CuI‐Catalyzed Selective 3‐Alkylation of Indoles with N‐Tosylhydrazones and the I2‐Mediated Further Cyclization to Chromeno[2,3‐b]Indoles

Miao, Chun‐Bao; Sun, Yi; He, Wei; X, Sun; Yang, Hai‐Tao

doi:10.1002/adsc.201800206

Cited by 16 publications

(6 citation statements)

References 44 publications

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“…Recently, Miao and his group demonstrated the CuI‐catalyzed reaction of indoles 6 with N ‐tosylhydrazones 35 prepared from the ortho‐/para‐hydroxybenzaldhydes to access selectively the C‐3 alkylated products 36 instead of the N ‐alkylated products (Scheme 19). [35] It is notable that the ortho ‐ or para ‐hydroxyl group was crucial for this developed strategy [36] . This protocol allowed the variety of functional group on indole scaffold 6 and electron‐donating as well as electron‐withdrawing groups containing indoles 6 reacted smoothly to give 36 in good yields, but unfortunately, N ‐protected indole having protected groups such as methyl, acetyl, and tosyl groups, failed to deliver desired product 36 .…”

Section: Application Of N‐tosylhydrazones For Derivatization Of Indolementioning

confidence: 99%

Recent Update on Alkylation of Indole and Its Derivatives Using N‐Tosylhydrazone

Vaishya,

Singhal,

Mehra

et al. 2023

ChemistrySelect

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N‐Tosylhydrazones are valuable synthons in various organic transformations to achieve potent bioactive heterocycles. N‐tosylhydrazones largely serve as 1,3‐dipolar species for cycloaddition reactions, diazo precursors for carbene or carbenoid reactions, and alternatives to parent carbonyl compounds. On the other hand, indole derivatives exhibit wide range of pharmacological and therapeutic activities including anticancer, antiviral, antimalarial, antiasthmatic, antibacterial and anti‐inflammatory. This review mainly highlights the recent developments in the synthetic usefulness of N‐tosylhydrazones derived from indole‐carboxaldehydes and other carbonyl compounds. Moreover, the synthetic potential, scope, limitations, and mechanism of these transformations have also been discussed.

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Section: Application Of N‐tosylhydrazones For Derivatization Of Indolementioning

confidence: 99%

Recent Update on Alkylation of Indole and Its Derivatives Using N‐Tosylhydrazone

Vaishya,

Singhal,

Mehra

et al. 2023

ChemistrySelect

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“…Moreover, their derivatives have been widely used as candidates for RNA-binding proteins and anticancer agents . At present, the reports on the synthesis of such fused heterocyclic scaffolds − are very few, which often suffered from limited substrates scope and harsh reaction conditions. Therefore, it is of great significance to develop new methods and catalysts for the synthesis under relatively mild conditions.…”

Section: Introductionmentioning

confidence: 99%

Design and Exploration of Iron Salt-Catalyzed Synthesis of Chromene[2,3-b] Indoles as a Laboratory Experiment for Undergraduates

et al. 2023

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Integrating new synthetic methods and experimental techniques from the latest research reports into undergraduate laboratory experiments is of great significance, as it enables students to learn the cutting-edge technology of organic chemistry and cultivates their experimental skills and innovative thinking. In this study, an experiment on the iron salt-catalyzed synthesis of chromone [2,3-b] indole derivatives, based on the latest report, was developed to train senior undergraduate students’ experimental skills and increase their basic knowledge in organic synthesis, especially those majoring in Organic Chemistry, Applied Chemistry, and Pharmaceutical Chemistry, among others. Incorporating this experiment into laboratory activities can strengthen students’ fundamental knowledge of organic chemistry, including Grignard reaction, substitution, addition, carbocation, tautomerism, intramolecular cyclization, and elimination, and enhance their skills in modern organic synthesis techniques, such as Schlenk technology for anhydrous and anaerobic operation, thin-layer chromatography for monitoring reaction progress, and column chromatography for the separation and purification of products. Additionally, this approach can help cultivate students’ scientific thinking and creativity and stimulate their enthusiasm for scientific research. The feasibility of introducing this latest scientific achievement into undergraduate laboratory experiments was verified by randomly selecting 12 undergraduates majoring in Applied Chemistry as pretest samples. The assessment results showed that the product yield obtained by different groups of students ranged from 72.6% to 85.8%, indicating a relatively high level of achievement, and the average score of the post-test was 81, which is a satisfactory outcome for such a comprehensive experiment.

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“…The presence of a hydrogen at C-3 and a carbonyl at C-2 distinguishes the indoles constructed herein from those previously prepared via the CDC strategy. Instead of other intractable groups, such as aryl, alkyl, or cyano, a sole carbonyl is installed at C-2, which is readily transformable to a variety of functional groups as illustrated by previous cases. − The existence of a labile hydrogen at C-3 further extends the structural flexibility. Such features make the current method adaptable to a range of diverse indoles.…”

Section: Introductionmentioning

confidence: 99%

Carboxylic Acid-Promoted Single-Step Indole Construction from Simple Anilines and Ketones via Aerobic Cross-Dehydrogenative Coupling

et al. 2018

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The cross-dehydrogenative coupling (CDC) reaction is an efficient strategy for indole synthesis. However, most CDC methods require special substrates, and the presence of inherent groups limits the versatility for further transformation. A carboxylic acid-promoted aerobic catalytic system is developed herein for a single-step synthesis of indoles from simple anilines and ketones. This versatile system is featured by the broad substrate scope and the use of ambient oxygen as an oxidant and is convenient and economical for both laboratory and industry applications. The existence of the labile hydrogen at C-3 and the highly transformable carbonyl at C-2 makes the indoles versatile building blocks for organic synthesis in different contexts. Computational studies based on the density functional theory (DFT) suggest that the rate-determining step is carboxylic acid-assisted condensation of the substrates, rather than the functionalization of aryl C−H. Accordingly, a pathway via imine intermediates is deemed to be the preferred mechanism. In contrast to the general deduction, the in situ formed imine, instead of its enamine isomer, is believed to be involved in the first ligand exchange and later carbopalladation of the α-Me, which shed new light on this indolization mechanism.

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CuI‐Catalyzed Selective 3‐Alkylation of Indoles with N‐Tosylhydrazones and the I₂‐Mediated Further Cyclization to Chromeno[2,3‐b]Indoles

Cited by 16 publications

References 44 publications

Recent Update on Alkylation of Indole and Its Derivatives Using N‐Tosylhydrazone

Recent Update on Alkylation of Indole and Its Derivatives Using N‐Tosylhydrazone

Design and Exploration of Iron Salt-Catalyzed Synthesis of Chromene[2,3-b] Indoles as a Laboratory Experiment for Undergraduates

Carboxylic Acid-Promoted Single-Step Indole Construction from Simple Anilines and Ketones via Aerobic Cross-Dehydrogenative Coupling

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