- Manipulating the enone moiety of levoglucosenone: 1,3-Transposition reactions including ones leading to isolevoglucosenone
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The manipulation of the enone moiety associated with the biomass-derived, homochiral and now abundant compound levoglucosenone (1) is described. While the trichloroacetimidates derived from the allylic alcohols 3 and 4 failed to engage in Overman-type rea
- Ma, Xinghua,Liu, Xin,Yates, Patrick,Raverty, Warwick,Banwell, Martin G.,Ma, Chenxi,Willis, Anthony C.,Carr, Paul D.
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p. 5000 - 5011
(2018/06/20)
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- Diastereoselective Weitz-Scheffer epoxidation of levoglucosenone for the synthesis of isolevoglucosenone and derivatives
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High-yielding epoxidation conditions for the cellulose pyrolysis product (?)-levoglucosenone (LGO) and 3-aryl derivatives of LGO have been developed. The reaction of LGO with hydrogen peroxide/base is known to give a Baeyer-Villiger reaction, however, it was found that the reactions of LGO or derivatives with tert-butylhydroperoxide/base affords solely epoxides through the Weitz-Scheffer reaction. A critical parameter in the successful isolation of the epoxide from LGO was to avoid all contact with water or alcohols during the reaction and workup. The epoxide products were reacted under Wharton conditions affording allylic alcohols and subsequent oxidation led to isolevoglucosenone or 3-arylisolevoglucosenone derivatives. Previously unreported reactions on isolevoglucosenone were then investigated.
- Ledingham, Edward T.,Greatrex, Ben W.
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p. 6107 - 6115
(2018/09/14)
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- The conversion of levoglucosenone into isolevoglucosenone
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Levoglucosenone (1), a compound that will soon be available in tonne quantities through the pyrolysis of acid-treated lignocellulosic biomass, has been converted into isolevoglucosenone (2) using Wharton rearrangement chemistry. Treatment of compound 1 with alkaline hydrogen peroxide gave the γ-lactones 5 and 6 rather than the required epoxy-ketones 3 and/or 4. However, the latter pair of compounds could be obtained by an initial Luche reduction of compound 1, electrophilic epoxidation of the resulting allylic alcohol 8 and oxidation of the product oxiranes 9 and 10. Independent treatment of compounds 3 and 4 with hydrazine then acetic acid followed by oxidation of the ensuing allylic alcohols finally afforded isolevoglucosenone (2). Details of the single-crystal X-ray analyses of epoxy-alcohols 9 and 10 are reported.
- Ma, Xinghua,Anderson, Natasha,White, Lorenzo V.,Bae, Song,Raverty, Warwick,Willis, Anthony C.,Banwell, Martin G.
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p. 593 - 599
(2015/04/27)
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- Pseudo enantiomeric carbohydrate olefin ligands - Case study and application in kinetic resolution in rhodium(I)-catalysed 1,4-addition
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In order to investigate significant differences in asymmetric induction for pseudo enantiomeric carbohydrate olefin ligands in rhodium(I)-catalysed 1,4-addition reactions, we designed a set of new olefin ligands differing in relative configuration and pyranoside conformation. With these, we have successfully elucidated structural requirements for metal binding and also identified an improved alternative for one pseudo enantiomer. Furthermore, we report the efficient kinetic resolution of a racemic 4-hydroxycyclopentenone derivative by 1,4-addition.
- Grugel, Holger,Albrecht, Fabian,Boysena, Mike M. K.
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supporting information
p. 3289 - 3294
(2015/02/05)
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- New chiral building blocks and branched 1,6-anhydro sugars from regio- and stereoisomeric Cerny epoxides
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The tandem epoxide→allyl alcohol rearrangement-cuprate cross-coupling previously described for the Cerny epoxide 1, to yield the allyl alcohol 2, was extended to the regioisomeric epoxy-tosylate 3, to yield allyl alcohol 4, and to the stereoisomeric epoxi
- Krohn, Karsten,Gehle, Dietmar,Floerke, Ulrich
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p. 4557 - 4562
(2007/10/03)
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- A new approach to isolevoglucosenone via the 2,3-sigmatropic rearrangement of an allylic selenide
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A convenient method is described for the synthesis of isolevoglucosenone 5, via allylic selenide 3, and its rearrangement to allylic alcohol 4, followed by oxidation with manganese oxide. Isolevoglucosenone 5, is produced in 62% overall yield.
- Witczak, Zbigniew J.,Kaplon, Peter,Kolodziej, Mark
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p. 143 - 148
(2007/10/03)
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- Chemoselective elaboration of O-linked glycopeptide mimetics by alkylation of 3-thioGalNAc
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A critical branch point in mucin-type oligosaccharides is the β1 → 3 glycosidic linkage to the core α-N-acetylgalactosamine (GalNAc) residue. We report here a strategy for the synthesis of O-linked glycopeptide analogues that replaces this linkage with a
- Marcaurelle,Bertozzi
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p. 1587 - 1595
(2007/10/03)
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- Lipase-mediated preparation of enantiopure isolevoglucosenone
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A route to enantiopure isolevoglucosenone, a regioisomer of levoglucosenone and a potential chiral building block, has been developed by employing lipase-mediated kinetic resolution as the key step.
- Kadota,ElAzab,Taniguchi,Ogasawara
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p. 1372 - 1374
(2007/10/03)
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- Thio-sugars. Part 5: From D-glucal to 3-deoxy-(1→2)-2-S-thiodisaccharides through isolevoglucosenone-a simple approach
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A new synthesis of isolevoglucosenone and its stereoselective functionalization into 3-deoxy-(1-2)-2-S-thiodisaccharides is described. The base-catalyzed conjugate addition of 1-thiosugars to isolevoglucosenone followed by the reduction of the C-4 keto function constitute a new two-step general approach to these classes of biologically important thio-sugars. Copyright (C) 2000 Elsevier Science Ltd.
- Witczak, Zbigniew J.,Chen, Hong,Kaplon, Peter
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p. 519 - 532
(2007/10/03)
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- Reactions of 2-hydroxy-6,8-dioxabicyclo[3.2.1]oct-3-ene with diethylaminosulfur trifluoride and with halogens. Facile synthesis of 1,6- anhydrohalohexopyranoses
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D-Galactal 1 reacts in THF in the presence of catalytic amounts of concentrated sulfuric acid to give (2R)-2-hydroxy-6,8-dioxabicyclo[3.2.1]oct- 3-ene (4) in a Ferrier-type rearrangement in 40% yield. When 4 is treated with diethylaminosulfur trifluoride
- Oberdorfer, Franz,Haeckel, Roland,Lauer, Gilbert
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p. 201 - 206
(2007/10/03)
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- A ready method for generating oxycarbinyl radicals for conjugate-addition-alkylation or radical cyclization reactions
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A ready method is described from generating oxycarbinyl radicals from alcohols, acetals and aldehydes which involves periodic addition of di-tert-butyl-hyponitrite (DBH) to a refluxing solution of the precursor.The resulting radicals may be trapped intermolecularly by α-enones in conjugate-addition-alkylation reactions, or intermolecularly in ring-forming reactions.Typically, small portions of DBH are added every 10-15 minutes until the reactant of interest has been consumed. Keywords: conjugate addition / carbohydrate α-enones / oxycarbinyl radicals
- Rao, B. Venkateswara,Chan, J. B.,Moskowitz, N.,Fraser-Reid, B.
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p. 428 - 432
(2007/10/02)
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