30020-98-5Relevant academic research and scientific papers
Regioselective 2-alkylation of indoles with α-bromo esters catalyzed by Pd/P,P=O system
Tian, Wei,Li, Bowen,Tian, Duanshuai,Tang, Wenjun
supporting information, p. 197 - 200 (2021/08/13)
A palladium-catalyzed 2-alkylation of indoles with α-bromo esters is developed by employing a P,P=O ligand. The method features excellent regioselectivities, mild reaction conditions, and good functional group compatibility. The employment of the P,P=O ligand as well as 4? molecular sieves were crucial for the success of the transformation. Mechanistic studies indicate the reaction proceed through a radical pathway.
Pd/β-cyclodextrin-catalyzed C-H functionalization in water: A greener approach to regioselective arylation of (NH)-indoles with aryl bromides
Duan, Xin Hong,Xu, Peng
supporting information, p. 19425 - 19431 (2021/11/09)
A greener and more practical strategy for the site-selective C-H arylation of (NH)-indoles via coupling of (hetero)aryl bromides was developed, in which β-cyclodextrin, acting as both a ligand for Na2PdCl4 and a host for indoles, enables the reactions to occur easily in water. The key advantage of this method is the ingenious merging of aqueous homogeneous catalysis and ligand mediation, leading to the highly regioselective formation of C3-arylindoles with a broad substrate scope and functional-group tolerance. Moreover, the regioselectivity can be switched from the C3 to the C2-position by varying the nature of the base without recourse to employing ArI as substrates.
C3-Arylation of indoles with aryl ketonesviaC-C/C-H activations
Dai, Hui-Xiong,Guo, Zi-Qiong,Ma, Biao,Wang, Xing,Wang, Zhen-Yu,Xu, Hui
supporting information, p. 9716 - 9719 (2021/09/30)
C3-Arylation of indoles with aryl ketones is accomplishedviapalladium-catalyzed ligand-promoted Ar-C(O) cleavage and subsequent C-H arylation of indole. Various (hetero)aryl ketones are compatible in this reaction, affording the corresponding 3-arylindoles in moderate to good yields. Further introduction of an indole moiety into the natural products desoxyestrone and evodiamine demonstrate the synthetic utility of this protocol.
In Situ Preparation of Palladium Nanoparticles for C-2 Selective Arylation of Indoles in Agro-Waste Extract Based Mixed Solvents
Jin, Weiwei,Liu, Chenjiang,Liu, Tianxiang,Sun, Yajun,Wang, Bin,Wang, Rui,Xia, Yu,Zhang, Yonghong
supporting information, p. 2470 - 2473 (2021/06/25)
An efficient and practical method for the in situ generation of palladium nanoparticles was successfully established in a water extract of pomelo peel ash. The produced palladium nanoparticles were characterized by energy-dispersive X-ray spectroscopy elemental mapping, field emission scanning electron microscopy, high-resolution transmission electron microscope, X-ray powder diffraction, and showed high catalytic activity for selective C-2 arylation of indoles. A series of 2-arylindoles were smoothly installed in moderate to good yields through the direct palladium-catalyzed cross-coupling reactions of indoles and iodoarenes without external ligand, base, oxidant, and preinstallation directing group.
Metal and Oxidant Free Construction of Substituted- and/or Polycyclic Indoles: A Useful Alternative to Bischler and Related Syntheses
De Crescentini, Lucia,Favi, Gianfranco,Mantellini, Fabio,Mari, Giacomo,Santeusanio, Stefania
, (2020/08/27)
A wide range of substituted indoles or polycyclic derivatives containing the indole core are easily accessible by acidic treatment of aromatic amines and 1,2-diaza-1,3-dienes. Unlike the related indole-Bischler synthesis, the regioselectivity of the method here reported is unique and predictable, the yields are generally good and also electron withdrawing substituted indoles are smoothly recovered.
Copper catalysed Gomberg-Bachmann-Hey reactions of arenediazonium tetrafluoroborates and heteroarenediazonium o-benzenedisulfonimides. Synthetic and mechanistic aspects
Antenucci, Achille,Barbero, Margherita,Dughera, Stefano,Ghigo, Giovanni
, (2020/10/20)
Gomberg-Bachmann-Hey reactions were carried out in the presence of copper as a catalyst and gave rise to biaryls or heterobiaryls in good yields and in mild reaction conditions. A computational study of some key points of the reaction was performed. The results are coherent with the experimental data and confirm some aspects of the mechanism. The reaction free energies for the reduction in benzene by CuI of a set of 40 (hetero)arenediazonium tetrafluoroborates were calculated. Both the experiments and the calculations showed that in the coupling with substituted solvents (toluene, bromobenzene, nitrobenzene and anisole) the binding to the ortho position was always favoured.
