Transition metal-free synthesis of quinolino[2′,3′3,4]pyrazolo[5,1-b]quinazolin-8(6H)-ones via cascade dehydrogenation and intramolecular N-arylation

2-(2-Chloroquinolin-3-yl)-3-(arylamino)2,3-dihydroquinazolin-4(1H)-one was converted to quinolino[2′,3′:3,4]pyrazolo[5,1-b]quinazolin-8(6H)-ones in the presence of KOtBu in DMSO at room temperature. The present method has the advantages of easy conditions, construction of highly novel five heterocycles, transition metalfree conditions, cascade dehydrogenation and intramolecular N-arylation and good to high yield of products.