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.
Copper-catalyzed intramolecular C–N bond formation reaction of 3-amino-2-(2-bromophenyl)dihydroquinazolinones: synthesis of indazolo[3,2-b]quinazolinones
A copper-catalyzed intramolecular C-N bond formation reaction of 3-amino-2-(2-bromophenyl)dihydroquinazolinones has been developed for the synthesis of indazolo[3,2-b]quinazolinones in moderate to good yields. The structure of the newly synthesized indazolo[3,2-b]quinazolinones was unambiguously confirmed by X-ray single-crystal diffraction analysis. Moreover, a possible mechanism for the formation of indazolo[3,2-b]quinazolinones is discussed. (C) 2013 Elsevier Ltd. All rights reserved.