Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• and 163 through a two-fold C–H activation under palladium catalysis. Silver carbonate and 2,6-lutidine were found to be an effective base and ligand, respectively, for providing the desired products 164 and 165 in good yields (Scheme 31). In 2015, an economic route for copper-catalyzed biaryl coupling

A Streptomyces P450 enzyme dimerizes isoflavones from plants

• Run-Zhou Liu,
• Shanchong Chen and
• Lihan Zhang

Beilstein J. Org. Chem. 2022, 18, 1107–1115, doi:10.3762/bjoc.18.113

• , which extends the insights into P450-mediated biaryl coupling reactions in biosynthesis. Keywords: biaryl coupling; cytochrome P450; dimerization; isoflavone; natural product; Introduction Dimerization is a ubiquitous biotransformation in nature. Almost all forms of life, including bacteria, fungi

• dimer with a rare 5,8’’ biaryl coupling skeleton. Likewise, C-8’’ was assigned as one of the coupling sites of 2. Three B-ring protons, H-2’ (δH 7.38, d), H-5’ (δH 7.02, d), and H-6’ (δH 7.48, dd), suggested that C-3’ was another coupling site. Thus, the structure of 2 was established as a 3’,8

• of cattleyaisoflavones in a concentration-dependent manner (Figure 2b and Figure S4, Supporting Information File 1), suggesting that P450 enzymes play a key role in isoflavone dimerization. The known bacterial P450 enzymes involved in biaryl coupling can be classified into four types, including

Functionalization of 4-bromobenzo[c][2,7]naphthyridine via regioselective direct ring metalation. A novel approach to analogues of pyridoacridine alkaloids

• Benedikt C. Melzer,
• Alois Plodek and
• Franz Bracher

Beilstein J. Org. Chem. 2019, 15, 2304–2310, doi:10.3762/bjoc.15.222

• -catalysed intramolecular tandem stannylation/biaryl coupling protocol gave the attempted pentacyclic products [32]. However, having the biaryls 20a and 20b prepared we intended to develop a new approach to pyrido[4,3,2-mn]acridines by an alternative intramolecular cyclization step. To reach that aim, the

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

• advantage of a chiral (R)-BINOL-bridge to link the two aromatic acids and obtained the coupling product with excellent stereocontrol (up to 100% de) (Scheme 1) [16][17][18][19]. In 1998, Martin et al. [20] applied this strategy to the asymmetric intramolecular biaryl coupling of sugar derivatives carrying 2

• of trans-4,5,9,10-tetrahydroxy-9,10-dihydrophenanthrene at room temperature (Scheme 4). In 1994, Meyers and Nelson [23][24] developed a copper-mediated asymmetric biaryl coupling with oxazoline as the chiral auxiliary to afford the biaryl-coupling products in high diastereomeric purity (dr = 93:7

• 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