Christian Adelwöhrer

University of Natural Resources and Life Science Vienna, Vienna, Vienna, Austria

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Publications (16)35.48 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: (13)C-Perlabeled cellulose was obtained in a seven-step approach from (13)C(6)-labeled d-glucose with a cationic ring-opening polymerization as the key step. Isopropylidene protection, benzylation of the remaining free 3-O-position and subsequent deprotection afforded 3-O-benzyl-(13)C(6)-glucose (2). Regioselective bis-pivaloylation followed by subsequent ortho-esterification provided the precursor for the cationic ring-opening polymerization, 3-O-benzyl-(13)C(6)-glucopyranose 1,2,4-orthopivalate (4). The actual polymerization step gave a stereo- and regioregular (13)C-perlabeled (1-->4)-beta-glucopyranan derivative, which was deprotected into fully labeled (13)C-cellulose, as the cellulose II allomorph with a DP of 40, in an overall 28% yield. All reaction steps were optimized beforehand with nonlabeled compounds toward high yields and high reproducibility and the final compound was comprehensively analytically characterized.
    Biomacromolecules 09/2009; 10(10):2817-22. · 5.37 Impact Factor
  • Christian Adelwöhrer, Yuko Yoneda, Fumiaki Nakatsubo, Thomas Rosenau
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    ABSTRACT: The synthesis of the perdeuterated cellulose solvents NMMO-d11 (9) and N,N-dimethylacetamide-d9 (14) is described. NMMO-d11 was obtained according to a five-step approach from non-labeled diglycolic acid (1) via diethylene glycole-d8 (4) and its bis-tosylate (5), which underwent cyclization with benzylamine to N-benzylmorpholine (6). The removal of the benzyl protecting group, methylation and N-oxidation completed the synthesis. DMAc-d9 (14) was obtained from deuterated acetic acid (10) and dimethylamine–carbon dioxide complex (17) with acidic alumina as the catalyst according to a solvent-free gas–solid reaction. Copyright © 2008 John Wiley & Sons, Ltd.
    Journal of Labelled Compounds 01/2008; 51(1):28 - 32.
  • F. Liebner, P. Schmid, C. Adelwöhrer, T. Rosenau
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    ABSTRACT: The elusive 4-methyl-3,4-dihydro-2H-[1,4]oxazine (2,3-dehydro-N-methylmorpholine, DNMM, 5) was confirmed to occur as degradation product of N-methylmorpholine-N-oxide (1) by trapping with the α-tocopherol-derived ortho-quinone methide in a hetero-Diels–Alder reaction with inverse electron demand. The regioselectivity of the addition was in good agreement with DFT computational data. An authentic sample of 5 was synthesized from formmorpholide (16) via 2-methoxy-formmorpholide in 38% overall yield.
    Tetrahedron 01/2007; 63(48):11817-11821. · 2.80 Impact Factor
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    ABSTRACT: 1,2,3-Triazoles with 1-position substituents, derived from α-tocopherol (vitamin E), were synthesized by 1,3-dipolar cycloaddition reactions of 5a-azido-α-tocopheryl acetate with alkynes, and were fully analytically characterized. NMR spectra of the compounds and crystal structures of derivatives with a truncated isoprenoid side chain are presented. The tocopheryl moiety is readily cleaved in basic media, as a prerequisite for the use in delivery systems showing pH-dependent drug release. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
    Annalen der Chemie und Pharmacie 05/2006; 2006(9). · 3.10 Impact Factor
  • Annalen der Chemie und Pharmacie 02/2006; 2006(9):2081 - 2086. · 3.10 Impact Factor
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    ABSTRACT: Bromination of the ethano-dimer of α-tocopherol (6) afforded pyrano-spirodimer of α-tocopherol (7) quantitatively, while the methano-dimer of α-tocopherol (10) produced a mixture of products, including the furano-spirodimer 11, pyrano-spirodimer 7, and 5-bromo-γ-tocopherol (12), the latter two formed in an unusual dealkylative fragmentation step. The mechanisms were studied by a combination of trapping reactions as well as kinetic and computational studies.
