Diels–Alder cycloadditions of N-arylpyrroles via aryne intermediates using diaryliodonium salts

• Huangguan Chen,
• Jianwei Han and
• Limin Wang

Beilstein J. Org. Chem. 2018, 14, 354–363, doi:10.3762/bjoc.14.23

• were well tolerated with N-methyl and N-phenyl groups (Scheme 1a) [7]. Ackermann et al. employed a 2,5-dimethylpyrrole derivative as substrate to deliver double arylated products at 3,4-positions of the pyrrole ring (Scheme 1b) [8]. Recently, the research group of Kita documented an oxidative biaryl

• coupling for pyrroles using a hypervalent iodine reagent and a stabilizer for pyrrolyliodonium intermediates (Scheme 1c) [9]. The reactions readily provided a variety of desired coupling products in good yields. In general, the mechanism of these arylations was postulated by generating aryl radicals with

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

• twofold oxidative cyclization. Findings The oxidative biaryl coupling reaction was originally described over 30 years ago using stoichiometric palladium(II) [9][10]. Quite recently, the reaction has been developed to proceed catalytically and widely applied as an atom economic approach to carbazoles [11

Recent advances in copper-catalyzed asymmetric coupling reactions

• Fengtao Zhou and
• Qian Cai

Beilstein J. Org. Chem. 2015, 11, 2600–2615, doi:10.3762/bjoc.11.280

• intramolecular oxidative biaryl-coupling through the formation of higher-order cyanocuprates. The authors realized an asymmetrical intramolecular reaction by means of inexpensive optically active auxiliary bridges. The most efficient chiral auxiliary was found to be a C2-symmetrical bridge bearing two