Efficient and recoverable novel pyranothiazol Pd (II), Cu (II) and Fe(III) catalysts in simple synthesis of polyfunctionalized pyrroles: Under mild conditions using ultrasonic irradiation

Abstract

AbstractThree novel Pd (II), Cu (II), and Fe (III) complexes were prepared from thiazole ligand through bidentate chelating mode. Alternative spectral and analytical tools were applied to elucidate their structural and molecular formulae. This study was extended to investigate stability and stoichiometry of complexes in solution, using standard methods. In addition, the best atomic distribution within structural forms was obtained by Material Studio Package via the density functional theory (DFT) method. This computational study fed us with significant physical characteristics for differentiation. Also, crystal surface properties in the packing system were studied using the Crystal explorer program, to evaluate the extent of contact between surfaces. Computational data discriminate Pd (II)‐thiazole (HYHPd) complex by some physical features, which may be promising in the catalytic field. This complex was selected to play a catalytic function to synthesize polyfunctionalized pyrrole derivatives using ultrasonic irradiation in a one‐pot reaction. The catalyst was selected for this application based on the history of Pd (II) complexes and the properties expected theoretically. A condensation reaction for aromatic aldehyde, aromatic amine, acetylacetone, and nitromethane was carried out under mild reaction conditions by ultrasonic irradiation. All reaction conditions were optimized among that variable Lewis acid catalysts in comparison to our new complexes. HYHPd catalyst displayed superiority in overall trials with high yield, short time, and green conditions (solvent H2O/EtOH). Also, the recovery of hetero‐catalyst was succeeded and reused by the same efficiency up to five times after that the efficiency was reduced. The mechanism of action was proposed based on the ability of Pd (II) for adding extra‐bonds overzaxis and supported by theoretical aspects.