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  • Organic Chemistry  (54)
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  • 21
    Electronic Resource
    Electronic Resource
    Edulon A, ein 2H-1-Oxapyrenderivat aus Plectranthus edulis (Labiatae) (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1969-1974 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Edulon A, a Derivative of 2H-1-Oxapyrene from Plectranthus edulis (LabiataeFrom the coloured leaf-glands of the above mentioned East-african labiate we have isolated Edulon A, A new, deeply coloured diterpenoid. Based mainly on spectroscopic arguments, we propose its structure to be (5a R, 1′ ζ)-10-(2′-acetoxy-1′-methylethyl)-6, 7, 9-trihydroxy-3, 5a-dimethyl-4, 5, 5a, 8-tetrahydro-2H,-l-oxapyrene-2, 8-dione (1a). The compound may be regarded as a 4, 5-seco-abietane derivative that has formed new bonds (between C(18 or 19)—COOH and C(12)—OH), and between C(3) and C (11)) by lactonisation and condensation, respectively.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610604
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  • 22
    Electronic Resource
    Electronic Resource
    Diterpenoide Drüsenfarbstoffe aus Labiaten: 22 neue Coleone und Royleanone aus Plectranthus lanuginosus (1982)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 2136-2163 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Leaf-gland Pigments from Labiatae: 22 Novel Diterpenoids (Coleons and Royleanones) from Plectranthus lanuginosusWe report the isolation and structure elucidation of 22 novel diterpenoids (named lanugones A, B, C, D, E, F, G, H, I, J, K, K′, L, M, N, O, P, Q, R, S and (155)-coleon C (28) and (155)-coleon D (29)) from the leaf-glands of the above-mentioned plant (see Table 1). Structurally they belong to the subgroups of royleanones and coleons with the following structural characteristics: 8-hydroxy-1-methyl-spi-ro[2,5]oct-5-ene-4,7-diones, p-quinomethanes, extended (vinylogous) quinones, di-osphenols and diketones. Compounds 28 and 29 are (15S)-epimers of the already known coleon C and coleon D (with (15 R)-configuration), respectively. Furthermore, the already known 6,7-didehydroroyleanone (1) has been isolated in small amount.The present investigation has uncovered the broadest range of diverse chromo-phoric systems and oxydation levels so far found amongst diterpenoids in a single plant species. Most important for an understanding of the metabolic fate of an iso-propyl group is the full range found with the following metabolic stages: isopropyl-→ hydroxyisopropyl → dihydrofuran and spirocyclopropane → allyl- and 2-hydroxypropyl groups.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19820650721
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  • 23
    Electronic Resource
    Electronic Resource
    Diterpenoide Chinomethane, vinyloge Chinone und ein Phyllocladan-Derivat aus Plectranthus purpuratus HARV. (Labiatae) (1982)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 2189-2197 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diterpenoids from Leaf Glands of Plectranthus purpuratus: p-Quinomethanes, Extended Quinones, p-Acylcatechols and a Novel Phyllocladanon DerivativeFrom the complex mixture of terpenoids from the title plant, the following novel diterpenoids have been isolated: 11-hydroxy-19-(3-methyl-2-butenoyloxy)- and 11-hydroxy-19-(3-methylbutanoyloxy)-5,7,9 (11), 13-abietatetraen-12-one (1a/1b), 11-hydroxy-19-(3-methyl-2-butenoyloxy)- and 11-hydroxy-19-(3-methylbutanoyl-oxy)-7,9(11), 13-abietatrien-6,12-dione (2a/2b), 6α, 11-dihydroxy-19-(3-methyl-2-butenoyloxy)- and 6α, 11 -dihydroxy-19-(3-methylbutanoyloxy)-7,9 (11), 13-abieta-trien-12-one (3a/3b), 11,12-dihydroxy-19-(3-methyl-2-butenoyloxy)- and 11,12-di-hydroxy-19-(3-methylbutanoyloxy)-8,11,13-abietatrien-7-one (4a/4b), and (16R)-17,19-diacetoxy-16-hydroxy-13β-kauran-3-one (=(16R)-17,19-diacetoxy-16-hydro-xyphyllocladan-3-one; 10). Compounds 2 and 3 are derivates of taxodione and taxodone, respectively, 4 is a derivative of cryptojaponol. The structure of 10 is Wised on a single-crystal-X-ray analysis and CD. data.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19820650724
