- Nickel-catalyzed C3-alkylation of indoles with alcohols: Via a borrowing hydrogen strategy
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An efficient method for the Ni-catalyzed C3-alkylation of indoles using readily available alcohols as the alkylating reagents has been developed. The alkylation was addressed with an air and moisture-stable binuclear nickel complex ligated by tetrahydroquinolin-8-one as the effective pre-catalyst. The newly developed transformation could accommodate a broad substrate scope including primary/secondary benzylic and aliphatic alcohols and substituted indoles. Mechanistic studies suggested that the reaction proceeds through a borrowing hydrogen pathway.
- Hu, Miao,Jiang, Yong,Sun, Nan,Hu, Baoxiang,Shen, Zhenlu,Hu, Xinquan,Jin, Liqun
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p. 10057 - 10062
(2021/06/15)
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- Efficient copper-catalyzed synthesis of C3-alkylated indoles from indoles and alcohols
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A highly efficient copper(II) catalyst system for alkylation of indoles with alcohols via hydrogen borrowing method has been developed to afford C3-alkylated indoles in good to excellent yields. Cu(OAc)2 in the combination with dppm ligand has been found to be the most suitable catalyst system for this alkylation reaction.
- Nguyen, Ngoc-Khanh,Nam, Duong Ha,Phuc, Ban Van,Nguyen, Van Ha,Tr?nh, Quang Thang,Hung, Tran Quang,Dang, Tuan Thanh
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- Manganese-Catalyzed Regioselective Dehydrogenative C-versus N-Alkylation Enabled by a Solvent Switch: Experiment and Computation
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The first base metal-catalyzed regioselective dehydrogenative alkylation of indolines using readily available alcohols as the alkylating reagent is reported. A single air-and moisture-stable manganese catalyst provides access to either C3-or N-alkylated indoles depending on the solvent used. Mechanistic studies indicate that the reaction takes place through a combined acceptorless dehydrogenation and hydrogen autotransfer strategy.
- Borghs, Jannik C.,Zubar, Viktoriia,Zubar, Viktoriia,Azofra, Luis Miguel,Sklyaruk, Jan,Rueping, Magnus,Rueping, Magnus
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p. 4222 - 4227
(2020/06/04)
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- Bifunctional Iron Complexes Catalyzed Alkylation of Indoles
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Cyclopentadienone iron carbonyl complexes have been applied in alkylation of indoles with various benzylic alcohols, aliphatic alcohols (butanol, ethanol, methanol and 2-methylpentanol) via the hydrogen autotransfer strategy in mild reaction conditions. Experimental works highlight the role of the bifunctional iron complexes and the base. These iron complexes demonstrated a broad applicability in mild conditions and extended the scope of substrates in iron catalyzed C?C bond formation. (Figure presented.).
- Seck, Charlotte,Mbaye, Mbaye Diagne,Gaillard, Sylvain,Renaud, Jean-Luc
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supporting information
p. 4640 - 4645
(2018/10/31)
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- Tandem organocatalysis and photocatalysis: An anthraquinone-catalyzed indole-c3-alkylation/photooxidation/1,2-shift sequence
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Quinones exhibit orthogonal ground- and excited-state reactivities and are therefore highly suitable organocatalysts for the development of sequential catalytic processes. Herein, the discovery of an anthraquinone-catalyzed thermal indole-C3-alkylation with benzylamines is described, which can be combined sequentially with a new visible-light-driven catalytic photooxidation/1,2-shift reaction. The one-flask tandem process converts indoles into 3-benzylindole intermediates, which are further transformed into new fluorescent 2,2-disubstituted indoline-3-one derivatives.
- Lerch, Stephanie,Unkel, Lisa-Natascha,Brasholz, Malte
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supporting information
p. 6558 - 6562
(2014/06/24)
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- Environmentally friendly and regioselective C3-alkylation of indoles with alcohols through a hydrogen autotransfer strategy
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The direct alkylation of indoles using KOH and alcohols, as initial source of the electrophile, under solvent-free conditions is a safe and environmentally benign strategy for selective modification of these structures at the C 3-position, without using hazardous and difficult to handle bromide or iodide derivatives or toxic and expensive transition metal catalysts. The protocol shows a broad scope, including halogenated indoles and secondary alcohols.
- Cano, Rafael,Yus, Miguel,Ramón, Diego J.
