Synthesis of 2,3-Ring Fused Pyrroles via Cu-Catalyzed 5-<i>exo</i>-dig Annulation of Alkyne-Tethered Enaminones

Li, Weishuang; Usman, Muhammad; Wu, Lin‐Yang; Liu, Wen‐Bo

doi:10.1021/acs.joc.9b02672

Cited by 11 publications

(5 citation statements)

References 57 publications

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“…By contrast, existing AD annulation is limited to a few simple N-heterocycles, requires a stoichiometric base for annulation, and is catalyzed using specially designed complexes, necessitating the development of base-free, efficient, and ligand-free catalytic systems for the synthesis of other heterocycles, containing oxygen and partially hydrogenated indole and an acridine system, because of their omnipresence in most therapeutic and natural products (Figure ). ,, …”

Section: Introductionmentioning

confidence: 99%

Catalytic Acceptorless Dehydrogenation of Amino Alcohols and 2-Hydroxybenzyl Alcohols for Annulation Reaction under Neutral Conditions

et al. 2021

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A base-free and acceptorless Ru-catalyzed dehydrogenative approach has been developed for the synthesis of N-heterocycles by using 1,3-dicarbonyls and amino alcohols through a domino sequential enamine formation and intramolecular oxidative cyclization strategy. This unified approach is also applicable for the synthesis of O-heterocycles involving 2-hydroxybenzyl alcohol as a coupling reactant via consecutive C-alkylation and intramolecular cyclization steps. The present protocol is general for the synthesis of varieties of biologically important scaffolds, such as tetrahydro-4H-indol-4-one, 3,4-dihydroacridin-1(2H)-one, and tetrahydro-1H-xanthen-1-ones derivatives using a single catalytic system, viz. RuH2CO(PPh3)3. Environmentally benign H2O and H2 are the only byproducts in this domino process. Moreover, RuH2CO(PPh3)3-catalyzed C3-alkylation of tetrahydro-4H-indol-4-one using alcohol as a alkylating partner is also described in this report. For the first time, a solvent-free gram-scale reaction for the acceptorless dehydrogenative annulation has been demonstrated. A plausible mechanism for the Ru-catalyzed base-free and acceptorless dehydrogenative annulation of amino alcohols or 2-hydroxybenzyl alcohols has been provided with several experimental investigations and spectroscopic evidence.

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Section: Introductionmentioning

confidence: 99%

Catalytic Acceptorless Dehydrogenation of Amino Alcohols and 2-Hydroxybenzyl Alcohols for Annulation Reaction under Neutral Conditions

et al. 2021

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“…Recently, Liu's group reported a copper-catalyzed 5-endodig cyclization of alkyne-tethered enaminones 209 for the synthesis of 2,3-ring fused pyrrole derivatives 210 in mild reaction conditions (Scheme 47). [69] In this reaction, the ketone functionality did not participate. As depicted in Scheme 46, the π-alkyne copper intermediate 211 generated through the coordination of the alkyne to Cu(I).…”

Section: Metal-catalyzed Cyclizations Of 4-acetylenic Ketones With Ammentioning

confidence: 94%

Progress in Cyclizations of 4‐Acetylenic Ketones: Synthesis of Furans and Pyrroles

Wang

Zhang

2020

ChemistrySelect

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4‐Acetylenic ketones are a class of useful and important synthons with functionalized alkynes and carbonyl groups in one molecular skeleton. They displayed unique reactivity via cyclizations that provided access to multi‐functional furans and pyrroles. This minireview offers a comprehensive coverage of the development of their multifaceted reactivity for synthetic applications in furans and pyrroles.

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“…However, the reactions with Nalkyne-substituted 13b (R 1 = CH 2 C≡CH, R 2 = Me) and unsubstituted 13c (R 1 = H, R 2 = Me) enaminones under these conditions did not give the desired products. 26 Scheme 5 Synthesis of 4,5,6,7-tetrahydroindol-4-ones via Cu-catalyzed 5-exo-dig annulation of alkyne-tethered enaminones Beccalli, Broggini et al 27 described the ruthenium-catalyzed conversion of 4-alkenyl-substituted isoxazol-5-ones into 1H-pyrroles, including 4,5,6,7-tetrahydroindoles. The process proceeds under thermal conditions in the presence of a ruthenium(II) catalyst without use of additional additives.…”

Section: Review Synthesismentioning

confidence: 99%

“…It was shown that a number of alkynyl-substituted enones, namely the derivatives of 2-(but-2-yn-1-yl)-3-(arylamino)cyclohex-2-en-1-ones 13 undergo CuI-catalyzed annulation to form tetrahydroindol-4-ones 14 (Scheme 5). 26…”

Section: Intramolecular Reactions Leading To Tetrahydroindoles 21 Rin...mentioning

confidence: 99%

Recent Advances in the Synthesis of Indoles with Partially Hydrogenated Benzene Ring (Tetrahydroindoles)

Mamedov,

Zhukova

2023

Synthesis

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In this review, a fragmentary analysis of 4,5,6,7-tetrahydroindoles was performed and, on its basis, the existing methods of their synthesis published over the past 15 years have been summarized, and analyzed, as well as, if necessary, an analysis of earlier works is carried out. The proposed reaction mechanism is considered, as well as factors that significantly influence the course of the process. Among such factors: temperature, type and content of the catalyst, promoting additives, method of the process, etc. Particular attention is paid to fundamentally new methods that make it possible to synthesize various derivatives of the mentioned heterocyclic systems from available and cheap reagents, and in some cases under environmentally benign conditions.1 Introduction2 Intramolecular Reactions Leading To Tetrahydroindoles2.1 Ring Closure Reactions with N–C2 Bond Formation (a)2.2 Ring Closure Reactions with C2–C3 Bond Formation (b)2.3 Ring Closure Reactions with C3–C3a Bond Formation (c)2.4 Ring Closure Reactions with C7a–N Bond Formation (e)2.5 Ring Closure Reactions with C4–C5 Bond Formation (g)2.6 Ring Closure Reactions with C3a–C4 Bond Formation (h)3 Intermolecular Reactions Leading To Tetrahydroindoles3.1 Ring Closure Reactions with N–C2 + C3–C3a Bond Formation (ac)3.2 Ring Closure reactions with N–C2 + C7a–N Bond Formation (ae)3.3 Ring Closure reactions with C3–C3a + C7a–N Bond formation (ce)3.4 Ring Closure Reactions with N–C2, C3–C3a, and C7a–N Bond Formation (ace)4 Recovery Processes (Hydrogenation) of Indoles and Oxidation of Perhydroindoles in the Synthesis of 4,5,6,7-Tetrahydroindoles5 Conclusion

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Synthesis of 2,3-Ring Fused Pyrroles via Cu-Catalyzed 5-exo-dig Annulation of Alkyne-Tethered Enaminones

Cited by 11 publications

References 57 publications

Catalytic Acceptorless Dehydrogenation of Amino Alcohols and 2-Hydroxybenzyl Alcohols for Annulation Reaction under Neutral Conditions

Catalytic Acceptorless Dehydrogenation of Amino Alcohols and 2-Hydroxybenzyl Alcohols for Annulation Reaction under Neutral Conditions

Progress in Cyclizations of 4‐Acetylenic Ketones: Synthesis of Furans and Pyrroles

Recent Advances in the Synthesis of Indoles with Partially Hydrogenated Benzene Ring (Tetrahydroindoles)

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