First Preparation of Optically Pure Ketals of p-Benzoquinone

March, Pedro de; Escoda, M.; Figueredo, Marta; Font, Josep; Álvarez‐Larena, Ángel; Piniella, J. F.

doi:10.1021/jo00117a048

Cited by 24 publications

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“…The first objective of this collective synthesis plan was the preparation of an intermediate that could act as a menisdaurilide ( 19 a ) surrogate. Different protected versions of this putative biosynthetic intermediate have previously been prepared by the groups of Gademann and de March in yields ranging from about 2 to 15 % over 7 to 11 steps . Our own synthesis started from 4‐hydroxyphenylacetic acid 18 , a plausible tyrosine‐derived biosynthetic precursor, which was subjected to a phenyliodine(III) diacetate‐mediated dearomatisation in MeOH to furnish the para ‐quinol methyl ether 23 (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

Bio‐inspired Total Synthesis of Twelve Securinega Alkaloids: Structural Reassignments of (+)‐Virosine B and (−)‐Episecurinol A

Antien

Lacambra

Cossío

et al. 2019

Chemistry A European J

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The so‐called Securinega alkaloids constitute a class of tetracyclic biologically active specialised metabolites isolated principally from subtropical plants belonging to the Phyllanthaceae family. Following a strategy based on alternative hypotheses for their biosynthesis, an easy and time‐efficient divergent synthesis enabled access to twelve of those alkaloids featuring (neo)(nor)securinane skeletons. Moreover, this work permitted to reassign the absolute configurations of (+)‐virosine B and (−)‐episecurinol A.

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Section: Resultsmentioning

confidence: 99%

Bio‐inspired Total Synthesis of Twelve Securinega Alkaloids: Structural Reassignments of (+)‐Virosine B and (−)‐Episecurinol A

Antien

Lacambra

Cossío

et al. 2019

Chemistry A European J

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“…2,3‐Allenoates are a class of interesting and versatile synthetic intermediates, which may undergo many reactions,1 such as nucleophilic addition reactions,2 electrophilic addition reactions,1f, 3 Morita–Baylis–Hillman reactions,4 rearrangements,5 cycloaddition6 and cyclization reactions,1c,7 etc 8. Many methods have been reported for the synthesis of allenoates,9 but the preparation of optically active 2,3‐allenoates is not very well established (Scheme ) 10–18.…”

Section: Introductionmentioning

confidence: 99%

Optically Active 2,3‐Allenoates via Palladium‐Catalyzed Carbonylation of Enantioenriched Propargylic Mesylates

Wang

2013

Adv Synth Catal

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Under mild conditions, optically active 2,3allenoates were synthesized from enantioenriched propargylic mesylates with moderate to excellent yields and high efficiency of chirality transfer by using palladium(0) bis(dibenzylideneacetone) (3 mol%) with (S)-(À)-5,5'-bis(diphenylphosphino)-4,4'-bi-1,3-benzodioxole [(S)-SEGPHOS] (3 mol%) as the catalyst and diammonium hydrogen phosphate (1.1 equiv.) as the base.

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“…Direct acetalization of p-benzoquinone with ethyleneglycol is not possible though, as had already been reported previously. [21] …”

Section: Resultsmentioning

confidence: 99%

Synthesis of Both Enantiomers of Conduritol C Tetraacetate and of meso‐Conduritol D Tetraacetate by Oxidation of Benzoquinone Bis(ethylene acetal)

Lang

Ziegler

2007

Eur J Org Chem

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Epoxidation of p‐benzoquinone bis(ethylene acetal) (1) with m‐chloroperbenzoic acid or hydrogen peroxide/benzonitrile afforded corresponding monoepoxide 2, which was converted into p‐benzoquinone mono(ethylene acetal) monoepoxide 5 with perchloric acid. Dihydroxylation of 1 with osmium tetroxide or ruthenium trichloride/sodium periodate afforded corresponding cis‐diol 6, which was subsequently acetylated to give diacetate 7. One ethyleneacetal moiety in 7 could be selectively hydrolyzed with silica gel/ferric chloride under solvent‐free conditions to give ketone 8, which, upon reduction with sodium borohydride and subsequent acetylation of the formed alcohol group, afforded two diastereomeric triacetates 10. Hydrolysis of the remaining acetal functions in the two diastereomers 10, followed by reduction of the second carbonyl group as described above, afforded racemic conduritol C and meso‐conduritol D tetraacetates 12 and 13, respectively. Enzymatic resolution of the racemic arabino‐configured triacetate 10 with Lipozym failed, while the ribo‐configured counterpart reacted smoothly to give enantiomerically pure D‐ribo‐ and L‐ribo‐configured triacetates 10. The latter pair of enantiomerically pure triacetates were converted into both enantiomers of conduritol C tetraacetate 13 as described for the racemic compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

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First Preparation of Optically Pure Ketals of p-Benzoquinone

Cited by 24 publications

References 0 publications

Bio‐inspired Total Synthesis of Twelve Securinega Alkaloids: Structural Reassignments of (+)‐Virosine B and (−)‐Episecurinol A

Bio‐inspired Total Synthesis of Twelve Securinega Alkaloids: Structural Reassignments of (+)‐Virosine B and (−)‐Episecurinol A

Optically Active 2,3‐Allenoates via Palladium‐Catalyzed Carbonylation of Enantioenriched Propargylic Mesylates

Synthesis of Both Enantiomers of Conduritol C Tetraacetate and of meso‐Conduritol D Tetraacetate by Oxidation of Benzoquinone Bis(ethylene acetal)

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