Carbonylative synthesis and functionalization of indoles

• Alex De Salvo,
• Raffaella Mancuso and
• Xiao-Feng Wu

Beilstein J. Org. Chem. 2024, 20, 973–1000, doi:10.3762/bjoc.20.87

• byproducts (Scheme 10) [23]. Two years later they developed two Pd-catalyzed reductive N-heteroannulations for the synthesis of fused indoles [24] and indoles isolated from two species of European Basidiomycetes [25] starting from suitably functionalized nitro compounds. Both in the first case and in the

• second case the reactions were catalyzed by 6 mol % of Pd(OAc)2 and carried out under 4 bar of CO. The fused indoles were obtained when adding 24 mol % of dppp (1,3-bis(diphenylphosphino)propane) at 120 °C for 70 hours in DMF. Instead, in the other case, PPh3 was used as ligand at 70 °C for 17–46 hours

• ]. Synthesis of fused indoles (top) and natural indoles present in two species of European Basidiomycetes (bottom) by reductive N-heteroannulation of suitably functionalized nitro compounds. Synthesis of 1,2-dihydro-4(3H)-carbazolones through N-heteroannulation of functionalized 2-nitrostyrenes in the presence

Photoredox catalysis enabling decarboxylative radical cyclization of γ,γ-dimethylallyltryptophan (DMAT) derivatives: formal synthesis of 6,7-secoagroclavine

• Alessio Regni,
• Francesca Bartoccini and
• Giovanni Piersanti

Beilstein J. Org. Chem. 2023, 19, 918–927, doi:10.3762/bjoc.19.70

• in CH2Cl2 at room temperature using our integrated photoreactor enabled efficient cyclization to give a decarboxylated compound with the correct mass (m/z 426.2) after 16 h. While we were delighted to find that the proposed radical–radical coupling in the synthesis of extracyclic fused indoles was

Regioselectivity of the S_EAr-based cyclizations and S_EAr-terminated annulations of 3,5-unsubstituted, 4-substituted indoles

• Jonali Das and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2022, 18, 293–302, doi:10.3762/bjoc.18.33

• summarizing recent relevant literature reports. Keywords: annulation; cyclization; fused indoles; regioselectivity; SEAr; Introduction Over the decades, countless cyclization and annulation reactions of substituted arenes/heteroarenes involving an electrophilic aromatic substitution (SEAr) reaction as the

• attractive cyclization and annulation of 3,5-unsubstituted, 4-substituted indoles have been reported in the recent past. Herein, we summarize these literature reports, with a special attention on the regiochemistry. Noteworthy is that although three reviews on the synthesis of 3,4-fused indoles have been

• [Pd(C3H5)Cl]2 and ligand L1 (Scheme 2) [11]. The reaction, that could also be considered as Friedel–Crafts type, intramolecular allylic alkylation, delivered nine-membered ring bearing 3,4-fused indoles 2 in moderate to good yields. In the asymmetric version of the reaction catalyzed by [Ir(cod)Cl]2

Synthesis and photophysical properties of novel benzophospholo[3,2-b]indole derivatives

• Mio Matsumura,
• Mizuki Yamada,
• Atsuya Muranaka,
• Misae Kanai,
• Naoki Kakusawa,
• Daisuke Hashizume,
• Masanobu Uchiyama and
• Shuji Yasuike

Beilstein J. Org. Chem. 2017, 13, 2304–2309, doi:10.3762/bjoc.13.226

• tetracyclic moieties are planar. The benzophosphole-fused indoles, such as phosphine oxide, phospholium salt, and borane complex, exhibited strong photoluminescence in dichloromethane (Φ = 67–75%). Keywords: benzophospholo[3,2-b]indole; DFT calculation; molecular structure; phosphole derivatives

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• by Nematollahi and co-workers from 3-substituted catechols 66 (Scheme 25, right) [70][71]. Interestingly, the formation of 68 and 69 proceeds under very high regioselectivity. Zeng et al. developed a method for the synthesis of 1,2-fused indoles 71 (Scheme 26) based on the reaction depicted in Scheme

• indole derivatives. Anodic anellation of catechol derivatives 66 with different 1,3-dicarbonyl compounds. Electrosynthesis of 1,2-fused indoles from catechol and ketene N,O-acetals. Reaction of N-acyliminium pools with olefins having a nucleophilic substituent. Synthesis of thiochromans using the cation

Palladium-catalyzed dual C–H or N–H functionalization of unfunctionalized indole derivatives with alkenes and arenes

• Gianluigi Broggini,
• Egle M. Beccalli,
• Andrea Fasana and
• Silvia Gazzola

Beilstein J. Org. Chem. 2012, 8, 1730–1746, doi:10.3762/bjoc.8.198

• construction of seven-membered ring-fused indoles. Readily available N-alkenyl-3(1H)-indoleacetic amides 30 were converted into the azepinoindole derivatives 31 or 32 by using the combination of PdCl2(MeCN)2, 1,4-benzoquinone and dioxane at 110 °C (Scheme 17) [71]. Although these reactions achieve only

• moderate yields, this strategy constitutes an alternative choice to the palladium-catalyzed cyclization of indole amides bearing a carbon–halogen bond to give medium and large ring-fused indoles [72]. Although a stoichiometric amount of Pd(OAc)2 is needed, intramolecular alkenylations of suitable 3

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• result in the formation of multi-ring products from a single substrate [149]. In 2010, a concise synthetic method for the generation of fused indoles (291–293), by a gold-catalyzed cascade cyclization of diynes 290 was developed by Hirano and co-workers [150]. The reaction gave aryl annulated[a