Microwave-assisted synthesis of 5,6-dihydroindolo[1,2-a]quinoxaline derivatives through copper-catalyzed intramolecular N-arylation

• Fei Zhao,
• Lei Zhang,
• Hailong Liu,
• Shengbin Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2013, 9, 2463–2469, doi:10.3762/bjoc.9.285

• synthesize 5,6-dihydroindolo[1,2-a]quinoxaline derivatives by CuI-catalyzed intramolecular N-arylation under microwave irradiation. This method rapidly afforded the tetracyclic products with good to excellent yields (83–97%) in short reaction times (45–60 min). Keywords: copper; 5,6-dihydroindolo[1,2-a

• approaches toward the synthesis of 5,6-dihydroindolo[1,2-a]quinoxaline derivatives have been reported [29][30][31][32][33][34][35][36][37][38][39][40][41][42]: (a) Ru- and Au-catalyzed cascade reactions between 2-(1H-indol-1-yl)anilines and alkynes [34][42]. (b) AlCl3-catalyzed Pictet–Spengler reactions

• moderate yields. In this study, we tried to overcome these limitations by using copper-catalyzed C–N coupling and microwave-assisted organic synthesis, and we present an efficient and practical protocol, which rapidly synthesized 5,6-dihydroindolo[1,2-a]quinoxaline derivatives by copper-catalyzed