Facile synthesis of indolo[3,2-a]carbazoles via Pd-catalyzed twofold oxidative cyclization

• Chao Yang,
• Kai Lin,
• Lan Huang,
• Wei-dong Pan and
• Sheng Liu

Beilstein J. Org. Chem. 2016, 12, 2490–2494, doi:10.3762/bjoc.12.243

• synthesis of 9-methoxycarbonylindolo[3,2-a]carbazole derivatives. The key steps in this approach involved an aromatic amination and an oxidative biaryl coupling. Via the present route, indolo[3,2-a]carbazole derivatives are available in 3–4 steps based on commercially available starting materials. Keywords

• : cyclization; indolo[3,2-a]carbazole; N-arylation; oxidative biaryl coupling; palladium catalysis; Introduction Many biologically active carbazole derivatives are of interest as drug-like templates. The indolo[3,2-a]carbazole skeleton, one of the isomeric indolocarbazoles, was firstly identified from nature

• methods for the construction of the indolo[3,2-a]carbazole skeleton were developed by Bergman [4][5], Cachet [6], and Zhiping Li [7]. Very recently, we also reported a novel strategy toward indolo[3,2-a]carbazoles [8], and the key transformations involved a biomimetic transamination/aromatic cyclization