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  • 1
    Electronic Resource
    Electronic Resource
    Wirkstoffe aus dem Fliegenpilz (1968)
    Springer
    Naturwissenschaften 55 (1968), S. 305-313 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00600445
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  • 2
    Electronic Resource
    Electronic Resource
    Die Entwicklung der Carotinoid-Chemie im Spiegel der Helvetica Chimica Acta 1922-1991 (1992)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 75 (1992), S. 941-994 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 58 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19920750402
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  • 3
    Electronic Resource
    Electronic Resource
    Rosafluin, ein neues Diapocarotindiol aus Rosenblüten. 8. Mitteilung über Rosenfarbstoffe7. Mitteilung: [1]. (1988)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 71 (1988), S. 1491-1497 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rosafluine, a Novel Diapocarotenediol from Rose PetalsA strongly fluorescent trace compound from rose petals was identified as the as yet unknown 10,10′-diapocarotene-10,10′-diol ( = 4,9-dimethyldodeca-2,4,6,8,10-pentaene-1,12-diol; 2).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19880710613
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  • 4
    Electronic Resource
    Electronic Resource
    (6R,9′Z)-Neoxanthin: Synthese, Schmelzverhalten, Spektren und Konformationsberechnungen (1994)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 77 (1994), S. 909-930 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (6R,9′Z)-Neoxanthin: Synthesis, Physical Properties, Spectra, and Calculations of Its Conformation in SolutionThe synthesis of pure and crystalline (9′Z)-neoxanthin (6) is described. MnO2 Oxidation of (9Z)-C15-alcohol 7 at room temperature produces a mixture 8/9 of (9Z)- and (9E)-aldehydes. Predominant formation of the required (9Z)-aldehyde 8 is achieved by performing the oxidation at - 10°. Condensation of 8 with the mono-Li salt of the symmetrical C10-diphosphonate 10 gave the (9Z)-C25-monophosphonate 11. The Wittig-Horner condensation of 10 with the allenic C15-aldehyde 1b, under selected conditions allows the preparation of pure and crystalline (9′Z)-15,15′-didehydroneoxanthin (12) and, after subsequent semireduction, of crystalline (15Z,9′Z)-neoxanthin (13). Thermal isomerisation of a AcOEt solution of 13 at 95° yields preferentially (9′Z)-neoxanthin (6). Our crystalline sample shows the highest ∊-values in the UV/VIS spectra ever recorded. The CD spectra display a pronounced similarity with those of corresponding violaxanthin isomers. In contrast to the (all-E)-isomer 5, (9′Z)-neoxanthin undergoes very little isomerisation when heated to its melting point. For comparison purposes, a crystalline probe of 6 is also isolated from lawn mowings. Extensive 1H-and 13C-NMR investigations at 600 MHz of a (D6)benzene solution using 2D-experiments such as COSY, TOCSY, ROESY, HMBC, and HMQC techniques permit the unambiguous assignment of all signals. Force-field calculations of a model system of 6 indicate the presence of several interconverting conformers of the violaxanthin end group, 66% of which possess a pseudoequatorial and 34% a pseudoaxial OH—C(3′). The torsion angle (ω1) around the C(6′)—C(7′) bond, known to be of prime importance for the shape of the CD spectra, varies with values of 87° for 55% and 263° for 45% of the molecules. Therefore, the molecules clearly display a preference for the ‘syn’-position of the C(7′)=C(8′) bond and the epoxy group. Unexpectedly, the double bonds of C(7′)=C(8′) and C(9′)=C(10′) are not coplanar. The deviation amounts to ± 20°, both in the ‘syn’ - and the ‘anti’-conformation.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19940770405
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  • 5
    Electronic Resource
    Electronic Resource
    Two New Syntheses of the Pyranojuglone Pigment α-Caryopterone (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 2324-2331 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By a simple process, 3-methoxyjuglone (= 8-hydroxy-2-methoxy-1,4-naphthoquinone; 9) has been synthesized from 1,2,4-trimethoxybenzene (5) and converted, after prenylation, to α-caryopterone (1; Scheme 1), a pyranojuglone pigment from Caryopteris clandonensis. On the other hand, juglone (= 5-hydroxy-1,4-naphthoquinone; 12) was regioselectively prenylated at C(2) via its 1-methoxy-cyclohexa-1,3-diene adduct 15 (Scheme 2). The 2-prenyljuglone (4) thus formed led to 1 after oxidation and other reactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680827
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  • 6
    Electronic Resource
    Electronic Resource
    Synthese von enantiomerenreinen Violaxanthinen und verwandten Verbindungen (1988)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 71 (1988), S. 931-956 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses of Enantiomerically Pure Violaxanthins and Related CompoundsThe epoxides 16 and ent-16, prepared by Sharpless-Katsuki oxidation of 15 in excellent yield and very high enantiomeric purity, were used as synthons for the preparation of (+)-(S)-didehydrovomifoliol (45), (+)-(6S, 7E, 9E)-abscisic ester 46, (+)-(6S, 7E, 9Z)-abscsic ester 47, (-)-(3S, 7E, 9E)-xanthoxin (49), (-)-(3R, 7E, 9E)-xanthoxin (50), (3S, 5R, 6S, 3′S,5′R, 6′S, all-E)-violaxanthin (1) (3R, 5R,6S,3′R,5′R,6′S, all-E)-violaxanthin (55) and their (9Z) (see 53, 57), (13Z) (see 54, 58), and (15Z) (see 60) isomers. The novel violadione (61) was prepared from 1 by oxidation with DMSO/Ac2O. By base treatment, 61 was converted into violadienedione (62), a potential precursor of carotenoids with phenolic end groups.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19880710502
