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  • 1985-1989  (3,492)
  • Organic Chemistry  (3,492)
  • 101
    Electronic Resource
    Electronic Resource
    Neue Sulfobutyl-haltige Bis(dimethinmerocyanin)-Farbstoffe mit isolierten Chromophoren im Molekül und deren Aggregationsverhalten in wässeriger Lösung (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 638-647 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel Bis(dimethinemerocyanine) Dyes with Isolated Chromophores in the Molecule Containing the Sulfobutyl Group and their Aggregation Tendency in Aqueous SolutionThe bis(dimethinemerocyanine) dyes 7a-c with Chromophores separated by a polymethylene chain as ‘isolator’ are synthesized in good yield. Their aggregation tendency in organic solvents, organic solvents/H2O mixtures, and in H2O is investigated. In organic solvents, the dyes 7a-b show a splitted absorption band, due to interaction of the two Chromophores of the dye. In H2O, 7a exhibits an intense absorption band at 496 nm (∊ = 224 300 1·mol-1·cm-1) with a small width \documentclass{article}\pagestyle{empty}\begin{document}$ (\tilde v_{{\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 2}}\right.\kern-\nulldelimiterspace} \!\lower0.7ex\hbox{$2$}}} = 1000\;{\rm cm}^{ - 1}) $\end{document} and shoulders at 552 and 580 nm. In presence of starch, this absorption band shifts to 617 nm, probably due to J-aggregation. The dye 7b shows the same spectral behaviour as 7a. In contrast, 7c exhibits an absorption band without splitting in organic solvents; the interaction of the Chromophores has disappeared. In H2O and in H2O containing starch, 7c shows a wide absorption band, due to interaction of the Chromophores of the dye.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720403
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  • 102
    Electronic Resource
    Electronic Resource
    Thermal and Photochemical Reactions of 1,2-Annelated Barrelenes and Hydrobarrelenes in the presence of transition-metal carbonyls (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 648-652 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The [Co2(CO)8]-mediated retro-Diels-Alder reaction of the annelated barrelenes 1 afforded the 1H-indol-2(3H)-one derivatives 3 (Scheme 1), while the hydrobarrelene 4a, under the same conditions, was converted to the anilide 6 (Scheme 2); 4b remained unaffected. The direct irradiation of 1 led to the annelated cyclooctatetraenes 7 (Scheme 3). On irradiation in the presence of excess of [Fe(CO)5], 1a, 1b, and 4a gave the tricarbonyliron complexes 8, 9, and 11, respectively (Schemes 3 and 4); under these conditions, 4b was inert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720404
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  • 103
    Electronic Resource
    Electronic Resource
    Synthesis of (+)-(4S, 8R)hyphen;8hyphen;Epi- and (-)-(4R, 8S)-4-Epi-β-bisabolol (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 653-658 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The first total enantioselective synthesis of (+)-(4S, 8R)-8-epi-β-bisabolol(+)-1 and of (-)-(4R, 8S)-4-epi-β-bisabolol ((-))-1) is reported. The key step in the synthesis is the kinetic resolution of (±)-5 by means of the Sharpless epoxidation yielding (-)- and (+}-6, respectively. Reduction of the epoxides with LiAlH4 gave the diols (+)-and(-)-7 which were transformed into (+)- and (-)-8, respectively, via the corresponding mesylate. Reaction of these epoxides with the Grignard reagent derived from homoprenylbromide, assisted by Li2CuCl4, finished the synthesis of the target compounds 1 with high diastereo- and enantioselectivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720405
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  • 104
    Electronic Resource
    Electronic Resource
    Structure Determination of New Isomeric Naphtho[2,3-b]furan-4,9-diones from Tabebuia avellanedae by the selective-INEPT technique (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 659-667 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Beside the known naphthoquinones, dehydro-α-lapachone (17) and lapachol (20), four new naphtho[2,3-b]-furan-4,9-diones, i.e. the 2-acetyl-5-hydroxy. 2-acetyl-8-hydroxy. (-)-5-hydroxy-2-(1′-hydroxyethyl), and (±)-8-hydroxy-2-(1′-hydroxyethyl) derivatives 16, 15, 12, and 13, respectively, and the new compound benzo[b]furan-6-carboxaldehyde (8) have been isolated from a CHCl3 extract of the inner stem bark of Tabebuia avellanedae LORENTZ ex GRISEB., together with four known naphthofurandiones, a dihydroisocoumarin derivative, (-)-6-hydroxymellein, and five benzoic-acid and three benzaldehyde derivatives which have not been reported previously from this plant. Structure determination of the isomeric 5- and 8-hydroxynaphtho[2,3-b]furan-4,9-diones was carried out unambiguously by a combination of selective-INEPT experiments and X-ray crystallographic analysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720406
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  • 105
    Electronic Resource
    Electronic Resource
    New Triterpenoid N-Acetylglycosides with Molluscicidal Activity from Tetrapleura tetraptera TAUB (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 668-674 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Activity-guided fractionation of the MeOH extract of the fruits of Tetrapleura tetraptera TAUB. (Mimosaceae) afforded 4 saponins 1-4, which exhibited strong molluscicidal properties against the schistosomiasis-transmitting snails Biomphalaria glabrata. Chemical, enzymatic, and spectral methods (DCI-MS, 1H-NMR, 13C-NMR) showed that they were N-acetylglycosides of oleanolic acid and of echinocystic acid. Apart from saponin 1 (aridanin), previously isolated from this plant, glycosides 2-4 are new naturally occurring compounds.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720407
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  • 106
    Electronic Resource
    Electronic Resource
    A Simple and Efficient Method for the Preparation of Binaltrorphimine and Derivatives and determination of their K opioid antagonist selectivity (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 675-677 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bimorphinans 1 (binaltrorphimine), 3, and 7 have been prepared by treatment of the parent morphinan-6-ones naltrexone (5), naloxone (4), and dihydrocodeinone (6), respectively, with N-methylhydrazine sulfate in AcOH at room temperature. Compound 3 showed opioid antagonist potency and selectivity for K receptors which were somewhat lower in comparison to 1.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720408
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  • 107
    Electronic Resource
    Electronic Resource
    Synthèse d'une sonde biotinylée à bras clivable allongé pour l'isolement des récepteurs de l'angiotensine II (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 678-689 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of a Biotinylated Probe with an Extended Cleavable Arm for Angiotensin II Receptors PurificationWe have synthesized a new biotinylated probe for angiotensin II receptors studies: biotinyl-NH(CH2)2—SS—(CH2)2—CO-Gly-∊ Ahx-[Ala1, Phe(4N3)8]angiotensin II (5). This molecule can be photoactivated through an arylazido group. 1H-NMR studies suggest that it adopts an extended conformation which should allow a simultaneous recognition of both streptavidin and hormone receptor. It has a good affinity for receptors (Kd = 1 nM) and hence is a promising tool in their detection (autoradiography, gold-, ferritin-, enzyme-, or fluorescent streptavidin derivatives) and separation (cell sorting, affinity chromatography). It can be monoiodinated (°6) at its tyrosine residue without a significant loss of affinity. Its extended cleavable arm allows an easy recovery of the ‘probe-receptor’ complex from streptavidin. An HPLC monitoring of the synthesis is described, particularly of the segment coupling 1 + 2 in presence of (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP). This method can be used as well for synthesis of the D-Phe8 derivative that has antagonist properties.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720409
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  • 108
    Electronic Resource
    Electronic Resource
    Cyclization Studies with N-Mannich bases of 2-substituted indoles (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 93-100 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the indoles 7, 15, 16 with a 3-methoxyphenyl group, attached via an α-side chain of 1,2,or 3 CH2 units, is reported. These compounds, after appropriate protection at C(3), were transformed into the N-[(dimethylamino)methyl]indoles 22, 23, and 24, respectively. When treated with AcCl, these N-Mannich bases gave, in two cases, stable N-(chloromethyl)indoles 25 and 26. In the presence of SnCl4, ring closure occurred via electrophilic attack of 1-methylideneindolium ions on the methoxyphenyl group. Formation of seven-membered rings (→ 27, 28) and eight-membered rings (→ 29) was found to be a favorable process. Cyclization to six-membered rings did not occur within this series.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720112
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  • 109
    Electronic Resource
    Electronic Resource
    Template-Dependent Incorporation of Spin-Labeled Thymidine Analogs into Viral DNA (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 110-116 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of novel pppUd analogs substituted at position C(5) with tethered nitroxide radicals is reported. It is shown that these analogs can serve as good substrates for E. coli DNA polymerase (Pol I) and T-4 DNA polymerase using lambda-phage DNA as template. The template-dependent incorporation of the substrates was established by radio-labeling and ESR experiments.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720114
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  • 110
    Electronic Resource
    Electronic Resource
    Asymmetric Diels-Alder reactions: X-Ray crystal-structure analysis of [N-((E)-But-2-enoyl)bornane-10,2-sultam]tetrachlorotitaniumPresented (WO) at the Annual Congress of the Royal Society of Chemistry, Canterbury, April, 1988. (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 123-130 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An X-ray diffraction analysis of the crystalline complex 2b (MLn — TiCl4) shows a chelation of the carbonyl O-atom and the upper SO2 O-atom by TiCl4, a slightly pyramidal N-atom, and a π -face-stereoselective shielding of the C(α)-Si face by the CH2(3) group. The Ti-atom is in a pseudo-octahedral environment.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720116
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  • 111
    Electronic Resource
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    6-Thia-1-aza-5λ5-phosphabicyclo[3.2.0]hept-3-ene und Isothiocyanatophosphin-sulfide aus (Methylidenamino)phosphinen, Schwefelkohlenstoff und Acetylen- oder Ethylen-Derivaten (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 139-146 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 6-Thia-l-aza-5λ5-phosphabicyclo[3.2.0]hept-3-enes and Isothiocyanatophosphine-sulfides from (Methylidenamino)phosphines, Carbon Disulfide, and Acetylene- or Ethylene Derivatives(Methylidenamino)phosphines react with carbon disulfide to 1,3,2-thiazaphosphete derivatives 2. Acetylenedicarboxylates give with 2 6-thia-l-aza-5λ5-phosphabicyclo[3.2.0]hept-3-enes 4a, b, and acrylates yield isothio-cyanatophosphin-sulfides 5a-c. The structures of 4a and 5a are proven by an X-ray diffraction analysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720118
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  • 112
    Electronic Resource
    Electronic Resource
    C45 und C50-Carotinoide. 6. Mitteilung5. Mitteilung, s. [1]. Synthese eines optisch aktiven cyclischen C20-Bausteins und von Decaprenoxanthin (= (2R, 6R, 2′R, 6′R)-2,2′-Bis(4-hydroxy-3-methylbut-2-enyl)-∊, ∊-carotin) (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 151-157 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: C45- and C50-Carotenoids: Synthesis of an Optically Active Cyclic C20-Building Block and of Decaprenoxanthin ( = (2R, 6R, 2′R, 6′R)-2,2′-Bis(4-hydroxy-3-methylbut-2-enyl)-∊, ∊-carotene)The synthesis of the optically active cyclic C20-building block (R, R)-15 and of the optically active C50-carotenoid (2R, 6R, 2′R, 6′R)-decaprenoxanthin (1) starting from (-)-β-pinene ((S)-2) is reported.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720120
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  • 113
    Electronic Resource
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    Synthesis of the Oviposition-Deterring Pheromone (ODP) in Rhagoletis cerasi L. Preliminary communication (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 165-171 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For the assignment of the configuration at C(8) and C(15) of the natural oviposition-deterring pheromone 1 in Rhagoletis cerasi L., the four possible stereoisomers of 1 are synthesized. By condensing the C6 building blocks (5R)-4 and (5S)-4 with the boron enolates of the C10 building blocks (4S)-13 and (4R)-13, followed by decarboxylative dehydration, all stereoisomers of 16 are available (Scheme 5). Glucosylation of 16 followed by formation of the taurin amide gives, after deprotection, the four stereoisomers (8R,15S)-1, (8R,15R)-1, (8R,15S)-1, and (8S,15S)-1 (Scheme 6).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720122
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  • 114
    Electronic Resource
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    Mitteilungen (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 185-192 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720125
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  • 115
    Electronic Resource
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    Masthead (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989) 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720201
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  • 116
    Electronic Resource
    Electronic Resource
    The Chemistry of Thujone. Part XIV.Part XIII [1]. Synthesis of biologically active aryl terpenoid analogues (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 205-212 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Employing thujone-derived intermediates, a series of achiral (9a-d; Scheme 1) and chiral (11b and 11d; Scheme 2) terpene analogues related to the biologically active ‘terpenoid’ hybrids have been prepared. The stereochemistry of the key epoxidation reaction was established by correlation of the product 11b with the previously reported alcohol (R)-20 of known absolute configuration (Scheme 3).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720204
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  • 117
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    Colchicine models: Synthesis and Antitubulin Activity of 2′-Monosubstituted and 2′, 5-Disubstituted 2,3,4,4′-Tetramethoxy-1,1′-biphenyls. Synthesis of 4,4′, 5′, 6′-tetramethoxy-1,1′-biphenyl-2,3′-dicarboxylic acidThis paper is dedicated to our friend and colleague Dr. Tetsuji Kametani, Hoshi College of Pharmacy, Tokyo, Japan, who died on October 11, 1988 (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 196-204 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reductive amination of 2,3,4,4′-tetramethoxtybiphenyl-2-carbaldehyde (4) with MeNH2 afforded methylamine 5 (Scheme 1), Hydroxymethylation of amine 8, prepared similarly from 4 by reductive amination with benzylamine followed by N-methylation, afforded alcohol 12 which was converted the 5-methyl-substituted methylamine 14 by conventional chemical reactions (Scheme 2), Methylamine 14 was also obtained from ester 16 after hydroxymethylation to alcohol 17 and conventional manipulation of alcohol and ester functions (Scheme 2). Both amines 5 and 14 as well as the 2′, 5-dimethyl-substituted biphenyl 26 prepared from the dialdehyde 25 by a Wolff-Kishner reduction, did not show noteworthy activity in the tubulin binding assay or as inhibitors of tubulin polymerization (Table). However, the 2′ethyl-substituted biphebyl 11 prepared from 4 by reaction with MeLi followed by dehyderation and catalytic reduction of styrene 10 (Scheme 1) showed appreciable activity in both assays, coming close to that of known phenyltropolone models. The X-ray analysis of 14·HCl and 11 showed significant difference in the orientation of the rings with respect to one another (Fig.).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720203
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  • 118
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    Sphinxolide, a 26-Membered Antitumoral Macrolide Isolated from an Unidentified Pacific Nudibranch (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 237-246 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that an unidentified nudibranch of Hawaiian waters contains a 26-membered macrolide, sphinxolide ((-)-1) with potent activity against the KB cell line. The structure of sphinxolide, a 2:1 mixture of (E/Z)-isomers at the formamide moiety, is established to be (-)-1 on the basis of extensive NMR and FAB-MS analysis, in combination with data for the products of mono- (→(-)-2) and diacetylation (→(+)-3).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720207
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  • 119
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    Biosynthesis of Homoterpenes in Higher Plants (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 247-253 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In higher plants, the two homoterpenes 4,8-dimethyinona-1,3,7-triene (1) and 4,8,12-trimethyltrideca-1,3,7,11-tetraene (2) are synthesized from the regular terpene alcohols nerolidol and geranyllinalool by fragmentation into the homoterpene and butenone. The biosynthetic pathway is evidenced by conversion of (2H)nerolidol in Hoya purpureo-fusca, Magnolia liliiflora nigra, Robinia pseudoacacia, and Philadelphus coronarius.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720208
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  • 120
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    Syntheses of α, β-Epoxy Silyl Ketones (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 264-270 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the α, β-epoxy-acylsilanes 1 and 2 starting from the allylic silyl alcohols (E)- and (Z)-3, respectively, by epoxidation with t-BuOOH/VO(acac)2 followed by oxidation with Collins reagent (CrO3/pyridine) in up to 70% overall yields, is described. The acid-catalyzed rearrangement of the epoxy-silyl alcohols 4A + B und 5A + B led to the novel unstable diastereoisomeric α-silyl-β-hydroxy-aldehydes 9 and 10, respectively. The structure of 10 was established by X-ray crystal-structure analysis of the corresponding alcohol 11.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720210
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  • 121
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    Highly Stereoselective Total Syntheses of 2,5-Anhydro-4-deoxy-D-ribo-hexonic Acid and of (1S)-1-C-(6-amino-7H-purin-8-yl)-1,4-anhydro-3-deoxy-D-erythro-pentitol (= cordycepin C)Enantiomerically pure 7-oxabicyclo[2.2.1]hept-5-en-2-yl derivatives (‘naked sugars’) as synthetic intermediates, Part V. Part III: [1]. Part IV: [2].Part of the planned Ph. D. thesis of F. G., University of Lausanne.Dedicated to Prof. Hans Dahn on the occasion of his 70th birthday (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 271-277 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Highly regio- and stereoselective monohydroxylation of the C=C bond of (+)-7-oxabicyclo[2.2.1]hept-5-en-2-one (8) was achieved via LiAlH4 reduction of the corresponding 5,6-exo-epoxy dimethyl acetal 9. The reaction gave exclusively (-)-(1R, 2R, 4S)-6,6-dimethoxy-7-oxabicyclo[2.2.1]heptan-2-exo-ol (10) which was transformed into 2,5-anhydro-3-O-benzyl-4-deoxy-D-ribo-hexonic acid (15) and 2,5-anhydro-4-deoxy-D-ribo-hexonic acid (6) via ozonolysis of (-)-(1R, 4S, 6R)-6-exo-benzyloxy-2-{[(tert-butyl)dimethylsilyl]oxy}-7-oxabicyclo[2.2.1]hept-2-ene (14). Cordycepin C (5) was derived from 6 and 4,5,6-triaminopyrimidine using CsF/DMF to generate the adenine heterocycle.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720211
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    Neue Dimethinmerocyanin-Farbstoffe mit der (Sulfobutyl)benzothiazol-Gruppe als Donor-Teilchromophor und deren Aggregationsverhalten in wässriger Lösung (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 295-306 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel Dimethinemerocyanine Dyes with the (Sulfobutyl)benzothiazole Group as Donor Part of the Chromophor and their Aggregation Tendency in Aqueous SolutionA series of novel dimethinemerocyanine dyes with the (sulfobutyl)benzothiazole group as the donor part of the chromophor is synthesized in good yield and their aggregation tendency in H2O without addition of salt investigated. The merocyanine dye 2b only gives J-aggregation in H2O. The dyes 1a-f and 2a exhibit an intense, red-shifted absorption band due to J-aggregation in H2O in the presence of Me4NCl. In contrast, the dyes 1g and 2c-f show a slightly red-shifted absorption band. The degree of aggregation in H2O is investigated by ultracentrifugation of the representative 2e. Indeed, the slightly red-shifted absorption band in H2O is due to aggregation of ‘oligomers’ of the dye. Contrary to the aggregation of ‘polymers’ of dyes (J-aggregation), we suggest the term ‘K’ band for the slightly red-shifted absorption band. The hemicyanine dye 5 gives the same absorption band in MeOH and in MeOH/H2O 1:3. The dye 11 shows an absorption band in H2O that is probably blue-shifted because of negative solvatochromism. The merocyanine dye 13 gives H-aggregation in H2O.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19890720214
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    Masthead (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989) 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890101
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  • 124
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    Isochino[1,2-a][2]benzazepine, IV. Zur Konformation der Isochino[1,2-a][2]benzazepine (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 1-3 
    Details
    ISSN: 0170-2041
    Keywords: Isoquino[1,2-a][2]benzazepines, conformation of ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Isoquino[1,2-a][2]benzazepines, IV1). - Conformation of Isoquino[1,2-a][2]benzazepinesBy treatment with mercury(II) acetate, the hexahydroisoquino[1,2-a][2]benzazepines 1 afford the aromatic isoquinolinium salts 4. On the basis of the mechanism of this reaction and of 1H NMR spectroscopic studies the cis-conformation of the ring system of 1 is very likely.
