Palladium-Catalyzed Oxidative Cross-Coupling of <i>N-</i>Tosylhydrazones with Indoles: Synthesis of <i>N-</i>Vinylindoles

Zeng, Xiaobao; Cheng, Guolin; Shen, Jinhai; Cui, Xiuling

doi:10.1021/ol401217h

Cited by 59 publications

(27 citation statements)

References 60 publications

(18 reference statements)

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“…Other references also describe that the aryl hydrazones are an important structural unit for the transformation of alkene or alkyne to pyrazoles. − We and other research groups demonstrated that tosylhydrazone have tremendous application in synthetic organic chemistry, especially in cyclization reactions. However, its reactivity toward indole has not been greatly explored. ,, Recent studies described that the reaction of tosylhydrazone with indole favors N-alkylation or N-vinylation of indole, rather than cyclization reactions with C2C3 bond (Scheme b). − We hypothesized that C2–N1 bond opening could be one of the driving forces for C2C3 bond activation.…”

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confidence: 99%

Ring-Opening of Indoles: An Unconventional Route for the Transformation of Indoles to 1H-Pyrazoles Using Lewis Acid

2018

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An unusual transformation of indoles to pyrazoles via an aromatic ring-opening strategy has been developed. The salient feature of this strategy involves the C2-N1 bond opening and concomitant cyclization reaction of the C2═C3 bond of the indole moiety with the tosylhydrazone, which proceeds under transition-metal and ligand free conditions. This ring-opening functionalization of indoles provides a wide scope of differently substituted pyrazoles.

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confidence: 99%

Ring-Opening of Indoles: An Unconventional Route for the Transformation of Indoles to 1H-Pyrazoles Using Lewis Acid

2018

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“…Solche Reaktionen wurden auch mit den Arylmetallspezies beobachtet, die durch eine C‐H‐Funktionalisierung mit CuI und [Cp*RhCl 2 ] 2 als Katalysator erhalten wurden. Außerdem wurde eine Insertion in die Pd‐N‐Bindung des Palladiumcarben‐Intermediats 33 vermerkt, die mit hoher Stereoselektivität N ‐vinylische Indole 32 ergab (Schema b) …”

Section: Hydrazoneunclassified

Neue Ansätze für die Synthese von Metallcarbenen

Jia

2016

Angewandte Chemie

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Metallcarbene sind vielseitige Verbindungen, deren Reaktivität sowohl durch das Metall als auch den Liganden gesteuert werden kann. Zur Synthese von Metallcarbenen nutzt man im Allgemeinen die Stickstoff‐Eliminierung von Diazoverbindungen, die allerdings häufig instabil, explosiv und toxisch sind, was ihren Einsatz in großskaligen Synthesen einschränkt. Demzufolge gibt es eine intensive Suche nach nachhaltigen und ungefährlichen Ersatzsubstraten für die zuverlässige Herstellung von Metallcarbenen. In diesem Aufsatz fassen wir die wichtigsten Fortschritte bei der Erzeugung, katalytischen Reaktionen und der Selektivitätskontrolle von Metallcarbenen zusammen, die nicht aus Diazoverbindungen gebildet wurden.

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“…In 2011, Wang and co‐workers described Cu‐catalyzed coupling of N ‐tosylhydrazones with benzoxazoles and benzothiazoles via C−H functionalization . Recently, Cui′s group reported the synthesis of N ‐vinylindoles involving Pd‐catalyzed reaction of N ‐tosylhydrazones with indoles . Recently, Abdallah Hamze and his group reported the coupling of N ‐tosylhydrazones, mainly with secondary aliphatic amines and a few examples of primary amines using Cu(acac) 2 and Cs 2 CO 3 in dioxane at 100 o C for 3 h. However, under these conditions benzylation of arylamine (anisidine) using N ‐tosylhydrazone of acetophenone failed to deliver the corresponding N ‐benzylated product and generated a styrene derivative .…”

Section: Introductionmentioning

confidence: 99%

Cu-Catalyzed Expeditious Synthesis of N-Benzylaminoheter-ocycles Using N-Tosylhydrazones and Aminoheteroarenes

et al. 2016

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N‐Tosylhydrazones were successfully coupled in the presence of CuI (10 mol%) with various heterocyclic amines to develop a convenient and high yielding protocol for the preparation of N‐benzylaminoheterocycles under microwave irradiation. This ligand‐free new methodology uses readily available starting materials and a cheaper copper catalyst. A wide range of O, N and S containing heteroarylamines and o‐phenylenediamine were explored to prepare N‐benzylaminoheterocycles and 1,2‐disubstituted benzimidazoles. The protocol was equally effective with N‐tosylhydrazones derived from aldehydes and ketones, especially ferrocene aldehyde to prepare an array of N‐benzylaminoheterocycles in good to excellent yields. Finally, the identified reaction conditions were utilized to prepare drug‐like molecules namely pyrido[1,2‐a]benzimidazole and N‐substituted‐2‐amino‐thiazole derivative as antitubercular agents.

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Palladium-Catalyzed Oxidative Cross-Coupling of N-Tosylhydrazones with Indoles: Synthesis of N-Vinylindoles

Cited by 59 publications

References 60 publications

Ring-Opening of Indoles: An Unconventional Route for the Transformation of Indoles to 1H-Pyrazoles Using Lewis Acid

Ring-Opening of Indoles: An Unconventional Route for the Transformation of Indoles to 1H-Pyrazoles Using Lewis Acid

Neue Ansätze für die Synthese von Metallcarbenen

Cu-Catalyzed Expeditious Synthesis of N-Benzylaminoheter-ocycles Using N-Tosylhydrazones and Aminoheteroarenes

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