- Rhodium-Catalyzed Selective C-H Trideuteromethylation of Indole at C7 Position Using Acetic- d6 Anhydride
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Rhodium-catalyzed C7-selective decarbonylative trideuteromethylation of indoles with commercially available Ac2O-d6 via C-H and C-C bond activation has been developed. The key to the high reactivity and regioselectivity of this trans
- Han, Xiaowei,Yuan, Yu,Shi, Zhuangzhi
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- Pd/β-cyclodextrin-catalyzed C-H functionalization in water: A greener approach to regioselective arylation of (NH)-indoles with aryl bromides
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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.
- Duan, Xin Hong,Xu, Peng
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supporting information
p. 19425 - 19431
(2021/11/09)
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- Electro-Oxidative C-N Bond Formation through Azolation of Indole Derivatives: An Access to 3-Substituent-2-(Azol-1-yl)indoles
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A practical protocol to synthesize 3-substituent-2-(azol-1-yl)indole derivatives has been developed via an electrochemical oxidative cross coupling process under mild conditions. This electro-oxidative C-N bond formation strategy tolerates a range of functional groups and is amenable to gram scale synthesis. Moreover, this method was applied to the late-stage functionalization of bioactive molecules.
- Zhou, Naifu,Zhao, Junhao,Sun, Chengbo,Lai, Yuqin,Ruan, Zhixiong,Feng, Pengju
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p. 16059 - 16067
(2021/10/01)
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- Arylation of indoles using cyclohexanones dually-catalyzed by niobic acid and palladium-on-carbons
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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.
- Ban, Kazuho,Sajiki, Hironao,Sawama, Yoshinari,Yamamoto, Yuta
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supporting information
p. 3898 - 3902
(2020/06/03)
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- Metal-free and regiospecific synthesis of 3-arylindoles
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A convenient, metal-free, and organic acid-base promoted synthetic method to prepare 3-arylindoles from 3-aryloxirane-2-carbonitriles and arylhydrazine hydrochlorides has been developed. In the reaction, the organic acid catalyzes a tandem nucleophilic ri
- Xie, Wenlai,Xu, Chuangchuang,Xu, Jiaxi
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p. 2661 - 2671
(2020/04/17)
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- Regiospecificity in Ligand-Free Pd-Catalyzed C-H Arylation of Indoles: LiHMDS as Base and Transient Directing Group
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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
- Camp, Clément,Canivet, Jér?me,Clot, Eric,Demarcy, Clément,Mohr, Yorck,Quadrelli, Elsje Alessandra,Renom-Carrasco, Marc,Thieuleux, Chloé,Wisser, Florian M.
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p. 2713 - 2719
(2020/03/11)
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- A micellar catalysis strategy applied to the Pd-catalyzed C-H arylation of indoles in water
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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.
- Vaidya, Gargi Nikhil,Fiske, Sneha,Verma, Hansa,Lokhande, Shyam Kumar,Kumar, Dinesh
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supporting information
p. 1448 - 1454
(2019/03/26)
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- Vinylic MIDA boronates: New building blocks for the synthesis of aza-heterocycles
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Abstract A two-step synthesis of structurally diverse pyrrole-containing bicyclic systems is reported. ortho-Nitro-haloarenes coupled with vinylic N-methyliminodiacetic acid (MIDA) boronates generate ortho-vinyl-nitroarenes, which undergo a "metal-free" nitrene insertion, resulting in a new pyrrole ring. This novel synthetic approach has a wide substrate tolerance and it is applicable in the preparation of more complex "drug-like" molecules. Interestingly, an ortho-nitro-allylarene derivative furnished a cyclic β-aminophosphonate motif. Old dog, new tricks: A two-step synthesis of structurally diverse pyrrole-containing bicyclic systems is reported. ortho-Nitro-haloarenes coupled with vinylic N-methyliminodiacetic acid (MIDA) boronates generate ortho-vinyl-nitroarenes, which undergo a "metal-free" nitrene insertion, resulting in a new pyrrole ring. This approach has a wide substrate tolerance and it is applicable in the preparation of more complex "drug-like" molecules. Interestingly, an ortho-nitro-allylarene derivative furnished a cyclic β-aminophosphonate motif.
- Llona-Minguez, Sabin,Desroses, Matthieu,Ghassemian, Artin,Jacques, Sylvain A.,Eriksson, Lars,Isacksson, Rebecka,Koolmeister, Tobias,Stenmark, P?l,Scobie, Martin,Helleday, Thomas
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supporting information
p. 7394 - 7398
(2015/05/13)
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- Palladium-catalyzed direct arylation of indoles with cyclohexanones
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A novel palladium catalyzed approach to 3-arylindoles was developed from indoles and cyclohexanones. Various cyclohexanones acted as aryl sources via an alkylation and dehydrogenation sequence using molecular oxygen as the hydrogen acceptor. This method showed good regioselectivity and afforded 3-arylindoles as the sole products.
