Transition‐Metal‐Catalyzed Regioselective Alkylation of Indoles with Alcohols

Putra, Anggi Eka; Takigawa, Kei; Tanaka, H; Ito, Yoshihiko; Oe, Yohei; Ohta, Tetsuo

doi:10.1002/ejoc.201300744

Cited by 86 publications

(36 citation statements)

References 45 publications

(12 reference statements)

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“…According to Shilov et al, this type of reaction can be referred as an indirect C-H activation [6], while others characterized this catalytic reaction as "borrowing hydrogen" methodology [23].…”

Section: Resultsmentioning

confidence: 99%

Regioselective Catalytic Alkylation of N-Heterocycles in Continuous Flow

Sipőcz¹,

Lengyel²,

Sipos³

et al. 2016

J Flow Chem

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A novel method for C-H functionalization of heteroaromatic rings by using continuous-flow reactors is reported. Direct alkylation reactions were investigated under heterogeneous catalytic conditions using simple transition metal catalysts at elevated temperature and pressure. As a model reaction, the alkylation of indole was attempted using cheap Raney W Nickel catalyst. Alcohols served both as alkylating agent and as reaction media. The targeted 3-alkyl-indoles were obtained in moderate to good yield with reasonable selectivity. Transient protection on the N-atom increased the selectivity up to 80%. The scope and limitations were also investigated. In summary, direct alkylation with alcohols represents a rapid (residence time of <1 min) and traceless process with high atom economy (88-92%, in those cases where transient protection was not applied).

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Section: Resultsmentioning

confidence: 99%

Regioselective Catalytic Alkylation of N-Heterocycles in Continuous Flow

Sipőcz¹,

Lengyel²,

Sipos³

et al. 2016

J Flow Chem

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“…The substituted 3‐methyl‐1 H ‐indoles and 3‐benzyl‐1 H ‐indoles were prepared according to procedures reported in the literature . Similarly, substituted 2‐(1 H ‐indol‐3‐yl)acetate and 3‐vinylindoles were also prepared according to literature procedures .…”

Section: Methodsmentioning

confidence: 99%

Cobalt‐Catalyzed C−H Nitration of Indoles by Employing a Removable Directing Group

Saxena

Kapur

2018

Chemistry An Asian Journal

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A mild and efficient C(sp )-H nitration of 3-substituted indoles, by using the economical and non-toxic cobalt nitrate hexahydrate [Co(NO ) ⋅6 H O] as a catalyst and tert-butyl nitrite (TBN) as the nitro source, is reported. This approach provides a unique methodology involving a site-selective C-N bond formation for preparation of C-2 substituted nitro indoles. Utilization of the tBoc as the removable directing group enhances the synthetic utility of the method.

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“…Ohta et al. reported the RuCl 2 (PPh 3 ) 3 /DPEphos (DPEphos=bis[(2‐diphenylphosphanyl)phenyl] ether) catalyzed reaction of indoles and benzylic alcohols in the presence of a large amount of tripotassium phosphate . Gopalaiah and co‐workers developed BIMs through an iron‐catalyzed oxidative coupling of benzylamines and indoles .…”

Section: Figurementioning

confidence: 99%

Synthesis Of Biologically Active Bis(Indolyl)Methane Derivatives by Bisindole Alkylation of Tetrahydroisoquinolines with Visible‐Light Induced Ring‐Opening Fragmentation.

Chen

Hong

et al. 2016

Asian J Org Chem

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Av isible-light photoredoxc atalyzed ring-opening functionalization of tetrahydroisoquinolines with bisindole alkylation has been developed, which expedites an ew vista for the synthesis of bis(indolyl)methaned erivatives. The transformation comprises as eries of cascade reactions, photoredox catalysis, amine oxidation, fragmentation and Friedel-Craft alkylation.Five of the prepared bis(indolyl)methane derivatives containing the para substitution group on the side chain of benzene suppressed cancer cell growth in human breast adenocarcinoma MDA-MB-231 cells, and one candidate demonstrated asignificant effect on cell migration.Bis(indolyl)m ethanes (BIMs), [1] are an importantt ype of alkaloid that have been widely isolated from marine and terrestrial natural sources, including plants, parasitic bacteria, tunicates, and sponges, etc. (Figure 1). [2] This BIMs alkaloids exhibit ab road spectrum of biological activities including antibacterial, [3] antitumor, [4] antimicrobial, [5] anti-fungal, [6] anti-inflammatory, [7] anti-hyperlipidemic, [8] antimetastatic, [9] and serve as poten-tial hypolipidemic and antiobesity agents, [10] etc. Moreover,t he oxidizedf orms of BIMs are utilized as colorimetric sensors. [11] Owing to their versatile activity and their prevalence in natural resources, syntheses of BIMs have continued to be of intense interest. While the condensation of indoles and carbonyl compounds in the presence of either protic acid or Lewis acid is the most traditional and practical methodf or the synthesis of bis(indolyl)methanes, [12] diversea pproaches toward BIMs have continued to thrive (Scheme1). Their importance can be Scheme1.Selectedexamples of the approaches to BIMs.

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Transition‐Metal‐Catalyzed Regioselective Alkylation of Indoles with Alcohols

Cited by 86 publications

References 45 publications

Regioselective Catalytic Alkylation of N-Heterocycles in Continuous Flow

Regioselective Catalytic Alkylation of N-Heterocycles in Continuous Flow

Cobalt‐Catalyzed C−H Nitration of Indoles by Employing a Removable Directing Group

Synthesis Of Biologically Active Bis(Indolyl)Methane Derivatives by Bisindole Alkylation of Tetrahydroisoquinolines with Visible‐Light Induced Ring‐Opening Fragmentation.

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