Regiodivergent Trifluoromethanesulfonic Acid‐Promoted Cycloisomerizations of Ynenamines to Fused Indoles

Alam, Khyarul; Kim, Jin Gyeong; Kang, Dong Yun; Park, Jin Kyoon

doi:10.1002/adsc.201801506

Cited by 10 publications

(7 citation statements)

References 38 publications

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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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Section: Resultsmentioning

confidence: 99%

C3‐Formylation of Indoles in Continuous Flow

Sung

Kim

et al. 2020

Bulletin Korean Chem Soc

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“…Figure displays the possible construction mechanism of P (BVS‐SO 3 H)‐SO 3 CF 3 . It is well known that HSO 3 CF 3 as a kind of protonic super organic acid, whose acidity is much higher in organic solvent than common acid such as H 2 SO 4 . And the triflate is stable enough that the redox reaction cannot happen.…”

Section: Resultsmentioning

confidence: 99%

High Catalytic Performance of Mesoporous Dual Brønsted Acidic Ternary Poly (Ionic Liquids) for Friedel‐Crafts Alkylation

Sha

Sheng

Zhou

et al. 2019

Applied Organom Chemis

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A newfangled cross-linked dual Brønsted acidic ternary mesoporous poly (ionic liquids)(MPILs) with mesoporous structure was successfully synthesized with divinylbenzene as cross linker, 1-vinyl-3-butyl imidazole bromide and sodium p-styrene sulfonate as functional group through an ordinary postmodification method and anion exchange process. A sponge-like mesoporous tunnel structure was observed and the obtained P (BVS-SO 3 H)-SO 3 CF 3 sample appeared a relatively high thermal stability, a large surface area (up to 286.8 m 2 /g) and great pore volume (0.73 cm 3 /g). The abundant dual acidic group of sulfonic acid and trifluoromethanesulfonic acid of the composite in the polymer framework impart Brønsted acidity. For the sake of demonstrating our claims, the sample has been used as a novel solid acid catalyst for the reaction of alkylation of o-xylene with styrene to 1-diphenylethane (PXE). Under optimal reaction conditions (reaction under 120°C for 3 hr, catalyst amount was 0.5 wt% of the reaction system, and the mass ratio of o-xylene/styrene was 7.5:1, a 100% conversion of styrene and 93.7% PXE yield was acquired. After four times recycle, the yield remains 53.3%. Comparing with the commercial liquid acid catalyst, it processing a higher catalytic property and recyclability. Moreover, this fresh dual acidic heterogeneous catalyst owning a promising future applied in other acidic catalytic reactions and provide a new method to modify catalyst.

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“…The substitution at the 3-position of the indole ring by a carboxyethyl or a tosyl group was mandatory to obtain 6-or 7membered rings, respectively (Scheme 49c). 64…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…Scheme 58 7-endo carbocyclizations of ynamides to cycloheptenes N-Alkynylated sulfoximines 74 238 and N-tosyl-2biarylynamides 64 240 also proved to be successful starting material for Brønsted acid-catalyzed reaction, giving exclusively the products 239, 241 corresponding to the 6-endo-dig processes with yields of 83-97% and 82-97%, respectively (Scheme 59). In 2013, the group of Hashmi reported the oxidative cyclization of arylynol ethers.…”

Section: Scheme 57 Brønsted Acid Mediated Cycloaromatization Of N-bia...mentioning

confidence: 99%

Brønsted Acid Catalyzed Carbocyclizations Involving Electrophilic Activation of Alkynes

et al. 2022

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This review focuses on the carbocyclization reactions of alkyne-containing substrates catalyzed by Brønsted acids. The electrophilic activation occurs either by direct protonation of the alkyne or by formation of an intermediate cation that further reacts with the alkyne to give the vinyl cation key intermediate. A specific highlight will be put on the selectivity of the various methodologies described herein and on the mechanistic rationale.

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Regiodivergent Trifluoromethanesulfonic Acid‐Promoted Cycloisomerizations of Ynenamines to Fused Indoles

Abstract: Scheme 3. Cycloisomerization of C3-unsubstituted and C3phenyl substituted indole ynenemines.Scheme 4. Further synthetic transformation of 4 a to biologically active indole analogues.UPDATES

Cited by 10 publications

References 38 publications

C3‐Formylation of Indoles in Continuous Flow

C3‐Formylation of Indoles in Continuous Flow

High Catalytic Performance of Mesoporous Dual Brønsted Acidic Ternary Poly (Ionic Liquids) for Friedel‐Crafts Alkylation

Brønsted Acid Catalyzed Carbocyclizations Involving Electrophilic Activation of Alkynes

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