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  • 1
    Electronic Resource
    Electronic Resource
    Biphenyltetrols and Dibenzofuranones from Oxidative Coupling of Resorcinols with 4-Alkylpyrocatechols: New Ciues to the Mechanism of Insect Cuticle Sclerotization (1991)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 74 (1991), S. 1205-1212 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidation of 4-alkylpyrocatechols 2 by means of an insect diphenoloxidase (laccase) or K3 [Fe(CN)6] yields, in the presence of resorcinols 1 (R2 = H), complex mixtures of products from which biphenyltetrols 3 (R3 = H) and dibenzofuranones 5 and 6 were isolated. It is suggested that similar homo-coupling products are formed from pyrocatechols 2b and 2c in insects during cuticle sclerotization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19910740607
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and Enzyme-Inhibition Studies of Phenylsemicarbazones derived from D-glucono-1,5-lactone and 2-acetamido-2-deoxy-D-glucono-1,5-lactone (1992)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 75 (1992), S. 323-334 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The carbohydrate-derived lactone phenylsemicarbazones 3 and 4 were prepared from 5 and 8 (Scheme). Treatment with 4-phenylsemicarbazide gave 6 and 7 (77:23) and 9 and 19 (76:24), respectively. Oxidation of 6 and 9 by CrO3-pyridine to 11 and 13, followed by deprotection, yeilded 3 and 4. The structure of 3 was established by X-ray analysis. Enzyme-inhibition studies using revealed that 3 is a competitive inhibitor with Ki = 23 μm. The activity of 4 was examined using N-acetylglucosaminidase from bovine kidney, Aspergillus niger, and Artemia salina. compound 4 was found to be a competitive inhibitor of all three enzymes with Ki values of 0.13, 6.0, and 0.71 μm and KM/Ki values of 6910, 45, and 465, respectively.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19920750129
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  • 3
    Electronic Resource
    Electronic Resource
    Einbauversuche mit (3H und 14C)-doppelmarkiertem Farnesol in Cantharidin. 5. Mitteilung zur Biosynthese des Cantharidins4. Mitt.: siehe [1]. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 1262-1272 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Incorporation experiments with (3H and 14C) doubly labelled farnesols into cantharidinAfter injection of 11′, 12-[3H]-7-[14C]-farnesol or 11′, 12-[3H]-5,6-[14C]-farnesol, the 3H-label is located specifically in the C(9)-methyl-group of cantharidin, whereas the 14C-labelling pattern follows an incorporation via acetic acid (Scheme 4). C-Atoms 5, 6 and 7 from the middle part of the farnesol molecule are utilized for cantharidin biosynthesis to an extent that is about 2.1-11% of the incorporation rate of the methyl groups C(11′) and C(12), depending on the position of the 14C-label in farnesol. These results confirm our earlier hypothesis [1] that the C10-molecule cantharidin is biosynthesized from the C15-precursor farnesol which is cleaved between C(1)-C(2), C(4)-C(5), and C(7)-C(8). The synthesis of 7-[14C]-farnesol and of 5,6-[14C]-farnesol is described.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19770600416
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  • 4
    Electronic Resource
    Electronic Resource
    Identifizierung von Farnesol als Zwischenstufe in der Biosynthese des Cantharidins aus Mevalonsäurelacton. 7.Mitteilung zur Biosynthese des Cantharidins6.Mitt.: siehe [1]. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 2756-2762 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Identification of farnesol as an intermediate in the biosynthesis of cantharidin from mevalonolactoneSimultaneous injection of 2-[14C]-mevalonolactone (2-[14C]-1) and (E,E)-11′,12-[3H]-farnesol (11′,12-[3H]-2) into Lytta vesicatoria L. (Coleoptera, Meloidae) yields doubly labelled cantharidin (3). The remainder of the precursor farnesol, re-isolated from the insects after the incubation period, has incorporated 14C-radioactivity. The labelling pattern in this farnesol, as determined by two independent degradative reaction sequences, is in agreement with the isoprene rule. Since specific incorporation of farnesol (2) into cantharidin (3), and of mevalonolactone (1) into both, farnesol (2) and cantharidin (3) is observed, the sesquiterpene alcohol 2 acts as an intermediate in the biosynthesis of the C10-compound 3 (Scheme 1).