    Notes: Die Hexahydroisochino[1,2-a][2]benzazepine 1 liefern bei der Umsetzung mit Quecksilber(II)-acetat die aromatischen Isochinolinium-Salze 4. Aufgrund des Mechanismus dieser Reaktion sowie 1H-NMR-spektroskopischer Untersuchungen konnte für 1 die cis-Konformation des Ringgerüstes wahrscheinlich gemacht werden.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/jlac.198919890102
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  • 125
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    Durolsulfonsäure-Derivate als neue Kupplungsreagenzien in der Nucleotidsynthese nach der Triestermethode (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 19-23 
    Details
    ISSN: 0170-2041
    Keywords: Nucleotide synthesis ; Durenesulfonic acid derivatives ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Durenesulfonic Acid Derivatives as New Condensing Reagents in the Nucleotide Synthesis Following the Triester MethodAs shown by the synthesis of a series of ribonucleotide blocks durenesulfonyl chloride/1-methylimidazole and 1-(3-durenylsulfonyloxy)-6-nitrobenzotriazole (15) are adventageous alternative condensing reagents for the triester method. Hereby the 2′-OH function of the ribose is protected by the 4-methoxybenzyl group, which can be removed suitably by dry TFA/anisole instead of trityl tetrafluoroborate.
    Notes: Wie durch Synthese einer Reihe von Ribonucleotidblöcken gezeigt wird, sind Durolsulfonylchlorid/1-Methylimidazol und 1-(3-Durylsulfonyloxy)-6-nitrobenzotriazol (15) vorteilhafte alternative Kupplungsreagenzien für die Triestermethode. Zum Schutz der Ribose-2′-OH-Funktion dient hierbei der 4-Methoxybenzyl-Rest, der sich anstelle von Trityltetrafluoroborat mit wasserfreiem TFA/Anisol leicht wieder entfernen läßt.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/jlac.198919890105
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  • 126
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    Synthesis, X-ray Diffraction, and CD of Cholesteno-as-triazines (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 25-29 
    Details
    ISSN: 0170-2041
    Keywords: Cholesteno-as-triazines ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese, Röntgen-Strukturanalyse und CD von Cholesteno-as-triazinen1)Die Synthesen von zwei neuen Ringsystemen, 5α-Cholest-2-eno[3,2-e]- (6) und 5α-Cholest-2-eno[2,3-e]-as-triazin (11) werden beschrieben. Während das Diketon 1 mit Semicarbazid-hydrochlorid selektiv zu Derivaten von 6 reagiert, ergibt S-Methylisothiosemicarbazid das andere mögliche Ringschlußprodukt 11 unter basischen Reaktionsbedingungen. Zwischen den beiden Typen konnte mit Hilfe einer Röntgen-Strukturanalyse von 9 unterschieden werden. Vergleich der UV- und CD-Spektren zeigt, daß außer den zwei Absorptionen, die im UV-Spektrum auftreten, zwei andere in den CD-Spektren beobachtet werden, die weiteren n - π*- oder nur wenig erlaubten π - π*-Übergängen zugeordnet werden können.
    Notes: The syntheses of two new ring systems, 5α-cholest-2-eno[3,2-e]-(6) and 5α-cholest-2-eno[2,3-e]-as-triazine (11) are described. While the reaction of diketone 1 with semicarbazide hydrochloride results selectively in derivatives of 6, S-methylisothiosemicarbazide under basic conditions affords the other possible ring closure product 11. An unequivocal decision between both types was made by X-ray analysis of compound 9. Comparison of the UV and CD spectra shows that besides the two absorptions appearing in the UV spectra additional ones can be observed in the CD, which may be assigned to further n - π* or only slightly allowed π - π* transitions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890106
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    Synthesis of Compounds with Juvenile Hormone Activity, XXVII. Synthesis of Enantiomerically Pure (10R,11S)-(+)-Juvenile Hormone 0 (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 41-44 
    Details
    ISSN: 0170-2041
    Keywords: Juvenile hormone 0 ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese von Verbindungen mit Juvenilhormon-Aktivität, XXVII1). - Synthese von enantiomerenreinem (10R,11S)-(+)-Juvenilhormon 0Es wird die Synthese von (10R,11S)-(+)-Juvenilhormon 0 (1) durch Anwendung einer verbesserten Methode für den Aufbau einer trisubstituierten Doppelbindung beschrieben.
    Notes: The synthesis of (10R,11S)-(+)-juvenile hormone 0 (1) was achieved by employing an improved method for the construction of a trisubstituted double bond.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890109
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    Resolution of (±)-trans-4-Aminoflavan (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 89-90 
    Details
    ISSN: 0170-2041
    Keywords: (±)-trans-4-Aminoflavan, resolution of ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The optical resolution and the determination of the absolute configuration [2S,4R configuration for the (+)-enantiomer ent-2, 2R,4S configuration for the (-)-enantiomer 2] of the title compound are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890118
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    Derivatives of 1,4-Naphthoquinone via 3-(Phenyliodonio)-1,2,4-trioxo-1,2,3,4-tetrahydronaphthalenide (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 167-170 
    Details
    ISSN: 0170-2041
    Keywords: Iodonium ylide ; 1,4-Naphthoquinones ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,4-Naphthochinon-Derivate aus 3-(Phenyliodonio)-1,2,4-trioxo-1,2,3,4-tetrahydronaphthalinidDie Titelverbindung 3 reagiert mit verschiedenen Elektrophilen wie Halogenwasserstoff-Säuren, Benzoylchlorid, Iodmethan und Brom unter Bildung von 3-Halogen-Derivaten der 2-Hydroxy-1,4-naphthochinone. 3 reagiert außerdem mit Dimethylsulfid zu einem Um-Ylidierungsprodukt; photochemisch bilden sich Furan-Derivate mit 2-Methyl-2-buten, Styrol und Phenylacetylen. Mit Schwefelkohlenstoff wird das 2-Thioxo-1,3-oxathiol-Derivat 15 gebildet.
    Notes: The title compound 3 reacts with various electrophiles such as hydrogen halides, benzoyl chloride, iodomethane, and bromine to afford 3-halo derivatives of 2-hydroxy-1,4-naphthoquinone. 3 reacts also with dimethyl sulfide to give a trans-ylidation product; photochemically, furan derivatives are formed with 2-methyl-2-butene, styrene, and phenylacetylene. Carbon disulfide affords the 2-thioxo-1,3-oxathiole derivative 15.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890132
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    Structural Variations of N-Acetylneuraminic Acid, 10. Synthesis of 2,7-, 2,8-, and 2,9-Dideoxy- and 2,4,7-Trideoxy-2,3-didehydro-N-acetylneuraminic Acids and Their Behavior Towards Sialidase from Vibrio cholerae (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 159-165 
    Details
    ISSN: 0170-2041
    Keywords: N-Acetylneuraminic acid ; Sialidase ; Vibrio cholerae ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Strukturelle Abwandlungen an N-Acetylneuraminsäure, 101). - Synthese von 2,7-, 2,8- und 2,9-Didesoxy- und 2,4,7-Tridesoxy-2,3-didehydro-N-acetylneuraminsäure und ihr Verhalten gegenüber Sialidase aus Vibrio choleraeDie peracetylierten Methylester-Derivate von 7-Desoxy-Neu5Ac (2c), 8-Desoxy-Neu5Ac (3a), 9-Desoxy-Neu5Ac (4a) und 4,7-Didesoxy-Neu5Ac (5a) wurden mit Trifluormethansulfonsäuretrimethylsilylester in die entsprechenden 2-Desoxy-2,3-didehydro-Derivate 2b-5b umgewandelt, wobei auch in wechselnder Menge die 4,5-Oxazolino-Abkömmlinge 6b-8b gebildet wurden. Hydrolyse von 2b-5b führte zu den freien Säuren 7-Desoxy-Neu5Ac2en (2c), 8-Desoxy-Neu5Ac2en (3c), 9-Desoxy-Neu5Ac2en (4c) und 4,7-Didesoxy-Neu5Ac2en (5c). Diese hemmen die Hydrolyse von 4-Methylumbelliferyl-α-Neu5Ac durch Sialidase aus Vibrio cholerae in einem signifikant unterschiedlichen Ausmaß. Der Vergleich ihrer ermittelten α-Seitenprofile mit demjenigen von Neu5Ac2en ermöglicht ein Verständnis für den sehr unterschiedlichen Einfluß auf die Enzymreaktion.
    Notes: The peracetylated methyl ester derivatives of 7-deoxy-Neu5Ac (2a), 8-deoxy-Neu5Ac (3a, 9-deoxy-Neu5Ac (4a), and 4,7-dideoxy-Neu5Ac (5a) were transformed by trimethylsilyl trifluoromethanesulfonate into the corresponding 2-deoxy-2,3-didehydro derivatives 2b-5b. As additional products, the 4,5-oxazolino derivatives 6b-8b were formed. Hydrolysis of 2b-5b yielded the free acids 7-deoxy-Neu5Ac2en (2c), 8-deoxy-Neu5Ac2en (3c), 9-deoxy-Neu5Ac2en (4c), and 4,7-dideoxy-Neu5Ac2en (5c). They showed significantly different inhibitory influences on the hydrolysis of 4-methylumbelliferyl-α-Neu5Ac by sialidase from Vibrio cholerae. The comparison of their evaluated α-side profiles with that of Neu5Ac2en (1c) enables a suitable explanation of their different inhibitory potencies.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890131
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    Cytochrom-P-450-Modellreaktionen. - Isolierung und Charakterisierung von Mangan(IV)- und Mangan(V)-Porphyrin-Komplexen (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 171-175 
    Details
    ISSN: 0170-2041
    Keywords: Carbon oxygenation ; Epoxidation ; Manganese(IV) porphyrins ; Monooxygenase model ; Nitridomanganese(V) porphyrins ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cytochrome P-450 Model Reactions. - Isolation and Characterization of Manganese(IV)- and Manganese(V)-Porphyrin ComplexesThe isolation at  -  78°C and characterization of the crystalline reactive Mn(IV)-phorphyrin complex TDCPPMn(IV)(C6H5IOCl)2 (3) is described. 3 is compared with the also synthesized manganese-phorphyrin complexes TDCPPMn(IV)(OCH3)2 (4) and TDCPPMn(V)N (5). The stoichiometric reaction of 3 with triphenylphosphine yields 2.5 equivalents of triphenylphosphine oxide, 1.0 equivalent of TDCPPMn(III)Cl (2), and 2.0 equivalents of iodobenzene. Olefins are epoxidized and cyclohexane is oxygenated by 3. With NH3, 3 reacts to the Mn(V)-nitrido complex TDCPPMn(V)N (5). Oxygenation reactions of the system TDCPPMn(III)Cl (2)/PhIO are described.
    Notes: Die Isolierung bei  -  78°C und Charakterisierung des kristallinen reaktiven Mn(IV)-Porphyrin-Komplexes TDCPPMn(IV)(C6H5-IOCl)2 (3) wird beschrieben. 3 wird mit den ebenfalls dargestellten Mangan-Porphyrin-Komplexen TDCPPMn(IV)(OCH3)2 (4) und TDCPPMn(V)N (5) verglichen. Die stöchiometrische Umsetzung von 3 mit Triphenylphosphan führt zu 2.5 Äquivalenten Triphenylphosphanoxid, 1.0 Äquivalent TDCPPMn(III)Cl (2) und 2.0 Äquivalenten Iodbenzol. Olefine werden von 3 epoxidiert und Cyclohexan wird von 3 oxygeniert. Mit NH3 reagiert 3 zu dem Mn(V)-Nitrido-Komplex TDCPPMn(V)N (5). Oxygenierungsreaktionen des Systems TDCPPMn(III)Cl (2)/PhIO werden beschrieben.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/jlac.198919890133
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    Antibiotika aus Gleitenden Bakterien, XXXVIII. Natürliche Strukturvarianten von Sorangicin A aus Sorangium cellulosum, So ce12 (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 213-222 
    Details
    ISSN: 0170-2041
    Keywords: Macrolide-polyether antibiotics ; Sorangicin B ; Sorangicin A variants ; Sorangium cellulosum ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Antibiotics from Gliding Bacteria, XXXVIII1). - Naturally Occurring Structural Variants of Sorangicin A Produced by Sorangium cellulosum, So ce12In addition to Sorangicin A (1) from fermentation extracts of Sorangium cellulosum a deoxygenated modification sorangicin B (2), the sorangicins A1 (3), A2 (4), and A3 (5) with isomeric triene moieties, and as isomers, in which the tetrahydrofuran ring has been opened, the sorangicins C (9), C2 (6), C3 (8), C4 (7) were isolated and their structures elucidated. The 21-O-β-D-glucosides sorangioside A (11) and B (12) and the 21-O-β-D-6′-deoxyglucosides sorangioside C (13) and C4 (14) were also found.
