Palladium‐Catalyzed Regioselective Synthesis of 1‐Hydroxycarbazoles Under Aerobic Conditions

Youn, So Won; Kim, Young Ho; Jo, Yoon Hyung

doi:10.1002/adsc.201801265

Cited by 13 publications

(11 citation statements)

References 110 publications

(29 reference statements)

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“…Ts-2-amino-3'-hydroxylbiaryls substrates (Scheme 3). 18 In this approach, the authors explored a dual directing group strategy to achieve a sterically hindered C-H bond (C2 position), providing a diverse range of 1-hydroxycarbazoles in a high and unusual regioselective fashion, mainly attributed to the presence of a hydroxyl moiety as a secondary directing group. The protocol represents an advance in the synthesis of 1-oxygenated carbazole alkaloids, with the benefit of a practical and sustainable approach, using the combination of a bidentate bipyridyl ligand, and ambient air as terminal oxidant of the Pd catalyst.…”

Section: C-h Activationmentioning

confidence: 99%

“…The sequence of 5-endo aminopalladation followed by a reductive elimination reactions release the naphthalene derivative and Pd(0), which is regenerated by O2. Investigations though 18 O isotopic labelling…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…and Pd(0), which is regenerated by O 2 . Investigations through 18 O isotopic labelling and with radical scavengers revealed oxygen radical incorporation on a delocalized Kekulé-type diradical intermediate of the polyene to afford a di-oxygenated intermediate (Scheme 11).…”

Section: Review Synthesismentioning

confidence: 99%

“…In 2019, Youn and co-workers demonstrated an aerobic palladium-catalyzed regioselective C-H activation strategy involving N-Ts-2-amino-3′-hydroxybiaryl substrates (Scheme 3). 18 In this approach, the authors explored a dual directing group strategy to achieve a sterically hindered C-H bond (C2 position), providing a diverse range of 1-hydroxy-…”

Section: Scheme 2 Palladium-catalyzed C-h Activation Via a Chemoselec...mentioning

confidence: 99%

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Recent Advances in Palladium-Catalyzed Oxidative Couplings in the Synthesis/Functionalization of Cyclic Scaffolds Using Molecular Oxygen as the Sole Oxidant

Barboza¹,

Dantas²,

Costa³

et al. 2021

Synthesis

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Over the past years, Pd(II)-catalyzed oxidative couplings enabled the achievement of molecular scaffolds with high structural diversity via C−C, C-N and C-O bond-formation reactions. In contrast to the use of stoichiometric amounts of more common oxidants, such as metal salts (Cu and Ag) and benzoquinone derivatives, the use of molecular oxygen in the direct or indirect regeneration of Pd(II) species presents itself as a more viable alternative in terms of economy and sustainability. In this review, we describe recent advances on the development Pd-catalyzed oxidative cyclizations/functionalizations, where molecular oxygen plays a pivotal role as the sole stoichiometric oxidant. 1 Introduction 2 Oxidative C-C and C-Nu Coupling 2.1 Intramolecular Oxidative C-Nu Heterocyclization Reactions 2.1.1 C-H Activation 2.1.2 Wacker/aza-Wacker Type Cyclization 2.1.3 Tandem Wacker/aza-Wacker and Cyclization/Cross Coupling Reactions 2.2 Intermolecular Oxidative C-Nu Heterocoupling Reactions 2.3 Intramolecular Oxidative (C-C) Carbocyclization Reactions 2.4 Intermolecular Oxidative C-C Coupling Reactions 2.4.1 Cyclization Reactions 2.4.2 Cross-Coupling Reactions 2.4.3 Homo-Coupling Reactions 3 Aerobic Dehydrogenative Coupling/Functionalization 4 Oxidative C-H Functionalization 5 Summary

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Section: C-h Activationmentioning

confidence: 99%

Section: Accepted Manuscriptmentioning

confidence: 99%

Section: Review Synthesismentioning

confidence: 99%

Section: Scheme 2 Palladium-catalyzed C-h Activation Via a Chemoselec...mentioning

confidence: 99%

See 2 more Smart Citations

Recent Advances in Palladium-Catalyzed Oxidative Couplings in the Synthesis/Functionalization of Cyclic Scaffolds Using Molecular Oxygen as the Sole Oxidant

Barboza¹,

Dantas²,

Costa³

et al. 2021

Synthesis

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show abstract

“…Substituted 1-hydroxycarbazoles are an important class of bioactive carbazoles that have been the targets of synthetic efforts over the last 15 years [ 47 , 48 ]. Many of these efforts begin with commercial 1-hydroxycarbazole, requiring numerous steps for regioselective substituent installation [ 49 ].…”

Section: Introductionmentioning

confidence: 99%

Lewis Acid-Catalyzed 2,3-Dihydrofuran Acetal Ring-Opening Benzannulations toward Functionalized 1-Hydroxycarbazoles

et al. 2022

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The development of a Lewis acid-catalyzed, intramolecular ring-opening benzannulation of 5-(indolyl)2,3-dihydrofuran acetals is described. The resulting 1-hydroxycarbazole-2-carboxylates are formed in up to 90% yield in 1 h. The dihydrofuran acetals are readily accessed from the reactions of enol ethers and α-diazo-β-indolyl-β-ketoesters. To highlight the method’s synthetic utility, a formal total synthesis of murrayafoline A, a bioactive carbazole-containing natural product, was undertaken.

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Pd(II)/Lewis Acid Catalyzed Intramolecular Oxidative C−H Amination to Construct Carbazoles with Dioxygen

Jiang

Dong

et al. 2023

Eur J Org Chem

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Transition‐metal‐catalyzed oxidative C−H amination reactions are among the most attractive topics in organic synthesis to construct nitrogen‐containing motifs. The challenge is that most of these reactions employed stoichiometric oxidants to achieve satisfied catalytic efficiencies. Herein, we report a Pd(II)/LA‐catalyzed (LA: Lewis acid) oxidative C−H amination reaction of 2‐acetaminobiphenyls to construct carbazoles by using dioxygen balloon as the sole oxidant source, and the presence of LA sharply improved the catalytic efficiency of Pd(OAc)2. Remarkably, in certain cases, the deacetylation of the annulation product happened under standard conditions to afford free carbazoles as the final product. The H/D exchange studies confirmed the reversibility of C−H activation and also disclosed multiple C−H activation sites by using −NAc and −NTs as the directing groups. In addition, the palladacycle compound was identified through 1H NMR characterizations and proved to be the intermediate prior to the carbazole formation.

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Palladium‐Catalyzed Regioselective Synthesis of 1‐Hydroxycarbazoles Under Aerobic Conditions

Cited by 13 publications

References 110 publications

Recent Advances in Palladium-Catalyzed Oxidative Couplings in the Synthesis/Functionalization of Cyclic Scaffolds Using Molecular Oxygen as the Sole Oxidant

Recent Advances in Palladium-Catalyzed Oxidative Couplings in the Synthesis/Functionalization of Cyclic Scaffolds Using Molecular Oxygen as the Sole Oxidant

Lewis Acid-Catalyzed 2,3-Dihydrofuran Acetal Ring-Opening Benzannulations toward Functionalized 1-Hydroxycarbazoles

Pd(II)/Lewis Acid Catalyzed Intramolecular Oxidative C−H Amination to Construct Carbazoles with Dioxygen

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