Regioselective Brønsted Acid-Catalyzed Annulation of Cyclopropane Aldehydes with N′-Aryl Anthranil Hydrazides: Domino Construction of Tetrahydropyrrolo[1,2-a]quinazolin-5(1H)ones
2020
Singh, Priyanka | Kaur, Navpreet | Banerjee, Prabal
A highly regioselective 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 desired tetrahydropyrrolo[1,2-a]quinazolin-5(1H)one in good to excellent yield with complete regioselectivity. This protocol tolerates a great variety of functional groups and thus provides a simple and step-efficient method for pyrroloquinazolinone synthesis.
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