59541-82-1Relevant academic research and scientific papers
One-Pot Asymmetric Oxidative Dearomatization of 2-Substituted Indoles by Merging Transition Metal Catalysis with Organocatalysis to Access C2-Tetrasubstituted Indolin-3-Ones
Zhao, Yong-Long,An, Jian-Xiong,Yang, Fen-Fen,Guan, Xiang,Fu, Xiao-Zhong,Li, Zong-Qin,Wang, Da-Peng,Zhou, Meng,Yang, Yuan-Yong,He, Bin
, p. 1277 - 1285 (2022/03/14)
A one-pot approach for the asymmetric synthesis of C2-tetrasubstituted indolin-3-ones from 2-substituted indoles was developed via merging transition metal catalysis with organocatalysis. This strategy involves two processes, including CuI catalyzed oxidative dearomatization of 2-substituted indoles using O2 as green oxidant, and followed by an proline-promoted asymmetric Mannich reaction with ketones or aldehydes. A series of C2-tetrasubstituted indolin-3-ones were obtained in 35–86% yields, 2:1->20:1 dr and 48–99% ee. Moreover, the synthetic 2-tetrasubstituted indolin-3-ones could be easily transformed into 1H-[1,3] oxazino [3,4-a]indol-5(3H)-ones via a [4+1] cyclization process. In addition, the synthetic compound 3 s show certain antibacterial activity against S. aureus ATCC25923 and multi-drug resistance bacterial strain of S. aureus (20151027077) and its MIC values up to 8 μg/mL and 16 μg/mL, respectively. (Figure presented.).
Polysubstituted Indole Synthesis via Palladium/Norbornene Cooperative Catalysis of Oxime Esters
Liu, Jiechun,Lin, Haojiang,Jiang, Huanfeng,Huang, Liangbin
supporting information, p. 484 - 489 (2022/01/20)
Polysubstituted indoles are prevalent in pharmaceuticals, agrochemicals, and organic materials. Presented herein is the fact that polyfunctionalized indoles can be efficiently constructed from easily accessible oxime esters and aryl iodides, involving a palladium/norbornene synergistic synthesis. The reaction is enabled by a unique class of electrophiles in palladium/norbornene cooperative catalysis, which are oxime esters derived from simple ketone. The broad substrate scope and high functional group tolerance could make this method attractive for the synthesis of polysubstituted indoles.
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.
Method for synthesizing 2-substituted indole compound from iodobenzene and oxime ester under catalysis of palladium
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Paragraph 0041-0048, (2022/01/05)
The invention belongs to the technical field of organic chemistry, and discloses a method for synthesizing a 2-substituted indole compound from iodobenzene and oxime ester under the catalysis of palladium. The method comprises the following steps of reacting an oxime ester compound with iodobenzene under the action of a palladium catalyst, a phosphine ligand and norbornene by taking an organic solvent as a reaction medium in a protective atmosphere, and carrying out subsequent treatment to obtain the 2-substituted indole compound. According to the method, palladium is used as a catalyst, the phosphine ligand is adopted, the yield is high, and the substrate applicability is wide. In addition, the oxime ester compound is used as a raw material, and the method has the advantages of cheap and easily-prepared raw materials, simple operation, mild reaction conditions and the like.
Regioselective mercury(I)/palladium(II)-catalyzed single-step approach for the synthesis of imines and 2-substituted indoles
Delgado, Francisco,Gutiérrez, Rsuini U.,Hernández-Montes, Mayra,Mendieta-Moctezuma, Aarón,Tamariz, Joaquín
, (2021/07/21)
An efficient synthesis of ketimines was achieved through a regioselective Hg(I)-catalyzed hydroamination of terminal acetylenes in the presence of anilines. The Pd(II)-catalyzed cycliza-tion of these imines into the 2-substituted indoles was satisfactorily carried out by a C-H acti-vation. In a single-step approach, a variety of 2-substituted indoles were also generated via a Hg(I)/Pd(II)-catalyzed, one-pot, two-step process, starting from anilines and terminal acetylenes. The arylacetylenes proved to be more effective than the alkyl derivatives.
