Sequential Reactions Initiated by Oxidative Dearomatization. Biomimicry or Artifact?

Jackson, Stephen; Wu, Kun‐Liang; Pettus, Thomas R. R.

doi:10.1002/9783527634606.ch20

Cited by 37 publications

(11 citation statements)

References 73 publications

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“…1 As a consequence, the asymmetric oxidative dearomatization of phenols has emerged as a promising tool for the synthesis of various natural products. 2 Conventionally, enantioselective transition-metal catalysis has been used for these transformations.…”

Section: 2mentioning

confidence: 99%

Chiral Ammonium Hypoiodite-catalyzed Enantioselective Oxidative Dearomatization of 1-Naphthols Using Hydrogen Peroxide

Uyanik¹,

Sasakura²,

Kaneko³

et al. 2015

Chemistry Letters

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A highly enantioselective oxidative dearomatization of 1-naphthol derivatives (Kita spirolactonization) catalyzed by chiral hypoiodite species prepared in situ from chiral quaternary ammonium iodide in the presence of hydrogen peroxide is reported.The oxidative dearomatization of phenol derivatives is an important pathway in the biosynthesis of many biologically active compounds.1 As a consequence, the asymmetric oxidative dearomatization of phenols has emerged as a promising tool for the synthesis of various natural products.2 Conventionally, enantioselective transition-metal catalysis has been used for these transformations.2b,2d,2f Recently, transition-metal-free oxidative dearomatization reactions 35 have been reported using chiral hypervalent organoiodines. 6 In particular, Kita's group 3 and our group 4 have developed highly enantioselective catalytic oxidative dearomatizations of phenol derivatives (Kita spirolactonization) using chiral iodoarenes (Scheme 1a). However, these chiral organoiodine(III) catalysts were prepared in situ from the corresponding iodoarenes and meta-chloroperbenzoic acid (m-CPBA), and meta-chlorobenzoic acid (m-CBA) was generated as a waste (Scheme 1c, left). Here, we report the enantioselective oxidative dearomatization of 1-naphthol derivatives 1 to spirolactones 2 using chiral ammonium hypoiodite catalysis 7,8 (Scheme 1b). The chiral hypoiodite active species is generated in situ from the corresponding chiral quaternary ammonium¹ and aqueous hydrogen peroxide as a mild and inexpensive oxidant, and water is the only by-product generated from the oxidant (Scheme 1c, right). Moreover, the use of nonhalogenated solvents such as toluene at ambient temperature is a major advantage over organoiodine(III)-catalyzed oxidation reactions, which often require halogenated solvents under lowtemperature conditions.Recently, we developed an in situ-generated chiral quaternary ammonium hypoiodite catalysis for the enantioselective oxidative cyclization of ketophenols to 2-acyl-2,3-dihydrobenzofurans or 2-acylchromans with the use of hydrogen peroxide or tert-butyl hydroperoxide (TBHP) as oxidants. 7 In these reactions, the chemoselective α-oxidation of carbonyl moieties preferentially proceeded, and phenol moieties served as intramolecular nucleophiles. However, during our studies on sixmembered oxidative cyclization to chromans (Scheme 2), 7b

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Section: 2mentioning

confidence: 99%

Chiral Ammonium Hypoiodite-catalyzed Enantioselective Oxidative Dearomatization of 1-Naphthols Using Hydrogen Peroxide

Uyanik¹,

Sasakura²,

Kaneko³

et al. 2015

Chemistry Letters

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“…Several elegant strategies have been developed for this transformation, 19 and here we brie y spotlight those based on hypervalent iodine. 20 In 1994, Hoshino s group reported the oxidative dearomatization of phenols bearing the oxime moiety suitably tethered at the ortho position to give the corresponding dihydroisoxazole using iodosobenzene as oxidant and camphor sulfonic acid as activator (Scheme 2).…”

Section: Design Of Structurally Flexible Hypervalent Iodine(iii)mentioning

confidence: 99%

Conformationally-Flexible Chiral Hypervalent Organoiodine Catalysts for Enantioselective Oxidative Transformations

Uyanik¹,

Ishihara

2012

J. Synth. Org. Chem. Jpn.

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“…[4] A similar proposal for frondosin biosynthesis has also been suggested by Pettus. [5] Although it has not yet been isolated as a natural product, we believe that hydroquinone 6 is a plausible intermediate in the biosynthesis of the frondosins. We have previously converted 6 into aureol, a marine sponge meroterpenoid closely related to the frondosins.…”

mentioning

confidence: 95%

“…We have previously converted 6 into aureol, a marine sponge meroterpenoid closely related to the frondosins. [6] The bicyclic framework of 6 (with its characteristic D 5,11 -double bond) has also been formed by acid-catalyzed rearrangement of avarol [7] (via sequential 1,2-methyl and hydride shifts [8] ) and by acidcatalyzed fragmentation of aureol. [9] Oxidation of hydroquinone 6 could form o-quinone methide 7, via either tautomerization of an intermediate quinone or direct oxidation at the benzylic C-10 position.…”

mentioning

confidence: 99%

A Biomimetic Synthetic Approach to the Frondosins

2016

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The frondosins are a family of five marine sponge-derived meroterpenoids. We propose that the 6-7 ring system common to each of the frondosins is biosynthesized via ring expansion of a 6-6 ring system. Compelling evidence in favour of this proposal was obtained in the form of a biomimetic synthesis of the frondosin 6-7 ring system, which features a highly stereo-and regio-selective ring expansion cascade reaction as the key step.

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Sequential Reactions Initiated by Oxidative Dearomatization. Biomimicry or Artifact?

Cited by 37 publications

References 73 publications

Chiral Ammonium Hypoiodite-catalyzed Enantioselective Oxidative Dearomatization of 1-Naphthols Using Hydrogen Peroxide

Chiral Ammonium Hypoiodite-catalyzed Enantioselective Oxidative Dearomatization of 1-Naphthols Using Hydrogen Peroxide

Conformationally-Flexible Chiral Hypervalent Organoiodine Catalysts for Enantioselective Oxidative Transformations

A Biomimetic Synthetic Approach to the Frondosins

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