green preparation of tetrahydrobenzimidazo[2,1-b]quinazolin-1(2h)-ones using γ-fe2o3@ ksf as novel and recyclable magnetic catalyst

The preparation of tetrahydrobenzimidazo[2,1-b]quinazolin-1(2h)-ones via a γ-fe2o3@ksf-catalyzed multicomponent coupling reaction of 2-aminobenzimidazole, benzaldehydes, and dimedone in solvent-free conditions is reported. γ-fe2o3@ ksf as a magnetic catalyst was prepared using the successive coating of a γ-fe2o3 shell on a ksf core and was characterized by different methods including ft-ir, xrd, tga and sem techniques. the merits of this method include limited use of organic solvents, excellent purity of products, and an easy workup technique. the tetrahydrobenzimidazo[2,1-b]quinazolin-1(2h)-ones were prepared in yields of 88- 94%. the catalyst was recovered through an external magnet and reused four times without any considerable loss of its activity.