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  • 1
    Electronic Resource
    Electronic Resource
    Rearrangement of N-substituted porphyrins. Preparation and structure of homoporphyrins (1975)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 97 (1975), S. 6175-6178 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00854a038
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  • 2
    Electronic Resource
    Electronic Resource
    Acid catalyzed isomerization and thermal rearrangement of nickel homoporphyrins (1975)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 97 (1975), S. 6178-6180 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00854a039
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  • 3
    Electronic Resource
    Electronic Resource
    Catalytic One-Pot Osmylation of Cyclohexadienes: Stereochemical and conformational studies of the resulting polyols (1992)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 75 (1992), S. 1052-1060 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Catalytic double osmylation is described for a series of cyclohexadienes in acetone/H2O in the presence of the co-oxidant N-methylmorpholine N-oxide (NMO). The formation of polyols occurred stereospecifically with cyclohexadienes 3,7, and 11a, leading thereby to tetrols 5a, and 9a and to allo-inositol (14a), respectively. To the contrary, trans-cyclohexadiene-diol 15a gave a mixture of the stereoisomeric inositols 18a (epi), 19a (neo), and 20a (chiro). High-field NMR let to clearcut conformational analyses of the polyhydroxylated derivatives.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19920750408
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  • 4
    Electronic Resource
    Electronic Resource
    Stereospecific Synthesis of 2-Oxazinyl-4-oxoazetidinecarbamates Starting from a 1,2-Diazepine. A new type of intramolecular transbenzoylationDedicated to Professor Edward C. Taylor at the occasion of his 65th anniversary. (1988)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 71 (1988), S. 822-834 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Azeitidinodiazepines 4b and 4c react with acylnitroso dienophiles 5a-c, specifically from their convexe α-side, but in a non-regiospecific way, leading thereby stereospecifically to the expected adducts 6a-d and 7a-d. The three-dimensional structures of 6a and 7a were determined by X-ray analyses which corroborated their NMR data. OsO4 cis-glycolization occurred in good yield with the inverse adducts 7a and 7e and led to the rearranged products 10. These latter ones result from an intramolecular N- to O-transbenzoylation of the short-lived intermediates 9 followed by fragmentation of the animal function. X-Ray analysis of 7a showed the N(10) atom to be pyramidal, a result which demonstrates that it does not have any pronounced benzamide character; otherwise no such N- to O-transbenzoylation would have taken place. Structure and relative configuration of 10a were ascertained by X-ray analysis which confirmed its NMR data as well as the stereochemical outcome of its formation.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19880710418
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  • 5
    Electronic Resource
    Electronic Resource
    A Torquospecific 1,5-Electrocyclization (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 2087-2097 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Saponification of homodiazepine 1a and 1b, in the absence of any proton donors, led to the formation of the 6π electron anionic species A which, by virtue of a 1,5-electrocyclization, is in equilibrium with the allylic anion B. This latter tricyclic species is thermodynamically less favoured than its bicyclic isomer A. Nevertheless, B could be trapped by acylation and led tupe-2 compounds which are the major reaction products. This is due to the fact that B is more nucleophilic and, therefore, much more reactive than A. The transoid topology of the tricyclic products 2 was demonstrated by 1H-NMR and by an X-ray diagram of 2d. The transoid geometry of 2 is a consequence of a torquospecific 1,5-electrocyclization (of A), which is due to a steric, and possibly even to an electronic factor.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700814
