I2-mediated C3-formylation of indoles by tertiary amine and H2O

Zhang, Bo; Liu, Bin; Chen, Jianbin; Wang, Jiehui; Liu, Miaochang

doi:10.1016/j.tetlet.2014.08.024

Cited by 15 publications

(6 citation statements)

References 42 publications

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“…Also, a comparably high yield without the aid of high temperatures was obtained for the designed catalytic system compared to Rose Bengal, CuCl 2 , and I 2 catalytic systems (Table 2, entries 6, 7, and 8). 2c,f, 22 The g-C 3 N 4 , a state-of art metal-free photocatalyst was also investigated under optimized condition. However, only 31% yield of the product was obtained (Table 2, entry 9).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Visible Light-Driven C-3 Functionalization of Indoles over Conjugated Microporous Polymers

et al. 2018

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Metal-free and heterogeneous organic photocatalysts provide an environmentally friendly alternative to traditional metal-based catalysts. This paper reports a series of carbazole-based conjugated microporous polymers (CMPs) with tunable redox potentials and explores their photocatalytic performance with regard to C-3 formylation and thiocyanation of indoles. Conjugated polymers were synthesized through FeCl3 mediated Friedel–Crafts reactions, and their redox potentials were well regulated by simply altering the nature of the core (i.e., 1,4-dibenzyl, 1,3,5-tribenzyl, or 1,3,5-triazin-2,4,6-triyl). The resulting CMPs exhibited high surface areas, visible light absorptions, and tunable semiconductor-range band gaps. With the highest oxidative capability, CMP-CSU6 derived from 1,3,5-tri(9H-carbazol-9-yl)benzene showed the highest efficiency for C-3 formylation and thiocyanation of indoles at room temperature. Notably, the as-made catalysts can be easily recovered with good retention of photocatalytic activity and reused at least five times, suggesting good recyclability. These results are significant for constructing high-performance porous polymer catalysts with tunable photoredox potentials targeting an efficient material design for catalysis.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Visible Light-Driven C-3 Functionalization of Indoles over Conjugated Microporous Polymers

et al. 2018

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“…We used continuous flow chemistry techniques to carry out the C3-formylations reported by Zhang et al and Wang et al 17,18 We expected the continuous flow method to provide a solution for the poor functional group tolerance and long reaction times seen in the conventional batch reaction methods. [17][18][19][20][21][22][23][24][25] First, the batch process was used to determine the flow-compatible conditions for the C3-formylation of indoles (Table 1). Insoluble reactants in the form of slurry clog the microchannel and disturb the continuous flow reaction (See Supporting Information section 2 for details).…”

Section: Resultsmentioning

confidence: 99%

C3‐Formylation of Indoles in Continuous Flow

Sung

Kim

et al. 2020

Bulletin Korean Chem Soc

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We have developed a continuous flow C3‐formylation technique for indoles using hexamethylenetetramine (HMTA) and iodine. A mixed solvent system of DMF–H2O (1:1, vol/vol) completely dissolves reagents and prevents clogging of microchannels during fluid flow. The continuous flow technique provides maximized mixing and excellent heat transfer efficiency. Thus, flow chemistry accelerates the rate of C3‐formylation of indoles in the absence of a strong acid, base, or metal catalyst. We show that high yields of C3‐formylated indoles (up to 83%) can be obtained at 150°C when the residence time is as low as 8 min.

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“…[2] Solid (56.2 mg, 69%)； [1] Solid (67.7 mg, 60%)； 5-fluoro-1H-indole-3-carbaldehyde(4m) [1] Solid (58. 1H-indole-3,5-dicarbaldehyde (4r) [6] Solid (46.8 mg, 54%)；…”

Section: S7mentioning

confidence: 99%

“…The widely used formylation strategy involves a Mannich-type addition followed by an oxidation/hydrolysis (Scheme 1, eq 1). 6 In this strategy, methylamines usually act as the carbon source of the HCO group under oxidative conditions. 6a-j The oxidation of methylamines gives iminium ions, and the attack of iminium ions on indoles provides Mannich addition product.…”

mentioning

confidence: 99%

Triphenylphosphine/1,2-Diiodoethane-Promoted Formylation of Indoles with N,N-Dimethylformamide

Lin

Xiao

Zhu

2021

Synlett

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Despite intensive studies on the synthesis of 3-formylindoles, it is still highly desirable to develop efficient methods for the formylation of indoles, due to the shortcomings of the reported methods, such as inconvenient operations and/or harsh reaction conditions. Here, we describe a Ph3P/ICH2CH2I-promoted formylation of indoles with DMF under mild conditions. A Vilsmeier-type intermediate is readily formed from DMF promoted by the Ph3P/ICH2CH2I system. A one-step formylation process can be applied to various electron-rich indoles, but a hydrolysis needs to be carried out as a second step in the case of electron-deficient indoles. Convenient operations make this protocol attractive.

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I2-mediated C3-formylation of indoles by tertiary amine and H2O

Cited by 15 publications

References 42 publications

Visible Light-Driven C-3 Functionalization of Indoles over Conjugated Microporous Polymers

Visible Light-Driven C-3 Functionalization of Indoles over Conjugated Microporous Polymers

C3‐Formylation of Indoles in Continuous Flow

Triphenylphosphine/1,2-Diiodoethane-Promoted Formylation of Indoles with N,N-Dimethylformamide

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