    Notes: Neben Sorangicin A (1) wurden aus den Fermentationsextrakten von Sorangium cellulosum eine desoxygenierte Variante Sorangicin B (2), die Sorangicine A1 (3), A2 (4) und A3 (5) mit isomerisiertem Trienteil und als Isomere, bei denen der Tetrahydrofuranring geöffnet ist, die Sorangicine C (9), C2 (6), C3 (8) und C4 (7) isoliert und in ihrer Struktur aufgeklärt. Zusätzlich wurden die 21-O-β-D-Glucoside Sorangiosid A (11) und B (12) und die 21-O-β-D-6′-Desoxyglucoside Sorangiosid C (13) und C4 (14) gefunden.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890142
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    Zur Regiochemie von [4 + 2]-Cycloadditionen mit Methylpyrano[3,4-b]indol-3-onen und unsymmetrischen Dienophilen (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 227-230 
    Details
    ISSN: 0170-2041
    Keywords: Diels-Alder reactions ; CC-Dienophiles ; Mesoxalate, diethyl- ; Pyrano[3,4-b]indol-3-ones ; Regiochemistry ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Regiochemistry of [4 + 2] Cycloadditions with Methylpyrano[3,4-b]indol-3-ones and Unsymmetric DienophilesThe methyl-substituted pyrano[3,4-b]indol-3-ones 1a, 1b react with acyclic, unsymmetric CC-dienophiles by Diels-Alder reaction/CO2-extrusion to yield selectively functionalized carbazoles 2. Dependent on the structure of the reaction partners, no, very poor, or high regioselectivity is observed. Diethyl mesoxalate reacts with 1a, 1b regioselectively to give new 2,3-difunctionalized indole derivatives 4a, 4b. These should be the result of a [4 + 2] cycloaddition/cycloreversion sequence. Diethyl pyrano[3,4-b]indoledicarboxylates 3a, 3b are proposed as intermediates.
    Notes: Die methylierten Pyrano[3,4-b]indol-3-one 1a, 1b reagieren mit acyclischen, unsymmetrischen CC-Dienophilen nach einer Diels-Alder-Reaktion/CO2-Extrusion zu selektiv funktionalisierten Carbazolen 2. In Abhängigkeit von der Struktur der Reaktionspartner wird keine oder geringe bis hohe Regioselektivität festgestellt. Diethylmesoxalat reagiert mit 1a, 1b regioselektiv zu neuen 2,3-difunktionalisierten Indolen 4a, 4b, die aus einer regiokontrollierten [4 + 2]-Cycloaddition und Cycloreversion resultieren, wobei Pyrano[3,4-b]indoldicarbonsäure-diethylester 3a, 3b als Intermediate auftreten dürften.
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    URL: http://dx.doi.org/10.1002/jlac.198919890144
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    Notizen / Notes Reactions of Organic Anions, 153. Methylthio(phenoxy)acetonitrile - A Synthetically Useful Monothioacetal (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 203-206 
    Details
    ISSN: 0170-2041
    Keywords: Acetonitrile, methylthio(phenoxy)- ; Acyl anion equivalents ; Nitroarenes, nucleophilic acylation of ; Phase transfer catalysis ; Vicarious nucleophilic substitution ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound 2 was synthesized and treated in basic medium with alkyl halides, electrophilic alkenes, aromatic nitro compounds, and phenylacetylene to give the products 3-6. The synthetic utility of this approach was also demonstrated by transformations of 3b into compounds 7-10.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/jlac.198919890139
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    Correction to the Contribution A Structural Study of Tryller′s and Schmitz′s Compounds and Related Substances (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 211-211 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890141
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    Asymmetric Syntheses via Heterocyclic Intermediates, XLII. Asymmetric Syntheses of Diastereomerically and Enantiomerically Pure (2R,3S)-threo-3-Arylserine Methyl Esters by the Bislactim Ether Method Asymmetric Synthesis of Chloramphenicol (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 223-225 
    Details
    ISSN: 0170-2041
    Keywords: Chloramphenicol ; Serine, 3-aryl-, methyl esters ; Bislactim ether method ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asymmetrische Synthesen über heterocyclische Zwischenstufen, XLII1). - Asymmetrische Synthese von diastereomeren- und enantiomerenreinen (2R,3S)-threo-3-Arylserin-methylestern nach dem Bislactimether-Verfahren. - Asymmetrische Synthese von ChloramphenicolDas Titanderivat 3 des Bislactimethers 1 von cyclo(-L-Val-Gly-) reagiert mit aromatischen Aldehyden 4 mit hoher Diastereoselektivität zu den syn-Addukten 5. Diese liefern bei der Hydrolyse neben L-Valin-methylester (6) und geringen Mengen Dipeptidester 8 die (2R,3S)-threo-Serin-methylester 7. Über den Ester ent-7d ist das Antibiotikum Chloramphenicol (9) nach bekannten Verfahren erhältlich.
    Notes: The titanium derivative 3 of the bislactim ether 1 of cyclo(-L-Val-Gly-) reacts with arylaldehydes 4 highly diastereoselectively to give the syn-addition products of type 5. On hydrolysis, these yield besides methyl L-valinate (6) and small amounts of the dipeptide ester 8 the (2R,3S)-threo-serine methyl esters of type 7. Chloramphenicol (9) can be obtained from the ester ent-7d by known methodology.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/jlac.198919890143
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    Asymmetrische Hetero-Diels-Alder-Reaktionen in wäßriger Lösung unter Verwendung von Aminosäureestern als chiralen Auxiliaren (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 231-238 
    Details
    ISSN: 0170-2041
    Keywords: 2-Azabicyclo[2.2.1]heptenes and -[2.2.2]octenes ; Chiral auxiliaries ; Diels-Alder reactions ; Hetero Diels-Alder reactions ; Piperidines, dehydro- ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asymmetric Hetero Diels-Alder Reactions in Aqueous Solution Using Amino Acid Esters as Chiral Auxiliaries(R)- and (S)-amino acid methyl ester hydrochlorides form with formaldehyde in THF/water mixtures iminium ions, which react already at 0°C as electron-deficient dienophiles in hetero Diels-Alder reactions with cyclopentadiene, cyclohexadiene, and openchain alkyl-substituted butadienes. The cycloadducts are isolated in high yields in multigram amounts and with diastereomer ratios (up to 93:7), which up to now could not be obtained with other chiral amines. With the aid of NOE experiments the absolute configurations of the major diastereomers are assigned. From the phenylglycine and the serine derivatives the chiral auxiliaries can be removed by hydrogenolytic methods and with the aid of the Mitsunobu reaction, respectively. Thus, ( - )-2-azabicyclo-[2.2.1]heptane is accessible in enantiomerically pure form.
    Notes: (R)- und (S)-Aminosäure-methylester-hydrochloride bilden mit Formaldehyd in THF/Wasser-Gemischen Iminium-Ionen, die als elektronenarme Dienophile mit Cyclopentadien, 1,3-Cyclohexadien und Alkyl-substituierten Butadienen bereits bei 0°C Hetero-Diels-Alder-Reaktionen eingehen. Die Cycloaddukte werden mit hohen Ausbeuten im Multigrammaßstab und mit Diastereomerenverhältnissen (bis zu 93:7) gebildet, die mit anderen chiralen Aminen bisher nicht erreicht werden konnten. Mit Hilfe von NOE-Experimenten werden die absoluten Konfigurationen der Hauptdiastereomeren zugeordnet. Aus den Phenylglycin- und den Serin-Derivaten können die chiralen Hilfsgruppen mittels hydrogenolytischer Methoden bzw. unter Anwendung der Mitsunobu-Reaktion abgespalten werden. So ist ( - )-2-Azabicyclo[2.2.1]-heptan in enantiomerenreiner Form zugänglich.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/jlac.198919890145
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  • 138
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    Kettenverlängerung von Kohlenhydraten: Synthese von C-Glycosiden und C-Nucleosiden aus Glyconsäuren und Glycarsäuren (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 247-254 
    Details
    ISSN: 0170-2041
    Keywords: Carbohydrates ; Chain elongation ; 1,3-Dicarbonyl compounds ; C-Nucleosides ; Pyrazoles ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chain Elongation of Carbohydrates: Synthesis of C-Glycosides and C-Nucleosides from Glyconic and Glycaric AcidsBy chain elongation using the C-phenylglycine method allyl residues can be attached to peracetylated glyconic and glycaric acids. Oxidative cleavage of the allylic double bond leads to 1,3-dicarbonyl compounds, which can be converted into optically pure C-glycosides and C-nucleosides by reaction with 1,2-dinucleophiles.
    Notes: Durch Kettenverlängerung mit Hilfe von C-Phenylglycin lassen sich peracetylierte Glyconsäuren und Glycarsäuren mit Allylresten C - C-verknüpfen. Oxidative Spaltung der Allyl-Doppelbindung ergibt 1,3-Dicarbonylverbindungen, aus denen sich durch Ringschlußreaktionen mit 1,2-Dinucleophilen stereochemisch einheitliche C-Glycoside und C-Nucleoside darstellen lassen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890147
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  • 139
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    Antibiotika aus Gleitenden Bakterien, XXXIX. Biosynthese von Sorangicin A in Sorangium cellulosum, So ce12 (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 309-313 
    Details
    ISSN: 0170-2041
    Keywords: Sorangicin ; Biosynthesis ; [13C]Acetates ; [13C]Methionine ; [13C]Carbonate ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Antibiotics from Gliding Bacteria, XXXIX1). - Biosynthesis of Sorangicin A in Sorangium cellulosum, So ce12The biogenesis of sorangicin A (1) was studied by feeding experiments with single and doubly labeled [13C]acetates as well as sodium [13C]hydrogencarbonate and [methyl-13C]methionine. Accordingly, 1 is assembled by linear condensation of twenty acetate units onto a malonate starter unit, which is completely preserved in 1. The carboxy group of the malonyl-CoA ester, identical with C-1 in 1, is labeled by [13C]carbonate or by carbon originating from [1-13C]acetate. The four methyl groups in 1 are derived from methionine.
    Notes: Die Biogenese von Sorangicin A (1) wurde durch Verfüttern von einfach und doppelt 13C-markierten Acetaten sowie von [13C]Natriumhydrogencarbonat und [Methyl-13C]Methionin untersucht. Demnach wird 1 durch lineare Kondensation von zwanzig Acetateinheiten an einen Malonatstarter aufgebaut, der vollständig in 1 enthalten ist. Die Carboxylgruppe des Malonyl-Co-A-esters, identisch mit C-1 in 1, wird durch [13C]Carbonat oder durch Kohlenstoff aus [1-13C]Acetat markiert. Die vier Methylgruppen in 1 stammen aus Methionin.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/jlac.198919890155
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  • 140
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    Inhaltsstoffe der Rinde von Dalbergia monetaria L. Drei neue Isoflavon-C-glucoside (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 331-335 
    Details
    ISSN: 0170-2041
    Keywords: Dalbergia monetaria ; (β-D-Glucopyranosyl)orobol ; C-Glucosides ; Orobol ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Components from the Stem Bark of Dalbergia monetaria L. - Three New Isoflavone C-GlucosidesFrom the stem bark of Dalbergia monetaria six C-glucosides of isoflavonoids have been isolated. Three of them represent new natural products: 6-(β-D-glucopyranosyl)orobol (6), 8-(6″-O-acetyl-β-D-glucopyranosyl)orobol (7), and 6-(O-acetyl-β-D-glucopyranosyl)orobol (5); in the latter, the position of the acetyl group in the glucose rest is not known. Furthermore, 8-(β-D-glucopyranosyl)orobol (8), 6,8-bis(β-D-glucopyranosyl)orobol (9), and 6,8-bis(β-D-glucopyranosyl)genistein (10) which have been already found in other plants could be identified. Additionally, the examined extracts contain friedelin (1) and the steroids β-sitosterol (2), stigmasterol (3), and campesterol (4).
    Notes: Aus der Rinde von Dalbergia monetaria wurden sechs C-Glucoside von Isoflavonoiden isoliert. Drei von ihnen stellen neue Naturstoffe dar: 6-(β-D-Glucopyranosyl)orobol (6), 8-(6″-O-Acetyl-β-D-glucopyranosyl)orobol (7) und 6-(O-Acetyl-β-D-glucopyranosyl)orobol (5), bei dem die Position der Acetylgruppe offen bleibt. Weiter wurden - die schon in anderen Pflanzen gefundenen - 8-(β-D-Glucopyranosyl)orobol (8), 6,8-Bis(β-D-glucopyranosyl)orobol (9) und 6,8-Bis(β-D-glucopyranosyl)genistein (10) identifiziert. Zusätzlich treten in den untersuchten Extrakten Friedelin (1) sowie die Steroide β-Sitosterol (2), Stigmasterol (3) und Campesterol (4) auf.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/jlac.198919890158
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  • 141
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    Peptidkonformationen, 50. Synthese und Konformationsanalyse von cyclischen Alanin-Analogen des Thymopoietins durch NMR-Spektroskopie und Molecular-Dynamics-Rechnungen im Vakuum und in Lösung (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 269-294 
    Details
    ISSN: 0170-2041
    Keywords: Cyclic pentapeptides ; Conformational analysis ; Immune stimulating peptides ; Molecular dynamics calculations in solution ; Peptides ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Peptide Conformations, 501). - Synthesis and Conformational Analysis of Cyclic Alanine Analogs of Thymopoietin by NMR Spectroscopy and Molecular Dynamics Calculations in Vacuo and in SolutionCyclic D-valine containing splenopentin (SP5), cyclo(-Arg-Lys-Glu-D-Val-Tyr-), its five alanine-substituted analogs and cyclo-(-Ala4-D-Ala-) have been synthesized and analysed by two-dimensional NMR spectroscopy in DMSO and H2O solution. The NOE- and ROE-derived conformations have been refined by molecular dynamics calculations in vacuo and in water. All these peptides show similar chemical shift values with and without protecting groups either in DMSO and in H2O. Conformational analysis based on NMR data showed βII′γ-structured backbones with D-amino acid in position i + 1 of the β turn. The populations of the side chain conformation of tyrosine and valine about χ1 have been determined by 3JHCαCβH coupling constants and NOE data and have been fixed in the preferred conformation during the MD calculations. Structure refinement of cyclo(-D-Val-Tyr-Arg-Lys-Ala-) and cyclo(D-Ala-Ala4-) by restrained molecular dynamics with respect to reduced charges, depending on the temperature dependencies of the NH chemical shifts resulted in a weak bending of the backbone caused by a γi turn on the opposite side of the molecule. A relationship between 13Cα-chemical shift values and peptide conformations is described. Biological testings showed a strong reduction of biological activity by substitution of D-valine and glutamic acid for alanine.