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  • 7
    Electronic Resource
    Electronic Resource
    Synthese von (6R, all-E)-Neoxanthin und verwandten Allen-Carotinoiden (1992)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 75 (1992), S. 773-790 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of (6R, all-E)-Neoxanthin and Related Allenic CarotenoidsWe present the first synthesis of enantiomerically pure neoxanthin (1) by a Wittig-Horner condensation between the ylide from the novel diethyl 12′-apo-15, 15′-didehydroviolaxanthin-12′-phosphonate (35) and the allenic C15-aldehyde 31 (Scheme 4) via the crystalline 15, 15′-didehydroneoxanthin (36; 70% yield). After partial hydrogenation of the triple bond of 36 and isomerisation of the (15Z)-intermediate 37, neoxanthin (1) was obtained in good yield. Similar syntheses gave (15Z, 9′Z)-neoxanthin (45; Scheme 5) and (9Z)-15, 15′-didehydroneoxanthin (47; Scheme 6). Comparison of the physical data of synthetic 1 with those of a freshly isolated sample of neoxanthin from the flowers of Trollius europaeus confirmed their identity. The unusually low melting point of 1 is caused by a very easy thermal isomerisation into a mixture of the neochromes 4 and 5 (Scheme 1). Such a thermal rearrangement is not observed with 15, 15′-didehydroneoxanthin (36). To explain this, we assume a zwitterionic excited state of the allenic group that induces the rearrangement of the violaxanthin end group into the furanoid epoxide (Scheme 7).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19920750314
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  • 8
    Electronic Resource
    Electronic Resource
    (all-E)-12′-Apozeaxanthinol, Persicaxanthine und Persicachrome (1988)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 71 (1988), S. 1689-1696 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (all-E)-12′-Apozeanthinol, Persicaxanthine, and PersicachromesReexamination of the so-called ‘persicaxanthins’ and ‘persicachromes’, the fluorescent and polar C25-apocarotenols from the flesh of cling peaches, led to the identification of the following components: (3R)-12′-apo-β-carotene-3,12′-diol (3), (3S,5R,8R, all-E)- and (3S,5R,8S,all-E)-5,8-epoxy-5,8-dihydro-12′-apo-β-carotene-3,12′-diols (4 and 5, resp.), (3S,5R,6S,all-E)-5,6-epoxy-5,6-dihydro-l2′-apo-β-carotene-3,12′-diol =persicaxanthin; (6), (3S,5R,6S,9Z,13′Z)-5,6-dihydro-12′apo-β-carotene-3,12′-diol (7; probable structure), (3S,5R,6S,15Z)-5,6-epoxy-5,6-dihydro-12′-apo-β-carotene-3,12′-diol (8), and (3S,5R,6S,13Z)-5,6-epoxy-5,6-dihydro-12′-apo-β-carotene-3,12′-diol (9). The (Z)-isomers 7-9 are very labile and, after HPLC separation, isomerized predominantly to the (all-E)-isomer 6.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19880710715
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesen von enantiomerenreinen Apoviolaxanthin-säuren, -olen und -alen (Persicaxanthin, Sinensiaxanthin und β-Citraurin-epoxid) und ihrer furanoiden Umlagerungsprodukte (1988)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 71 (1988), S. 1983-1998 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Enantiomerically Pure Apoviolaxanthinoic Acids, Apoviolaxanthinols, and Apoviolaxanthinals (Including Persicaxanthin, Sinensiaxanthin, and β-Citraurin Epoxide) and of their Furanoid Rearrangement ProductsStarting from (1′S,2′R,4′S,2E,4E)-5-(1′,2′-epoxy-4′-hydroxy-2′,6′,6′-trimethylcyclohexy1)-3-methy1-2,4-pentadienal (3), a recently described synthon [6], a full range of C20-, C25-, C27-, and C30-polyenic acids, alcohols, and aldehydes and their (8R)- and (8S)-diastereoisomeric furanoid rearrangement products was prepared. The synthetic C25-alcohols proved to be identical with persicaxanthin (= 12′-apoviolaxanthin-12′-ol) and perisicachromes (= 12′-apoauroxanthin-12′-ols) and the C27-alcohols analogously with sinensiaxanthin and sinensiachromes. A correlation between the sign of the Cotton effects in the CD spectra of 5,6-and 5,8-epoxides and their configuration at C(6) and C(8), respectively, was established.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19880710817
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  • 10
    Electronic Resource
    Electronic Resource
    Epoxidierung von Cucurbitaxanthin A: Herstellung von Cucurbitaxanthin B und seines 5′,6′-Epimeren (1993)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 76 (1993), S. 952-956 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Epoxidation of Cucurbitaxanthin A: Preparation of Cucurbitaxanthin B and of Its 5′,6′-EpimerCucurbitaxanthin A (= (3S,5R,6R,3′S)-3,6-epoxy-5,6-dihydro-β,β-carotene-5,3′-diol; 1) isolated from red pepper (Capsicum annuum var. longum nigrum) was trimethylsiylated and then epoxidized with monoperphthalic acid. After deprotection and chromatographic separation, cucurbitaxanthin B (= (3S,5R,6R, 3′S,5′R,6′S)-3,6:5′,6′-diepoxy-5,6,5′,6′-tetrahydro-β,β-carotene-5,3′-diol; 2) and 5′,6′-diepicucurbitaxanthin B (= (3S,5R,6R, 3′S,5′S,6′R)-3,6:5′,6′-diepoxy-5,6,5′,6′-tetrahydro-β,β-carotene-5,3′-diol; 5) were obtained and carefully characterized. They show mirror-like CD spectra and, therefore, emphasize the importance of the torsion angle of C(6)-C(7) on the electronic interaction between the polyene chain and the chiral end group.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19930760217
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