DBUH+I3 complex an efficient catalyst for the synthesis of 2-phenyl benzimidazole and benzothiazole derivatives

Abstract

Herein, we have reported the facile synthesis of various benzimidazole / benzothiazole by using DBU-Iodine-Iodide as a green and simple catalyst. The R₂NH+I₃ complexes have been formed by reacting an aqueous mixture of ammonium iodide and molecular iodine with the aqueous solution of amine. The structure of R₂NH+I₃ complexes has confirmed by spectroscopic techniques. The prepared amine-iodine complexes have screened as a catalyst in the synthesis of benzimidazole / benzothiazoles. Among the screened catalyst DBUH+I₃ complex has been found as an efficient catalyst. The synthesis of benzimidazoles and benzothiazoles has been achieved with the reaction of o-phenylene diamine /o- amino thiophenol and various substituted aryl aldehyde using DBUH+I₃ as a catalyst. The present protocol has offered some advantages over other reported protocols such as the mild reaction condition, commercially available precursors, inexpensive catalyst, short reaction time, the broad scope of the substrate, high yield, simple isolation of the product, and environmentally benign method.