arylethynes to give 1‐aryl‐substituted naphthalenes through catalysis by rhodium and ruthenium porphyrins has been investigated. When performed at temperatures above 130 °C, this reaction affords a mixture of triarylbenzenes and 1‐aryl‐substituted naphthalenes. The yields of naphthalene derivatives range from low to high, depending on the temperature and the phenyl substituents. The concentrations of the initial compounds affect the selectivity of the reaction: the dimerization/trimerization ratios in 1,2‐dichlorobenzene increase as concentration decreases. The reaction mechanism is determined by the peculiar structure of the catalyst ligand and involves the formation of a vinylidene intermediate of the metalloporphyrins. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)