One-pot three-component construction of benzo[4,5]imidazo[1,2-a]benzo[4,5]thieno[3,2-d]pyrimidines through [5+1+3] cascade cyclization

Abstract

A one-pot three-component method for the effective construction of 12-arylbenzo[4,5]imidazo[1,2-a]benzo[4,5]thieno[3,2-d]pyrimidines through [5 + 1+3] cascade cyclization of o-nitrochalcones, 2-aminobenzimidazoles, and elemental sulfur is described. The target products are synthesized through the simultaneous formation of two C–S bonds and two C–N bonds. The salient features of this protocol are the use of commercially available starting materials and inexpensive and easy-to-handle solid sulfur source, transition-metal-free condition, wide substrate scope, high yield, and simple workup procedures. The method can also be extended to the synthesis of gram scale.