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19770600827
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  • 5
    Electronic Resource
    Electronic Resource
    Reaktionen von o-Chinonen mit Aminen und Proteinen. 4. Mitteilung3. Mitt.: s.[1].. 7a-Methyl-5,6-dioxo-5,6,7,7a-tetrahydroindol-Derivate aus 4-Methylbrenzcatechin und Enaminen (1982)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 1279-1284 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of o-Quinones with Amines and Proteins. 7a-Methyl-5,6,7,7a-tetrahysroindole Derivatives from 4-Methylcatechol and EnaminesMethyl l-[2′-(methoxycarbonyl)ethyl]-7a-methyl-5,6-dioxo-5.6.7,7a-tetrahydro-indole-3-carboxylate (1) was isolated after the oxidation of 4-methylcatechol with silver (1) oxide in the presence of b̃-alanine methyl ester in glacial acetic acid. The formation of 1 requires in situ dehydrogenation of the b̃-aminocarboxylate and addition of the resulting enamine to 4-methyl-1,2-benzoquinone. Reaction of ethyl 3-(phenylamino)crotonate with 4-methyl-1,2-benzoquinone afforded ethyl 2,7a-dimethyl-5,6-dioxo-1-phenyl-5,6,7,7a-tetrahydroindole-3-carboxylate (6). Despite the fact that the yields are low, the addition of enamines to o-quinones represents an interesting novel extension of the Nenitzescu-reaction which is well known in the p-quinone series. Compound 1 may be considered as a novel model for the crosslinking of proteins by o-quinones. Formation of 1 was, however, not observed under physiological conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19820650418
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  • 6
    Electronic Resource
    Electronic Resource
    Einbauversuche mit Geraniol und Farnesol in Cantharidin. 4. Mitteilung zur Biosynthese des Cantharidins3. Mitt. siehe [1].Korrespondenzautor: W.-D. Woggon. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 844-866 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the incorporation of geraniol and farnesol into cantharidinEarlier investigations [1] have shown that cantharidin (1) is biosynthesized by the male Lytta vesicatoria L. (Meloidae, Coleoptera) from the common terpenoid precursors mevalonate and farnesol (3). To prove if geraniol (2) is incorporated via farnesol (3) into cantharidin (1) the following geraniols have been synthesized and injected into either larvae or male adult Lytta vesicatoria, partly in a mixture with synthetic 11′, 12-[3H]-farnesol as an internal standard: 2-[14C]-, 7-[14C]-, 7′, 8-[14C]-, 7′, 8-[3H]-geraniol. Unexpectedly, geraniol (2) was not specifically incorporated into cantharidin (1) perhaps due to its higher toxicity or its faster degradation relative to the other precursors before incorporation. The incorporation of U-[14C]-leucine, U-[14C]-isoleucine and 1-[14C]-glucose into cantharidin (1) via their metabolites is evident by degradation studies, whereas 1-[14C]- and 2-[14C]-glycine do not serve as precursors for cantharidin (1).
