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  • 1
    Electronic Resource
    Electronic Resource
    Enantioselective Syntheses and Absolute Configurations of Viridiene and Aucantene, Two Constitutents of Algae Pheromone BouquetsDedicated to Prof. Dr. F. Lingens on the occasion of his 60th birthday (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 2062-2073 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Viridiene ((+)-6; (+)-(3R,4S)-3-((1Z)-1,3-butadienyl)-4-vinylcyclopentene) and aucantene ((+)-18; (+)-(4R,5R)-4-((1E)-1-propenyl)-5-vinylcyclohexene) are constituents of the pheromone bouquets of several brown algae species. Key synthons to the title compounds are optically active γ-lactones with known or experimentally determined absolute configurations. Horse liver alcohol dehydrogenase, which catalyses the oxidation of meso- and racemic non-meso diols to chiral lactones, and pig-liver esterase, which catalyzes the saponification of meso-diesters to chiral half-esters, were utilized for the asymmetric synthesis of such precursors. The racemic non-meso diol rac-1 is converted to the two stereoisomeric γ-lactones (+)-2 and (+)-3 which are readily separated. meso-Diol 12 is oxidized to the chiral γ-lactone (-)-11. Its enantiomer (+)-11 is obtained by enantioselective saponification of the meso-diester 9 with pig-liver esterase. Appropriately designed syntheses lead from these chiral intermediates to both enantiomers (+)- and (-)-6 of viridiene and (+)- and (-)-18 of aucantene. In addition, kinetically controlled reduction of the racemic aldehydes rac-5a and rac-15 with horse liver alcohol dehydrogenase offers a convenient alternative to the enantioselective preparation of the enantiomers of the two hydrocarbons 6 and 18. Chromatography of 6 on triacetylated cellulose as a stationary chiral phase confirms the enantiospecificity of the synthetic routes designed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680731
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  • 2
    Electronic Resource
    Electronic Resource
    Die absolute Konfiguration der Iridale und Cycloiridale unterschiedlicher HerkunftDr. G. Ohloff zum 65. Geburtstag mit den besten Wünschen gewidmet (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 287-294 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Absolute Configuration of Iridals and Cycloiridals of Different OriginNatural irones are known to occur in enantiomeric forms within Iris oils of different origin. They are formed by oxidative degradation of the cycloiridals (C31-triterpenoids) found in rhizomes of various Iris species. The absolute configuration of iridals from different varieties is determined by ozonolysis of the triterpenoids and comparison of their degradation products with authentic samples of known configuration. It is shown that the initial cyclization of squalene resulting in the formation of a monocyclic seco-ring-A iridal has the same stereo-chemical course throughout all Iris species studied. The subsequent cyclization of the homofarnesyl side chain of the iridals, however, produces cycloiridals with enantiomeric irone moieties within different subspecies of the sword lilies.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720213
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  • 3
    Electronic Resource
    Electronic Resource
    Studies on the Biosynthesis of Iridals and Cycloiridals (1988)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 71 (1988), S. 1331-1338 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The incorporation of [2-14C]acetate, [2-14C]mevalonate, and [3H]squalene proved the squalenoid nature of the iridals, novel triterpenoids from rhizomes of swordlilies. Methionine is readily incorporated into cycloiridalls of Iris pallida dalmatica, thus indicating that the methylation of iridals via S-adenosyl-L-methionine leads to the formation of the irone moiety of the bicyclic compounds. The 3H/14C ratio of the transferred labelled methyl group remained unchanged. Therefore, the methylation/cyclization of the terpenoid side chain of iridals must proceed by a concerted mechanism without formation of a cyclopropanoid intermediate.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19880710544
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  • 4
    Electronic Resource
    Electronic Resource
    Stereoselektive Synthese von 2′-substituierten 2-Vinylcyclo-propancarbonsäuren und -carbaldehyden; Darstellung von Homologen des Braunalgen-Lockstoffs Ectocarpen (1979)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1979 (1979), S. 986-996 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereoselective Synthesis of 2′-Substituted 2-Vinylcyclopropanecarboxylic Acids and -carbaldehydes; Preparation of Homologues of the Seaweed Pheromone EctocarpeneVersatile and sterically unequivocal syntheses are described for derivatives of 2-(1-alkenyl)cyclopropanecarboxylic acid and -carbaldehyde as intermediates in the preparation of 1,2-bis(1-alkenyl)cyclopropanes and substituted 1,4-cycloheptadienes. Starting from ethyl trans-2-formyl-cyclopropanecarboxylate (13) they lead to 1,2-cyclopropanedicarbaldehyde (18), protected on one side, which may undergo stepwise olefinations. The advantages of using these bifunctional cyclopropane compounds are that few synthetic steps are involved, the products are easily separated, and good yields are obtained. By this method, we have prepared inter alia the natural products dictyopterenes 1-3 with cyclopropane structure and ectocarpene (4) with 1,4-cycloheptadiene structure. The possibility of separating them from their diastereomers are described.
