Synthesis Of Pyrrolo[1,2-a]quinoxaline Derivatives By One-pot Three-component Reactions

Pyrrolo[1,2-a]quinoxaline derivatives have important biological and physiological activities,which can as important building blocks are widely applied in medical synthesis and other fields.Moerover,some of these compounds possess unique fluorescence properties,which can be used for amyloid fibril detection and dyestuff synthesis.Therefore,the synthesis of quinoxaline derivatives attract new drug researchers' attention.One-pot multi-component reactions have many advantages such as higher atom utilization,more simple operation and environmental conservation,therefore multi-component reactions have great significance in green organic chemistry.Aldo-X bifunctional reagents containing one aldehyde and another functional group,are widely used in the synthesis of heterocyclic compounds because of their rich reactivity.2-Alkoxy-2,3-dihydrofuran is a masked aldo-X bifunctional building block,which can be used to synthesize benzo-heterocycle compounds.We have developed a three-component reaction of 2-alkoxy-2,3-dihydrofuran,o-phenylenediamine and aromatic ketones to construct pyrrolo[1,2-a]quinoxalines,this reaction was performed in nitromethane by using boron trifluoride etherate as catalyst.Initially,the above-mentioned reaction includes two steps,firstly,2-alkoxy-2,3-dihydrofuran reacted with o-phenylenediamine to produce a N-(2-aminophenyl)pyrrole derivative;secondly,the obtained compound could act as a 1,5-bisnucleophile to react with a ketone or aldehyde through a Mannich-type reaction.Morever,further investigation revealed that the reaction of 2-alkoxy-2,3-dihydronfuran and anthranilamide could proceed well to generate an unexpected product,pyrrolo[1,2-a]quinazolin-5(1H)-one was obtained.