Rose bengal as photocatalyst: visible light-mediated Friedel–Crafts alkylation of indoles with nitroalkenes in water

Yu, Zongyi; Zhao, Jianzhang; Yang, Fan; Tang, Xiaofei; Wu, Yufeng; Ma, Cunfei; Song, Bo; Lei, Yun; Meng, Qingwei

doi:10.1039/c9ra09227g

Cited by 28 publications

(29 citation statements)

References 53 publications

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“…Thereafter, indole attacks the iminium ion B to afford intermediate C , which upon sequential oxidation, Friedel‐Crafts reaction with 23 and subsequent elimination of the aniline moiety furnishes the product 25 . Recently, Meng and co‐workers reported a redox‐neutral photoredox‐catalyzed C3‐alkylation of indoles with electron deficient β ‐nitrostyrenes to afford the corresponding coupling products in moderate to good yields [21] …”

Section: Functionalization Via C−c Bond Formationmentioning

confidence: 99%

“…Importantly, the robustness of the synthetic method and utility of the final product Recently, Meng and co-workers reported a redoxneutral photoredox-catalyzed C3-alkylation of indoles with electron deficient β-nitrostyrenes to afford the corresponding coupling products in moderate to good yields. [21] In 2017, Molander and co-workers demonstrated an elegant approach for the site-selective alkylation of N-heterocyclic compounds 28 with stable alkyltrifluoroborate salts 29 under oxidative organophotoredox catalytic regime, furnishing corresponding monalkylated N-heterocyclic compounds 30 in high selectivity (Scheme 6). [22] A large variety of N-heterocyclic compounds, such as quinoline, isoquinoline, quinoxaline, indazole, among others, were successfully alkylated with numerous primary, secondary and tertiary alkyltrifluoroborate salts using potassium perdisulphate as a terminal oxidant and mesityl-substituted acridinium salt (PC-4) as an organophotocatalyst.…”

Section: Alkylationmentioning

confidence: 99%

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Organophotoredox‐Catalyzed Late‐Stage Functionalization of Heterocycles

et al. 2021

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In the last decade, visible light photoredox catalysis promoting radical‐based organic transformations has received enormous synthetic applicability, as they allow unfolding of site‐selective reactivities under mild reaction conditions. Moreover, the photoredox transformations utilizing organic dyes as photocatalysts are attractive with regard to low cost, less toxicity, easy availability and high functional group tolerance. The organophotoredox‐catalyzed reaction technologies enabling direct, efficient and selective late‐stage functionalization of various heterocycles leading to the formation of various C−C and C−X (X=N, P, O, S, Se, Br) bonds have emerged at the forefront of synthetic methodologies available to synthetic chemists. This minireview summarizes the developments made in the last five years in the field of late‐stage functionalization of heterocycles governed by various organophotocatalysts and intends to provide the readers a comprehensive overview of this research field with representative examples and mechanistic insights.

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Section: Functionalization Via C−c Bond Formationmentioning

confidence: 99%

Section: Alkylationmentioning

confidence: 99%

Organophotoredox‐Catalyzed Late‐Stage Functionalization of Heterocycles

et al. 2021

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“…[139] Meng et al developed a novel and facile visible light-induced Friedel-Crafts alkylation of indoles with nitroalkenes for the synthesis of nitroalkylated indoles using Rose Bengal as the photocatalyst (Scheme 91). [140] This method employs water as the solvent without the need of any bases or metals. The plausible mechanism is shown in scheme 91.…”

Section: Rose Bengal Photocatalysismentioning

confidence: 99%

Recent Developments in Photo‐Catalyzed/Promoted Synthesis of Indoles and Their Functionalization: Reactions and Mechanisms

2020

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The use of clean and renewable light sources is increasingly common in organic synthesis due to its safety, practicality and economy. Recently, photoredox catalysis has shown great application values in organic transformations because of its advantages of environmentally friendly and abundant resources. Indoles and their derivatives (indolines, oxindoles and isatins) are the core skeletons of some important organic compounds and widely‐present in various natural products and pharmaceuticals with different biological activities. Therefore, the research on the synthesis and modification of indoles is particularly important for chemists and pharmacologists. This review summarizes the effects of photocatalysis on indole synthesis and modification in recent decades. These transformations are accomplished by using metal photocatalysts (i. e., Ir, Ru, Ni, Cu, Fe, Au, Rh, TiO2, etc.) or non‐metallic photocatalysts (i. e., Rose Bengal, Eosin Y, quinones, naphthols, N‐heterocyclic carbenes, carbazoles, pyrylium salts, etc.), or without the need of photocatalysts. The detailed mechanisms of these photo‐catalyzed/promoted organic reactions are also highlighted deeply. And we hope this review will be helpful to researchers interested in this promising field of photocatalyzed transformations.

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“…1 Energy transfer, oxidative quenching and reductive quenching photocatalytic cycles of a generic TADF PC with donor (D) and acceptor (A) substrates (Sub). include acridinium salts 22,23 and organic dyes such as eosin Y, 24,25 fluorescein 26,27 and rose bengal 28,29 (cf. Fig.…”

Section: Introductionmentioning

confidence: 99%

Organic thermally activated delayed fluorescence (TADF) compounds used in photocatalysis

2021

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Rose bengal as photocatalyst: visible light-mediated Friedel–Crafts alkylation of indoles with nitroalkenes in water

Abstract: A novel and facile visible-light-mediated alkylation of indoles and nitroalkenes has been developed.

Cited by 28 publications

References 53 publications

Organophotoredox‐Catalyzed Late‐Stage Functionalization of Heterocycles

Organophotoredox‐Catalyzed Late‐Stage Functionalization of Heterocycles

Recent Developments in Photo‐Catalyzed/Promoted Synthesis of Indoles and Their Functionalization: Reactions and Mechanisms

Organic thermally activated delayed fluorescence (TADF) compounds used in photocatalysis

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