Copper‐Catalyzed Synthesis of 1‐Amino‐5‐arylindazolo[3,2‐b]quinazolin‐7(5H)‐ones via a Ring‐Opening Reaction of 4‐Halogenated Isatin.

The domino reaction of 4-halogenated isatins and 2-amino-N′-arylbenzohydrazides catalyzed by CuI in the presence of Cs2CO3 is described. A possible reaction mechanism containing the consecutive condensation, cyclization, C–N bond Ullmann coupling, ring-opening and decarboxylation is put forward according to the control experiments. This procedure provides an efficient method for the synthesis of fused polycyclic 1-amino-5-arylindazolo[3,2-b]quinazolin-7(5H)-ones derivatives in good yields.