Arylation of indoles using cyclohexanones dually-catalyzed by niobic acid and palladium-on-carbons
Ban, Kazuho,Sajiki, Hironao,Sawama, Yoshinari,Yamamoto, Yuta
supporting information, p. 3898 - 3902 (2020/06/03)
3-Arylindoles were easily constructed from indoles and cyclohexanone derivatives using a combination of catalytic niobic acid-on-carbon (Nb2O5/C) and palladium-on-carbon (Pd/C) under heating conditions without any oxidants. The Lewis acidic Nb2O5/C promoted the nucleophilic addition of indoles to the cyclohexanones, and the subsequent dehydration and Pd/C-catalyzed dehydrogenation produced the 3-arylindoles. The additive 2,3-dimethyl-1,3-butadiene worked as a hydrogen acceptor to facilitate the dehydrogenation step.
Ascorbic Acid as an Aryl Radical Inducer in the Gold-Mediated Arylation of Indoles with Aryldiazonium Chlorides
Medina-Mercado, Ignacio,Asomoza-Solís, Eric Omar,Martínez-González, Eduardo,Ugalde-Saldívar, Victor Manuel,Ledesma-Olvera, Lydia Gabriela,Barquera-Lozada, José Enrique,Gómez-Vidales, Virginia,Barroso-Flores, Joaquín,Frontana-Uribe, Bernardo A.,Porcel, Susana
supporting information, p. 634 - 642 (2019/12/11)
In recent years interest in the development of protocols that facilitate the oxidative addition of gold to access mild cross-coupling processes mediated by this metal has increased. In this context, we report herein that ascorbic acid, a natural and readily accessible antioxidant, can be used to accelerate the oxidative addition of aryldiazonium chlorides onto AuI. The aryl–AuIII species generated in this way, has been used to prepare 3-arylindoles in a one-pot protocol starting from anilines and para-, meta-, and ortho- substituted aryldiazonium chlorides. The mechanism underlying the oxidative addition has been examined in detail based on EPR analyses, cyclic voltammetry, and DFT calculations. Interestingly, we have found that in this protocol, the chloride atom induces the AuII/AuIII oxidation step.
Catalytic Au(i)/Au(iii) arylation with the hemilabile MeDalphos ligand: Unusual selectivity for electron-rich iodoarenes and efficient application to indoles
Rodriguez, Jessica,Zeineddine, Abdallah,Sosa Carrizo, E. Daiann,Miqueu, Karinne,Saffon-Merceron, Nathalie,Amgoune, Abderrahmane,Bourissou, Didier
, p. 7183 - 7192 (2019/08/07)
The ability of the hemilabile (P,N) MeDalphos ligand to trigger oxidative addition of iodoarenes to gold has been thoroughly studied. Competition experiments and Hammett correlations substantiate a clear preference of gold for electron-enriched substrates both in stoichiometric oxidative addition reactions and in catalytic C-C cross-coupling with 1,3,5-trimethoxybenzene. This feature markedly contrasts with the higher reactivity of electron-deprived substrates typically encountered with palladium. Based on DFT calculations and detailed analysis of the key transition states (using NBO, CDA and ETS-NOCV methods in particular), the different behavior of the two metals is proposed to result from inverse electron flow between the substrate and metal. Indeed, oxidative addition of iodobenzene is associated with a charge transfer from the substrate to the metal at the transition state for gold, but opposite for palladium. The higher electrophilicity of the gold center favors electron-rich substrates while important back-donation from palladium favors electron-poor substrates. Facile oxidative addition of iodoarenes combined with the propensity of gold(iii) complexes to readily react with electron-rich (hetero)arenes prompted us to apply the (MeDalphos)AuCl complex in the catalytic arylation of indoles, a challenging but very important transformation. The gold complex proved to be very efficient, general and robust. It displays complete regioselectivity for C3 arylation, it tolerates a variety of functional groups at both the iodoarene and indole partners (NO2, CO2Me, Br, OTf, Bpin, OMe?) and it proceeds under mild conditions (75 °C, 2 h).
Abnormal NHC supported palladacycles: Regioselective arylation of heteroarenes via decarboxylation
Jose, Anex,Vijaykumar, Gonela,Vardhanapu, Pavan K.,Mandal, Swadhin K.
, p. 51 - 57 (2018/02/09)
We report synthesis of two new palladium(II) complexes of abnormal N-heterocyclic carbene ligands. The catalytic activity of these palladium(II) complexes was examined for the decarboxylative arylation of N-methylindole-carboxylic acids. An exclusive regioselectivity and very good yields were obtained with a variety of aryl halide partners.
