Palladium-Catalyzed Cascade Reaction of 2-Amino-N′-arylbenzohydrazides with Triethyl Orthobenzoates To Construct Indazolo[3,2-b]quinazolinones
摘要:
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.
Regioselective Brønsted Acid-Catalyzed Annulation of Cyclopropane Aldehydes with <i>N</i>′-Aryl Anthranil Hydrazides: Domino Construction of Tetrahydropyrrolo[1,2-<i>a</i>]quinazolin-5(1<i>H</i>)ones
作者:Priyanka Singh、Navpreet Kaur、Prabal Banerjee
DOI:10.1021/acs.joc.9b03170
日期:2020.3.6
synthesis of tetrahydropyrrolo[1,2-a]quinazolin-5(1H)one derivatives was achieved by reacting cyclopropane aldehydes with N'-aryl anthranil hydrazides in the presence of p-toluene sulfonic acid (PTSA). The transformation involves domino imine formation and intramolecular cyclization to form 2-arylcyclopropyl-2,3-dihydroquinolin-4(1H)-one, followed by nucleophilic ring opening of the cyclopropyl ring to form