    Notes: Cyclisches, D-Valin enthaltendes Splenopentin (SP5), cyclo(-Arg-Lys-Glu-D-Val-Tyr-), seine fünf positionsweise substituierten Alanin-Analogen und das Modellpeptid cyclo(-Ala4-D-Ala-) wurden synthetisiert und in DMSO und Wasser durch zweidimensionale NMR-Spektroskopie untersucht. Die aus NOE- bzw. ROE-Daten gewonnenen Konformationen wurden mit Molecular-Dynamics-Methoden zum Teil auch unter Einschluß des Lösungsmittels Wasser verfeinert. Alle Peptide zeigen ähnliche 1H- und 13C-chemische Verschiebungen sowohl mit als auch ohne Schutzgruppen an den Seitenketten in DMSO und in Wasser. Die Konformationsuntersuchungen anhand von NOE- und ROE-Spektroskopie, 3JHNCαH-Kopplungskonstanten und anderen Daten ergeben übereinstimmend eine βII′γ-Struktur der Grundgerüste mit der D-Aminosäure in der i + 1-Position der βII′-Schleife. Die Seitenkettenkonformationen von Tyrosin und Valin konnten durch 3JHCαCβH-Kopplungskonstanten und NOE-Daten bestimmt werden. Sie wurden in den Rechnungen in der bevorzugten Konformation fixiert. Die Strukturverfeinerung von cyclo(-D-Val-Tyr-Arg-Lys-Ala-) und cyclo(-Ala4-D-Ala-) durch Restrained-MD unter Berücksichtigung reduzierter Ladungen, die sich experimentell aus der Temperaturabhängigkeit der chemischen Verschiebungen der NH-Protonen ergaben, zeigten ein Abknicken des Grundgerüstes durch eine auf der Gegenseite der βII′γ-Wasserstoffbrükkenbindungen angeordnete γi-Schleife. Die Abhängigkeit der chemischen Verschiebung der 13Cα-Kohlenstoffe von der Position der Aminosäuren im Grundgerüst konnte in einen systematischen Zusammenhang gebracht werden. Biologische Tests ergaben eine starke Reduktion der biologischen Aktivität bei Substitution der Glutaminsäure und D-Valin durch Alanin.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/jlac.198919890150
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  • 142
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    Strukturbestimmung des 2:1-Addukts von (Cyanmethyl)phosphonsäurediethylester an k-Strophanthidin (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 315-319 
    Details
    ISSN: 0170-2041
    Keywords: k-Strophanthidin derivative, 2D-NMR ; Wittig reaction with unsaturated lactones ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Structure Eludication of the 2:1 Adduct from Diethyl (Cyanomethyl)phosphonate and k-StrophanthidinThe structure of the previously unknown reaction product, formed from diethyl (cyanomethyl)phosphonate and k-strophanthidin under protic conditions, was determined to be 3 by two-dimensional NMR techniques (13C,1H-shift correlation via 1JCH and nJCH as well as 1H,1H-shift correlation) and from NOE difference spectra. A suggestion regarding the reaction pathway according to Scheme 2 is discussed.
    Notes: Die Struktur eines früher unbestimmt gebliebenen Reaktionsprodukts, das sich unter protischen Bedingungen aus k-Strophanthidin und (Cyanmethyl)phosphonsäure-diethylester bildet, wird mit zweidimensionalen NMR-Techniken (13C,1H-Verschiebungskorrelation via 1JCH und nJCH sowie 1H,1H-Verschiebungskorrelation) und aus NOE-Differenzspektren als 3 bestimmt. Ein Vorschlag zum Ablauf der Umsetzung gemäß Schema 2 wird zur Diskussion gestellt.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/jlac.198919890156
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    Thion- und Dithioester, 47. α,β-ungesättigte Thion- und Dithioester durch Kondensationsreaktionen (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 321-330 
    Details
    ISSN: 0170-2041
    Keywords: Thionoesters ; Dithioesters ; Horner-Wittig reaction ; Peterson synthesis ; Aldol reaction (Mukaiyama) ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Thiono- and Dithioesters, 471). - α,β-Unsaturated Thiono- and Dithioesters by Condensation ReactionsCondensation of (dimethoxyphosphinyl)thionoacetate 4 (X = O) and -dithioacetate 4 (X = S) with aldehydes, catalysed by aqueous potassium carbonate, leads in a Horner-Wittig reaction to the formation of the α,β-unsaturated thionoesters 5a-o and dithioesters 6a, b as well as their Diels-Alder dimers 7c-e. (Trimethylsilyl)thionoacetate 13 and -dithioacetate 18 react with aldehydes in a Peterson synthesis to yield the thionoesters 5c, g, j-m, p-r and the dithioesters 6b, f-h. (Trimethylsilyl) ketene dithioacetal 19 adds in an aldol reaction to O,O acetals of aldehydes and ketones to give the β-alkoxy dithioesters 22, which may be transformed by elimation of alcohol into the α,β-unsaturated dithioesters 23.
    Notes: Die Kondensation der (Dimethoxyphosphinyl)thionacetate 4 (X = O) und -dithioacetate 4 (X = S) mit Aldehyden unter Katalyse von wäßrigem Kaliumcarbonat liefert in einer Horner-Wittig-Reaktion die α,β-ungesättigten Thionester 5a-o und Dithioester 6a, b sowie ihre Diels-Alder-Dimeren 7c-e. Mit Aldehyden und dem (Trimethylsilyl)thionacetat 13 sowie dem -dithioacetat 18 werden in einer Peterson-Synthese die Thionester 5c, g, j-m, p-r sowie die Dithioester 6b, f-h erhalten. O,O-Acetale von Aldehyden und Ketonen reagieren mit dem (Trimethylsilyl)ketendithioacetal 19 unter Tritylperchlorat-Katalyse in einer Aldoladdition zu den β-Alkoxy-dithioestern 22, die sich durch Eliminierung von Alkohol in die α,β-ungesättigten Dithioester 23 überführen lassen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890157
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    Antibiotika aus Gleitenden Bakterien, XLI. Zur Konstitution der Myxovirescine B - T und Biogenese des Myxovirescins A (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 345-355 
    Details
    ISSN: 0170-2041
    Keywords: Myxovirescins ; [13C-Methyl]malonate ; Myxococcus virescens ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Antibiotics from Gliding Bacteria, XLI1). - On the Constitution of Myxovirescins B-T and Biogenesis of Myxovirescin AThe gliding bacteria Myxococcus virescens Mx v48 produce the myxovirescins A-T, macrocyclic lactam-lactones which differ in ring size, oxidation levels of C-121, C-20, and C-24, alkylation at C-16, and in the presence of a double bond at C26-C27. Incorporation experiments using [2,3-13C2]succinic acid as well as diethyl [13C-methyl]malonate indicate that the 16-ethyl group in myxovirescin A originates from the succinate/methyl malonate path.
    Notes: Myxobakterien des Stammes Myxococcus virescens Mx v48 produzieren einen Antibiotika-Komplex, Myxovirescine A-T, makrocyclische Lactam-Lactone, die sich in ihrer Ringgröße, den Oxidationsstufen des C-121, C-20 und des C-24, der Alkylierung an C-16 und durch eine Doppelbindung an C26-C27 unterscheiden. Markierungsversuche mit [2,3-13C2]Bernsteinsäure sowie mit [13C-Methyl]malonsäure-diethylester beweisen, daß 16-Ethyl im Myxovirescin A aus dem Succinat/Methylmalonat-Pfad stammt.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jlac.198919890160
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    Die Synthese von Perrottetin F und G, zwei acyclische Bis(bibenzyl)ether aus Radula perrottetii (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 401-403 
    Details
    ISSN: 0170-2041
    Keywords: Bis(bibenzyl) ether ; Perrottetins ; Radula perrottetii ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Perrottetin F and G, Two Linear Bis(bibenzyl) Ethers from Radula perrottetiiPerrottetin F and G, two acyclic bis(bibenzyls) with an ether linkage were synthesized using Ullmann and Wittig reactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890170
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  • 146
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    Eine einfache Synthese von N-Methyl-L-histidin (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 387-388 
    Details
    ISSN: 0170-2041
    Keywords: L-Histidine, N-methyl- ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Simple Preparation of N-Methyl-L-histidineN-Methyl-L-histidine is efficiently prepared in two steps starting from Nα-trityl-l-histidine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890166
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    Synthese eines mit D-Glucuronsäure konjugierten Metaboliten von Ciamexon (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 393-395 
    Details
    ISSN: 0170-2041
    Keywords: Glucuronidation ; Invertomers ; Esterase ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of a Metabolite of Ciamexon Conjugated with D-Glucuronic AcidReaction of the alcohol 2 with the glucuronic acid derivative 6 in the presence of Ag triflate yields the protected β-D-glucuronide 8 by rearrangement of the orthoester 7. After deacetylation and saponification with pig liver esterase, the deblocked glucuronide 3 can be isolated. Due to the aziridine ring the glucuronic acid derivatives of 2 consist of a mixture of invertomers, as shown by 1H-NMR spectroscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890168
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    Reactions of Acenaphthylene-1,2-quinone Monoxime with Some Phosphorus Ylides. - Synthesis of Acenaphtho [1,2-x]-Fused Compounds (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 397-399 
    Details
    ISSN: 0170-2041
    Keywords: Acenaphtho[1,2-b]pyridines ; Wittig-type reaction ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By applying a Wittig reaction on the monoxime 1 with phosphorus ylide 2 the oximes 3(I,II) are isolated whereas with ylide 5 the pyridine derivative 8 is obtained. Reaction of 1 with the bis-salt 9 in the presence of lithium ethoxide gives through a Wittig and a “Wittig-type” reaction the fluoranthene 11. Hydrogenation of compound 3(I) to oxime 12 and thermal cyclization of the latter leads to the formation of the polycyclic compound 15.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890169
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    Intramolekulare Cycloadditionen mit Isobenzofuranen, V. Synthese von rac-Thiamarmelerin, einem Thiophenanalogon eines natürlich vorkommenden Furanosesquiterpens (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 405-408 
    Details
    ISSN: 0170-2041
    Keywords: Thieno[2,3-c]furan ; Cycloaddition, intramolecular ; Benzothiophene ; Marmelerin, thiophene analogue of ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intramolecular Cycloaddition Reactions with Isobenzofurans, V1). - Synthesis of rac-Thiamarmelerin, a Thiophene Analogue of a Naturally Occurring Furanosesquiterpenerac-Thiamarmelerin (7b) is prepared by an intramolecular Diels-Alder reaction of a thieno[2,3-c]furan.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890171
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    [3.3.3]Propelladiendicarbonitrile (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 503-513 
    Details
    ISSN: 0170-2041
    Keywords: [3.3.3]Propellanecarbonitriles ; Tricyclo[3.3.3.01.5]undecane-3,7-dione ; NBS Bromination ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: [3.3.3]Propelladienedicarbonitriles1)The 3,7-diketone 5 reacts with 4-chlorothiophenol in the presence of titanium tetrachloride/triethylamine to afford equal amounts of the vinyl sulfides C2/C5-6 in 95% yield. Equilibration of the 1:1 mixture of C2/C5-6 is catalyzed by trifluoroacetic acid and produces a 3:2 ratio of C2/C5-7 in almost quantitative yield. Potassium cyanide supported on aluminium oxide in boiling 2-methyl-2-butanol converts the latter into a mixture of the α,β-unsaturated dinitriles 1b, 11, 13, and 14, which are separated by chromatography. The intermediates 8 and 10 as well as the products 9 and 12 resulting from the addition of hydrogen cyanide to 1b and 11, respectively, are isolated in the same way. The dinitrile 1b is brominated by N-bromosuccinimide to afford a mixture of endo-15, exo-15, endo,endo-16, endo,exo-16, and 17, most of which are separated by chromatography. The endo-bromodinitrile endo-15 reacts with potassium methoxide in methanol to yield the exo-methoxydinitrile 18. The configuration of the dinitriles endo-15, endo,endo-16, and 18 is established by NOE difference spectroscopy and X-ray diffraction analyses.
    Notes: Das 3,7-Diketon 5 reagiert mit 4-Chlorthiophenol in Gegenwart von Titan(IV)-chlorid/Triethylamin zu gleichen Mengen der Bis(vinylsulfide) C2/C5-6 (65% Ausb.), die unter Trifluoressigsäure-Katalyse zu einem (3:2)-Gemisch äquilibriert werden. Oxidation von C2/C5-6 mit Natriumperborat-tetrahydrat in Essigsäure ergibt fast quantitativ die Bis(vinylsulfone) C2/C5-7. Diese liefern mit Kaliumcyanid auf Aluminiumoxid in siedendem 2-Methyl-2-butanol ein Gemisch der α,β-ungesättigten Dinitrile 1b, 11, 13 und 14, die chromatographisch getrennt werden So werden auch die Zwischenstufen 8 und 10 sowie Folgeprodukte von 1b und 11, nämlich die Trinitrile 9 und 12, isoliert. das Dinitril 1b wird mit N-Bromsuccinimed zu einem Gemisch von endo-15, exo-15, endo,endo-16, endo,exo-16 und 17 bromiert, das größtenteils chromatographisch getrennt wird. Das endo-Bromdinitril endo-15 reagiert mit Kaliummethanolat in Methanol zum exo-Methoxydinitril 18. Die Konfiguration der Dinitrile endo-15, endo,endo-16 und 18 wird durch NOE-Differenz-Spektren und Röntgenstrukturanalyse bewiesen.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890190
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  • 151
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    Electrophilic Cyclization of Doubly Activated Imines with Lewis Acids and Trialkylsilyl Triflates Synthesis of Pyrrole and Azepine Derivatives (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 559-564 
    Details
    ISSN: 0170-2041
    Keywords: α-Amino acids, nonproteinogenic ; Azepine ; Cyclization, electrophilic ; Pyrrolidines ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Elektrophile Cyclisierung doppelt aktivierter Imine mit Lewis-Säuren und Trialkylsilyl-trifluormethansulfonaten. - Synthese von Pyrrol- und Azepin-DerivatenDie Cyclisierung des (Pentenylimino)malonats 8a ergibt in Abhängigkeit von der verwendeten Lewis-Säure entweder die Pyrrolidine 11a und 12a oder das Hexahydro-1H-furo[3,4-b]pyrrol 13a als Hauptprodukte. Der Isopropylester 8b cyclisiert unter allen Reaktionsbedingungen bevorzugt zum Lactonester 13b. Cyclisierung des Heptenylimins 9 liefert ausschließlich die epimeren Octahydro-1H-furo[3,4-b]azepine 17 und 18. Hierbei kann das thermodynamisch stabilere 17 in großem Überschuß erhalten werden. Verseifung und Decarboxylierung von 17 ergibt das Derivat 20 einer cyclischen nichtproteinogenen α-Aminosäure. Das Octenylimin 10 ließ sich unter den getesteten Bedingungen nicht cyclisieren.
    Notes: The cyclization of the (pentenylimino)malonate 8a gives either the pyrrolidines 11a and 12a or the hexahydro-1H-furo[3,4-b]-pyrrole 13a as main products depending on the Lewis acid used. The isopropyl ester 8b cyclizes under all reaction conditions preferentially to give the lactone ester 13b. Cyclization of the heptenylimine 9 yields exclusively the epimeric octahydro-1H-furo-[3,4-b]azepines 17 and 18. The thermodynamically more stable 17 could be obtained in large excess. Saponification and decarboxylation of 17 gives the cyclic nonproteinogenic α-amino acid derivative 20. The octenylimine 10 could not be cyclized under several conditions tested.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890198
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  • 152
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    Benzenepentamine - Its Easy Accessibility and Use in Syntheses of Pyrazinoquinoxalines (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 617-621 
    Details
    ISSN: 0170-2041
    Keywords: Benzenepentamine ; Benzopyrazines ; N-Heterocycles ; Nitroarenes ; Pyrazinoquinoxalines ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Benzolpentamin - leichter Zugang und Gebrauch in einfachen Pyrazinochinoxalin-SynthesenFür das nach 60 Jahren wiederentdeckte Benzolpentamin (6) wird ein einfacher Syntheseweg beschrieben, der das sehr empfindliche, farblose 6 in methanolischer Lösung nahezu quantitativ liefert. Mit den zwei maskierten Formen A und B des Glyoxals kondensiert 6 selektiv und in guten Ausbeuten unter Bildung zweier Amino-substituierter Pyrazinochinoxaline: 7a mit Phenanthren bzw. 8a mit Anthracen-artiger Struktur. Weniger selektiv reagiert das α-Diketon Benzil mit 6, wobei die entsprechenden Tetraphenyl-Derivate 7b und 8b der beiden Pyrazinochinoxalin-Ringsysteme erhalten werden. Das vormals unbekannte, bei Reduktionen von 1,3,5-Trinitrobenzoltriamin neben Benzolhexamin erhaltene Nitrobenzolpentamin (9) wird ebenfalls vorgestellt. Die Strukturen dieser zwei Multiamine wurden aufgrund spektroskopischer Daten von ihren Kondensationsprodukten mit α-Di ketonen abgeleitet, z. B. im Falle des neuen Pentamins 9 von seinen ersten Derivaten 7c-e des Pyrazino[2,3-f]chinoxalins.
