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  • 1
    Digitale Medien
    Digitale Medien
    A Correlation Analysis of C:N 13C Chemical Shifts. The Use of Substituted Benzaldehyde (2-Hydroxycyclohexyl)hydrazones as Probes (1994)
    s.l. : American Chemical Society
    The @journal of organic chemistry 59 (1994), S. 5895-5900 
    Details
    ISSN: 1520-6904
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/jo00099a016
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  • 2
    Digitale Medien
    Digitale Medien
    Phase Dependence of Conformational Motions in Solids. The tert-Butyl Rotation in (1R*,2S*,5R*)-5-tert-Butyl-2-hydroxycyclopentanecarboxylic Acid (1995)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 117 (1995), S. 2327-2335 
    Details
    ISSN: 1520-5126
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/ja00113a022
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  • 3
    Digitale Medien
    Digitale Medien
    Basic forms of supramolecular self-assembly organized by parallel and antiparallel hydrogen bonds in the racemic crystal structures of six disubstituted and trisubstituted cyclopentane derivatives (2001)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. 539-550 
    Details
    ISSN: 1600-5740
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Notizen: A selection of stereoisomeric 2-hydroxy-1-cyclopentanecarboxamides, a 4-tert-butyl derivative and three tert-butyl derivatives of the respective carboxylic acid were subjected to X-ray crystallography. The optically active molecules (I)–(VI) form racemic crystals. Each racemic structure is basically determined by two intermolecular hydrogen bonds of O—H...O=C—XH and O=C—X—H...OH types (X = O, NH). The partially similar patterns of close packing observed reflect five basic forms of supramolecular self-assembly. In the racemic crystals of chiral molecules, there are homo- and heterochiral chains of molecules formed by the principal (O—H...O=C) hydrogen bonds. These chains assemble either in a parallel or antiparallel mode. The parallel homochiral chains (hop) observed in structure (II), (1R*,2R*)-2-hydroxy-1-cyclopentanecarboxamide, demand the polar space group Pca21, while the parallel heterochiral chains (hep) are organized in antiparallel layers with space group P21/n in structure (VI), (1R*,2S*,5R*-5-tert-butyl-2-hydroxy-1-cyclopentanecarboxylic acid). Heterochiral chains in an antiparallel array (hea) are found in (I), (1R*,2S*)-2-hydroxy-1-cyclopentanecarboxamide, and (V) [(1R*,2S*4S*)-4-tert-butyl-2-hydroxy-1-cyclopentanecarboxylic acid, space group P21/c]. Structures (IV), (1R*,2S*,4R*)-4-tert-butyl-2-hydroxy-1-cyclopentanecarboxylic acid, and (III), (1R*,2R*,4S*)-4-tert-butyl-2-hydroxy-1-cyclopentanecarboxamide, reveal that homochiral chains in an antiparallel array (hoa; cross-linked by heterochiral dimers held together by the second hydrogen bonds) can be formed by either translation (space group P\bar 1) or a screw axis (space group P21/c). These alternatives are denoted hoa1 and hoa2. Similarly, within each pattern (hea, hep and hop) two slightly different alternatives can be expected. The partial similarities in the identified five patterns of hydrogen bonding are described by graph-set notations. Structures (I), (IV) and (V) can be characterized by a common supramolecular synthon, while the highest degree of similarity is shown by the isostructurality of (I) and (V).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1107/S0108768101006723
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  • 4
    Digitale Medien
    Digitale Medien
    Stereochemical studies, 73. Saturated heterocycles, 60 (1985)
    Springer
    Monatshefte für Chemie 116 (1985), S. 857-868 
    Details
    ISSN: 1434-4475
    Schlagwort(e): 1,1′-Carbonyldiimidazole ; Substituted 1,3-oxazine-2,4-diones with condensed skeleton ; IR ; 1H-NMR ; 3C-NMR
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung cis- undtrans-N-Alkyl-,N-Aralkyl- undN-Aryl-2,4-dioxo-, tri- und tetramethylen-perhydro-1,3-oxazine wurden aus 2-Carboxamido-1-cycloalkanolen und 1,1′-Carbonyldiimidazol dargestellt. Mit Hilfe der IR,1H- und13C-NMR Spektroskopie wurden die Struktur, diecis- odertrans-Annellierung der Ringe und die bevorzugte Konformation der flexiblencis-Isomeren im Vergleich zumcis-trans Isomerenpaar nachgewiesen. Ähnlich zu den früher untersuchten 1,3-Oxazine-2- und -4-onen ist hier ebenfalls das „O-endo“ Konformere bevorzugt; in diesem ist der Sauerstoffaxial angeordnet, und zwar unabhängig von der Zahl der alicyklischen Ringatome und dem flexibleren Oxazindionring.
