The formation of orthoquinones in the dimethyldioxirane oxidation of phenols

Crandall, Jack K.; Zucco, Martine; Kirsch, R.; Coppert, David M.

doi:10.1016/0040-4039(91)80053-9

Cited by 50 publications

(16 citation statements)

References 12 publications

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“…The transformation of cation-radical 11 to the products observed can proceed through at least five main channels depending on reaction conditions. As 11 is very acidic, proton loss (path A) thus forming radical intermediate (12), followed by immediate another electron transfer thus forming the cyclohexadienone cation (16) which readily collapses with an external source of nucleophiles to the final product 6, represents the first reaction channel. The second channel also leads to the same product where primary attack of an external nucleophile on cation-radical 11 (path B), followed by electron transfer from radical (13) thus forming cationic intermediate (17), which stabilises by proton loss to the product 6 is anticipated as the possible reaction pathway.…”

Section: Methodsmentioning

confidence: 99%

The effect of the reaction conditions on the course of the reactions of hindered phenols with N-F reagents

Stavber¹,

Jereb²,

Zupan³

2002

Arkivoc

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Abstract2,4,6-Trialkyl substituted phenols were selectively transformed in high yield to para-quinols or para-quinol ethers by reaction with the N-fluoro-1,4-diazoniabicyclo[2.2.2]octane salt analogues Selectfluor TM F-TEDA-BF 4 or Accufluor TM NFTh in acetonitrile in the presence of water or alcohols. At low temperature 2,4,6-tri-tert-butylphenol in pure acetonitrile gave 2-fluoro and 4-fluoro substituted cyclohexadienone products with both reagents, while at elevated temperature 2-fluoro-4,6-di-tert-butylphenol was quantitatively formed. The mechanism postulated the SET proccess, thus forming cation-radical intermediates, as the key step of the reaction was proposed.

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Section: Methodsmentioning

confidence: 99%

The effect of the reaction conditions on the course of the reactions of hindered phenols with N-F reagents

Stavber¹,

Jereb²,

Zupan³

2002

Arkivoc

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“…To date, numerous methods have been reported for the preparation of p -quinones by the oxidation of phenols or their derivatives [ 12 , 13 , 14 ]. For instance, the oxidation of phenols with Fremy’s radical [ 15 ], MeReO 3 [ 16 ], dimethyldioxirane [ 17 ], or benzeneseleninic anhydride [ 18 ] mostly gives p -quinones, unless blocked by a substituent. However, there have been only a few studies on the direct conversion of a phenol into an o -quinone.…”

Section: Introductionmentioning

confidence: 99%

IBS-Catalyzed Regioselective Oxidation of Phenols to 1,2-Quinones with Oxone®

2012

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We have developed the first example of hypervalent iodine(V)-catalyzed regioselective oxidation of phenols to o-quinones. Various phenols could be oxidized to the corresponding o-quinones in good to excellent yields using catalytic amounts of sodium salts of 2-iodobenzenesulfonic acids (pre-IBSes) and stoichiometric amounts of Oxone® as a co-oxidant under mild conditions. The reaction rate of IBS-catalyzed oxidation under nonaqueous conditions was further accelerated in the presence of an inorganic base such as potassium carbonate (K2CO3), a phase transfer catalyst such as tetrabutylammonium hydrogen sulfate (nBu4NHSO4), and a dehydrating agent such as anhydrous sodium sulfate (Na2SO4).

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“…An appealing strategy is the direct conversion of readily available phenols (1)b yanet 4e À oxidation, first into the corresponding catechols (2), and subsequent dearomatization to give the ortho-quinones 3 (Scheme 1A). [6] Challenges to this approach include controlling the regioselectivity of the initial oxygenation (ortho vs. para)a sw ell as finding suitable oxidant systems that are compatible with the sensitive ortho-quinone products.O xidants such as Fremyss alt, [7] dimethyldioxirane, [8] or MeReO 3 -H 2 O 2 [9] either lack regioselectivity or favor generation of the para-quinone unless this position is blocked with asubstituent. Recently,the group of Lumb developed an elegant solution to this challenge through the use of biomimetic aerobic copper catalysis,i nspired by the mechanism of the tyrosinase enzyme.…”

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confidence: 99%

Dearomatization of Electron‐Deficient Phenols to ortho‐Quinones: Bidentate Nitrogen‐Ligated Iodine(V) Reagents

2019

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Despite their broad utility, the synthesis of ortho‐quinones remains a significant challenge, in particular, access to electron‐deficient derivatives remains an unsolved problem. Reported here is the first general method for the synthesis of electron‐deficient ortho‐quinones by direct oxidation of phenols. The reaction is enabled by a novel bidentate nitrogen‐ligated iodine(V) reagent, a previously unexplored class of compounds which we have termed Bi(N)‐HVIs. The reaction is extremely general and proceeds with excellent regioselectivity for the ortho over para isomer. Functionalization of the ortho‐quinone products was examined, resulting in a facile one‐pot synthesis of catechols, as well as the incorporation of a variety of heteroatom nucleophiles. This method represents the first synthetic application of Bi(N)‐HVIs and demonstrates their potential as a platform for the further development of highly reactive, but also highly tunable, I(V) reagents.

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The formation of orthoquinones in the dimethyldioxirane oxidation of phenols

Cited by 50 publications

References 12 publications

The effect of the reaction conditions on the course of the reactions of hindered phenols with N-F reagents

The effect of the reaction conditions on the course of the reactions of hindered phenols with N-F reagents

IBS-Catalyzed Regioselective Oxidation of Phenols to 1,2-Quinones with Oxone®

Dearomatization of Electron‐Deficient Phenols to ortho‐Quinones: Bidentate Nitrogen‐Ligated Iodine(V) Reagents

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