Construction of benzo-fused indolizines, pyrrolo[1,2-a]quinolines via alkyne–carbonyl metathesis

Nayak, Maloy; Kim, Ikyon

doi:10.1039/c5ob01383f

Cited by 40 publications

(29 citation statements)

References 50 publications

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“…These include palladium-catalyzed reactions, [14][15][16][17] 1,2-alkyl migration, 18 DDQ-mediated intramolecular cyclizations, 19 flash vacuum pyrolysis, 20 photosubstitution reactions, 21 and alkynecarbonyl metathesis. 22 Lautens et al reported a palladium catalyzed direct arylation of geminal dibromo-olefins with a boronic acid via tandem Suzuki-Miyura coupling reaction. 23 Larock et al reported a copper catalyzed tandem synthetic methodology for the synthesis of pyrrolo-and indolo[2,1-a]isoquinolines.…”

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confidence: 99%

Synthesis of pyrrolo[1,2-a]quinolines and ullazines by visible light mediated one- and twofold annulation of N-arylpyrroles with arylalkynes

2016

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1-(2-Bromophenyl)-1H-pyrrole and 1-(2,6-dibromophenyl)-1H-pyrrole react in the presence of catalytic amounts of rhodamine 6G () and N,N-diisopropylethylamine (DIPEA) under blue light irradiation with aromatic alkynes and subsequently cyclize intramolecularly to form pyrrolo[1,2-a]quinoline and ullazines. The reactions proceed at room temperature, avoid transition metal catalysts, and provide the target compounds in one pot in moderate to good yields. Mechanistic investigations suggest that the photo excited is reduced by DIPEA to form the corresponding radical anion , which is again excited by 455 nm light. The excited radical anion of donates an electron to the aryl bromide giving an aryl radical that is trapped by aromatic alkynes. The intermediate vinyl radical cyclizes intramolecularly and yields the product after rearomatization.

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confidence: 99%

Synthesis of pyrrolo[1,2-a]quinolines and ullazines by visible light mediated one- and twofold annulation of N-arylpyrroles with arylalkynes

2016

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“…[182] The intramolecular alkyne-aldehyde metathesis of 1-(2-haloaryl)-1Hpyrrole-2-carbaldehydes, catalyzed by trifluoroacetic acid, gave benzo-fused indolizines 131 (Table 5, entry 9). [183] Indolizine-1carbaldehyde derivatives 132 were obtained in good yields via a 1,3-dipolar cycloaddition of phenylpropiolaldehydes promoted by cesium carbonate (Table 5, entry 10). [184] 10.…”

Section: Transition Metal-free Synthesis Of Indolizinesmentioning

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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“…84 The parent pyrrole derivative 87 was prepared via Sonogashira coupling and subsequently transformed into the desired indolizine by heating in TFA. 84 The parent pyrrole derivative 87 was prepared via Sonogashira coupling and subsequently transformed into the desired indolizine by heating in TFA.…”

Section: Scheme 54mentioning

confidence: 99%

Recent advances in the synthesis of indolizines and their π-expanded analogues

2016

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Indolizine (pyrrolo[1,2-a]pyridine) is one of the five isomers of indole and it serves as a precursor for widespread indolizidine alkaloids. The straightforward synthesis of indolizines based on classical methodologies such as Scholtz or Chichibabin reactions has overshadowed numerous new strategies that have been revealed especially within the last ten years. The desire to achieve substitution patterns which were hard to build sparked the discovery of completely new pathways, e.g. transition metal-catalyzed reactions and approaches based on oxidative coupling. In this review, selected strategies toward indolizines published since 2005 are briefly summarized, commented upon, compared, and illustrated. The literature discussed here involves reactions based on either pyridine or pyrrole scaffolds, as well as selected methodologies leading to π-expanded indolizines.

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Construction of benzo-fused indolizines, pyrrolo[1,2-a]quinolines via alkyne–carbonyl metathesis

Cited by 40 publications

References 50 publications

Synthesis of pyrrolo[1,2-a]quinolines and ullazines by visible light mediated one- and twofold annulation of N-arylpyrroles with arylalkynes

Synthesis of pyrrolo[1,2-a]quinolines and ullazines by visible light mediated one- and twofold annulation of N-arylpyrroles with arylalkynes

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

Recent advances in the synthesis of indolizines and their π-expanded analogues

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