<i>ortho</i>-Quinone Methides from <i>para</i>-Quinones: Total Synthesis of Rubioncolin B

Lumb, Jean‐Philip; Choong, Kevin C.; Trauner, Dirk

doi:10.1021/ja803498r

Cited by 122 publications

(52 citation statements)

References 13 publications

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“…It has been speculated that further oxidative rupture within this p-quinone methide gives rise to brazilide A (102) by a successive series of lactonizations [38]. Trauner has exploited the equilibrium between a p-quinone and its o-quinone methide tautomer in the synthesis of rubioncolin B (106) [39]. Exposure of advanced intermediate 103 to PIDA, in the presence of the desilylating reagent tris(dimethylamino)sulfonium difluorotrimethylsilicate (TASF), is presumed to initially gives rise to a p-quinone that is in equilibrium with o-quinone methide 104 (Scheme 20.27).…”

Section: Intramolecular Cycloadditionsmentioning

confidence: 99%

Sequential Reactions Initiated by Oxidative Dearomatization. Biomimicry or Artifact?

Jackson

Pettus

2011

Biomimetic Organic Synthesis

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Section: Intramolecular Cycloadditionsmentioning

confidence: 99%

Sequential Reactions Initiated by Oxidative Dearomatization. Biomimicry or Artifact?

Jackson

Pettus

2011

Biomimetic Organic Synthesis

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“…On the basis of these results,atentative mechanism of this reaction is proposed in Scheme 3. Phenylallyl ether 1a first undergoes a[3,3]-sigmatropic rearrangement to give the dearomatized intermediate A.B aseinduced dehydrohalogenation of A then affords alkenylk etone B,w hich then cyclizes to give the aromatized intermediate C. [12,22] Thed esired product 2a is ultimately constructed via tautomerization of C, [12,14] another aromatizing process.T he byproduct naphthol 3a is possibly produced by direct reduction of the intermediate A by base or solvent.…”

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confidence: 99%

A Simple and Efficient Access to Naphtho[b]furans by Claisen Rearrangement/Cyclization of Bromonaphthyl 3‐Phenylallyl Ethers

et al. 2015

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At ransition-metal-free Claisen rearrangement/cyclization reaction was developed for the synthesis of naphthofuran derivatives from bromonaphthyl 3-phenylallyl ethers.T he nature of the base employed in this reactionp lays an important role in determining the ratio for the formation of naphthofurana nd naphthol products. By using K 2 CO 3 as base and DMFa ss olvent, we have synthesized av ariety of functionalized naphthofurans in good to high yields (49-92 %) and with satisfactory selectivities.Keywords: bromonaphthyl ethers;C laisen rearrangement;c yclization;n aphthofurans;t ransitionmetal-free Naphtho [b]furans are important structural motifst hat find presence in manyn atural products [1] and pharmaceutical agents.[2] As ac onsequence,n umerous efficient synthetic strategies have been developed for the construction of this structure.A mong the protocols reported to date,m ost involve the use of versatile starting substrates [3] in combination with as uitable transition-metal catalyst, such as Pd, [4] Pt, [5] In, [6] Ru, [7] Au, [8] Ag, [9] Fe, [10] Cu.[11] Despite of theirs ynthetic versatility,t he cost of transition-metal catalysts and the difficulty associated with removing transition-metal impuritiesf rom finalp roductsm ay restrict the practical applicability of these methods.Not surprisingly,t ransition-metal-free approaches to prepare naphthofurans have also been pursued. Fore xample,i n2 012, Thomas et al. [12] reported that naphtho [b]furans could be obtained in high yields by af acile microwave-assistedC laisen rearrangement of naphthyl 2-propynyl ethers (Scheme 1a). Unfortunately,e xpensive and highly hygroscopic CsF was used as base to promote this reaction. More recently, Rueping [13] and Yoshimi et al. [14] prepared as erieso f naphtho[b]furans in good yields,u tilizing at ransitionmetal-free Heck-type cyclization/isomerization reaction of halonaphthyle thers (Scheme 1b). However, these transformationsr equirede ither highly basic KOtBu or UV light, thus limiting their functional group tolerance.T herefore,t he development of as imple,s traightforward and cost-effective method to synthesize naphtho [b]furans is highly desirable. Herein, we report at ransitionm etal-free process for the synthesis of naphtho [b]furans from bromonaphthScheme1.Generals trategiesf or the constructiono ft he naphtho [b]furan skeleton through at ransition-metal-free system. 2442

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“…321 A facile tautomerization of alkyl substituted 1,4-benzoquinone (214) to o-quinone (215) methide is the highlight of this cycloaddition (Scheme 63).…”

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confidence: 99%

Recent advances in 1,4-benzoquinone chemistry

Abraham¹,

Joshi²,

Pardasani³

et al. 2011

J. Braz. Chem. Soc.

165

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As 1,4-benzoquinonas são encontradas em toda a natureza, podendo ser sintetizadas por diversas estratégias. Esta revisão apresenta os desenvolvimentos recentes das metodologias de síntese, das reações de ciclo adição, da química computacional e dos estudos de pulso radiolítico. Destaca ainda a sua significância química e biológica e de seus compostos derivados.1,4-Benzoquinones are ubiquitous in nature and can be synthesized by diverse strategies. Recent developments on their synthetic methodologies, cycloaddition reactions, computational chemistry and pulse radiolytic studies are reported in this review. Their chemical and biological significance as well as their derivates' are also covered.

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ortho-Quinone Methides from para-Quinones: Total Synthesis of Rubioncolin B

Abstract: A concise synthesis of rubioncolin B is described, which features an unprecedented intramolecular Diels−Alder reaction involving an ortho-quinone methide and a naphthofuran moiety. The ortho-quinone methide is generated through a surprisingly facile tautomerization of a para-quinone.

Cited by 122 publications

References 13 publications

Sequential Reactions Initiated by Oxidative Dearomatization. Biomimicry or Artifact?

Sequential Reactions Initiated by Oxidative Dearomatization. Biomimicry or Artifact?

A Simple and Efficient Access to Naphtho[b]furans by Claisen Rearrangement/Cyclization of Bromonaphthyl 3‐Phenylallyl Ethers

Recent advances in 1,4-benzoquinone chemistry

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