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  • 24
    Electronic Resource
    Electronic Resource
    1,6-Eliminationsreaktionen an Spirocoleonon; Charakterisierung der ersten Spiro[(methylcyclopropan)-phenanthren]-1,3-dion-Derivate (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 209-215 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of the First Spiro[(methylcyclopropan)-phenanthrene]-1,3-dione Derivatives by 1,6-Elimination Reactions of SpirocoleonsSpirocoleons, e.g. coleon J (1), on treatment with 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) in aprotic solvents, undergo enolization followed by a rapid 1,6-elimination with formation of the hitherto unknown 2-methyl-spiro[cyclopropane-1,2′(1′H)-phenanthrene]-1′,3′(4′bH)-dione system, e.g. 3. In protic solvents, base-catalyzed solvolysis of the spirocyclopropane predominates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670126
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  • 25
    Electronic Resource
    Electronic Resource
    8α,9α-Epoxy-7-oxoroyleanon, ein Diterpen-Epoxychinon aus einer abessinischen Plectranthus-Art (Labiatae) (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1116-1120 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 8α,9α-Epoxy-7-oxoroleyanone, a Diterpenoid Epoxyquinone from an Abyssinian Plectranthus Species (Labiatae)Reexamination of the title plant, in additon to the previously identified abietanoid hydroxy-1,4-benzoquinones 1a, 1b, 1c, 1e, 1f, 1g, and 1h, yielded the known 7α-acetoxyroleanone ( = 7-O-acetylhorminone; 1d) and the novel 8α, 9α-epoxy-7-oxoroyleanone (2a). Spectroscopic methods, partial synthesis by epoxidation of 7-oxoroyleanone (1h), and chiroptical correlation establish the structure 2a. Royleanone 2a is the first diterpenoid epoxyquinone isolated so far. Moreover, a detailed 13C-NMR analysis of the royleanones 1b, 1c, 1e, 1g, and 1h lead to the complete assignment of their spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670425
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  • 26
    Electronic Resource
    Electronic Resource
    Synthesen von Dibenzo[b,e][1,4]dioxin-2,3-chinonen, einschliesslich der Ecklonochinone A und B sowie der Isoecklonochinone A und B (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 860-881 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses of Dibenzo[b,e][1,4]dioxin-2,3-quinones Including the Ecklonoquinones A and B and the Isoecklonoquinones A and BOxidation of monomesyloxy-substituted pyrocatechols with MnO2 in toluene using phase-transfer conditions leads in high yield to monomesyloxy-substituted dibenzo[b,e][1,4]dioxin-2,3-quinones with loss of one mesyloxy group. In this way, ecklonoquinone A (2), ecklonoquinone B (3), isoecklonoquinone A (43), and isoecklonoquinone B (44) were prepared. Their structures are based on X-ray analyses of ecklonoquinone-A leucoacetate (45) and the mesyloxy-substituted quinone 20. The reddish-violet dibenzodioxin-diquinone 49 was prepared from an intermediate of the iso-series. The parent compound 1 has been synthesized in yields better than 50% from pyrocatechol and methyl 2,5-dioxo-2,5-dihydrobenzoate as oxidant and 2-methoxypyridin as catalyst. To rationalize the specific effect on the dimerisation step of the mesyloxy group, the intermediacy of 1,4-quinone monoacetals is proposed. This also applies to a proposed biogenetic scheme.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680407
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  • 27
    Electronic Resource
    Electronic Resource
    Drüsefarbstoffe aus Labiaten: Identifizierung von 17 Abietanoiden aus Plectranthus sanguineus BRITTEN (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 975-983 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pigments from Leaf-Glands from Labiatae: 17 Quinonoid Abietanoids from Plectranthus sanguineus BRITTENFrom the glandular trichomes of the title plant from Nyasaland, Malawi, 17 abietanoid quinones and hydroquinones were isolated and identified, the most interesting amongst them being the novel tricyclic, sevenmembered anhydride 8. A detailed HPLC separation of the compounds is presented.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700407