    Tetrahedron. 01/2006; 62(8):1772-1776.
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    ABSTRACT: [structure: see text] Chromanol-type compounds act as antioxidants in biological systems by reduction of oxygen-centered radicals. Their efficiency is determined by the reaction rate constants for the primary antioxidative reaction as well as for disproportionation and recycling reactions of the antioxidant-derived radicals. We studied the reaction kinetics of three novel chromanols: cis- and trans-oxachromanol and the dimeric twin-chromanol, as well as ubichromanol and ubichromenol, in comparison to alpha-tocopherol and pentamethylchromanol. The antioxidant-derived radicals were identified by optical and electron spin resonance spectroscopy (ESR). The kinetics of the primary antioxidative reaction and the disproportionation of the chromanoxyl radicals were assessed by stopped-flow photometry in different organic solvents to simulate the different polarities associated with biomembranes. Furthermore, the reduction of the chromanoxyl radicals by ubiquinol and ascorbate was measured after laser-induced one-electron chromanol oxidation in ethanol and in a micellar system, respectively. The rate constants showed that twin-chromanol had better radical scavenging properties than alpha-tocopherol and a significantly slower disproportionation rate of its corresponding chromanoxyl radical. In addition, the radical derived from twin-chromanol is reduced by ubiquinol and ascorbate at a faster rate than the tocopheroxyl radical. Finally, twin-chromanol can deliver twice as many reducing equivalents, which makes this compound a promising new candidate as artificial antioxidant in biological systems.
    The Journal of Organic Chemistry 05/2005; 70(9):3472-83. · 4.56 Impact Factor
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    ABSTRACT: Novel tri-functional triazines for the modification of cellulosic fibers are prepared from cyanuric chloride. The compounds employ a monochlorotriazinyl (MCT) anchor group for fixation, an active substance showing slow release properties, and a reactivity tuner to facilitate release control. While the compounds are completely stable under dry conditions, the active substances are released simply by surrounding humidity. The reagents offer intriguing perspectives for the preparation of modified cellulosics for single-use application in fields such as healthcare, cosmetics, or personal hygiene.
    Polymer. 01/2005; 46(5):1453-1458.
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    ABSTRACT: Not Available Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Return: Query Results Return items starting with number Query Form Database: Astronomy Physics arXiv e-prints
    Annals of the New York Academy of Sciences 01/2005; 1031:344-7. · 4.38 Impact Factor
  • Christian Adelwöhrer, Thomas Rosenau
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    ABSTRACT: Condensation of γ-tocopherol with aldehydes provides 2,4-disubstituted 1,3,8-trioxaphenanthrenes in a simple one-pot reaction. The reaction proceeded under acid catalysis according to a two-step alkylation–acetalisation mechanism in yields between 58 and 81%. The title compounds are precursors for the thermal generation of ortho-quinone methides, which can be in situ reduced to give antioxidants of the 5a-substituted α-tocopherol-type. The products were analytically characterized by NMR and HRMS.
    Tetrahedron. 01/2005; 61(38):9070-9074.
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    ABSTRACT: New isoxazoline derivatives of α-tocopherol (1), the main component of vitamin E, were synthesized in a facile, two-step sequence consisting of nitration followed by 1,3-dipolar cycloaddition. 5-Nitromethyl-γ-tocopheryl acetate (3), obtained from the cheap α-tocopheryl acetate (2) by direct nitration in one step, acted as the nitrile oxide precursor in the reaction with various alkenes. The facile conversion proceeded in the presence of equimolar amounts of PhNCO and catalytic amounts of triethylamine. The NMR spectra of the product isoxazolines 5−13, showing strongly temperature-dependent resonances of the 4′′-CH, 4-CH2 and the acetyl group, are discussed, and the crystal structures of model compounds containing a methyl group instead of the isoprenoid side chain are presented. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
    Annalen der Chemie und Pharmacie 03/2004; 2004(6):1323 - 1329. · 3.10 Impact Factor
  • Christian Adelwöhrer, Thomas Rosenau, Wolfgang H Binder, Paul Kosma
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    ABSTRACT: Reaction of tocopheryl bromide 2a or chromanyl bromide 2b with triphenyl phosphine produced phosphomium salt intermediates (3a–b), which further reacted with acyl chlorides to novel furotocopherol compounds 4–11 in good yields. The cyclization proceeded according to a two step esterification–Wittig mechanism. Similarly, furotocopheryl dimer 12 was prepared starting from oxalyl chloride. The coupling of tocopheryl phosphonium salt 3a onto modified polystyrene provided a new, vitamin E-loaded resin.
