4757-69-1Relevant articles and documents
A palladium-catalyzed Barluenga cross-coupling – Reductive cyclization sequence to substituted indoles
Rahman, S. M. Ashikur,S?derberg, Bj?rn C. G.
, (2021/07/20)
A short and flexible synthesis of substituted indoles employing two palladium-catalyzed reactions, a Barluenga cross-coupling of p-tosylhydrazones with 2-nitroarylhalides followed by a palladium–catalyzed, carbon monoxide–mediated reductive cyclization has been developed. A one-pot, two-step methodology was further developed, eliminating isolation and purification of the cross-coupling product. This was accomplished by utilizing the initially added 0.025 equivalents of bis(triphenylphosphine)palladium dichloride, thus serving a dual role in the cross-coupling and the reductive cyclization. It was found that addition of 1,3-bis(diphenylphosphino)propane and carbon monoxide after completion of the Barluenga reaction afforded, in most cases, significantly better overall yields.
Iron-Catalyzed Radical Activation Mechanism for Denitrogenative Rearrangement Over C(sp3)–H Amination
Roy, Satyajit,Das, Sandip Kumar,Khatua, Hillol,Das, Subrata,Singh, Krishna Nand,Chattopadhyay, Buddhadeb
, p. 8772 - 8780 (2021/03/16)
An iron-catalyzed denitrogenative rearrangement of 1,2,3,4-tetrazole is developed over the competitive C(sp3)–H amination. This catalytic rearrangement reaction follows an unprecedented metalloradical activation mechanism. Employing the developed method, a wide number of complex-N-heterocyclic product classes have been accessed. The synthetic utility of this radical activation method is showcased with the short synthesis of a bioactive molecule. Collectively, this discovery underlines the progress of radical activation strategy that should find wide application in the perspective of medicinal chemistry, drug discovery and natural product synthesis research.
Modular counter-Fischer?indole synthesis through radical-enolate coupling
Chung, Hyunho,Kim, Jeongyun,Gonzalez-Montiel, Gisela A.,Cheong, Paul Ha-Yeon,Lee, Hong Geun
supporting information, p. 1096 - 1102 (2021/01/26)
A single-electron transfer mediated modular indole formation reaction from a 2-iodoaniline derivative and a ketone has been developed. This transition-metal-free reaction shows a broad substrate scope and unconventional regioselectivity trends. Moreover, important functional groups for further transformation are tolerated under the reaction conditions. Density functional theory studies reveal that the reaction proceeds by metal coordination, which converts a disfavored 5-endo-trig cyclization to an accessible 7-endo-trig process.
Preparation method of indole compound
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Paragraph 0090-0092, (2020/12/29)
The invention discloses a preparation method of a novel efficient indole compound, which comprises the following steps: by using o-nitroalkylbenzene containing various substituents as a raw material,controlling the reaction temperature to be 70-160 DEG C in an organic solution under the protection of inert gas and the participation of inorganic base, thereby obtaining the indole compound; preparing the novel indole compound containing various substituent groups through a hydrocarbon activation reaction catalyzed by a metal rhodium catalyst. The synthetic method is not reported in literature,the raw materials are easy to synthesize, no reducing agent needs to be added additionally, the method is simple in step, the indole compound containing various substituent groups does not need to beconstructed in one step through a nitroso intermediate, and the yield is high; The method is simple in unit operation, low in equipment requirement and suitable for rapidly synthesizing the indole compounds containing various substituent groups.
Regiospecificity in Ligand-Free Pd-Catalyzed C-H Arylation of Indoles: LiHMDS as Base and Transient Directing Group
Camp, Clément,Canivet, Jér?me,Clot, Eric,Demarcy, Clément,Mohr, Yorck,Quadrelli, Elsje Alessandra,Renom-Carrasco, Marc,Thieuleux, Chloé,Wisser, Florian M.