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  • 28
    Electronic Resource
    Electronic Resource
    Struktur und Partialsynthese von dimerem Coleon F (1988)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 71 (1988), S. 1638-1641 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structure and Partial Synthesis of Dimeric Coleon FColeon F (1a), on standing in solution, slowly dimerizes to the labile C(7)-epimeric spiro-dihydrofuranes 2a/2b whose structures were elucidated by spectroscopic methods. Oxydative addition of 1a to another molecule of 1a in the presence of Fétizon's reagent rapidly yields 2a/2b, thus confirming their structures as (4bS,9RS,10′aS)4,4a,10′,10′a-tetrahydro-1′,6-dihydroxy-1,2,4a,7′,8′,10′a-hexamethyl-3′,7-bis(2-propenyl)-spiro[3H,9H-phenanthren-9,5′-5′H-phenanthro[1,10-bc]furan]-2,3,5,8,9′-pentone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19880710708
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  • 29
    Electronic Resource
    Electronic Resource
    Drüsenfarbstoffe aus Labiaten: Strukturen von 16 Diterpenen (Coleone und Royleanone) aus Coleus coerulescensGÜRKE (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 871-884 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Leaf-gland pigments from labiatae: structures of 16 diterpenoids (coleons and royleanones) from Coleus coerulescens GÜRKEThe Abyssinian labiate Coleus coerulescens has been investigated for its leaf-gland pigments. From the very complex mixture of abietanoic diterpenoids the following pure constituents were isolated and their structures established: (1)Diosphenols: coleon C (1a), 16-O-acetyl-coleon C (1b), coleon W (1f);(2)A/B-trans-6, 7-diketones: coleon D (2b), 16-O-acetyl-coleon D (2c), coleon V (2a);(3)Spiro-coleons: 7,12-bis(O-desacetyl)-coleon N(3a), 12-O-desacetyl-coleon N (3b), coleon O (4), 6,12-bis (O-desacetyl)-coleon R (5a), 12-O-desacetyl-coleon R (5b), 3-O-desacetyl-3-O-formyl-coleon Y (5g);(4)Royleanones: The abeo-compounds 6a, 6b, and 7.Main compounds are 3b, 5e and 5g. This is the first record of a co-occurrence of diosphenols, 6,7-dioxo-coleons, spiro-coleons and royleanones. Preliminary experiments show that solvolytic opening of the cyclopropane-ring followed by tautomerisation, oxidation to hydroxy-p-benzoquinones or elimination to quinomethanes and subsequent nucleophilic attack of the solvent leads to compounds with a 2′-substituted propyl group at C(13), thus supporting the biosynthesis of the unusual coleon E side chain.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610235
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  • 30
    Electronic Resource
    Electronic Resource
    1H- und 13C-NMR.-spektroskopische Untersuchungen an den vier diastereomeren (±)-Dihydropalustraminsäure-methylestern; Strukturkorrelation mit (-)-Dihydropalustraminsäure-methylester sowie mit dem Alkaloid Palustrin. 14. Mitteilung über Schachtelhalmalkaloide13. Mitt., s. [1a] (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 899-904 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H-and13C-NMR. spectra of methyl esters of the diastereomeric (±)-dihydropalustramic acids; structural correlation of (-)-dihydropalustramic acid with the alkaloid palustrinUnambiguous assignment of cis-trans configuration at the piperidine ring of the four diastereomeric methyl esters of the (±)-dihydropalustramic acids is based on the interpretation of 1H- and 13C-NMR. data. (-)-Dihydropalustramic acid, the important degradation product of the alkaloid palustrin is shown to be threo-cis-[6-(1-hydroxypropyl)-2-piperidyl]acetic acid. The same conclusion holds for palustrin and dihydropalustrin. Therefore, palustrin is threo-cis-17-(1-hydroxy-propyl)-1,5,10-triazabicyclo[11.4.0]heptadec-15-en-11-one.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610237
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