nano tio2@sio2 as an efficient and reusable catalyst for the synthesis of multi-substituted imidazoles

nano tio2 supported on sio2 (nano tio2@sio2) as a solid lewis acid, was described to be an effective and reusable catalyst for one-pot three-component reaction of benzil, aryl aldehydes and ammonium acetate for the synthesis 2-aryl-4,5-diphenyl-1h-imdazoles synthesis. to explore the high efficacy of the catalytic system the four-component cyclization of benzil, aryl aldehydes, ammonium acetate and anilines has also been accomplished successfully to obtain their 1,2-diaryl-4,5-diphenyl-1h-imidazole adducts. a plausible mechanism has also been expressed. the catalyst has been recovered and its reusability confirmed in 4 runs. high yields, simple operation, easy-work procedure, mild reaction conditions in addition with reusability are some advantages of this protocol.