    Notes: Benzenepentamine (6) has been rediscovered after about 60 years. A simple and very efficient synthetic route is described which yields the very sensitive, colourless 6 in methanolic solution in nearly quantitative yield. Condensations of 6 with two masked forms A and B of glyoxal conveniently lead to two types of amino-substituted pyrazinoquinoxalines, one with an angular phenanthrene-type topology (7a), or one with the linear anthracene-type structure (8a), respectively, with acceptable yields. The α-diketone benzil also reacts with 6, but less selectively, forming the corresponding tetraphenyl derivatives 7b an 8b of both these heterotricyclic ring systems. The heretofore unknown nitrobenzenepentamine (9), formed in addition to benzenehexamine in reduction reactions of 1,3,5-trinitrobenzenetriamine, has also been obtained. Based on spectroscopic data, the structures of these two multiamines have been deduced from their condensation products with α-diketones, in the case of the new pentamine 9 from its first derivatives 7c-e of pyrazino[2,3-f]quinoxaline.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890204
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  • 153
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    Synthesis and Stereochemistry of the Dibromides of Exocyclic α,β-Unsaturated Ketones (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 651-654 
    Details
    ISSN: 0170-2041
    Keywords: Ketones ; α,β-Unsaturated Ketones ; Bromination ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese und Stereochemie der Dibromide von exocyclischen α,β-ungesättigten KetonenDie exocyclisch α,β-ungesättigten Ketone 1-6 addieren Brom unter Bildung der entsprechenden Dibromide 7-12. Mittels NMR-Methoden wurden die relativen Konfigurationen und die Stereochemie der Produkte bestimmt. Die Bromierung von 3-Benzylidenflavanon (3) und der analogen Thioverbindung 5 erwies sich als hoch stereoselektiv.
    Notes: The dibromides 7-12 have been synthesized by addition of bromine to exocyclic α,β-unsaturated ketones 1-6. The relative configurations and the stereochemistry of the products have been determined by NMR methods. Bromination of 3-benzylideneflavanone (3) and its thio analogue 5 proved to be highly stereoselective.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890208
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  • 154
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    Regioselektive Benzylierungen an Hydroxyalkyl-3-morpholinonen (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 665-669 
    Details
    ISSN: 0170-2041
    Keywords: Morpholinones ; Benzylation, selective ; Imidates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Regioselective Benzylations of Hydroxyalkyl-3-morpholinonesHydroxyalkylmorpholinones of type 2 can be selectively benzylated either at the nitrogen of the amide group, or at the carbonyl oxygen, or at the hydroxyl function, according to the reaction conditions employed. Attempts to benzylate with the aid of benzyl trichloroacetimidate (15) resulted in a “reimidation reaction” not yet described in the literature. All products are characterized unambiguously by their NMR spectra.
    Notes: Hydroxyalkylmorpholinone vom Typ 2 können je nach Reaktionsbedingungen am Amidstickstoff, an der Hydroxyl-Gruppe oder am Carbonylsauerstoff benzyliert werden. Beim Versuch der Benzylierung mittels Trichloracetimidsäure-benzylester (15) kommt es teilweise zu einer bis jetzt nicht beschriebenen „Umimidatisierung“. Alle Produkte werden durch NMR-Spektroskopie eindeutig identifiziert.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890210
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  • 155
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    Synthese von (+)-Taxodion (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 677-686 
    Details
    ISSN: 0170-2041
    Keywords: Iron carbonyl complexes ; (+)-Taxodion ; Terpenes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of (+)-TaxodioneA stereoselective synthesis of (+)-taxodione (1) starting from (-)-abietic acid (2) via the ironcarbonyl complex 4 is described. Conversion of the carboxyl function of 4 into a methyl group via 5 and 6 proceeds in excellent overall yield. The next steps are the introduction of oxygen functions in the positions 12 and 6. Oxidation with BSA yields the quinonemethide 1. The 1H- and 13C-NMR resonances of all compounds have been assigned.
    Notes: Eine stereoselektive Synthese von (+)-Taxodion (1) aus (-)-Abictinsäure (2) über den Eisencarbonyl-Komplex 4 wird beschrieben. Die Überführung der Carboxyl-Funktion von 4 in eine Methyl-Gruppe ist über 5 und 6 in sehr guter Gesamtausbeute möglich. Anschließend werden Sauerstoff-Substituenten gezielt in die Positionen 12 und 6 eingeführt. Mit BSA wird im letzten Schritt zum Chinonmethid 1 oxidiert. Die 1H- und 13C-NMR-Resonanzen aller Verbindungen sind eindeutig zugeordnet worden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890212
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  • 156
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    Eine neue Synthese von (S)-(+)-Glycerin-tosylat (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 691-693 
    Details
    ISSN: 0170-2041
    Keywords: (S)-Glycerol tosylate ; D-Ribono-γ-lactone ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Novel Synthesis of (S)-(+)-Glycerol TosylateEnantiomerically pure (S)-(+)-glycerol tosylate (3) was prepared from D-(+)-ribono-γ-lactone (4) in 43% overall yield.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890215
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  • 157
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    Ein Methanoditetrazolo-[1,3,6,8]tetrazecin aus 5-(Chlormethyl)tetrazol und Hexamethylentetramin (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 689-690 
    Details
    ISSN: 0170-2041
    Keywords: Methanoditetrazolo-[1,3,6,8]tetrazecine ; Hexamethylenetetramine ; Tetrazole, 5-(chloromethyl)- ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Methanoditetrazolo-[1,3,6,8]tetrazecine from 5-(Chloro-methyl)tetrazole and HexamethylenetetramineIn contrast to N-substituted 5-(chloromethyl)tetrazoles (1; R=alkyl, aryl), the parent compound 1 (R=H) reacts with hexamethylenetetramine to give the methanoditetrazolo-[1,3,6,8]tetrazecine 4, a rather unusual system. This compound which is also produced on reaction of 7 with formaldehyde occurs in the (6RS,13RS) form.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890214
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  • 158
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    Ein α-Methylanthrachinon aus Streptomyceten (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 699-701 
    Details
    ISSN: 0170-2041
    Keywords: α-Methylanthraquinones ; Streptomycetes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An α-Methylanthraquinone from StreptomycetesFrom cultures of several streptomycete strains producing isochromanquinone antibiotics (4, 5), 3,8-dihydroxy-1-methylanthraquinone-2-carboxylic acid (2b), one of the rare naturally occurring α-methylanthraquinones, was isolated. Native compounds of this group became known only as insect pigments (e.g. 1d) and later on as constituents of a few plants. A common biosynthesis of benzoisochromanquinones and α-methylanthraquinones is discussed.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890217
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  • 159
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    Die Synthese des Octacidomycins (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 719-726 
    Details
    ISSN: 0170-2041
    Keywords: Antibiotics ; Octacidomycin ; Oligocarboxylic acids ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Synthesis of OctacidomycinThe total synthesis of octacidomycin (1), a novel oligocarboxylic acid antibiotic, and some shorter new model acids (19, 21, 24) is described. Key compounds in a series of fragment condensations of C19-, C5- and C2-units are α,α′-bis(bromopentyl)-substituted azealic- (6) and 3-(benzyloxypropyl)malonic esters (7). A six-step synthesis yields bacteriostatically active octacidomycin (14=1). 14 and its octamethyl ester 15 are identical with the native products in all chemical and spectroscopic properties. Further combinations of fragments give tri-, tetra-, and pentacarboxylic acids. These demonstrate the flexibility of this widely variable synthetic method leading to new carboxylic acids and hydrocarbons.
    Notes: Die Totalsynthese von Octacidomycin (1), einem neuartigen Oligocarbonsäure-Antibioticum, und einigen kürzerkettigen, neuen Modellcarbonsäuren (19, 21, 24) wird beschrieben. Schlüsselverbindungen in einer Folge von Fragmentkondensationen von C19-, C5- und C2-Einheiten (Abb. 1) sind α,α′-bis(brompentyl)substituierte Azelainsäure- (6) und 3-(Benzyloxypropyl)malonsäureester (7). In einer sechsstufigen Synthese entsteht bakteriostatisch voll aktives Octacidomycin (14 = 1). 14 und dessen Octamethylester 15 sind mit den nativen Produkten chemisch und spektroskopisch identisch. Weitere Kombinationen von Fragmenten liefern Tri-, Tetra- und Pentacarbonsäuren. Sie zeigen die Flexibilität dieses weiträumig variierbaren, zu neuen Carbonsäuren und Kohlenwasserstoffen führenden Syntheseweges.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890220
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  • 160
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    Reaktionen der Methylencyclopropane, XI Asymmetrische Nickel(0)-katalysierte [3 + 2]-Cycloadditionen von Methylencyclopropanen mit chiralen Acrylsäure-Derivaten (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 739-750 
    Details
    ISSN: 0170-2041
    Keywords: Asymmetric induction ; Chiral acrylic acid derivatives ; Chiral 3-methylenecyclopentane derivatives ; [3+2] Cycloadditions, Ni(0)-catalyzed ; Methylenecyclopropanes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Methylenecyclopropanes, XI. - Asymmetric Nickel(0)-Catalyzed [3+2] Cycloadditions of Methylenecyclopropanes with Chiral Derivatives of Acrylic AcidThe nickel(0)-catalyzed codimerisation of methylenecyclclopropane 1a or 2,2-dimethylmethylenecyclopropane (1b) with the chiral derivatives of acrylic acid 2a-2f leads to the optically active 3-methylenecyclopentanecarboxylic esters 3a, 3c-3f, 4a, and 4c, or amides 3b and 4b in good yields. The diastereomeric excess accessible depends on the steric demand of the chiral auxiliaries, de values up to 98% can be achieved. Some improvements of the preparation of optically pure auxiliaries are also decribed.
    Notes: Bei der Nickel(0)-katalysierten Codimerisierung von Methylencyclopropan (1a) oder 2,2-Dimethylmethylencyclopropan (1b) mit den chiralen Acrylsäure-Derivaten 2a-2f werden die 3-Methylencyclopentancarbonsäureester bzw. -amide (3a-3f, 4a-4c) in guten Ausbeuten gewonnen, wobei, in Abhängigkeit von den sterischen Gegebenheiten der chiralen Hilfsstoffe, Diastereomerenüberschüsse bis zu 98% de erzielt werden. Einige Verbesserungen in der Darstellung der optisch reinen Hilfsgruppen werden ebenfalls beschrieben.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890222
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  • 161
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    Synthese von O-Glycopeptid-Sequenzen des N-Terminus von Interleukin-2 (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 751-769 
    Details
    ISSN: 0170-2041
    Keywords: Glycopeptide synthesis ; Interleukin-2 ; O-Glycoproteins ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of O-Glycopeptides of the N-Terminus of Interleukin-2The synthesis of a number of O-glycopeptides with different lengths of chain of between 3 and 10 amino acids that are part of the N-terminus of interleukin-2 is described. The key intermediate for the syntheses is O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-D-galactopyranosyl)-N-(9-fluorenylmethoxycarbonyl)-L-threonine tert-butyl ester (9b), to which suitably protected amino acids and peptides can be added C- or N-terminally. 9b is an element, which allows to insert glycosylated hydroxyamino acids with the Fmoc/tBu combination of protective groups, which are approved in peptide synthesis. During the syntheses peptide blocks are used. With the deprotected products it is possible to test the structural specificity of glycosyl transferases.
    Notes: Es wird eine Serie von O-Glycopeptiden mit unterschiedlicher Kettenlänge von 3-10 Aminosäuren synthetisiert, die Struktur-elemente des N-Terminus von Interleukin-2 darstellen. Schlüsselbaustein der Synthesen ist O-(2-Acetamido-3,4,6-tri-O-acetyl-2-desoxy-α-D-galactopyranosyl)-N-(9-fluorenylmethoxycarbonyl)-L-threonin-tert-butylester (9b), der sowohl C- wie auch N-terminal verlängert werden kann. Mit 9b liegt ein Baustein vor, der das Einfügen von glycosylierten Hydroxyaminosäuren mit der bei Peptidsynthesen bewährten Schutzgruppenkombination Fmoc/tBu in Peptidketten erlaubt. Bei dem Aufbau der Ketten wird von Blocksynthesen Gebrauch gemacht. Die Substrate eignen sich zur Überprüfung der Strukturspezifität von Glycosyltransferasen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890223
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  • 162
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    Photoaddition of 2-Pyridones and 2-Quinolones to Conjugated Dienes (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 781-788 
    Details
    ISSN: 0170-2041
    Keywords: Conjugated dienes ; Oxetanes ; Photoaddition ; 2-Pyridones ; 2-Quinolones ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photoaddition von 2-Pyridonen und 2-Chinolonen an konjugierte DieneBeim Bestrahlen von 2-Pyridonen 1 in Gegenwart von cyclisch konjugierten Dienen 2 erhält man [4 + 4]-Cycloadditions-Produkte. Einige der Photoprodukte sind thermisch nicht stabil und lagern sich bei Raumtemperatur zu [2 + 2]-Addukten um. Bestrahlung von 2-Pyridonen 1 und 2-Chinolon mit nicht cyclisch konjugierten Dienen führt zu [2 + 2]-Cycloadditions-Produkten und 2-substituierten Derivaten, wahrscheinlich über eine Oxetan-Zwischenstufe.
    Notes: Irradiation of 2-pyridones 1 in the presence of excess cyclic conjugated dienes 2 gave [4 + 4] cycloaddition products. Some of the photoproducts were thermally unstable and underwent rearrangement at room temperature to give [2 + 2] adducts. Irradiation of 2-pyridones and 2-quinolones with noncyclic conjugated dienes afforded [2 + 2] cycloaddition products and 2-substituted derivatives, the latter being derived probably from an oxetane intermediate.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890225
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  • 163
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    Studies on Amino Acids and Peptides, 13 Improved Synthesis of 5-Thioxo-L-proline and of Some N-Acyl and S-Alkyl Derivatives as Building Blocks in Peptide Synthesis (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 819-823 
    Details
    ISSN: 0170-2041
    Keywords: L-Proline, S-alkyl-5-thioxo-, N-acyl-5-thioxo- ; Peptide building blocks ; 5-Thioxo-L-proline ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We herein report an improved synthetic pathway to 5-thioxo-L-proline (2) (using R,S nomenclature, the L form here possesses the S configuration). Compound 2 is synthesized from naturally occurring 5-oxo-L-proline (1) at room temperature with 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide (3) (Lawesson′s reagent, LR). The synthesis is an improved version of our previously published method. The optical purity of 2 has been proven by thin-layer chromatography based on chiral ligand exchange. The synthesis of N-acyl and S-alkyl derivatives of 5-thioxo-L-proline (Top-OH), 5-thioxo-L-proline methyl ester (Top-OCH3), and the pseudodipeptide Boc-L-Phe-Top-OCH3 is also described.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890231
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  • 164
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    Studies on Cinnamonitriles: The Reaction of Cinnamonitriles with Cyclopentanone (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 935-936 
    Details
    ISSN: 0170-2041
    Keywords: Cinnamonitriles ; Cyclopentanone ; Indene ; Cyclopentapyran ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclopentanone reacts with arylidenemalononitriles 1a-c to give dihydro-4,6-indenedicarbonitriles 5a-c. Similarly, the diethyl dihydro-4,6-indenedicarboxylate derivative 6 is formed when treating ethyl α-cyanocinnamate (1d) with cyclopentanone. Cyclopenta[b]pyrans 5a-c are obtained from the reaction of diarylidene derivatives of cyclopentanone with malononitrile.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890246
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  • 165
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    Zur Synthese und Dimroth-Umlagerung von 4-(Dialkylamino)-2H-1,3,5-oxadiazin-2-thionen (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 931-934 
    Details
    ISSN: 0170-2041
    Keywords: 1,3,5-Oxadiazine-2-thiones ; 1,3,5-Thiadiazin-2-ones ; Chloroformamidines ; Ring transformation reactions ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Concerning the Synthesis and the Dimroth Rearrangement of 4-(Dialkylamino)-2H-1,3,5-oxadiazine-2-thionesThe title compounds 3 are readily obtained by reaction of N,N-dialkylchloroformamidines 2 with potassium thiocyanate. The amidines 2 can be prepared profitably from isocyanide dichlorides 1 with the aid of N-(trimethylsilyl)dialkylamines. The thiones 3 behave very sensitively towards acids and are rearranged completely to 4-(dialkylamino)-2H-1,3,5-thiadiazin-2-ones 4 by treatment with acetic acid.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890245
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  • 166
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    Synthesis of Mono- and Sesquiterpenoids, XVI Synthesis of (-)-Pereniporins A and B, Sesquiterpene Antibiotics from a Basidiomycete (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 939-943 
    Details
    ISSN: 0170-2041
    Keywords: (-)-Pereniporin A ; (-)-Pereniporin B ; Antibiotics ; Sesquiterpene ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Starting from (S)-3-hydroxy-2,2-dimethyl-1-cyclohexanone (5), the enantioselective total syntheses of (-)-pereniporins A (1) and B (2) were achieved in 33 steps (0.6% overall yield) and in 28 steps (1.8% overall yield), respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890248
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  • 167
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    Synthesis of (-)-Biopterin (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 963-967 
    Details
    ISSN: 0170-2041
    Keywords: Biopterin ; Aldol-type reaction, stereoselective ; (S)-Lactate, ethyl ; 1-Propanol, (1S,2S)-1-(2-furyl)-2-(trityloxy)- ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese von (-)-BiopterinFür die Synthese von (-)-Biopterin (1) dient das aus (S)-Milchsäure-ethylester gebildete (1S,2S)-1-(2-Furyl)-2-(trityloxy)-1-propanol (6) als Baustein für die Seitenkette.
