Synthesis of symmetrical two-substituted pyrrole derivatives by three-component reaction between arylglyoxals, pyrrole and actylacetone

Three-component reaction between arylglyoxals, acetylacetone and pyrrole in the presence of catalytic amounts of ZnCl2 in ethanol as the solvent lead to the synthesis of new symmetrical two-substituted pyrrole derivatives in high yields. All of the products of this reaction were solid and separated and purified by simple filtration and washing with diethyl ether and there was not need to time-consuming and laborious chromatography methods for purification of the products. When the reaction was conducted in the presence of a primary amine, the four-component reaction between arylglyoxal, pyrrole, acetylacetone and the primary amine, symmetrical terpyrrole derivatives were obtained in low yields in the cases of 2-naphthylglyoxal and 4-chlorophenylglyoxal; but further reactions lead to complex mixture of products and the isolation of product from the reaction mixture was impossible. All the products isolated from the above reactions were new and their structures were deduced from their 1H and 13C NMR and IR spectral data.