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 R3NHI3 complexes have been formed by reacting an aqueous mixture of ammonium iodide and molecular iodine with the aqueous solution of amine. The structure of R3NHI3 complexes has been confirmed by spectroscopic tech­niques. The prepared amine–iodine complexes were screened as a catalysts in the synthesis of benzimidazole/benzothiazoles. Among the screened catal­ysts DBUHI3 complex has been found as most efficient catalyst. The syn­thesis of benzimidazoles and benzothiazoles has been achieved with the react­ion of o-phenylene diamine/o-aminothiophenol and various substituted aryl aldehyde using DBUHI3 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.