Site‐selective Oxidative Dearomatization of Phenols and Naphthols into <i>ortho</i>‐Quinols or Epoxy <i>ortho</i>‐Quinols using Oxone as the Source of Dimethyldioxirane

Cabrera-Afonso, María Jesús; Carreño, M. Carmen; Urbano, Antonio

doi:10.1002/adsc.201900660

Cited by 7 publications

(6 citation statements)

References 63 publications

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“…Because extensive decomposition was observed during the ensuing epoxidation of 22a – 22d when using m -CPBA, other reaction conditions were investigated. After some experimentation using dibenzocycloheptenol as a model, treating the methyl ether 23a with dimethyldioxirane (DMDO) , gave the epoxide, which, without purification, furnished 16 in 65% and 17 in 9% yields over two steps. Ideally, a suitable protecting group (P) of the alcohol, which was required to avoid concurrent oxidation during the DMDO-mediated epoxidation, should also facilitate the C–OP bond cleavage during the semipinacol rearrangement.…”

Section: Resultsmentioning

confidence: 99%

Substituted 9-Anthraldehydes from Dibenzocycloheptanol Epoxides via Acid-Catalyzed Epoxide Opening/Semipinacol Rearrangement

et al. 2021

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Starting from benzaldehyde derivatives, the corresponding dibenzocycloheptenol could be prepared in five steps. Under both substrate (secondary vs tertiary alcohol and the substituents on the aromatic ring(s)) and condition control, the subsequent epoxidation and acid-catalyzed epoxide opening/semipinacol rearrangement/aromatization afforded the corresponding 9-anthraldehydes in good yields, up to 88% over two steps. The presence of the electron-withdrawing group(s) on the aromatic ring(s) suppressed the rate of the epoxidation while the subsequent semipinacol rearrangement step required heating; the presence of the electron-donating group(s), on the other hand, frequently led to the decomposition during the epoxidation. From the mechanistic studies, the semipinacol rearrangement of the epoxide could precede the ionization at the bisbenzylic position, yielding the aldehyde intermediate. The ensuing dehydrative aromatization led to the formation of 9-anthraldehyde. Conversely, nucleophilic addition to the aldehyde and dehydrative aromatization with concomitant loss of formic acid led to anthracene.

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Section: Resultsmentioning

confidence: 99%

Substituted 9-Anthraldehydes from Dibenzocycloheptanol Epoxides via Acid-Catalyzed Epoxide Opening/Semipinacol Rearrangement

et al. 2021

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“…More recently, the group of Urbano also reported the synthesis of (±)‐ 81 by simply treating 88 with dimethyldioxirane generated in situ from acetone and Oxone (Scheme 12). [41c] …”

Section: Ortho‐quinols In (Bio)chemical Synthesis Of Natural Productsmentioning

confidence: 99%

ortho‐Quinols in (Bio)Synthesis of Natural Products

et al. 2023

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6-Alkyl-6-hydroxycyclohexa-2,4-dienone derivatives, commonly referred to as ortho-quinols, and their simple ester and ether variants constitute a class of organic compounds that aroused much interest amongst chemists over the past 70 years for several reasons related to organic synthesis, natural product chemistry and biochemistry. It was very early on that organic chemists understood the potential of the unique yet versatile chemical reactivity of such compounds to synthesize more complex structures, and it soon emerged that ortho-quinols could constitute key intermediates in the biosynthesis of certain natural products of various origins. This minireview discusses the chemistry of ortho-quinols from the point of view of their role in the synthesis and biosynthesis of natural products. Examples of completed syntheses of natural products mostly taken in the literature of the last 20 years or so, together with some chosen pieces from older but pioneering and most remarkable works, are highlighted to illustrate this discussion.

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“…Till date, a myriad of versatile synthetic strategies has been discovered and labelled in the literature for carrying out such valued transformations. For example, oxidative dearomatization of phenols and naphthols can generate the valuable para ‐ and ortho ‐quinol derivatives which itself has tendency to produce a vast variety of heterocyclic molecules e. g. ortho ‐quinols with different dienophiles in a [4+2]‐manner of many natural products such as wasabidienone B1, grandifloracin, epoxysorbicillinol and so on [458–466] . To this context, More and Ramana studied the production of natural products consisting chroman as well as tetrahydronaphthalene frameworks.…”

Section: Miscellaneous Reactionsmentioning

confidence: 99%

“…For example, oxidative dearomatization of phenols and naphthols can generate the valuable para-and ortho-quinol derivatives which itself has tendency to produce a vast variety of heterocyclic molecules e. g.ortho-quinols with different dienophiles in a [4 + 2]-manner of many natural products such as wasabidienone B1, grandifloracin, epoxysorbicillinol and so on. [458][459][460][461][462][463][464][465][466] To this context, More and Ramana studied the production of natural products consisting chroman as well as tetrahydronaphthalene frameworks. The authors have reported oxone-mediated dearomatization of benzofuran to o-quinone methides (o-QMs) followed by intramolecular [4 + 2]-cycloaddition with a variety of dienophiles like aldehydes, ketones, and olefins to expeditious construction of central [6,6,6,6]-tetracyclic core of integrastatins, epicoccolide A, and epicocconigrone A, (Scheme 196).…”

Section: Oxidative Dearomatization Of the Aromatic Systemsmentioning

confidence: 99%

Applications of Oxone® in Organic Synthesis: An Emerging Green Reagent of Modern Era

2022

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Presently, the major cornerstone of the research community is to develop green as well as sustainable protocols involving inexpensive catalysts and/or reagents without the usage of hazardous solvents under globally friendlier conditions in order to shelter both mankind and environment. Therefore, needless to say, there is always a supreme need to surrogate the older, costlier and unsafe strategies with the novel economically inexpensive and environmental benign ones. To this context, in recent past, oxone® (triple salt), a very cheap oxidizing agent having the chemical formula 2KHSO5 ⋅ KHSO4 ⋅ K2SO4 and enwrapped with the unique characteristics like easy handling, non‐toxic, safe, eco‐friendly, non‐polluting, stable, and nicely soluble in water, in addition to its utility for large‐scale synthesis etc. Bearing the importance of this versatile reagent in mind, we envisioned to update the recent advances made in this direction. Consequently, in this particular review article, the developments made in the arena of oxone chemistry covering from 2013 to 2020 have been revealed as no report appeared in the literature after a wonderful Chem. Rev. published by the group of Hussain in 2013. Herein, a comprehensive detail of a variety of oxidative transformations along with the complete plausible mechanistic steps have been exposed. For sure, present review would be a very helpful tool to the scientific community not only working in the area of organic synthesis but also to the researchers working in other branches of science and technologies as well.

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Site‐selective Oxidative Dearomatization of Phenols and Naphthols into ortho‐Quinols or Epoxy ortho‐Quinols using Oxone as the Source of Dimethyldioxirane

Cited by 7 publications

References 63 publications

Substituted 9-Anthraldehydes from Dibenzocycloheptanol Epoxides via Acid-Catalyzed Epoxide Opening/Semipinacol Rearrangement

Substituted 9-Anthraldehydes from Dibenzocycloheptanol Epoxides via Acid-Catalyzed Epoxide Opening/Semipinacol Rearrangement

ortho‐Quinols in (Bio)Synthesis of Natural Products

Applications of Oxone® in Organic Synthesis: An Emerging Green Reagent of Modern Era

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