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Journal ArticleDOI

Diels–Alder trapping of in situ generated dienes from 3,4-dihydro-2H-pyran with p-quinone catalysed by p-toluenesulfonic acid

01 Feb 2017-Organic and Biomolecular Chemistry (The Royal Society of Chemistry)-Vol. 15, Iss: 5, pp 1115-1121
TL;DR: This comprehensive study portrays that p-toluenesulfonic acid is a more efficient catalyst for the reaction between p-quinones and 3,4-dihydro-2H-pyran, than the Lewis acids.

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Abstract: This comprehensive study portrays that p-toluenesulfonic acid is a more efficient catalyst for the reaction between p-quinones and 3,4-dihydro-2H-pyran, than the Lewis acids. The products were accomplished by the Diels–Alder cycloaddition reaction and their mechanistic pathways have been formulated. The impact of C2 and C2,5 substituents of the p-quinones on the cycloaddition reaction has been explored. Remarkably, it is the first report to explore this kind of in situ generated diene for the Diels–Alder cycloaddition reaction.

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Topics: Cycloaddition (65%), Diene (56%), Lewis acids and bases (54%) ...read more
Citations
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Journal ArticleDOI
25 May 2020-Angewandte Chemie
Abstract: An efficient enantioselective construction of tetrahydronaphthalene-1,4-diones as well as dihydronaphthalene-1,4-diols by a chiral phosphoric acid catalyzed quinone Diels-Alder reaction with dienecarbamates is reported. The nature of the protecting group on the diene is key to the success of achieving high enantioselectivity. The divergent "redox" selectivity is controlled by using an adequate amount of quinones. Reversible redox switching without erosion of enantioselectivity was possible from individual redox isomers.

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15 citations


Journal ArticleDOI
TL;DR: Pro-aromatic and volatile 1-methyl-1,4-cyclohexadiene (MeCHD) was used for the first time as a valid H-atom source in an innovative method to reduce ortho or para quinones to obtain the corresponding catechols and hydroquinones in good to excellent yields.

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Abstract: Pro-aromatic and volatile 1-methyl-1,4-cyclohexadiene (MeCHD) was used for the first time as a valid H-atom source in an innovative method to reduce ortho or para quinones to obtain the corresponding catechols and hydroquinones in good to excellent yields. Notably, the excess of MeCHD and the toluene formed as the oxidation product can be easily removed by evaporation. In some cases, trifluoroacetic acid as a catalyst was added to obtain the desired products. The reaction proceeds in air and under mild conditions, without metal catalysts and sulfur derivatives, resulting in an excellent and competitive method to reduce quinones. The mechanism is attributed to a radical reaction triggered by a hydrogen atom transfer from MeCHD to quinones, or, in the presence of trifluoroacetic acid, to a hydride transfer process.

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6 citations


Journal ArticleDOI
Abstract: On prepare un compose tricyclique de structure voisine de celle des precurseurs des podocarpanes, par cycloaddition du vinylcyclohexene avec l'acide benzoquinone-1,4 carboxylique. On etudie la structure cristalline du compose et on explique par une etude theorique la stereochimie de la reaction

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6 citations



References
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Journal ArticleDOI
17 May 2002-Angewandte Chemie
Abstract: The Diels-Alder reaction has both enabled and shaped the art and science of total synthesis over the last few decades to an extent which, arguably, has yet to be eclipsed by any other transformation in the current synthetic repertoire. With myriad applications of this magnificent pericyclic reaction, often as a crucial element in elegant and programmed cascade sequences facilitating complex molecule construction, the Diels-Alder cycloaddition has afforded numerous and unparalleled solutions to a diverse range of synthetic puzzles provided by nature in the form of natural products. In celebration of the 100th anniversary of Alder's birth, selected examples of the awesome power of the reaction he helped to discover are discussed in this review in the context of total synthesis to illustrate its overall versatility and underscore its vast potential which has yet to be fully realized.

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1,277 citations


Book
01 Jan 1974-
Abstract: This is Part 2 of the second volume of a three volume work devoted to the chemistry of quinonoid compounds. Part 1 is published simultaneously, as is a volume set containing both parts. The work is intended to form a comprehensive review of the current state of research in quinonoid compounds starting with general and theoretical aspects and encompassing, among other things, physical and chemical methods, mass spectra, PES, chiroptical properties, chemiluminescence, recent advances in the synthesis of quinonoid compounds and in photochemistry, chemistry and biochemistry.

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707 citations


Journal ArticleDOI
Do Hyun Ryu1, E. J. Corey1Institutions (1)
TL;DR: The strong acid triflimide ((CF3SO2)2NH) protonates chiral oxazaborolidines to form superactive, stable, chiral Lewis acids which are highly effective catalysts for a wide variety of enantioselective Diels-Alder reactions, documented herein by more than 20 examples.

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Abstract: The strong acid triflimide ((CF3SO2)2NH) protonates chiral oxazaborolidines to form superactive, stable, chiral Lewis acids which are highly effective catalysts for a wide variety of enantioselective Diels-Alder reactions, documented herein by more than 20 examples.

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175 citations


Journal ArticleDOI
TL;DR: Two synthetic derivatives of illimaquinone, in which the 6-hydroxyl group at the ortho position to one of carbonyl groups of the quinone ring was modified, proved ineffective in inhibiting the human immunodeficiency virus type 1 reverse transcriptase RNase H function, suggesting involvement of the 6'-hydroxym group in blocking the enzymatic activity.

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Abstract: We studied the effect of the natural marine substance illimaquinone on the catalytic activities of reverse transcriptase from human immunodeficiency virus type 1. Illimaquinone inhibited the RNase H activity of the enzyme at concentrations of 5 to 10 microgram/ml, whereas RNA-dependent DNA polymerase and DNA-dependent DNA polymerase activities were considerably less susceptible to this inhibition. Two synthetic derivatives of illimaquinone, in which the 6'-hydroxyl group at the ortho position to one of carbonyl groups of the quinone ring was modified, proved ineffective in inhibiting the human immunodeficiency virus type 1 reverse transcriptase RNase H function, suggesting involvement of the 6'-hydroxyl group in blocking the enzymatic activity.

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113 citations


Journal ArticleDOI
Joshua N. Payette1, Hisashi Yamamoto1Institutions (1)
TL;DR: Cationic oxazaborolidine 2 affords Diels−Alder adducts of ethyl acrylate and 2-substituted cyclopentadienes, derived from the corresponding mixture of regioisomers, as single isomers in excellent yields and enantioselectivities.

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Abstract: Cationic oxazaborolidine 2 affords Diels−Alder adducts of ethyl acrylate and 2-substituted cyclopentadienes, derived from the corresponding mixture of regioisomers, as single isomers in excellent yields and enantioselectivities. Furthermore, Diels−Alder adducts of 1-substituted cyclopentadienes are obtained through a one-pot procedure whereby ethyl acrylate is initially employed to consume all 2-substituted cyclopentadiene. Subsequently, various 2,5-disubstituted benzoquinones are added to react with remaining 1-substituted cyclopentadiene. Remarkably, reaction occurs selectively at the double bond coordinated anti to catalyst 2 to provide adducts containing adjacent all-carbon quaternary stereocenters in high yields and excellent enantioselectivities.

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94 citations


Performance
Metrics
No. of citations received by the Paper in previous years
YearCitations
20202
20191
19831