ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1374-1392 
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 2141-2150 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Fragmentation Reactions of N-Acyldienamines Giving Conjugated EniminesAzetidinodiazepines 1 and 2, when heated up to 200°C, lead to the enimines 5 and 6, respectively. The mechanism of this fragmentation was elucidated via thermolysis of the educts 8 and 10. The first one gives the enimine 5 and N-methylurethane 9 when heated in methanol. The second one gives the doubly-deuterated enimine 13, a result which shows that the N-deuteriodienamine 11 is a short-lived intermediate leading, via a many-stage prototropy, to the final enimine. Benzoylazetidinodiazepines 16 and 18, when heated in trifluoroacetic acid, lead in a similar way to the corresponding enimines 17 and 19, respectively, as well as to benzoic acid. Ammonolysis of the azetidinodiazepines 21 and 23 leads not only to the cleavage of the carbamoyl group but also to ring-opening of the β-lactam ring with formation of the dihydrodiazepines 22 and 24. Similarly, ammonolysis of the monocyclic educt 28 gives the enimine 29.
    Notes: Werden die Azetidinodiazepine 1 und 2 auf 200°C erhitzt, so erhält man die Enimine 5 und 6. Der Mechanismus dieser Fragmentierung wurde anhand der Thermolyse der Edukte 8 und 10 ermittelt. Im ersten Fall erhält man, in Gegenwart von Methanol, das Enimin 5 sowie N-Methylurethan 9. Im zweiten Fall gelangt man zu dem teilweise doppelt deuterierten Enimin 13, wobei vermutlich das N-deuterierte Dienamin 11 als Zwischenprodukt in einer mehrstufigen Prototropie durchlaufen wird. Durch Erhitzen in Trifluoressigsäure werden die Benzoylazetidinodiazepine 16 und 18 zu Benzoesäure und den Eniminen 17 und 19 gespalten. Die Ammonolyse der Azetidinodiazepine 21 und 23 führt nicht nur zur Abspaltung der Carbamoylgruppe, sondern auch zur Öffnung des β-Lactamrings, wobei die Dihydrodiazepine 22 und 24 erhalten werden. Das monocyclische Edukt 28 ergibt durch Ammonolyse das Enimin 29.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1434-193X
    Keywords: Carbohydrates ; Amino sugars ; Imidazole ; Glycosidases ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Some naturally occurring carbohydrates, of which several hydroxy groups had been selectively protected, were condensed with formamidine to give the expected imidazole derivatives in the D-arabino (9), D-lyxo (12), L-xylo (17), D-threo (21), and in the L- and D-erythro (24) series. Introduction of a strong leaving group at the remaining free alcohol function of these products led at once to intramolecular SN2 cyclisation to the corresponding bicyclic aza sugar derivatives. This was followed by total deprotection to give the target aza sugars in the L-xylo (7), L-ribo (14), D-arabino (19), as well as in the D-threo (22) and the L- and D-erythro (26) series. Inhibitory assays with four glycosidases showed that the D-arabino aza sugar 19 is the only potent inhibitor (for an α-mannosidase of jack bean).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 1359-1361 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: UV irradiation of the bicyclic enimine 1 led stereospecifically to the anti-tricyclic isomer 2 which reverted back to 1, either by thermal activation or by acid catalysis at room temperature. Catalytic hydrogenation of 2 gave compound 4 whose configuration was fully ascertained by high-field 1H-NMR measurements.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...