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supporting information
p. 3394 - 3397
(2013/07/11)
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- Transition-Metal-Catalyzed Regioselective Alkylation of Indoles with Alcohols
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The regioselective alkylation of indoles with alcohols as alkylating reagents was developed by using Pd/C or RuCl2(PPh3) 3/DPEphos {DPEphos = bis[(2-diphenylphosphanyl)phenyl] ether}as catalysts. The reaction of indole with benzyl alcohol in the presence of Pd/C and K2CO3 at 80 °C for 24 h without any solvent under in air yielded 90 % of 3-benzylindole. The corresponding 3-benzylindole was obtained in 99 % yield when the reaction was catalyzed by RuCl 2(PPh3)3/DPEphos in the presence of K 3PO4 at 165 °C for 24 h under argon. Several types of alcohols were treated with indoles under these conditions to give the corresponding 3-alkylated indoles in high yields (up to 99 %). This reaction may involve the catalyst-mediated transformation of alcohols to aldehydes, nucleophilic addition of indole to the resulting aldehydes accompanied by dehydration, and then hydrogenation. Copyright
- Putra, Anggi Eka,Takigawa, Kei,Tanaka, Hatsuki,Ito, Yoshihiko,Oe, Yohei,Ohta, Tetsuo
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p. 6344 - 6354
(2013/10/21)
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- Rapid and general protocol towards catalyst-free friedel-crafts C-alkylation of indoles in water assisted by microwave irradiation
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An efficient and simplified protocol for uncatalyzed FriedelCrafts alkylation of indoles using microwave irradiation in water is described. A series of functionalized indole derivatives has been synthesized in very short times with moderate to good yields. The combination of microwave irradiation and superheated water offers significant advantages over conventional methods, such as higher selectivities, simplicity, shorter reaction times, and no need for a catalyst.
- De Rosa, Margherita,Soriente, Annunziata
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experimental part
p. 1029 - 1032
(2010/04/25)
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- [Cp*IrCl2]2-catalyzed indirect functionalization of alcohols: Novel strategies for the synthesis of substituted indoles
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We report novel iridium(III)-catalyzed reactions that afford substituted indoles via the indirect functionalization of alcohols via C-3 selective alkylation of indoles with alcohols and a one-pot cascade strategy from amino- or nitro-phenyl ethyl alcohols, which incorporates oxidative cyclization and C-3 alkylation.
- Whitneys, Simon,Grigg, Ronald,Derrick, Andrew,Keep, Ann
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p. 3299 - 3302
(2008/02/12)
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- Palladium-catalyzed enantioselective C-3 allylation of 3-substituted-1H- indoles using trialkylboranes
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We have developed a new enantioselective C-3 allylation of 3-substituted indoles using allyl alcohol and trialkylboranes. Asymmetric syntheses of 3,3-disubstituted indolines and indolenines in enantiomeric excesses up to 90% have been achieved using the bulky borane 9-BBN-C6H13 as the promoter of the reaction. The dependence of the selectivity on the nature of the borane suggests that the boron reagent has a role beyond promoting ionization of the allyl alcohol. A protocol for oxidation of indolenines to oxindoles has also been developed and led to a formal synthesis of (-)-phenserine. Copyright
- Trost, Barry M.,Quancard, Jean
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p. 6314 - 6315
(2007/10/03)
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- THE USE OF o-MITROARYLACETONITRILES IN THE MITSUNOBU REACTION: MECHANISTIC IMPLICATIONS AND SYNTHETIC APPLICATIONS
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o-Nitroarylacetonitriles (1) have been used as carbon acid participants in the Mitsunobu reaction to yield 2-(o-nitroaryl)-2-alkylacetonitriles (2).Reductive cyclization of 2 afforded 3-alkylindoles (3) in moderate yield.The use of o-nitroarylacetonitrile
- Macor, John E.,Wehner, Jennifer M.
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p. 349 - 365
(2007/10/02)
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- THE USE OF o-NITROARYLACETONITRILES AS CARBON ACID PARTICIPANTS IN THE MITSUNOBU REACTION
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The use of o-nitroarylacetonitriles as carbon acids in the Mitsunobu reaction is discussed as a method of carbon-carbon bond formation.This reaction represents a rare example of a carbon acid participating in a Mitsunobu reaction.
- Macor, John E.,Wehner, Jennifer M.
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p. 7195 - 7198
(2007/10/02)
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