Palladium-Catalyzed Cascade Reaction of 2‑Amino‑<i>N</i>′‑arylbenzohydrazides with Triethyl Orthobenzoates To Construct Indazolo[3,2‑<i>b</i>]quinazolinones

A palladium-catalyzed sequential cyclization/C–H activation cascade reaction of 2-amino-N′-arylbenzohydrazides with triethyl orthobenzoates has been developed, providing indazolo­[3,2-b]­quinazolinones in good to high yields. Two key intermediates of the reaction, 2-phenyl-3-(phenylamino)­quinazolinone and C–H insertion palladacycle, were isolated, and their structures were unambiguously confirmed by X-ray crystallography. This method represents an unprecedented example of a halogen-free protocol to access indazolo­[3,2-b]­quinazolinones. Moreover, this chemistry also provides a useful tool for the discovery of fluorescent materials.