7.15 Synthesis of para- and ortho-Quinones

Weaver, Marisa G.; Pettus, Thomas R. R.

doi:10.1016/b978-0-08-097742-3.00717-5

Cited by 7 publications

(6 citation statements)

References 189 publications

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“…Recognizing these challenges, we envisioned that a catalytic aerobic ortho ‐oxygenation of phenols could allow entry to this transformation . Phenols are readily available starting materials, but their ortho ‐oxygenation has historically required a multi‐step sequence, or a synthetic oxidant that can be difficult to use in sequential transformations . In the current context, we questioned whether our aerobic ortho ‐oxygenation could be interfaced with a hydrazine or hydrazide coupling reaction to provide ortho ‐azophenols in a one‐pot, sequential process from phenols.…”

Section: Methodsmentioning

confidence: 99%

Synthesis of ortho‐Azophenols by Formal Dehydrogenative Coupling of Phenols and Hydrazines or Hydrazides

Esguerra

Lumb

2017

Chemistry A European J

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Azophenols are important chromophores and reagents in organic synthesis, with applications as pigments and molecular switches. Here, we describe a catalytic aerobic process that couples phenols and hydrazines or hydrazides for their synthesis. The key aromatic C-N bond is formed by condensation between the hydrazine or hydrazide and an ortho-quinone, which triggers a redox-isomerization to install the azo-functionality. Notable features include rapid access to highly functionalized azophenols with a range of electronic configurations, including "push-pull" systems, conditions that employ simple, unactivated substrates, occurrence at room temperature using an earth-abundant and commercially available copper catalyst, and production of water as the only stoichiometric byproduct.

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Section: Methodsmentioning

confidence: 99%

Synthesis of ortho‐Azophenols by Formal Dehydrogenative Coupling of Phenols and Hydrazines or Hydrazides

Esguerra

Lumb

2017

Chemistry A European J

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“…Synthetic routes toward highly substituted para -quinones often involve iterative multistep functionalization sequences incorporating Friedel–Crafts, 10 directed metalation, 11 and arene/phenol oxidation strategies. 10 12 Single-step ring forming methodologies are highly attractive, particularly those that are modular, convergent and redox-neutral. 13 A handful of approaches directed toward this means have been developed, 10 including a recent contribution from our laboratory.…”

Section: Introductionmentioning

confidence: 99%

Ring Forming Approaches to para-Quinones: Toward a General Diels–Alder Disconnection

Newton¹,

Budwitz²

2022

Synlett

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para-Quinones feature extensively as targets and/or intermediates throughout a number of chemical and biological subdisciplines, highlighting the importance of efficient preparative methods. This Synpacts article provides an overview of ring forming approaches to para-hydroquinones and para-benzoquinones, concluding with our recent contribution concerning the development of 2,5-bis(tert-butyldimethylsilyloxy)furans as vicinal bisketene equivalents in the Diels–Alder reaction.1 Introduction2 Ring Forming Approaches to para-Quinones2.1 Hauser–Kraus Annulation2.2 Moore–Liebeskind Rearrangement2.3 Wulff–Dötz Reaction2.4 Oxidative Bergman Cyclization2.5 Diels–Alder Strategies2.5.1 Ketene–Enol Equivalents2.5.2 Bisketene Equivalents3 Toward an Improved Bisketene Equivalent4 Conclusion

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“…Although phenols are more attractive starting materials, their ortho-oxygenation has historically required a multi-step sequence or a synthetic oxidant, which can be difficult to use in one-pot sequential transformations. 42 Recognizing these challenges, we saw an opportunity to apply a catalytic aerobic ortho-oxygenation recently developed by our group [43][44][45] as a means of intersecting the TTQ cascade directly from phenols (Scheme 4). This would enable a formal dehydrogenative coupling of phenols and amines to provide ortho-iminophenols, and potentially access to a broad array of 1,2-oxy-aminoarenes in a one-pot cascade.…”

Section: Introductionmentioning

confidence: 99%

Unified Synthesis of 1,2-Oxy-aminoarenes via a Bio-inspired Phenol-Amine Coupling

Esguerra

Lumb

2017

Chem

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1,2-Aminophenols and their related nitrogen-containing heterocycles are ubiquitous in medicine, agriculture, and materials science. Here, we describe a bio-inspired and unified approach for their synthesis through a direct, catalytic aerobic coupling of phenols and amines. Key to the formation of the aromatic C-N bond is a facile condensation between the amine and an ortho-quinone, which triggers redox isomerization to an ortho-iminophenol before a series of downstream events. We discuss the factors that govern regioselectivity during aerobic ortho-oxygenation of the phenol and condensation of the amine, and we demonstrate synthetic utility by preparing a structurally diverse family of immunosuppressive heterocycles and the indole alkaloid cephalandole A. Our conditions involve a wide range of simple, un-activated substrates, occur at room temperature with an earth-abundant copper-catalyst and a commercially available diamine ligand, and produce water as the only stoichiometric by-product.

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7.15 Synthesis of para- and ortho-Quinones

Cited by 7 publications

References 189 publications

Synthesis of ortho‐Azophenols by Formal Dehydrogenative Coupling of Phenols and Hydrazines or Hydrazides

Synthesis of ortho‐Azophenols by Formal Dehydrogenative Coupling of Phenols and Hydrazines or Hydrazides

Ring Forming Approaches to para-Quinones: Toward a General Diels–Alder Disconnection

Unified Synthesis of 1,2-Oxy-aminoarenes via a Bio-inspired Phenol-Amine Coupling

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