    Additional Material: 11 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19770600314
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  • 7
    Electronic Resource
    Electronic Resource
    Experimente zum kompetitiven Einbau der Stereoisomeren des Farnesols in Cantharidin. 6. Mitteilung zur Biosynthese des Cantharidins5. Mitt.: siehe [1]. (1977)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 60 (1977), S. 2288-2294 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Experiments on the competitive incorporation of farnesol-stereoisomers into cantharidinFarnesol (2) has been demonstrated to be an efficient precursor for cantharidin (1), into which it is transformed by elimination of C(1), C(5), C(6), C(7) and C(7′) [1]. The following incorporation experiments with doubly labelled (3H and 14C) stereoisomers of farnesol present strong evidence that (E,E)- farnesol ((E,E)-2) in fact is the precursor for cantharidin, whereas (2E, 6Z)-2 and (Z,Z)-2 are not utilized for the biosynthesis of cantharidin. A possible mechanism for the incorporation of (2Z,6E)-farnesol ((2Z,6E)-2) to an extent of 56,8% relative to (E,E)-2 is discussed.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19770600719
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  • 8
    Electronic Resource
    Electronic Resource
    Über die absolute Konfiguration der Cantharsäure und des PalasoninsII. Mitt. zur Biosynthese des Cantharidins; I. Mitt. siehe [1a]. (1974)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 57 (1974), S. 32-64 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The absolute configurations of (+)-cantharic acid, a chiral derivative of the achiral insect defensive substance cantharidin (1), and of palasonin, a lower homologue of 1 occurring in the plant Butea frondosa, were shown to be represented by formulas 2 and 3, respectively (scheme 1). These results were obtained by application of the Horeau method (table 1) on the (+)-cantharic acid derivatives (+)-5, (-)-7, and (-) 11 (scheme 2), and the palasonin derivatives (+)-29 and (+)-30 (scheme 4), as well as by comparison of the chiroptical properties (tables 2 and 3) of a number of derivatives, prepared from either cantharic acid or palasonin. - Attempts to incorporate various radioactively labelled precursors into palasonin (3), using young and adult plants, have been so far unsuccessful.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19740570106
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  • 9
    Electronic Resource
    Electronic Resource
    Biosynthesis of juvenile hormone in the cecropia moth. labelling pattern from 1-[14C]-propionate through degradation to single carbon atom derivativesPresented at the 169 ACS National Meeting, Philadelphia, April 6. II. 1975. (1975)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 58 (1975), S. 1037-1048 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the adult made cecropia moth, 1-[14C]-propionate is incorporated specifically into juvenile hormone I (1). By chemical degradation it was found that only C(7) and C(11) are labelled, each carbon atom bearing 50% of the radioactivity originally present in JH-I. It is concluded that propionate serves as a precursor of homomevalonate, which in turn is a precursor for JH-I. Application of 2-[14C]-propionate and 3-[14C]-propionate leads to extensive randomization of the label. Apparently propionate is metabolized such that C(2) and C(3) can be reused as smaller fragments-probably acetate-while C(1) is either highly diluted or removed from the propionate in a metabolically inactive form.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19750580407
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  • 10
    Electronic Resource
    Electronic Resource
    N-Acylcatecholamine und 3,4-Dihydro-6,7-isochinolindiole aus N-Acyl-3,4-dimethoxyphenethylaminen (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 1189-1193 
    Details
    ISSN: 0170-2041
    Keywords: Catecholamines ; Isoquinolinediols ; Bischler-Napieralski reaction ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: N-Acylcatecholamines and 3,4-Dihydro-6,7-isoquinolinediols from N-Acyl-3,4-dimethoxyphenethylaminesThe N-[2-(3,4-dimethoxyphenyl)ethyl]acetamides 2a and 2e are cleaved with boron tribromide to yield as expected the catechols 3a and 3e whereas, under the same conditions, mixtures of the catechols 3b, 3c, 3f, or 3g and 1-(haloalkyl)dihydroisoquinolines 4b, 4c, 4f, or 4g are formed from the corresponding halogenated acetamides 2b, 2c, 2f, and 2g, respectively. The trifluoracetamide 2d yields exclusively the cyclization product 4d. Since higher halogenated 1-(haloalkyl)-3,4-dihydroisoquinolines are formed in the Bischler-Napieralski reaction - if at all - under quite drastic conditions only, the use of boron tribromide provides a new entry into this series.
    Notes: Die N-[2-(3,4-Dimethoxyphenyl)ethyl]acetamide 2a und 2e liefern mit Bortribromid erwartungsgemäß die Catechole 3a bzw. 3e, während aus den halogenierten Acetamiden 2b, 2c, 2f und 2g Mischungen aus den korrespondierenden Catecholen 3b, 3c, 3f bzw. 3g und den 1-(Halogenalkyl)dihydroisochinolinen 4b, 4c, 4f, bzw. 4g entstehen. Das Trifluoracetamid 2d liefert ausschließlich das Dihydro-1-(trifluormethyl)isochinolin 4d. Da höher halogenierte 1-(Halogenalkyl)-3,4-dihydroisochinoline mit der Bischler-Napieralski-Reaktion - wenn überhaupt - nur unter drastischen Reaktionsbedingungen zugänglich sind, bietet die Verwendung von BBr3 eine neue Möglichkeit zur Herstellung dieser Verbindungen.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890290
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