New applications of phosphoric acid supported on alumina (H_3PO_4-Al_2O_3) as a reusable heterogeneous catalyst for preparation of 2,3-dihydroquinazoline- 4(1H)-ones, 2H-indazolo[2,1-b]phthalazinetriones, and benzo[4,5]imidazo[1,2-a]pyrimidines

摘要

An eco-friendly procedure for synthesis of 2,3-dihydroquinazoline-4(1H)- one, 2H-indazolo[2,1-b]phthalazinetrione, and benzo[4,5]imidazo[1,2-a]pyrimidine derivatives by three-component reaction, with phosphoric acid supported on alumina as catalyst, is described.Noticeable features of the method are that it is solvent-free, workup is easy, yields are excellent, and the catalyst is reusable.