    Notizen: Abstract N-Substituted-2-carboxamido-1-cycloalkanols were cyclized with 1,1′-carbonyldiimidazole to synthesizecis- andtrans-N-alkyl-,N-aralkyl- andN-aryl-2,4-dioxo tri- and tetramethyleneperhydro-1,3-oxazines. The structures of the compounds and theircis ortrans ring anellation were confirmed by IR,1H- and13C-NMR spectroscopy, and thecis andtrans pairs of isomers were compared to establish the predominant conformation of the flexiblecis isomers. It was found that—similarly to the 1,3-oxazin-2- and -4-ones studied earlier—the “O-endo” conformers are preferred, in which the 1-oxygen atom isaxial to the alicyclic ring; this is independent of the number of ring atoms in the alicycle, and of the presence of an oxazinedione ring, even though this is more flexible that the ring of oxazinones.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00809162
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  • 5
    Digitale Medien
    Digitale Medien
    Stereochemical studies 98. Saturated heterocycles 100. Synthesis of stereoisomeric 2-ethylimino-3,1-perhydrobenzoxazines and benzothiazines (1987)
    Springer
    Monatshefte für Chemie 118 (1987), S. 503-509 
    Details
    ISSN: 1434-4475
    Schlagwort(e): 3,1-Perhydrobenzoxazines ; 3,1-Perhydrobenzothiazines ; Conformational analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Aus den stereoisomerencis- undtrans-2-Hydroxymethyl-1-cyclohexylaminen und ihrenN-Methyl- undN-Benzylderivaten (4 a–c,5 a–c) wurden mit Ethylisothiocyanat die entsprechenden Thiocarbamate (6 a–c,7 a–c) erhalten. Behandlung der Verbindungen6 und7 mit Methyljodid und anschließend Alkali ergab die 3,1-Perhydrobenzoxazine8 a–c,9 a–c, während mit HCl die Cyclisierung zu den 3,1-Perhydrobenzothiazinen10 a–c,11 a–c eintrat. Es wurde festgestellt, daß die bevorzugte Konformation derN-unsubstituiertencis-Isomeren8 a und10 a die „N-innen“-Form ist, während die derN-substituierten Derivate8 b,c und10 b,c bevorzugt in der „N-außen“-Form vorliegen.