, p. 2713 - 2719 (2020/03/11)
A highly efficient catalyst-base pair for the C-H arylation of free (NH)-indoles in the C-3 position is reported. Ligand-free palladium acetate coupled with lithium hexamethyldisilazide (LiHMDS) catalyzed the regiospecific, i.e. 100% regioselective, C-3 a
Asymmetric N-Hydroxyalkylation of Indoles with Ethyl Glyoxalates Catalyzed by a Chiral Phosphoric Acid: Highly Enantioselective Synthesis of Chiral N,O-Aminal Indole Derivatives
Wang, Le,Zhou, Jia,Ding, Tong-Mei,Yan, Zhi-Qiang,Hou, Si-Hua,Zhu, Guo-Dong,Zhang, Shu-Yu
, p. 2795 - 2799 (2019/04/30)
A method of SPINOL-derived chiral phosphoric acid catalyzed asymmetric intermolecular N-hydroxyalkylation of multisubstituted indoles with ethyl glyoxalates is described in this report. This protocol provides an alternative, convenient, and direct strategy for efficient access to structurally unique α-chiral indole N,O-acyclic aminals with a broad substrate scope and good to excellent enantioselectivities. The synthetic utility of this methodology is illustrated by a gram-scale experiment and the subsequent efficient synthesis of more complex chiral N,O-aminal indole derivatives.
A micellar catalysis strategy applied to the Pd-catalyzed C-H arylation of indoles in water
Vaidya, Gargi Nikhil,Fiske, Sneha,Verma, Hansa,Lokhande, Shyam Kumar,Kumar, Dinesh
supporting information, p. 1448 - 1454 (2019/03/26)
The selective control over multiple competing C-H sites would enable straightforward access to functionalized indoles. In this context, we report here a modular and selective C-H arylation of indoles following the micellar catalysis approach using the third generation "designer" surfactant SPGS-550-M in the presence of 1 mol% of [(cinnamyl)PdCl]2 under mild conditions. Thus, access to high value C-arylated (C-3 and C-2) indoles was achieved fulfilling the "triple bottom line philosophy" of green chemistry. The nature of the phosphine ligand was found to be critical for achieving site-selectivity, DPPF and DPPP being the most effective in promoting the arylation at C3-H and C2-H, respectively. The reaction is scalable and offers high chemo- (C vs. N) and regio-selectivity (C-3 vs. C-2) with a wide range of functional group tolerance. The surfactant aqueous solution can be recycled and reused without compromising on product yields.
Transition-Metal-Free C3 Arylation of Indoles with Aryl Halides
Chen, Ji,Wu, Jimmy
supporting information, p. 3951 - 3955 (2017/03/27)
We report an unprecedented transition metal-free coupling of indoles with aryl halides. The reaction is promoted by KOtBu and is regioselective for C3 over N. The use of degassed solvents devoid of oxygen is necessary for the success of the transformation. Preliminary studies implicate a hybrid mechanism that involves both aryne intermediates and non-propagative radical processes. Electron transfer is also a distinct possibility. These conclusions were substantiated by EPR data, isotopic labeling studies, and the use of radical scavengers and electron transfer inhibitors.
Copper-mediated intramolecular aza-Wacker-type cyclization of 2-alkenylanilines toward 3-aryl indoles
Yang, Rui,Yu, Jin-Tao,Sun, Song,Zheng, Qingheng,Cheng, Jiang
, p. 445 - 448 (2017/01/11)
A copper-mediated intramolecular aza-Wacker-type cyclization was developed for the direct and efficient synthesis of 3-aryl indoles using 2-alkenylanilines in moderate to good yields with good functional group compatibility. This strategy shows the high efficiency, operational simplicity as well as broad substrate scope.
Palladium/Copper Cocatalyzed Coupling Reaction of Aroyl Hydrazides with Indoles
Liu, Congrong,Yang, Fulai
supporting information, p. 1213 - 1217 (2016/12/28)
An unprecedented palladium/copper cocatalyzed coupling reaction of indoles with simple aroyl hydrazides has been developed under aerobic conditions. A range of aroyl hydrazides underwent palladium/copper cocatalyzed oxidative arylation with indoles open to air in a 1:1 mixture of dimethyl sulfoxide and nitromethane to give structurally diverse 2-arylindoles or 3-arylindoles in moderate to good yields. The reaction well tolerates a wide variety of functional groups such as alkoxy, halo, ester.