    Notes: The synthesis of (-)-biopterin (1) was accomplished by employing (1S,2S)-1-(2-furyl)-2-(trityloxy)-1-propanol (6), derived from ethyl (S)-lactate, as building block for the side chain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890252
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  • 168
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    Pheromone Synthesis, CXV Synthesis of (Z)-2-Ochtoden-1-ol, (E)-2-Ochtoden-1-al, and (Z)-2-Ochtoden-1-al, the Pheromone Components of the Boll Weevil (Anthonomus grandis) (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 969-973 
    Details
    ISSN: 0170-2041
    Keywords: Boll weevil pheromone ; Pheromones ; 2-Ochtoden-1-ol ; 2-Ochtoden-1-al ; Olefin cyclization ; Olefin inversion ; Anthonomus grandis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Pheromonsynthesen, CXV. - Synthese von (Z)-2-Ochtoden-1-ol (E)-2-Ochtoden-1-al und (Z)-2-Ochtoden-1-al, den Pheromonkomponenten des Baumwollsamenkäfers (Anthonomus grandis)Es wird die Synthese von geometrisch reinem (Z)-2-Ochtoden-1-ol (1), (E)-2-Ochtoden-1-al (2) und (Z)-2-Ochtoden-1-al (3) aus Myrcen beschrieben.
    Notes: The synthesis of geometrically pure (Z)-2-ochtoden-1-ol (1), (E)-2-ochtoden-1-al (2), and (Z)-2-ochtoden-1-al (3) was achieved starting from myrcene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890253
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  • 169
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    Carboxy- and Cyano-Hydroxylation of Alkenes. Synthesis of 3-Hydroxy-4-amino Acids and Butyrolactones via the Isoxazoline Route (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 985-990 
    Details
    ISSN: 0170-2041
    Keywords: Carboxy-hydroxylation ; γ-Amino acids ; γ-Lactones ; Muscimol, dihydro- ; Isoxazolines ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Carboxy- und Cyanohydroxylierung von Alkenen. - Synthese von 3-Hydroxy-4-aminosäuren und Butyrolactonen nach der Isoxazolin-MethodeDichlor- und Dibromformaldoxime sind nützliche Komponenten bei 1,3-dipolaren Cycloadditionen. Sie lassen sich leicht und mit hohen Ausbeuten in situ durch Dihalogenierung von Glyoxalsäure-aldoxim mit N-Brom- und N-Chlorsuccinimid oder tert-Butylhypochlorit herstellen. Dehydrohalohalogenierung mit Kaliumhydrogencarbonat in Gegenwart von Alkenen liefert 3-Haloisoxazoline in einer Eintopf-Reaktion. Reduktion mit Eisenpentacarbonyl ergibt β-Hydroxynitrile. Methoxylierung und katalytische Reduktion führt zu β-Hydroxyestern. Allylalkohole und Allylamine werden mit Halogen-nitriloxiden in Butyrolactone(DL-Angelicalacton)bzw. DL-3-Hydroxy-4-aminosäuren (Carnitin, 4-Amino-3-hydroxybuttersäure) übergeführt. Die Lactonisierung erfolgt optimal durch Erhitzen der γ-Silyloxyester in Eisessig mit Kaliumhydrogensulfat als Katalysator. Ferner wird die Synthese von N-Boc-Dihydromuscimol beschrieben.
    Notes: Dichloro- and dibromoformaldoximes are useful 1,3-dipolar cycloaddition reagents. They are conveniently preparated in situ, in high yields by dihalogenation of glyoxalic acid aldoxime with N-bromo- and N-chlorosuccinimide or tert-butyl hypochlorite. Dehydrohalogenation with potassium hydrogen carbonate in the presence of alkenes gives 3-halo-isoxazolines in a one-pot reaction. Reduction with iron pentacarbonyl gives β-hydroxynitriles. Methoxylation and catalytic reduction give β-hydroxy esters. Allyl alcohols and allylamines are transformed with halonitrile oxides into butyrolactones (DL-angelica lactone) and DL-3-hydroxy-4-amino acids (carnitine, 4-amino-3-hydroxybutyric acid), respectively. The lactonization is best effected by heating the γ-silyloxy ester in acetic acid with potassium hydrogen sulfate as catalyst. A synthesis of N-Boc-dihydromuscimol is described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890255
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  • 170
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    Steroide mit einer 17-Spiro-dithiolanon-Struktur (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 997-1001 
    Details
    ISSN: 0170-2041
    Keywords: Steroids ; Androstane, derivative ; Antialdosteron test ; Vasoconstriction test ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Steroids with 17-Spiro-dithiolanone StructureUtilizing a newly developed cyclization reaction in the pregnane side chain, the compound 3 was transformed into the dithiolanones 6 and 7 which are of interest as potential diuretic agents. Compounds 13a - 13c, possessing a structural similarity to corticosteroids, can be prepared from the corresponding 17-(acyloxy)-21-(mesyloxy) derivatives 12a - 12c by treatment with a 10-fold excess of potassium thioacetate.
    Notes: Mit Hilfe einer neuen Abwandlung in der Pregnan-Seitenkette von 3 wird die Synthese der Dithiolanone 6 und 7 als potentiell wirksame Diuretica beschrieben. Die corticoidnahen Strukturen 13a - 13c mit einer Dithiolanon-Seitenkette lassen sich aus den entsprechenden 17-(Acyloxy)-21-(mesyloxy)-Derivaten 12a - 12c durch Behandlung mit einem 10fachen molaren Überschuß an Kaliumthioacetat darstellen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890257
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  • 171
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    Reactions of 4-(Dicyanomethylene)-3-methyl-1-phenyl-2-pyrazolin-5-one Towards Amines and Phenols (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 1037-1040 
    Details
    ISSN: 0170-2041
    Keywords: 2-Pyrazolin-5-one derivatives ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3-Methyl-1-phenyl-2-pyrazoline-4,5-dione (3) condenses readily with malononitrile in refluxing ethanol to yield 4-(dicyanomethylene)-3-methyl-1-phenyl-2-pyrazolin-5-one (4). Compound 4 readily reacts with aliphatic, aromatic, and heterocyclic amines to yield 4-substituted (aminocyanomethylene)-3-methyl-1-phenyl-2-pyrazolin-5-ones (8). o-Substituted arylamines afford also 4-substituted (arylcyanomethylene)pyrazolones, which readily cyclize to give the 4-azolylidene pyrazolones 9a-c. Secondary and tertiary amines and activated phenols condense with 4 by hydrogen cyanide elimination to yield compounds 10a-c and 10a, b, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890262
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  • 172
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    Synthesis of Malonaldehyde Monoacetals (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 1045-1047 
    Details
    ISSN: 0170-2041
    Keywords: Hydrolysis, selective ; Malonaldehyde ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a series of malonaldehyde monoacetals is described. Selective hydrolysis or transacetalisation of 1,1,3,3-tetramethoxypropane and its analogues was proved to be a very general technique.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890264
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  • 173
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    The First Condensation Product of Malononitrile with Ribose (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 1049-1049 
    Details
    ISSN: 0170-2041
    Keywords: D-Ribose ; Malononitrile ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For the first time the 2-amino-3-furancarbonitrile 1 could be obtained as condensation product of ribose with malononitrile in the presence of zinc chloride.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890265
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  • 174
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    Synthesis of a Renin Inhibitor of the Azapeptide Type (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 1085-1087 
    Details
    ISSN: 0170-2041
    Keywords: Azapeptides ; Renin inhibitor ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese eines Renin-Inhibitors vom Azapeptid-TypDas Azapeptid-Derivat 12 wird in einer 7-Stufen-Synthese durch Kupplung der Komponenten 5 und 11 im letzten Schritt erhalten. Während der Azaaminosäure-Rest in 5 durch eine Hydrazin/Isocyanat-Addition aufgebaut wird, werden die übrigen Kupplungen nach der Carbodiimid/HOBt-Methode durchgeführt. Verbindung 12 erwies sich als Inhibitor des Enzyms Renin.
    Notes: The azapeptide derivative 12 is obtained in a 7-step synthesis by coupling the components 5 and 11 in the last step. Whereas the azaamino acid residue in 5 is generated by a hydrazine/isocyanate addition, the other coupling steps are done using the carbodiimide/HOBt method. Compound 12 could be shown to inhibit the enzyme renin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890273
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  • 175
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    Konformation von Anthranilsäurepeptiden, 2 Anthranilsäure-Glycin-Sequenzen als Bauteil „schalenförmiger“ Cyclopeptide (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 1089-1092 
    Details
    ISSN: 0170-2041
    Keywords: Peptides ; Anthranilic acid peptides ; Quantummechanical calculations ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Conformation of Anthranilic Acid Peptides, 2. - Anthranilic Acid-Glycine Sequences as Parts of “Bowl-Shaped” CyclopeptidesThe cyclopeptides 1 and 2 are synthesized in four steps from N-(tert-butoxycarbonyl)(Boc)anthranilic acid and glycine methyl ester hydrochloride. One- and two-dimensional NMR methods are used to find the preferred conformations. Intramolecular hydrogen bridges are confirmed by the temperature gradients of the chemical shifts of the amide protons and by NOE results. All data support a structure where the macrocycle 2 adopts a bowl-shaped conformation. But fast ring inversion is observed on the NMR time-scale for both cycles 1 and 2. Force-field calculations (MMP2/H) and quantummechanical calculations (AM 1) support the conformation derived from NMR spectra.
    Notes: Die vierstufige Synthese der Cyclopeptide 1 und 2 aus N-(tert-Butoxycarbonyl)(Boc)anthranilsäure und Glycin-methylester-hydrochlorid wird beschrieben. Die Ringverbindungen werden durch ein- und zweidimensionale NMR-Methoden auf Vorzugskonformationen untersucht. Aus den Temperaturgradienten der chemischen Verschiebung der Amidprotonen und den NOE-Ergebnissen lassen sich Hinweise auf intramolekulare Wasserstoffbrücken ableiten, die in 2 mit einem schalenförmigen, peptidischen Makrocyclus vereinbar sind. Für beide beschriebenen Peptide 1 und 2 wird jedoch eine in der NMR-Zeitskala schnelle Ringinversion beobachtet. Kraftfeldmethoden (MMP2/H) und quantenmechanische Rechnungen (AM 1) dienen zur Unterstützung der Konformationsvorschläge.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890274
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  • 176
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    Glycosyl Imidates, 42 Selectively Protected Lactose and 2-Azido Lactose, Building Blocks for Glycolipid Synthesis (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 1099-1106 
    Details
    ISSN: 0170-2041
    Keywords: Lactose ; Azidolactose ; Glycosyl acceptors ; Glycosyl donors ; Regioselective protection ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Glycosylimidate, 42. - Selektiv geschützte Lactose und 2-Azidolactose als Bausteine für die Synthese von GlycolipidenDurch regioselektive Alkylierung der 3′-OH-Gruppe von Benzyl-β-lactosid mit der Stannylierungsmethode wurden die 3′-OH- und 4′-OH-ungeschützten Lactosederivate 5 und 10 sowie das 4′-OH-ungeschützte Lactosederivat 9 hergestellt, das aufgrund seiner unterschiedlichen Schutzgruppe für 3′-OH für weitere Umwandlungen geeignet ist. Diese Bausteine sind wertvolle Glycosylakzeptoren für die Synthese von Glycolipiden. Zur Synthese von Glycosyldonoren mit Gal(β1 → 4)GlcNAc-Struktur wurde das 2-Azidolactosederivat 19 verwendet. Durch regioselektive Alkylierung der 3′-OH-Gruppe mit der Stannylierungsmethode sowie durch Anwendung anderer regioselektiver Schutzgruppen-Verfahren wurden die Trichloroacetimidate 17, 24 und 30 hergestellt, die aufgrund ihrer speziellen Schutzgruppen für 3′-OH, 4′-OH und 6′-OH für weitere Umwandlungen geeignet sind.
    Notes: Performing regioselective alkylation at 3′-OH of benzyl β-lactoside 1 by the stannylation method we prepared the 3′-OH- and 4′-OH-unprotected lactose derivatives 5 and 10 and the 4′-OH-unprotected lactose derivative 9 containing a different protecting group at 3′-OH, suitable for further transformations. These building blocks are valuable glycosyl acceptors in glycolipid synthesis. For the synthesis of glycosyl donors with Gal(β1 → 4)GlcNAc-structure we used the 2-azido lactose derivative 19. By regioselective alkylation of 3′-OH by the stannylation method and application of other common regioselective protecting procedures we prepared the trichloroacetimidates 17, 24, and 30 containing special protecting groups at 3′-OH, 4′-OH, and 6′-OH which are suitable for further transformations in these positions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890276
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  • 177
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    Synthesis of Polymerizable Hexose Derivatives (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 1127-1130 
    Details
    ISSN: 0170-2041
    Keywords: Carbohydrates ; Hexose derivatives, polymerizable ; Hydrogels ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymerizable esters of methacrylic and acrylic acid with di-O-isopropylidenehexoses as alcohol components have been synthesized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890280
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  • 178
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    Reaction of Some Cyclic Dienamines of Carbothioic Acid Anilides with Malononitrile (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 1131-1134 
    Details
    ISSN: 0170-2041
    Keywords: Dienamines, cyclic ; Carbothioic acid anilides ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Morpholino enamines 1,2, and 3 of 2-(cyclopentylidene)-1-cyclopentanone, 2-(1-cyclohexenyl)-1-cyclohexanone, and 2-(cycloheptylidene)-1-cycloheptanone, respectively, react with aryl isothiocyanates to yield 1-cycloalkene-1-carbothioic acid anilides 4, 5, and 6, respectively. Compounds 4 and 5 react with malononitrile to give the hexahydroisoquinolines 9 and the cyclopenta[c]pyridine 11, respectively.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890281
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  • 179
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    Facile Reductive Cleavage of Oximes with a Low-Valent Titanium Reagent (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 1139-1140 
    Details
    ISSN: 0170-2041
    Keywords: Oximes, cleavage of ; Titanium, low-valent ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The application of the TiCl4/SnCl2 reagent system in the reductive deoximation of various ketoximes and aldoximes under mild conditions is reported. The corresponding carbonyl compounds were formed in high yields.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890283
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  • 180
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    Nitriles in Heterocyclic Synthesis: A Novel Synthesis of 2-Amino-3-pyrrolecarbonitriles (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 1145-1146 
    Details
    ISSN: 0170-2041
    Keywords: 3-Pyrrolecarbonitriles, 2-amino- ; Malononitriles, phenylacyl ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Amino-3-pyrrolecarbonitriles are prepared by the reaction of phenacylmalononitrile with primary aromatic amines using a catalytical amount of concd. HCl.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890285
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  • 181
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    On the Chemistry of Latrunculins A and B (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 1171-1188 
    Details
    ISSN: 0170-2041
    Keywords: Actin ; Latrunculins ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Über die Chemie der Latrunculine A und BDas chemische Verhalten von Latrunculin A (1) und B (2) (Lat A und B) unter verschiedenen Reaktionsbedingungen wird beschrieben. Die Kombination der Makrolid-, THP-Lactol- und 2-Thiazolidinon-Ringsysteme führt zu interessanten unerwarteten chemischen Umwandlungen. Die Strukturen zweier neuer, aus Latrunculia magnifica isolierter Lats, 6,7-Epoxy-Lat A (3) und Lat M (4), werden diskutiert.