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  • 6
    Electronic Resource
    Electronic Resource
    Chelate-Controlled Asymmetric Synthesis of 2-Substituted 2,3-Dihydropyridin-4(1H)-ones: Synthesis of D- and L-aminodeoxyaltrose derivatives (1995)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 78 (1995), S. 61-72 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Asymmetric methylation and phenylation of the chiral pyridinium salt 7, as well as methylation of chiral pyridinium salt 18, with Grignard reagents occurred in good yield and with good-to-excellent diastereoselectivities (Schemes 2 and 3, resp.). These results are best explained by assuming chelate control to govern the asymmetric alkylation/arylation process. The minimum-energy conformations of the out-of-plane twisted pyridinium salts 7 and 18, as determined by the ‘Molecular Simulations Cerius-Dreiding II’ program, are in good agreement with the postulated asymmetric chelate-control mechanism.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19950780106
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  • 7
    Electronic Resource
    Electronic Resource
    On the Way to Glycoprocessing Inhibitors. Synthesis of an imidazo-L-xylo-piperidinose derivative (1995)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 78 (1995), S. 1837-1842 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An eight-step synthetic sequence led from the known D-xylo-pentodialdose 8 to imidazo-L-xylo-piperidinose 15, the key steps being the build-up of imidazole compound 12 by a van Leusen methodology and the intramolecular SN2 ring closure of the O-triflated benzylidene derivative 13. xylo-Piperidinose 15 appears in a half-chair conformation like the oxocarbonium ions which are the postulated intermediates in the glycoprocessing of the pyranose polysaccharides. This bicyclic azasugar should be a glycosidase inhibitor.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19950780717
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  • 8
    Electronic Resource
    Electronic Resource
    Methylketen: Herstellung durch Pyrolyse von Butanon und Reaktion mit Iminen unter Bildung von methylierten Azetidinonen (1983)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1393-1408 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Methylketene: Synthesis by Pyrolysis of Butanone and Reaction with Imines Yielding Methylated AzetidinonesDuring the pyrolysis of acetone with a ketene lamp trace amounts of butanone and methylketene are produced. These compounds result from break-off reactions of radical reaction chains of acetone. Pyrolysis of butanone leads to a mixture of ketene (70%) and methylketene (30%). The latter reacts with imines to give methylated β-lactams. The rate of these cycloaddition reactions is several powers of ten greater than the one observed with ketene. The 8-methyl-5-azanonamdienes 7, 10, 26, and 31 are obtained in good yields when the corresponding diazepines are reacted with the pyrolysis gas of butanone. Similar experimental conditions lead to the methylated azetidinones 13, 15, 16, and 18 in moderate yields whereas the known thiazolines 19, 20, and 21 do not react at all. The action of 26 and 30 against several pathogenic bacterial strains was tested; however, no antibacterial properties could be detected.
    Notes: Die Bildung sehr kleiner Mengen von Butanon und Methylketen während der Pyrolyse von Aceton mit einer Ketenlampe wird als Ergebnis einer radikalischen Kettenreaktion nachgewiesen. Die Pyrolyse von Butanon unter den gleichen Bedingungen führt zu einem Gemisch von Keten (70%) und Methylketen (30%). Letzteres reagiert mit Iminoderivaten um einige Zehnerpotenzen schneller als Keten selbst, wobei methylierte β-Lactame entstehen. Auf diese Weise werden in guten Ausbeuten die trans-8-Methyl-5-aza-1,3-nonamdienderivate 7, 10, 26, 29 und 31 sowie in mäßigen Ausbeuten die monocyclischen methylierten Azetidinone 13, 15, 16 und 18 erhalten. Die bekannten Thiazolinderivate 19, 20 und 21 reagieren jedoch nicht mit dem pyrolytisch erzeugten Methylketen. Das 5-Azanonamdien-5-carboxamid 26 sowie die 5-Azanonamdien-1-carbonsäure 30 zeigen kein antibiotisches Verhalten gegenüber verschiedenen pathogenen Bakterienstämmen.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198319830811