    Notes: Variationsfähige und sterisch eindeutige Synthesen von Derivaten von 2-(1-Alkenyl)cyclopropan-carbonsäure und -carbaldehyd als Zwischenstufen für die Darstellung von 1,2-Bis(1-alkenyl)-cyclopropanen und substituierten 1,4-Cycloheptadienen wurden ausgearbeitet. Sie gehen aus von trans-2-Formylcyclopropancarbonsäure-ethylester (13) und führen über einseitig geschützten 1,2-cyclopropandicarbaldehyd (18), der stufenweise olefiniert werden kann. Die Vorteile der Verwendung derartiger bifunktioneller Cyclopropanderivate sind die geringe Zahl von Syntheseschritten bei guten Ausbeuten sowie die unproblematische Trennung der Zwischenprodukte. Unter anderem werden alternative Wege zu den Cyclopropan- und 1,4-Cycloheptadien-Naturstoffen, wie den Dictyopterenen 1-3 und Ectocarpen (4) beschrieben und Möglichkeiten zur Trennung von deren Diastereomeren angegeben.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197919790709
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  • 5
    Electronic Resource
    Electronic Resource
    Synthese und spektroskopische Eigenschaften pflanzlicher all-cis-Polyolefine (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 92-98 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Spectroscopic Properties of Plant all-cis-PolyolefinsPlant all-cis-polyolefins of the type 1a-c have been prepared by oxidative decarboxylation of the corresponding fatty acids or by synthesis starting with 1-chloro-4,7,10-tridecatriyne (5a) or 1-chloro-4,7-tridecadiyne (5b). Their spectroscopic properties are described.
    Notes: Pflanzliche all-cis-Polyolefine vom Typ 1a-c werden durch oxidative Decarboxylierung der entsprechenden Fettsäuren bzw. aus 1-Chlor-4,7,10-tridecatriin (5a) und 1-Chlor-4,7-tridecadiin (5b) synthetisiert. Ihre spektroskopischen Eigenschaften werden beschrieben.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198119810115
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  • 6
    Electronic Resource
    Electronic Resource
    Darstellung von 3-(3-Indolyl)milchsäuren. _Eine neue Synthese von rac-Blepharismon, dem niedermolekularen Konjugationsgamon von Blepharisma japonicum (1983)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 226-230 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation of 3-(3-Indolyl)lactic Acids,- A new synthesis of rac-Blepharismone, the Low Molecular Conjugation Gamone of Blepharisma japonicumA versatile and effective synthesis of rac-3-(3-indolyl)lactic acid derivatives offers - among other natural products of interest - good access to rac-blepharismone (7), the racemate of the conjugation inducing gamone of the ciliate Blepharisma japonicum [formerly B. intermedium (Bhandary)], and to analogues of this compund. Indoles 1, unsubstituted in position 3, are alkylated with methyl rac-2,3-epoxypropanoate (2) to give the methyl rac-3-(3-indolyl)lactates 3 which are easily hydrolyzed to yield the corresponding acids 4. rac-3-(5-Hydroxy-3-indolyl)lactic acid (5), the possible biogenetic precursor of blepharismone (7), is obtained from 5-benzyloxyindole (1b). Ozonolysis of the pyrrole system and hydrogenolysis lead to (formamido)phenone derivatives 6. rac-Blephraismone (7) has been produced in this way with 11% overall yield starting from 1b.
    Notes: Eine leistungsfähige und variationsfähige Synthese von 3-(3-Indolyl)milchsäure-Derivaten bietet, unter anderem, einen guten Zugang zu rac-Blepharismon (7) und Analoga dieser Verbindung. Blepharismon induziert bei dem Ciliaten Blepharisma japonicum [früher B. Intermedium (Bhandary)] die zum Kernaustausch führende Konjugation. In Position 3 unsubstituierte Indole 1 werden mit rac-2,3-Epoxypropionsäure-methylester (2) zu den rac-3(3-Indolyl)milchsäure-methylestern alkyliert, die sich leicht zu den entsprechenden Säuren 4 verseifen lassen. Mit 5-Benzyloxyindol (1b) erhält man rac3-(5-Hydroxy-3-indolyl)milchsäure (5), eine mögliche Vorstufe in der Blepharismon-Biosynthese. Spaltung des Pyrrolsystems durch Ozonolyse und Hydrogenolyse liefert die (Formamido)phenon-Derivate 6. Mit 1b erhält man auf diesem Weg rac-Blepharismon (7) in 11proz. Gesamtausbeute.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198319830207
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  • 7
    Electronic Resource
    Electronic Resource
    Synthese isomerer 1,3,5,8-Undecatetraene (1982)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1982 (1982), S. 579-584 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Isomeric 1,3,5,8-Undecatetraenes(3E,5Z,8Z)-1,3,5,8-Undecatetraene (1a) is the smelling principle of the gametes of the brown alga Spermatochnus paradoxus. The synthesis of the isomeric 1,3,5,8-undecatetraenes 1a-c and their spectral properties are described.
