One-pot palladium-catalyzed synthesis of functionalized 10H-pyrido[1,2-a]quinoxalin-10-ones under copper-free conditions

Reactions of 3-substituted-2-chloroquinoxalines, terminal alkynes, and 1,3-dicarbonyl compounds in the presence of palladium catalyst afforded a number of 6,8,9-trisubstituted-10H-pyrido1,2-a]quinoxalin-10-ones in 60–86% reaction yields. This one-pot protocol provided an efficient, practical, and direct method for the synthesis of pyrido1,2-a]quinoxalines from readily available starting materials in the absence of a copper salt.