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  • 9
    Electronic Resource
    Electronic Resource
    Zur Synthese von 8-Amino-5-aza-1,3-nonamdienderivaten (1983)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1374-1392 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Synthesis of 8-Amino-5-aza-1,3-nonamdiene DerivativesStarting from glycine derivatives and the diazepines 1, 8-succinimido-5-aza-1,3-nonamdienes 5 and 8-phthalimido-5-aza-1,3-nonamidienes 8 are synthesized stereospecifically in trans configuration. Cleavage of the side-chain leads in particular to the unstable 8-amino-5-aza-1,3-nonamdiene derivative 11b which, after N-acylation, yields the crystalline N-acylamino-β-lactams 12-15. The nicotinic acid derivatives 17 and 26 provide after several steps, the last one being a photo-induced ring expansion, the diazepine pairs 19/20 and 27/28. These diazepines react with ketene derivatives to give stereospecifically by cycloaddition the trans β-lactams 21/23 and 29/30. Cleavage of the CH2CH2-SiMe3 protective groups of the adducts 21 and 23 using tetra-n-butylammonium fluoride causes unexpectedly cleavage of the benzoyl group and migration of the double bond yielding the enimines 24 and 25
    Notes: Ausgehend von Glycinderivaten und den Diazepinen 1 werden die 8-Succinimido-5-aza-1,3-nonamdiene 5 und die 8-Phthalimido-5-aza-1,3-nonamdiene 8 stereospezifisch mit trans-Konfiguration hergestellt. Durch Abbau der Seitenkette gelangt man speziell zu dem instabilen trans-8-Amino-5-aza-1,3-nonamdienderivat 11b, das durch N-Acylierung die kristallinen N-Acylamino-β-lactame 12-15 liefert. Aus Nicotinsäurederivaten 17 und 26 werden die Diazepinpaare 19/20 und 27/28 als Gemische in einem photochemischen Prozeß hergestellt. Diese Diazepine ergeben durch Cycloadditionsreaktionen mit Ketenderivaten auf stereospezifische Weise die trans-β-Lactame 21/23 und 29/30. Bei der Abspaltung der CH2CH2-SiMe3-Schutzgruppe aus den Addukten 21 und 23 mit Tetra-n-butylammonium-fluorid tritt unerwartet Abspaltung der Benzoylgruppe auf, wobei unter Doppelbindungswanderung die Enimine 24 und 25 enstehen.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198319830810
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  • 10
    Electronic Resource
    Electronic Resource
    1H-1,2-Diazepine als Edukte zur Synthese von 5-Aza-1,3-nonamdienen, eine neue Klasse von bicyclischen β-Lactamen (1983)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1361-1373 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 5-Aza-1,3-nonamdienes, a New Class of Bicyclic β-Lactams, Prepared from 1H-1,2-Diazepines5-Aza-1,3-nonamdiene derivatives 8, 9, and 11-16 are obtained by nonconcerted [2 + 2] cycloaddition reactions of 1H-1,2-diazepines with ketenes. These azetidinodiazepines represent a new class of bicyclic β-lactams which resemble structurally somewhat the cephalosporin antibiotics. Nevertheless, since they lack an acidic function in α position to the bridgehead nitrogen atom, they were not expected to show any antibiotic activity. When monosubstituted ketenes are used in cycloaddition reactions with 1,2-diazepines, trans-azetidinodiazepines are obtained in a stereospecific way. The 5-aza-1,3-nonamdiene derivatives 21 and 22 are obtained in two steps from 1H-1,2-diazepines 2a and 2b and the ketene iminium salt 18.
    Notes: Die 5-Aza-1,3-nonamdienderivate 8, 9 und 11-16 werden durch nichtkonzertierte [2 + 2]-Cycloaddition von 1H-1,2-Diazepinen an Ketene hergestellt. Sie bilden eine neue Klasse von bicyclischen β-Lactamen die strukturell den Cephalosporinantibiotika etwas ähneln. Diese Addukte besitzen jedoch keine saure Gruppe in α-Stellung zum Brückenkopfstickstoffatom; auch war keine bakteriostatische Wirkung zu erwarten. Ausgehend von monosubstituierten Ketenen und 1,2-Diazepinen werden stereospezifisch die trans-β-Lactame erhalten. Die Azetidinodiazepine 21 und 22 werden in zwei Stufen durch Cycloaddition der 1H-1,2-Diazepine 2a und 2b mit dem Keteniminiumsalz 18 hergestellt.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198319830809
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