Synthesis of Substituted Anilines from Cyclohexanones Using Pd/C-Ethylene System and Its Application to Indole Synthesis
Maeda, Katsumi,Matsubara, Ryosuke,Hayashi, Masahiko
supporting information, p. 1530 - 1534 (2021/03/08)
The synthesis of anilines and indoles from cyclohexanones using a Pd/C-ethylene system is reported. A simple combination of NH4OAc and K2CO3 under nonaerobic conditions was found to be the most suitable to perform this reaction. Hydrogen transfer between cyclohexanone and ethylene generates the desired products. The reaction tolerates a variety of substitutions on the starting cyclohexanones.
An iron(iii)-catalyzed dehydrogenative cross-coupling reaction of indoles with benzylamines to prepare 3-aminoindole derivatives
Chen, Wei-Li,Li, Kun,Liang, Cui,Liang, Wang-Fu,Liao, Wei-Cong,Mo, Dong-Liang,Qiu, Pei-Wen,Su, Gui-Fa
supporting information, p. 9610 - 9616 (2021/12/09)
We report a green cascade approach to prepare a variety of 3-aminoindole derivatives in good to excellent yields through an iron(iii)-catalyzed dehydrogenative cross-coupling reaction of 2-arylindoles and primary benzylamines under mild reaction conditions. Mechanistic studies show that a cascade reaction involves a tert-butyl nitrite (TBN)-mediated nitrosation of 2-substituted indoles and a 1,5-hydrogen shift to afford indolenine oximes, sequential iron(iii)-catalyzed condensation and a 1,5-hydrogen shift over four steps in a one-pot reaction. The reaction shows a broad substrate scope of indoles and benzylamines and tolerates a wide range of functional groups. Moreover, the reaction is easily performed at the gram scale without producing waste after the reaction is completed. The 3-aminoindole product is purified by simple extraction, washing, and recrystallization without flash column chromatography. A double imine ligand containing the 3-aminoindole unit is facile to obtain in a 52% yield in one step. The present method highlights readily available starting materials, a simple purification procedure, and the usage of cheap, nontoxic, and environmentally benign iron(iii) catalysts. This journal is
Chiral Br?nsted Acid from Chiral Phosphoric Acid Boron Complex and Water: Asymmetric Reduction of Indoles
Yang, Kai,Lou, Yixian,Wang, Chenglan,Qi, Liang-Wen,Fang, Tongchang,Zhang, Feng,Xu, Hetao,Zhou, Lu,Li, Wangyang,Zhang, Guan,Yu, Peiyuan,Song, Qiuling
supporting information, p. 3294 - 3299 (2020/01/21)
A new chiral Br?nsted acid, generated in situ from a chiral phosphoric acid boron (CPAB) complex and water, was successfully applied to asymmetric indole reduction. This “designer acid catalyst”, which is more acidic than TsOH as suggested by DFT calculations, allows the unprecedented direct asymmetric reduction of C2-aryl-substituted N-unprotected indoles and features good to excellent enantioselectivities with broad functional group tolerance. DFT calculations and mechanistic experiments indicates that this reaction undergoes C3-protonation and hydride-transfer processes. Besides, bulky C2-alkyl-substituted N-unprotected indoles are also suitable for this system.
Room-Temperature Palladium(II)-Catalyzed Direct 2-Arylation of Indoles with Tetraarylstannanes
Liu, Yuxia,Wang, Chao,Huang, Linjuan,Xue, Dong
supporting information, p. 1613 - 1618 (2020/09/15)
A palladium(II)-catalyzed direct 2-arylation of indoles by tetraarylstannanes with oxygen (balloon) as the oxidant at room temperature has been developed. Various tetraarylstannanes can be employed as aryl sources for 2-arylation of indoles in up to 89% yield, providing a practical and efficient catalytic protocol for accessing 2-arylindoles.
Well-defined (NHC)Pd(N–heterocyclic carboxylate)(OAc) complexes-catalyzed direct C2-arylation of free (NH)-indoles with arylsulfonyl hydrazides
Yang, Jin,Zong, Ling-Li,Zhu, Xiao-Ting,Zhu, Xin-Ying,Zhao, Jian-Yi
, (2020/08/24)
A series of well-defined (NHC)Pd(N–heterocyclic carboxylate)(OAc) complexes (N–heterocyclic carboxylate = pyridine-2-carboxylate, quinoline-2-carboxylate and isoquinoline-1-carboxylate) were synthesized and fully characterized by NMR spectra, HR-MS and X-ray single crystal diffraction. The obtained complexes were then used for direct C2-arylation of free (NH)-indoles with arylsulfonyl hydrazides. With low catalyst loading, all complexes exhibited high catalytic activities for the arylation reactions.
