Tuning the Regioselectivity of Gold-Catalyzed Internal Nitroalkyne Redox: A Cycloisomerization and [3 + 2]-Cycloaddition Cascade for the Construction of <i>spiro</i>-Pseudoindoxyl Skeleton

Kumar, Chepuri V. Suneel; Ramana, Chepuri V.

doi:10.1021/ol502213w

Cited by 56 publications

(16 citation statements)

References 71 publications

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“…Harnessing the reactivity of isatogen toward a cycloaddition reaction, Kumar and Ramana reported a gold-catalyzed redox Scheme 88. Proposed Mechanism for Gold-Catalyzed (4 + 1) Annulation between 4-Methoxy- 110 Two intramolecular events, a gold-catalyzed redox of nitroakyne to isatogen 220 and its subsequent (3 + 2) cycloaddition with a suitably positioned olefin unit, led to the formation of tricyclic cores. A structurally distinct tricyclic core construction was accomplished by varying the chain length from the central nitrogen.…”

Section: Gold-catalyzed Carbene-transfer Reactions Based On N−o Conta...mentioning

confidence: 99%

Nitrene Transfer and Carbene Transfer in Gold Catalysis

et al. 2020

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Catalytic transformations involving metal carbenes are considered one of the most important aspects of homogeneous transition metal catalysis. Recently, gold-catalyzed generation of gold carbenes from readily available alkynes represents a significant advance in metal carbene chemistry. This Review summarizes the advances in the gold-catalyzed nitrene-transfer reactions of alkynes with nitrogen-transfer reagents, such as azides, nitrogen ylides, isoxazoles, and anthranils, and gold-catalyzed carbene-transfer reactions, involving oxygen atom-transfer reactions of alkynes with nitro compounds, nitrones, sulfoxides, and pyridine N-oxides, through the presumable α-imino gold carbene and α-oxo gold carbene intermediates, respectively. Gold-catalyzed processes are reviewed by highlighting their product diversity, selectivity, and applicability, and the mechanistic rationale is presented where possible.

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Section: Gold-catalyzed Carbene-transfer Reactions Based On N−o Conta...mentioning

confidence: 99%

Nitrene Transfer and Carbene Transfer in Gold Catalysis

et al. 2020

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“…A regioselectivity of gold‐catalyzed cycloisomerization of internal nitroalkynes was also reported for the synthesis of N ‐oxide‐3 H ‐indoles 55 (Scheme 36). [88] The products were used as substrates for spiro‐pseudoindoxyl rings via a [3+2 ] ‐cycloaddition reaction. The cooperative gold‐photoredox catalysis for the diarylative hydroalkoxylation of (ethynyl)azidobenzene with arenediazonium salts led to the diarylated 3 H ‐indoles 56 (Scheme 37).…”

Section: Synthesis Of 3h‐indolesmentioning

confidence: 99%

Recent Developments in the Cyclization of Alkynes and Nitrogen Compounds for the Synthesis of Indole Derivatives

Neto

Zeni

2021

Asian J Org Chem

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This review is intended to highlight the most useful approaches for the synthesis of indole derivatives (azaindoles, carbazoles, carbolines, indazoles, 3H-indoles, indolines, indolizines, isoindoles, and isoindolines), which were described by using transition-metal catalyzed cyclization reactions of alkynes and nitrogen compounds. The methodologies carried out under metal-free conditions will also be illustrated herein. This review will cover the data published mostly in the past decade. Synthesis of 6-AzaindolesAzaindoles, although rare in nature, have attracted a significant attention because some synthetic structures containing this nucleus exhibit biological activities. [17] The synthetic methods describing the preparation of azaindoles are limited. Usually their synthesis was achieved from the cyclization reaction of substrates containing aminopyridines. [18] Transition Metal-Free Synthesis of 6-AzaindolesWe have nominated two methodologies for the preparation of 6-azaindoles, which were developed using alkynes and nitrogen compounds in a metal-free protocol. In the first, an electrophilic cyclization condition, using iodine as an electrophilic source, was applied to 2-(azidomethyl)-3-alkynyl-pyrroles in the preparation of 4-iodo-6-azaindoles 1 (Scheme 1, eq 1). [19] The second approach described the preparation of 2,5-disubstituted 6azaindoles 2 from base-catalyzed intramolecular cyclization of 2-(azidomethyl)-3-alkynyl-pyrroles (Scheme 1, eq 2). [20] 3. Synthesis of 7-Azaindoles Transition Metal-Catalyzed Synthesis of 7-Azaindoles Silver-Catalyzed Synthesis of 7-AzaindolesSilver-catalyzed cyclization reactions of alkynes constitute powerful strategies for the construction of heterocycles. In particular, the 7-azaindoles could be obtained by these approaches. A general method for the preparation of aryl-[a] Dr. J.

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“…Transition‐metal (TM)‐catalyzed transfer oxygenation of alkynes is an efficient strategy for the synthesis of carbonyl compounds . TM‐catalyzed oxygen atom transfer to the activated alkynes is a process of addition‐elimination by using nucleophilic [O] donors such as nitro, nitrone, sulfoxide, and epoxide (Scheme a) . Although intramolecular oxygenation of alkynes and cycloisomerization of 2‐alkynylnitroarenes have been intensively reported, the utilization of noble metal (such as Pd, Au etc.)…”

Section: Introductionmentioning

confidence: 99%

“…Although intramolecular oxygenation of alkynes and cycloisomerization of 2‐alkynylnitroarenes have been intensively reported, the utilization of noble metal (such as Pd, Au etc.) was essential for the success of previous work . Recently, our group demonstrated an efficient and simple method for the synthesis of fluorine‐containing C2‐quaternary indolin‐3‐ones via cycloisomerization of nitroalkynes with the Cu/B 2 pin 2 system .…”

Section: Introductionmentioning

confidence: 99%

Copper/Diboron‐Mediated Intramolecular Oxygenation and Allylation/Benzylation of Nitroalkynes for the Synthesis of C2‐Quaternary Indolin‐3‐ones

Zhou

Song

2018

Chemistry An Asian Journal

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A direct strategy for intramolecular transfer oxygenation of alkynes and cycloisomerization of 2-nitroalkynes to synthesize a wide range of C2-quaternary indolin-3-ones was developed by a copper/diboron system. The desired allylation, benzylation and propargylation products were obtained in moderate to excellent yields with good functional group tolerance. The mechanism study indicated that this protocol involved a radical process.

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Tuning the Regioselectivity of Gold-Catalyzed Internal Nitroalkyne Redox: A Cycloisomerization and [3 + 2]-Cycloaddition Cascade for the Construction of spiro-Pseudoindoxyl Skeleton

Cited by 56 publications

References 71 publications

Nitrene Transfer and Carbene Transfer in Gold Catalysis

Nitrene Transfer and Carbene Transfer in Gold Catalysis

Recent Developments in the Cyclization of Alkynes and Nitrogen Compounds for the Synthesis of Indole Derivatives

Copper/Diboron‐Mediated Intramolecular Oxygenation and Allylation/Benzylation of Nitroalkynes for the Synthesis of C2‐Quaternary Indolin‐3‐ones

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