Heterodiene syntheses with .alpha.,.beta.-unsaturated carbonyl compounds

Desimoni, G.; Tacconi, G.

doi:10.1021/cr60298a001

Cited by 319 publications

(88 citation statements)

References 38 publications

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“…ortho-Quinone methides are widely used in organic synthesis for carrying out "reverse electron demand" Diels-Alder [4+2] cycloadditions with electron-rich alkenes, to give chroman derivatives (1,2,4). Because of this utility, various thermal methods for generating o-QMs have been developed during the last two decades, including methods involving Ag,O oxidation of phenols (5), high-temperature dehydration of o-hydroxybenzyl alcohols (6), fluoride-induced desilylation of silyl ethers (7), and thermal extrusion of small molecules (8).…”

Section: Introductionmentioning

confidence: 99%

1995 Merck Frosst Award Lecture Quinone methides: relevant intermediates in organic chemistry

Wan¹,

Barker²,

Diao³

et al. 1996

Can. J. Chem.

152

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ortho and para-Quinone methides (2-methylene-3,5-cyclohexadien-I-one and 4-methylene-2,5-cyclohexadien-1-one, respectively) are intermediates in a variety of important chemical systems. In particular, o-quinone methides are useful in synthesis for the construction of chroman ring systems. A brief account of the relevance of quinone methide chemistry will be provided. This is followed by a review of recent studies from our laboratory on efficient methods for the photogeneration of quinone methides, concentrating on the use of hydroxy-substituted benzyl alcohols in aqueous media. It is shown that this method is general since it provides access too-, 171-, andp-quinone methide isomers. When appropriately substituted, all of these quinone methide isomers have been spectroscopically characterized by laser flash photolysis, making this technique the one of choice for studying the dynamics of these reactive intermediates. The mechanism of photochemical generation from hydroxybenzyl alcohols and extensions of the reaction to photogeneration of fluorenyl and biphenyl quinone methides will also be presented.Key words: quinone methide, biphenyl quinone methide, carbocation, photosolvolysis, photodehydroxylation, hetero-DielsAlder reaction.R6surnC : Les mCthides d'o-et p-quinones (respectivement 2-mCthylknecyclohexa-3,5-dikn-I-one et 4-mCthylknecyclohexa-2,5-dikn-1-one) sont des intermediaires dans une variCtC de systkmes chimiques importants. En particulier, les mCthides d'oquinones sont utiles en synthkse pour la construction de systkmes incorporant le noyau chromane. On fournit un bref rCsumC de l'importance de la chimie des methides de quinone. On prCsente ensuite une revue des Ctudes rCcentes rCalisCes dans notre laboratoire sur des mCthodes efficaces de photogCnCration des mCthides de quinone, en se concentrant sur l'utilisation, en milieux aqueux, d'alcools benzyliques substituCs par des groupes hydroxyles. On montre que cette mCthode est gCnCrale puisqu'elle permet d'obtenir facilement les isomkres ortho, mCta et para des methides de quinone. Lorsqu'ils sont substituts d'une faqon adtquate, tous ces isomkres de methides de quinone ont pu Etre caractCrisCs d'un faqon spectroscopique par photolyse Cclair au laser qui en fait une technique de choix pour I'ttude dynamique de ces intermkdiaires rCactifs. On prCsente aussi le mecanisme de la gCnCration photochimique B partir des alcools hydroxybenzyliques et des extensions de la rCaction B la photogtntration des mCthides de quinones dCrivCs du fluortnyle et du biphinyle.Mots clCs : mtthide de quinone, mCthide de quinone du biphinyle, carbocation, photosolvolyse, photodCshydroxylation, riaction d' hCtCro-Diels-Alder.[Traduit par la ridaction]

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Section: Introductionmentioning

confidence: 99%

1995 Merck Frosst Award Lecture Quinone methides: relevant intermediates in organic chemistry

Wan¹,

Barker²,

Diao³

et al. 1996

Can. J. Chem.

152

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“…1, reagieren mit Mehrfachbindungssystemen bevorzugt nach dem Schema der [4+2]-Cycloaddition (Diels-Alder- Reaktion) [5][6][7][8][9], Alle Skelettatom e des Diens und des Dienophils gehen als Skelettatom e in das neugebil dete Ringsystem ein. Dabei muß die Bildung regioisomerer Produkte (II, III) in Betracht gezogen w er den [9].…”

Section: Cycloadditionsreaktionen Unter Vollständigem Einbau Des Dienunclassified

“…Elektronenarm e 1, addieren bevorzugt elektronenreiche Dienophile in konzertierter und/oder m ehrstufiger Reaktion [5][6][7][8][9].…”

Section: Cycloadditionsreaktionen Unter Vollständigem Einbau Des Dienunclassified

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Reaktionen 4,4-Bis(trifluormethyl)-substituierter Heterodiene mit Alkinen / Reactions of 4,4-Bis(trifluoromethyl) Substituted Heterodienes with Alkynes

Burger

Sewald

Huber

et al. 1989

Zeitschrift Für Naturforschung B

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“…[1] They are highly reactive and unstable intermediates in organic synthesis. This is because of the restoration of aromaticity after cycloaddition, which has been utilized for the construction of polycyclic ring systems that are otherwise difficult to synthesize.…”

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confidence: 99%

[4+2] Cycloaddition of ortho‐Quinone Methides Promoted by Ionic Liquids: an Efficient and Mild Protocol for the Synthesis of Tetrahydropyranobenzopyrans

et al. 2004

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Heterodiene syntheses with .alpha.,.beta.-unsaturated carbonyl compounds

Cited by 319 publications

References 38 publications

1995 Merck Frosst Award Lecture Quinone methides: relevant intermediates in organic chemistry

1995 Merck Frosst Award Lecture Quinone methides: relevant intermediates in organic chemistry

Reaktionen 4,4-Bis(trifluormethyl)-substituierter Heterodiene mit Alkinen / Reactions of 4,4-Bis(trifluoromethyl) Substituted Heterodienes with Alkynes

[4+2] Cycloaddition of ortho‐Quinone Methides Promoted by Ionic Liquids: an Efficient and Mild Protocol for the Synthesis of Tetrahydropyranobenzopyrans

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