Unexpected pyrazine ring annulation in the Cu-catalyzed reaction of aryl bromides with 1,2-diamines. Synthesis of novel pyrazino2,3-fperimidine fluorophores

Key Points

• This research aims to explore the Cu(I)-catalyzed N-arylation reaction leading to unexpected pyrazine ring formation.
• Utilized Cu(I) catalyst for N-arylation with indole or carbazole and 6-bromo-1,3-dimethyl-1H-perimidin-2(3H)-one.
• Investigated the role of diamine ligands in facilitating pyrazine ring annulation.
• Determined optimal conditions for the reaction to enhance yield and scope.
• Observed unexpected formation of pyrazine rings during the reaction, indicating a novel synthetic pathway.
• Synthesis of new pyrazino[2,3-f]perimidine fluorophores with potential applications.
• Characterization of products suggests favorable photophysical properties.