Synthesis of quinoxalines by cyclization of α-arylimino oximes of α-dicarbonyl compounds
摘要:
Heating the title compounds 1 at reflux in acetic anhydride yields quinoxalines 3 and 4 via a presumed aryliminoiminyl radical 5, resulting from homolytic cleavage of the N-O bond in the intermediate ester 2. The observed regioselectivity of the reaction is also rationalized by implicating such a radical. (C) 2000 Elsevier Science Ltd. All rights reserved.
An easy and efficient copper-catalyzed reaction for the synthesis of quinoxalines from o-phenylenediamines and nitroolefins is developed. This reaction could proceed well without additional base and be applied to various available substrates with a one-step synthetic procedure in moderate to good yields. (c) 2012 Elsevier Ltd. All rights reserved.