    Notes: The chemical behavior of latrunculins A (1) and B (2) (Lat A and B) under a variety of reaction conditions is described. The combination of the macrolide, the THP-lactol, and the 2-thiazolidinone rings was found to result in interesting unpredicted chemical transformations. The structures of two new Lats, 6,7-epoxy-Lat A (3) and Lat M (4) isolated from Latrunculia magnifica are discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890289
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  • 182
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    Enantiomerically Pure Building Blocks from Sugars, 10 2,3-Dihydropyranones with Contiguous Chiral Centers: Practical Routes for Their Aquisition and Evaluation of their Reaction Potential (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 1163-1170 
    Details
    ISSN: 0170-2041
    Keywords: Pyranoid enediolones ; Glycal esters, hydroxy-3-oxo- ; 4-Pyranones, dihydro- ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Enantiomerenreine Bausteine aus Zuckern, 10. - 2,3-Dihydropyranone mit benachbarten Chiralitätszentren: Ein praktikabler Weg zu ihrer Darstellung und Ermittlung ihres ReaktionspotentialsEin praktikables, in präparativem Maßstab durchführbares Verfahren zur Überführung von D-Glucose in pyranoide Endiolonester mit (R,R)-Konfiguration in benachbarten Chiralitätszentren wird beschrieben. Die vierstufige Reaktionsfolge beinhaltet Hydrolyse des leicht zugänglichen Bis-acetonids der α-D-ribo-Hexos-3-ulose (12) und Basen-induzierte Acylierung in den beiden letzten Stufen; sie liefert die Acetyl-(3), Benzoyl-(4), und Pivaloyl-Derivate (6) der Dihydropyranone in Gesamtausbeuten über 40%. Noch einfacher zugänglich ist das von D-Maltose abgeleitete Dihydropyranon 11 (69%), und zwar durch Tieftemperaturbenzoylierung und nachfolgende DMSO/Acetanhydrid-Behandlung. - Mit dem Tribenzoat 4 als Modellverbindung wurden präparativ brauchbare, einfach durchführbare Additionsreaktionen untersucht; sie führten zu einem ungewöhnlichen Chiralitätstransfer von einer Seite des pyranoiden Rings auf die andere bei Baseninduzierter Addition von Methanol (4 → 23), zu C-verzweigten (4 → 18) bzw. C-extendierten Produkten (4 → 19) und zu einem eigenartigen Aceton-Photoaddukt mit O,O-Isopropyliden-Gruppe (4 → 24). Die diesen Additionen zugrundeliegenden Mechanismen sowie die erzielbaren Regio- und Diastereoselektivitäten werden diskutiert.
    Notes: A practical, large-scale adaptable four-step procedure has been developed for the conversion of D-glucose into pyranoid enediolone esters with (R,R)-configuration in contiguous chiral centers, involving hydrolysis of the readily accessible bis-acetonide of α-D-ribo-hexos-3-ulose (12) and base-mediated acylation. The sequence provides the acetyl (3), benzoyl (4) and pivaloyl (6) dihydropyranones in overall yields well exceeding 40%, whilst the maltose-derived glucosyloxy-substituted analogue 11 is accessible even more efficiently (69%) by low-temperature benzoylation followed by DMSO/acetic anhydride treatment. - With the tribenzoate 4 as a model simply feasible addition reactions of preparative interest were evaluated, resulting in a unique transfer of chirality from one side of the pyranoid ring to the other upon treatment with methanol/K2CO3 (4 → 23), in C-branching (4 → 18) or C-extension (4 → 19), and in an unusual photoaddition of acetone to an O,O-isopropylidene-dihydropyrane (4 → 24). Particular attention is given to rationalization of the mechanisms underlying these additions and the regio- and diastereoselectivities attainable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890288
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  • 183
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    Notizen/Notes Formation of Trisubstituted 1,2,4-Triazoles in the Cyclodehydration of 2-Hydrazinothiazoles: Competition of Two Reaction Routes (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 75-77 
    Details
    ISSN: 0170-2041
    Keywords: Cyclodehydration of 2-hydrazinothiazoles ; Thiazolo[2,3-c]-s-triazoles ; 1,2,4-Triazoles, trisubstituted ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The intramolecular cyclodehydration of ethyl (2-hydrazinothiazol-4-yl)acetates 1a - f has been re-examined. The reactions yield the desired thiazolo[2,3-c]-s-triazoles 2a - f together with the unexpected trisubstituted 1,2,4-triazoles 3a - f.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890114
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  • 184
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    Preparation of New Terpenyl β-D-Glucopyranosides by a Modified Königs-Knorr Procedure (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 79-81 
    Details
    ISSN: 0170-2041
    Keywords: Königs-Knorr procedure ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ten new hemi- and monoterpenyl β-D-glucopyranosides have been prepared by a modification of the Königs-Knorr procedure which utilises silver fluoroacetate as a soluble catalyst coupled with the introduction of a basic ion-exchange resin to effect the deacetylation step. Most of these compounds could not be obtained in acceptable yields using the classical procedure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890115
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  • 185
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    Synthese chiraler Liposomenbausteine mit s-Triazin als verknüpfende Partialstruktur (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 51-57 
    Details
    ISSN: 0170-2041
    Keywords: Amphiphiles, chiral ; Liposomes ; s-Triazine ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Chiral Liposome Building Blocks with s-Triazine as Linking Unit1)In order to synthesize a variable system of well-defined one- and two-chain chiral amphiphiles that are able to form liposomes, we choose s-triazine as linking unit between the lipophilic and hydrophilic moieties. The lipophilic part is made of long-chain alcohols or alkylamines, whereas the hydrophilic part of the molecules is formed by the trifunctional amino acids L-cysteine, L-serine, or L-lysine. These are linked to the s-triazine with their ω-functional group. Because of the amino acid structure of the new lipids it is possible to examine their optical purity by thin-layer chromatography. On the investigation of their liposome-building properties only the cysteine amphiphiles with two alkyl chains are found to be capable of forming vesicles.
    Notes: Um ein variables System ein- und zweikettiger chiraler Amphiphile zu synthetisieren, die sich als Liposomenbausteine eignen, wurde s-Triazin als Verknüpfungseinheit zwischen lipophilem und hydrophilem Molekülteil ausgewählt. Der lipophile Teil besteht aus langkettigen Alkoholen oder Alkylaminen, während der hydrophile Teil der Moleküle durch die trifunktionellen Aminosäuren L-Cystein, L-Serin oder L-Lysin gebildet wird. Diese sind über ihre ω-Funktion mit dem s-Triazin verbunden. Aufgrund der Aminosäurestruktur der neuen Lipide ist eine dünnschichtchromatographische Kontrolle ihrer optischen Reinheit möglich. Bei der Untersuchung der neuen Verbindungen auf ihre Eignung als Vesikelbausteine erweisen sich nur die zweikettigen Cystein-Amphiphile als Liposomenbildner.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890111
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  • 186
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    Diazepines, 27. Effects of Substituents on the Bromination of 2,3-Dihydro-1,4-diazepinium Salts (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 133-135 
    Details
    ISSN: 0170-2041
    Keywords: Bromination ; Diazepinium salts, dihydro ; Steric effects, long-range ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Diazepine, 27. - Substituenten-Einfluß auf die Bromierung von 2,3-Dihydro-1,4-diazepinium-SalzenDie Bromierung der Ringposition 6 von 2,3-Dihydro-1,4-diazepinium-Salzen 1 sowie der p-Stellung von 6-Phenylresten wird sterisch nicht nur durch Substituenten in vicinalen Ringpositionen sondern auch durch solche in den Stellungen 1, 2 und 4 behindert.
    Notes: Bromination at the 6-position of 2,3-dihydro-1,4-diazepinium salts 1 or at the p-position of a 6-phenyl substituent is subject to steric hindrance, not only by substituents at vicinal sites in the ring(s), but also by substituents at the 1-, 2-, and 4-positions.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890127
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  • 187
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    Synthese von 14,17-überbrückten 11β-Arylsteroiden (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 151-158 
    Details
    ISSN: 0170-2041
    Keywords: Antiprogestational activity ; Steroids, 11β-aryl-substituted ; Steroids, 14,17-ethano-bridged ; [4 + 2] Cycloaddition of steroidal 14,16-dienes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of 14,17-Bridged 11β-ArylsteroidsThe search for new progesterone antagonists led to the synthesis of 14,17-bridged 11β-arylsteroids. The key step was a stereo- and regioselective [4 + 2] cycloaddition of electron-deficient olefins to steroidal 14,16-dienes. The resulting new structures were examined with respect to progesterone receptor binding and to anti-progestational activity.
    Notes: Auf der Suche nach neuen Progesteron-Antagonisten wurden 14,17-überbrückte 11β-Arylsteroide synthetisiert. Schlüsselschritt des Verfahrens war die stereo- und regioselektive [4 + 2]-Cycloaddition elektronenarmer Olefine an steroidale 14,16-Diene. Die auf diese Weise zugänglichen neuen Strukturen wurden auf Progesteronrezeptor-Affinität und antigestagene Wirkung geprüft.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890130
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  • 188
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    A Simple Way to 3-[(1R,2S,5R and 5S)-5-Methoxymethoxy-2-methyl-1,2-epoxycyclohexyl]propanal, a Synthon for the Total Biomimetic Synthesis of (-)-Progesterone (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 207-209 
    Details
    ISSN: 0170-2041
    Keywords: Baeyer-Villiger reaction ; (-)-Progesterone ; Steroids ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cyclohexylpropanals 21 and 22 were obtained in a 5-step synthesis, starting from the hydroxy diketone 5. Rearrangement of the hydroxy lactones 9 and 10 into epoxy esters 19 and 20, respectively, by potassium hydride in HMPA and 2-iodopropane was the key step of this synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890140
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  • 189
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    Enantioselektive Phasentransfer-Katalyse durch optisch aktive Kronenether (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 181-185 
    Details
    ISSN: 0170-2041
    Keywords: Phase-Transfer catalysis, enantioselective ; Crown ethers, chiral ; Cyanide addition to unsaturated ketones ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Enantioselective Phase-Transfer Catalysis by Optically Active Crown Ethers1)1,2-Bis(hydroxymethyl)-15-crown-5 (1a), its dibenzyl ether (1b), and a series of esters with substituted benzoic acids (3) were probed as enantioselective phase-transfer catalysts. Optical yields were observed in epoxidations of unsaturated ketones by hypochlorite and in cyanide additions to such compounds. The maximum ee value was 45%. Polar side groups of the optically active crown ethers proved to be vital for enantiomeric excesses.
    Notes: 1,2-Bis(hydroxymethyl)-15-krone-5 (1a), ihr Dibenzylether (1b) und eine Anzahl von Estern mit substituierten Benzoesäuren (3) wurden als enantioselektive Phasentransfer-Katalysatoren erprobt. Optische Ausbeuten wurden bei der Epoxidierung von ungesättigten Ketonen mit Hypochlorit und bei der Cyanid-Addition an solche Verbindungen beobachtet, wobei das erreichte Maximum bei 45% ee lag. Polare Seitengruppen der optisch aktiven Kronenether erwiesen sich als notwendig für Enantiomerenüberschüsse.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890135
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  • 190
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    Verbesserte Synthese einiger 3,7-Dicyan-1,5-dimethylsemibullvalene aus 1,5-Dimethylbicyclo[3.3.0]octan-3,7-dion (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 191-196 
    Details
    ISSN: 0170-2041
    Keywords: 3,7-Semibullvalenedicarbonitriles ; Bicyclo[3.3.0]octadiene-3,7-dicarbonitriles ; NBS Bromination ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Improved Synthesis of 3,7-Dicyano-1,5-dimethylsemibullvalenes from 1,5-Dimethylbicyclo[3.3.0]octane-3,7-dione1)The mixture of the isomeric unsaturated dinitriles C2/Cs-3 (2:1) is brominated by N-bromosuccinimide in dichloromethane to afford more than 18 products, which were separated in part through chromatography. Besides the known 2,4,8-tribromodinitrile 8a and tetrabromodinitriles 8b and 9, double bond isomers of 4-bromodinitriles were isolated (as mixtures exo-4/exo-5 = 4:1 and endo-4/endo-5 = 3:1) as well as the dibromodinitriles exo-6, endo-6, and 7. The structures of the products are deduced from proton and carbon-13 spectra. The configuration of the 4-bromodinitriles 4 and 5 is assigned through comparison of HPLC retention times. Zinc-copper couple in tetrahydrofuran smoothly debrominates the dinitriles exo-6 and 8a to yield the 3,7-dicyanosemibullvalenes 1a and b, respectively. Deuterated dibromo-3,7-dicyanosemibullvalenes are prepared from the α-deuterated bicyclooctanedione [D8]-2. A kinetic isotope effect of 2-3 is found for the bromination of the allylic positions of the dinitriles C2/Cs-[D6]-3.
    Notes: Bromierung eines Gemisches der isomeren ungesättigten Dinitrile C2/Cs-3 (2:1) mit N-Bromsuccinimid in Dichlormethan ergibt über 18 Produkte, die zum Teil chromatographisch getrennt wurden. Neben dem 2,4,8-Tribrom- (8a) und den Tetrabromdinitrilen 8b und 9, die bereits bekannt waren, werden Gemische doppelbindungsisomerer 4-Bromdinitrile (exo-4/exo-5 = 4:1 und endo-4/endo-5 = 3:1) sowie die Dibromdinitrile exo-6, endo-6 und 7 isoliert. Die Struktur der Produkte wird aus 1H- und 13C-NMR-Spektren abgeleitet, die Konfiguration der 4-Bromdinitrile 4 und 5 durch Vergleich von HPLC-Retentionszeiten. Zink/Kupfer in Tetrahydrofuran debromiert die Dinitrile exo-6 und 8a glatt zu den 3,7-Dicyansemibullvalenen 1a bzw. b Aus dem α-deuterierten Bicyclooctandion [D8]-2 werden deuterierte 3,7-Dicyansemibullvalene hergestellt. Dabei zeigt die Allylbromierung der Dinitrile C2/Cs-[D6]-3 einen kinetischen Isotopeneffekt von ca. 2-3.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890137
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  • 191
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    Studien zur Synthese von Mitomycinen. 6. Funktionalisierung von Benzopyrrolizinen in 1,2-Stellung (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 239-246 
    Details
    ISSN: 0170-2041
    Keywords: Mitomycins ; Cytostatica ; 3H-Benzopyrrolizidines ; cis-Hydroxylation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on the Synthesis of Mitomycins, 61). - Functionalization of Benzopyrrolizines in 1,2-PositionBenzopyrrolizinones 4, accessible from dihydro derivatives 3 on several routes, form cis-diols 8 on reaction with N-methylmorpholine N-oxide in the presence of small amounts of OsO4. Diols 8 could be protected selectively. Reduction of the lactame group in 3d with production of 14b is effected by BH3/dimethyl sulfide. An indirect reduction of 4d is achieved by addition of phenylselenyl hydride and reaction of 15a with BH3/THF. Oxidative elimination of the phenylselenyl group in 15b gave the first 3H-benzopyrrolizine 16 with an electron-donating substituent in position 9. 16 easily isomerizes to give the 9H-tautomer 17.