    Notes: (3E,5Z,8Z)-1,3,5,8-Undecatetraen (1a) ist der Geruchsstoff von Gameten der Braunalge Spermatochnus paradoxus. Die Synthese der isomeren 1,3,5,8-Undecatetraene 1a-c und ihre spektroskopischen Eigenschaften werden beschrieben.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198219820318
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  • 8
    Electronic Resource
    Electronic Resource
    Synthese und biologische Aktivitäten von (+)- und (-)-Multifiden (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2266-2271 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Biological Activities of (+)- and (-)-Multifidene(+)-Multifiden 1, the specific messenger for androgametes of the phaeophyte Cutleria multifida, is about 100 times more active than the (-)-enantiomer of 1. Both enantiomers are conveniently prepared by chromatographic resolution of the diastereomeric carbamates 5a/b or 5c/d which give easy access to (+)- and (-)-1 by only a few subsequent steps.
    Notes: (+)-Multifiden 1, der spezifische Signalstoff für Androgameten der Braunalge Cutleria multifida, ist etwa 100fach wirksamer als das (-)-Enantiomere von 1. Die optische Reindarstellung beider Antipoden gelingt durch chromatographische Trennung der diastereomeren Carbamate 5a/b und 5c/d, aus denen (+)-und (-)-1 in nur wenigen Schritten zugänglich sind.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198119811214
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  • 9
    Electronic Resource
    Electronic Resource
    Isolation and structure determination of new spiro-bicyclic triterpenoids from Iris pseudacorus (1990)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 563-567 
    Details
    ISSN: 0170-2041
    Keywords: Iridals ; Iris pseudacorus L. ; Spiroiridals ; Triterpenoids ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four novel types of iridals (compounds 8, 9, 15 and 16) have been isolated from lipid extracts of roots and rhizomes of I. pseudacorus and their structures (except the stereochemistry of 15 at C-13 and C-26 and of 16 at C-13) elucidated by oxidative degradation combined with spectroscopic methods. They are up to now unknown triterpenoids with unusual spiro-bicyclic structures. The possible biogenesis of these compounds is descussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1990199001105
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  • 10
    Electronic Resource
    Electronic Resource
    Ein Beitrag zur Darstellung von Alkyl-cycloheptadienen: Synthese von Ectocarpen und seinen Homologen (1973)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1973 (1973), S. 1252-1262 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A Contribution to the Preparation of Alkylcycloheptadienes: Synthesis of Ectocarpen and its HomologuesEctocarpen (1), the sex attractant for the androgametes of the marine brown alga Ectocarpus siliculosus is (S)-all-cis-1-(1-butenyl)-2,5-cycloheptadiene. It is synthesized by Cope rearrangement of cis- and trans-2-(cis-1,3-hexadienyl)-1-vinylcyclopropane (2). The preparation of several 2,5-cycloheptadiene derivatives substituted at C-1 by aliphatic residues is described. Starting with 2-vinylcyclopropanal, the unsaturated side chain is introduced by Wittig reaction and the resulting divinylcyclopropane system pyrolyzed to the appropriate 2,5-cycloheptadiene system. In the cis/trans isomers, this isomerization occurs readily below room temperature. Owing to steric hindrance, the cis/cis compounds require higher temperatures. The highest temperature is necessary for the rearrangement of the trans cis- and trans/trans-divinylcyclopropanes presumably because prior transformation to the cis-divinylcyclopropane takes place. The divinylcyclopropane system is more labile in derivatives with a more highly unsaturated side chain.
    Notes: Ectocarpen (1), der Androgameten-Lockstoff der Braunalge Ectocarpus siliculosus, ist (S)-all-cis-1-(1-Butenyl)-2,5-cycloheptadien. Es läßt sich durch Cope-Umlagerung aus cis- und trans-2-(cis-1,3-Hexadienyl)-1-vinylcyclopropan (2) darstellen. Die Synthese einiger an C-1 aliphatisch substituierter 2,5-Cycloheptadien-Derivate aus 2-Vinylcyclopropylaldehyd durch Wittig-Reaktion und anschließende Valenzisomerisierung wird beschrieben. Die cis/trans- Isomeren der Divinylcyclopropan-Zwischenstufe gehen die Umlagerung zum Cycloheptadien-System bereits unterhalb Raumtemperatur ein; die cis/cis-Isomeren benötigen wegen sterischer Hinderung höhere Temperaturen. Die trans/cis- und trans/trans-Isomeren erfordern die höchsten Temperaturen, da vermutlich eine Umwandlung zur cis-Verbindung vorgelagert ist. Eine höher ungesättigte Seitenkette labilisiert die Divinylcyclopropan-Verbindungen.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197319730804
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