    Tetrahedron 04/2003; 59(18):3231–3235. · 2.80 Impact Factor
  • Source
    Christian Adelwoehrer, Thomas Rosenau, Lars Gille, Paul Kosma
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    ABSTRACT: Condensation of trimethylhydroquinone with aldehydes provides 2,4-disubstituted 5,7,8-trimethyl-4H-benzo[1,3]dioxin-6-ols in a straightforward one-pot reaction. These compounds are 3-oxa-derivatives of α-tocopherol (vitamin E) and represent an interesting novel class of phenolic antioxidants. The formation reaction proceeds according to a two-step mechanism consisting of electrophilic substitution and acetalization, and provides the product as a cis/trans-mixture of diastereomers.
    ChemInform 01/2003; 34(31).
  • Christian Adelwöhrer, Thomas Rosenau, Paul Kosma
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    ABSTRACT: The reaction of α-tocopheryl acetate (vitamin E acetate, 3) with concentrated nitric acid proceeds according to a non-radical, two-step mechanism, producing 5-nitromethyl-γ-tocopheryl acetate (4) in good yields. In the first step, oxidation of 3 affords a benzylic cation intermediate (8), which in the second step adds nitrite to give 4. The acetyl group, which stabilizes intermediate 8 intramolecularly, remains bound to the tocopheryl moiety throughout the reaction.
    Tetrahedron 01/2003; 59(41):8177-8182. · 2.80 Impact Factor
  • Gregor Kraft, Christoph Muss, Christian Adelwöhrer, Thomas Rosenau
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    ABSTRACT: The syntheses of several perdeuterated substances—some of them isotopically labeled (15N) in addition—are described, which act as direct solvents of cellulose either on their own, such as N-methylmorpholine N-oxide (NMMO), 1-butyl-3-methylimidazolium acetate (BMIM-OAc), or 1-ethyl-3-methylimidazolium acetate (EMIM-OAc), or in combination with auxiliaries, such as N,N-dimethylacetamide (DMAc—for the cellulose solvent DMAc/LiCl). NMMO-d11 (9) was obtained in an eight-step approach from non-labeled diglycolic acid (1) via diethylene glycol-d8 (4) and its bis-tosylate (5), which underwent ring closure with benzylamine to N-benzylmorpholine-d8 (6). Debenzylation, methylation and oxidation completed the synthetic sequence, which was also able to provide the 15N-labeled product (9a) by usage of 15N-benzylamine. DMAc-d9 (14) was obtained from deuterated acetic acid (10) and dimethylamine-d6–carbon dioxide complex (13) in a solvent-free gas-solid reaction with acidic alumina as the catalyst. Employing the CO2-complex of 15N-dimethylamine-d6 afforded the 15N-labeled product 15N-DMAc-d9 (14a) in a similar way. The two ionic liquids EMIM-OAc (21) and BMIM-OAc (22) were obtained from imidazole in three-step sequences starting with butylation and ethylation, respectively. The resulting 1-alkyl imidazoles were purified, and subsequently methylated according to a novel protocol using dimethylcarbonate-d6. Addition of acetic acid-d4 caused traceless degradation of the methylcarbonate anions and exchange for acetate. In all syntheses, the reaction steps were optimized with non-labeled compounds towards high yields and high reproducibility before entering the “hot runs” with deuterated and otherwise isotopically labeled material.
    Cellulose 16(1). · 3.48 Impact Factor