    Notes: Benzopyrrolizinone 4, die aus Dihydroderivaten 3 auf mehreren Wegen zugänglich sind, bilden mit N-Methylmorpholin-N-oxid in Gegenwart geringer Mengen OsO4 cis-Diole 8, die differenziert geschützt werden können. Eine Reduktion der Lactamgruppe von 3d unter Bildung von 14b gelingt mit BH3/Dimethylsulfid. 4d ließ sich indirekt reduzieren: Addition von Phenylselenwasserstoff ergab 15a, das in 15b übergeführt wurde. Durch oxidative Eliminierung der Phenylselenylgruppe konnte daraus erstmals ein 3H-Benzopyrrolizin 16 mit elektronenreichem Substituenten in 9-Stellung erhalten werden, das leicht zum 9H-Tautomeren 17 isomerisiert. Eine Bishydroxylierung von 16 zum Glycol 18 gelingt ohne Isomerisierung in guten Ausbeuten.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890146
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  • 192
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    Synthese der Hydroxypiperidinalkaloide (±)-Cassin, (±)-Spectalin, (±)-Spicigerin-methylester, der (±)-Azimsäure und (±)-Carpamsäure (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 255-261 
    Details
    ISSN: 0170-2041
    Keywords: Alkaloids ; Piperidine alkaloids ; 3-Pyridinols; 2,6-dlialkylated ; Bromine-lithium exchange and alkylation, regiospecific ; Hydrogenation of 3-pyridinols ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of the Piperidine Alkaloids (±)-Cassine, (±)-Spectaline, (±)-Spicigerine Methyl Ester and of (±)-Azimic Acid and (±)-Carpamic AcidThe piperidine alkaloids (±)-cassine (1), (±)-spectaline (2), (±)-spicigerine methyl ester (3), (±)-azimic acid (4), and (±)-carpamic acid (5) have been synthesized stereoselectively in the following way: In the SEM ether 7 of 2,6-dibromo-3-pyridinol (6) the bromine atom in position 2 can be regiospecifically exchanged with nBuLi to give 8. Reaction of 8 with methyl iodide gave the key compound 9 exclusively. In the presence of Kumada′s NidpppCl2 catalyst in ether solution 9 reacts with the Grignard reagents from the bromides 14-18 to give the products 19-23. Methanolysis of the products gave the substituted 3-pyridinol derivatives 24-28. Subsequent acetalisation led to 29, 30 and hydrolysis to 31, 32. Hydrogenation of 28-32 with Rh on alumina catalyst and 90 bar pressure gave exclusively the (±) products 33, 34, 3, 4, and 5 with (2r,3c,6c) configuration. Hydrolysis of the ethylene acetal group in 33 and 34 gave (±)-1 and (±)-2.
    Notes: Die Piperidinalkaloide (±)-Cassin (1), (±)-Spectalin (2), (±)-Spicigerin-methylester (3) sowie (±)-Azimsäure (4) und (±)-Carpamsäure (5) werden stereoselektiv synthetisiert: Im SEM-Ether 7 des 2,6-Dibromo-3-pyridinols (6) erfolgt bei der Reaktion mit nBuLi ein regiospezifischer Austausch des Bromatoms in Position 2. Die entstandene Li-Verbindung 8 läßt sich mit Methyliodid zur Schlüsselverbindung 9 methylieren. Diese reagiert in Gegenwart von Kumadas NidpppCl2-Katalysator in Ether mit den Grignard-Reagenzien aus den Bromiden 14-18 zu den 6-substituierten Pyridinen 19-23. Methanolyse und Hydrolyse liefern die 3-Pyridinol-Derivate 24-28 und durch nachfolgende Acetalisierung 29, 30 sowie durch Hydrolyse 31, 32. Die Hydrierung von 28-32 mit Rh auf Alox-Katalysator unter 90 bar Druck ergibt ausschließlich die (±)-Produkte 33, 34, 3, 4 und 5 mit (2r,3c,6c)-Konfiguration. Hydrolyse der Ethylenacetalgruppe in 33 und 34 ergibt (±)-1 und (±)-2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890148
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  • 193
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    Mehrstufige reversible Redoxsysteme, LIII. 4,4′-Bipyridin-1,1′-diylbisborane (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 299-301 
    Details
    ISSN: 0170-2041
    Keywords: Bipyridinediylbisboranes ; Redox systems ; Cyclovoltammetry ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Multistep Reversible Redox Systems, LIII1). - 4,4′-Bipyridine-1, 1′-diylbisboranesThe 2:1 adducts 1b-1e of boranes with 4,4′-bipyridine have been synthesized. The donor strength of the boranes is reflected in the UV and 1H-NMR spectra as well as in the redox properties of the adducts which are compared to 4,4′-bipyridine and its bisquaternary salt 1a. The adducts 1b and 1c constitute a new type of two-step redox systems in which the radical anions show high thermodynamic stability [KSEM(1b) = 1.23 ⋅ 104, KSEM(1c) = 1.17 ⋅ 109].
    Notes: Die 2:1-Addukte 1b-1e von Boranen an 4,4′-Bipyridin werden beschrieben. Die Donorstärke der Borane spiegelt sich in den UV-und 1H-NMR-Spektren sowie dem Redoxverhalten der Addukte, die mit 4,4′-Bipyridin (BP) und dessen Bisquartärsalz 1a verglichen werden. 1b und 1c stellen neuartige zweistufige Redoxsysteme dar mit hoher thermodynamischer Stabilität der Radikalstufe [KSEM(1b) = 1.23 ⋅ 104, KSEM(1c) = 1.17 ⋅ 109].
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890152
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  • 194
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    Synthetic Microbial Chemistry, XXI. Synthesis of Differanisole A, an Inducer of Differentiation (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 303-305 
    Details
    ISSN: 0170-2041
    Keywords: Differanisole A ; Leukemia cells; differentiation inducer against ; Differentiation inducer ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of differanisole A (3,5-dichloro-2-hydroxy-4- methoxy-6- propylbenzoic acid, 1) was achieved in five steps from 2-pentanone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890153
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  • 195
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    Terpenes and Terpene Derivatives, XXV. Oreodaphnenol - A Sesquiterpene Alcohol with a New Carbon Skeleton (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 307-308 
    Details
    ISSN: 0170-2041
    Keywords: Essential oil ; Phoebe oil ; Lauraceae ; Oreodaphne porosa ; Sesquiterpenes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: From the essential oil of Oreodaphne porosa (commercial “Phoebe oil”) a sesquiterpene alcohol with a new carbon skeleton, oreodaphnenol (1), could be isolated. The structure and relative stereochemistry were deduced from detailed NMR studies and by degradation to the ketone 2.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890154
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  • 196
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    Steroids, XLI. Neighbouring Group Participation, X. Neighbouring Group Participation and Fragmentation During the Solvolysis of the Epimers of 3-Methoxy-16-(tolylsulfonyloxymethyl)-estra-1,3,5(10)-trien-17-ol (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 263-267 
    Details
    ISSN: 0170-2041
    Keywords: Estra-1,3,5(10)-trien-17-ol, 16-hydroxymethyl-3-methoxy- ; Neighbouring Group Participation ; Steroid oxetane ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Steroide, XLI1). - Nachbargruppen-Beteiligung, X2). - Nachbargruppen-Beteiligung und Fragmentierung während der Solvolyse der Epimeren von 3-Methoxy-16-(tolylsulfonyloxymethyl)estra-1,3,5(10)-trien-17-olAus den vier Epimeren von 16-Hydroxymethyl-3-methoxyestra-1,3,5(10)-trien-17-ol wurden die 16-Tolylsulfonyloxymethyl-17-acetate 1b, 3b, 4b, 7b und -17-tetrahydropyranyl-acetale 1c, 3c, 4c, 7c hergestellt. Alkalische Methanolyse von 1b und 7b führt zu an den D-Ring des Steroid-Skeletts kondensierten α- und β-Oxetanen. Umsetzung von 3b und 4b führt zum Fragmentierungsprodukt 5. Unter gleichen Bedingungen entstehen aus 1c, 3c, 4c, 7c die 16-Methoxymethyl-Derivate 1d, 3d, 4d, 7d.
    Notes: The four possible isomers of 16-hydroxymethyl-3-methoxyestra-1,3,5(10)-trien-17-ol were converted into the 16-tolylsulfonyloxymethyl-17-acetoxy esters 1b, 3b, 4b, 7b and into the 16-tolylsulfonyloxymethyl-17-tetrahydropyranyl acetals 1c, 3c, 4c, 7c. On alkaline methanolysis of 1b and 7b, the α and β oxetanes 2 and 8 condensed to the D ring in the sterane skeleton were formed, while 3b and 4b yielded the fragmented product 5. Under similar experimental conditions, the acetals 1c, 3c, 4c, 7c were transformed into the 16-methoxymethyl derivatives 1d, 3d, 4d, 7d.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890149
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  • 197
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    Selenonium-Salze und Selenonium-ylide von Cyclopentadien, Pentafulvenen, Indol und Pyrrol (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 415-422 
    Details
    ISSN: 0170-2041
    Keywords: Selenonium salts of indole, pentafulvenes, and pyrrole ; Selenonium ylides of cyclopentadiene and pyrrole ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Selenonium Salts and Selenonium Ylides of Cyclopentadiene, Pentafulvenes, Indole, and PyrroleBy condensation of selenoxides with trimethylsilylcyclopentadiene (1) the selenoniocyclopentadienides 3 and 4 are formed. The reaction of selenoxides and trifluoroacetic anhydride with pentafulvenes gives rise to the mono- and diselenonium salts 8 and 6, with indole the 3-selenonium salt 10 is formed, and with pyrrole a mixture of the 2- and 3-selenonium salts 16 and 17 is obtained. The 2-isomers are quantitatively rearranged to the 3-isomers by trifluoroacetic acid. Deprotonation of 16 and 17 leads to the formation of the 2- and 3-selenoniopyrrolides 26 and 27, respectively.
    Notes: Selenoxide bilden mit Trimethylsilylcyclopentadien (1) die Selenoniocyclopentadienide 3 und 4. Selenoxide und Trifluoracetanhydrid reagieren mit Pentafulvenen zu den Mono- und Diselenonium-Salzen 8 und 6, mit Indol zu dem 3-Selenonium-Salz 10 und mit Pyrrol zu den 2- und 3-Selenonium-Salzen 16 und 17. Die 2-Isomere lagern mit Trifluoressigsäure quantitativ in die 3-Isomere um. Deprotonierung von 16 und 17 führt zu den 2-und 3-Selenoniopyrroliden 26 und 27.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890174
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  • 198
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    Stereoisomere Aromastoffe, XXXI Tetrahydro-2-methylthiophen-3-ol - Struktur und Eigenschaften der Stereoisomeren (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 859-862 
    Details
    ISSN: 0170-2041
    Keywords: Thiophen-3-ol, tetrahydro-2-methyl- ; Flavor substances, chiral ; Chirality and odor ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereoisomeric Flavor Substances XXXI1). - Tetrahydro-2-methylthiophen-3-ol - Structure and Properties of the StereoisomersTetrahydro-2-methylthiophen-3-ol (6) has been synthesized and separated by liquid chromatography to yield cis (6a/6a′) and trans isomers (6b/6b′). Using (S)-tetrahydro-5-oxo-2-furancarboxylic acid chloride, 6a/6a′ and 6b/6b′ are transformed into the diastereomeric esters 7-10 which are separated by liquid chromatography. Hydrolysis of the esters yields the optically pure stereoisomers 6a, 6a′, 6b, and 6b′. Absolute configuration and sensory characteristics of these stereoisomers are given.
    Notes: Tetrahydro-2-methylthiophen-3-ol (6) wurde synthetisiert und flüssigkeitschromatographisch in cis- (6a/6a′) und trans-Isomere (6b/6b′) getrennt. Durch Umsetzung mit (S)-Tetrahydro-5-oxo-2-furancarbonsäurechlorid werden aus 6a/6a′ und 6b/6b′ die diastereomeren Ester 7-10 gebildet, deren flüssigkeitschromatographische Trennung und anschließende Hydrolyse zu den optisch reinen Stereoisomeren 6a, 6a′, 6b und 6b′ führt. Absolute Konfiguration und sensorische Bewertung der Stereoisomeren werden mitgeteilt.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890237
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  • 199
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    Marine Bakterien, I. Synthese von Pentabrompseudilin, einem cytotoxischen Phenylpyrrol aus Alteromonas luteo-violaceus (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 863-881 
    Details
    ISSN: 0170-2041
    Keywords: Alteromonas luteo-violaceus ; Bromopyrrole ; Marine bacteria ; Pentabromopseudiline ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Marine Bacteria, I. - Synthesis of Pentabromopseudiline, a Cytotoxic Phenylpyrrole from Alteromonas luteo-violaceusA new synthesis of 2,3,4-tribromo-5-(3,5-dibromo-2-hydroxyphenyl)pyrrole (1a, pentabromopseudiline), an antibiotic, enzymeinhibitory and cytotoxic active constituent of the marine bacterium Alteromonas luteo-violaceus, is described. For investigation of structure-activity relationships further 2-phenylpyrroles are investigated. Key step in their synthesis is the Grignard reaction of 2-(1,3-dioxan-2-yl)ethylmagnesium bromide (9d) with benzoyl chlorides yielding γ-phenyl-γ-ketoaldehydes 24, and the Paal-Knorr cyclisation of the latter.
    Notes: Eine neue Synthese für 2,3,4-Tribrom-5-(3,5-dibrom-2-hydroxyphenyl)pyrrol (1a, Pentabrompseudilin), einem antibakteriell, enzyminhibitorisch und cytotoxisch wirksamen Inhaltsstoff aus dem marinen Bakterium Alteromonas luteo-violaceus, wird beschrieben. Für die Untersuchung von Struktur-Wirkungs-Beziehungen werden zahlreiche weitere 2-Phenylpyrrole in einer Reaktionsfolge hergestellt, deren Schlüsselschritte die Grignard-Reaktion von 2-(1,3-Dioxan-2-yl)ethylmagnesiumbromid (9d) mit Benzoylchloriden zu γ-Phenyl-γ-ketoaldehyden 24 und deren Paal-Knorr-Cyclisierung sind.
    Additional Material: 11 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890238
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  • 200
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    Radical Additions in Aqueous Medium: Direct Synthesis of 5-Allyl-Substituted γ-Lactones from Allylic Bromides/Zinc and Methyl γ-Oxocarboxylates (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 891-893 
    Details
    ISSN: 0170-2041
    Keywords: γ-Lactones ; Radical additions ; Felkin-Anh model ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Radikaladditionen im wäßrigen Medium: Eine direkte Synthese von 5-allylsubstituierten γ-Lactonen aus Allylbromiden/Zink und γ-Oxo-carbonsäureesternNach einer von Luche publizierten Methode werden die 5-allyl-substituierten γ-Lactone 2a-2d in guten Ausbeuten aus den γ-Oxocarbonsäureestern 1a-1c und Allylbromiden/Zinkstaub im wäßrigen Medium hergestellt. Die Diastereoselektivität dieser Allylierungsreaktion wird mit der durch Lewis-Säure-induzierten Allyltrimethylsilan-Addition an chirale Aldehyde verglichen.
    Notes: Following a procedure published by Luche, 5-allyl-substituted γ-lactones 2a-2d are prepared in good yield from methyl γ-oxocarboxylates 1a-1c and allyl bromides/zinc dust in aqueous medium. The diastereoselectivity of this allylation reaction is compared to that of Lewis acid promoted additions of allyltrimethylsilane to chiral aldehydes.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890240
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