- Chen, Shanping,Liao, Yunfeng,Zhao, Feng,Qi, Hongrui,Liu, Saiwen,Deng, Guo-Jun
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supporting information
p. 1618 - 1621
(2014/04/17)
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- Palladium-catalyzed direct denitrogenative C-3-arylation of 1H-indoles with arylhydrazines using air as the oxidant
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A novel palladium-catalyzed approach to direct C-3-arylation of 1H-indoles with arylhydrazines using air as the oxidant via C-N bond cleavage has been developed. Various substituents are tolerated in this system in moderate to good yields. This reaction could also be compatible with a larger scale. Thus, this strategy using arylhydrazines as arylating reagents provides a powerful method for constructing substituted 3-aryl-1H-indoles. Copyright
- Chen, Yongxin,Guo, Shuaibo,Li, Kangning,Qu, Jinpeng,Yuan, Hua,Hua, Qiuru,Chen, Baohua
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supporting information
p. 711 - 715
(2013/03/29)
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- Direct synthesis of 3-arylindoles via annulation of aryl hydroxylamines with alkynes
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3-Arylindoles are produced in moderate to excellent yields from the reaction between aryl hydroxylamines and alkynes catalyzed by 10 mol % iron(II) phthalocyanine [Fe(Pc)]. Terminal and internal alkynes afford 3-aryl substituted indoles exclusively. Elect
- Lamar, Angus A.,Nicholas, Kenneth M.
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scheme or table
p. 3829 - 3833
(2009/09/08)
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- Regioselective synthesis of indoles via reductive annulation of nitrosoaromatics with alkynes
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(equation presented) Indoles are produced regioselectively and in moderate yields by two new processes: (a) from the [Cp*Ru(CO)2]2-catalyzed reaction of nitrosoaromatics (ArNO) with alkynes under carbon monoxide and (b) in a two-step sequence involving the (uncatalyzed) reaction of ArNO with alkynes, followed by reduction of the intermediate adduct.
- Penoni, Andrea,Volkmann, Jerome,Nicholas, Kenneth M.
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p. 699 - 701
(2007/10/03)
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- Mechanistic Studies on the Reaction of Nitro- and Nitrosoarenes with Vinyl Grignard Reagents
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The reaction of ortho-substituted nitrobenzenes with 3 mol vinylmagnesium halides gives mainly 7-substituted indoles together with minor amounts of the aniline from complete reduction of the nitroarene.Under the same experimental conditions, para-substituted nitrobenzenes essentially lead to the corresponding anilines, with indoles being recovered in very low yield.Nitrosoarenes react with 2 mol Grignard reagent to give almost the same product distribution.An accurate analysis of the stoichiometry of the reaction established that in the first stage of the reaction nitroarenes are attacked at the oxygen atoms and are reduced to nitrosoarenes via enolate elimination.The nitroso derivative can undergo a 1,2-addition to give an N-aryl-N-vinylhydroxylamino magnesium salt.Hydrolysis of this intermediate affords hydroxylamine and the carbonyl derivative corresponding to the vinyl Grignard reagent, as proved by the reaction of nitroarenes with 2 mol Grignard reagent.In the presence of an excess of vinyl magnesium halide, a complete reduction to vinylaniline derivatives, which hydrolyse to aniline, occurs.The effect of the bulkiness of the substituent both in the nitroarene and in the Grignard reagent, the orientation of alkylation and the relative reaction rates of indole and aniline formation suggest that indoles arise via a completely different route: i.e. an inverse 1,2-addition to the N=O double bond.The N-aryl-O-vinylhydroxylamino magnesium salt intermediate can undergo a -sigmatropic rearrangement followed by a rapid ring closure.The third mole of Grignard reagent acts as a base on this bicyclic intermediate, re-aromatizing the six-membered ring.Elimination of water ultimately leads to the indole.
- Bosco, Marcella,Dalpozzo, Renato,Bartoli, Giuseppe,Palmieri, Gianni,Petrini, Marino
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p. 657 - 663
(2007/10/02)
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- A VERSATILE AND EFFICIENT PROCESS TO 3-SUBSTITUTED INDOLES FROM ANILINES
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Borane-mediated reductive elimination of α-thiomethyl-, α-hydroxy-, or α-alkoxy-, α'-substituted oxindoles affords 3-substituted indoles in high yield.Isatins, available via several routes from oxindoles, also afford indoles.
- Wierenga, Wendell,Griffin, John,Warpehoski, Martha A.
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p. 2437 - 2440
(2007/10/02)
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