    Notizen: Abstract With ethyl isothiocyanate, the stereoisomericcis- andtrans-2-hydroxymethyl-1-cyclohexylamines and theirN-methyl andN-benzyl derivatives (4 a–c,5 a–c) furnished the corresponding thiocarbamates (6 a–c,7 a–c). Treatment of compounds6 and7 with methyl iodide and subsequent alkali treatment afforded 3,1-perhydrobenzoxazines8 a–c,9 a–c, while cyclization of compounds6 and7 to the 3,1-perhydrobenzothiazines10 a–c,11 a–c was performed with HCl. It was found that the predominant conformation of theN-unsubstitutedcis isomers8 a and10 a is theN-inside form, while theN-substituted derivatives8 b,c and10 b,c have theN-outside preferred conformation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00809932
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  • 6
    Digitale Medien
    Digitale Medien
    Synthesis and Stereochemistry of Stereoisomeric 1,3-Oxazino- and 1,3-Thiazino[4,3-a]isoquinolines (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 803-809 
    Details
    ISSN: 0009-2940
    Schlagwort(e): 1,3-Oxazino[4,3-a]isoquinolien / 1,3-Thiazino [4,3-a]isoquinoline / Conformational analysis ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Starting from the 6,7-dialkoxy-1-[bis(hydroxymethyl)methyl]-1,2,3,4-tetrahydroisoquinolines 2 and 3, the 4-imino-substituted 1-(hydroxymethyl)-9,10-dialkoxy-2H, 4H-1,6,11b-tetrahydro-1.3-oxazino-and -thiazino [4,3-a]isoquinoline diastereomers 6a-c, 7a-c, 8a-c, 9a-c, 14, and 15 and the 4-substituted 1,6,7,11b-tetrahydro 1,3-oxazino[4,3-a]isoquinoline diastereomers 16-24 were prepared. the relative configurations and the predominant conformation of these products were determined by NMR spectroscopy and for 18 by X-ray diffraction methods. the prepared 1,3-oxazino[4,3-a]isoquinoline diastereomers have predominantly trans conformations (16, 18, 22, 23), whereas cis conformations (cis-A) prevail for 20, 21 and f24. Thus, the first evidence for either trans- or cis-A conformations in 1,3-oxazino[4,3-a] isoquinolines is presented.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19901230427
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  • 7
    Digitale Medien
    Digitale Medien
    Stereochemical Studies, 106. - Saturated Heterocycles, 110 Synthesis of Methylene-bridged Partially Saturated Quinazolones (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 259-264 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Aus den Estern (5-8) der di-endo (1 und 2) und di-exo (3 und 4) Norbornan- und Norbornen-ß-aminosäuren wurden mit Imidaten die Methylen-überbrückten Tetrahydro- (18 und 20) und Hexahydro-4-chinazolinone (17 und 19) sowie aus den entsprechenden Aminosäureamiden (9-12) mit 4-Chlorbenzaldehyd die Hexahydro- (14 und 16) und Octahydro-4-chinazolinone (13 und 15) gewonnen. Die Tetrahydro-Verbindungen 18a, b konnten zu Hexahydro- (17a, b) oder Octahydro-Derivaten (13b) reduziert werden. Die Reaktion mit Aldehyd ist stereospezifisch, wobei sich nur die 2- und 8a-Wasserstoffatome in identischen Stereopositionen enthaltenden Isomere bilden. Die im carbocyclischen Ring eine Doppelbindung enthaltenden 4-Chinazolone zersetzen sich beim Kochen in Lösung oder beim Schmelzen, wobei sich Cyclo-pentadien abspaltet und substituierte 4(3H)-Pyrimidinon-Derivate bilden.
    Notizen: With imidates, esters (5-8) of di-endo (1 and 2) and di-exo (3 and 4) norbornane- and norbornene-ß-amino acids yield methylene-bridged tetrahydro- (18 and 20) and hexahydro-4-quinazolinones (17 and 19); the reaction of the corresponding carboxamides (9-12) with 4-chlorobenzaldehyde furnish hexahydro- (14 and 16) and octahydro-4-quinazolinones (13 and 15). The tetrahydro derivatives 18a, b can be selectively reduced to the hexahydro (17a, b) or octahydro (13b) compounds. The reaction with aldehyde is stereospecific; only the isomers containing the 2-H and 8a-H atoms in identical steric positions are formed. When boiled in a solvent or heated to melting, the 4-quinazolines having a double bond in the carbobicycle split off cyclopentadiene with formation of the 2-substituted 4(3H)-pyrimidinones (21).
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19871200302
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  • 8
    Digitale Medien
    Digitale Medien
    Saturated Heterocycles, 252Part 251: F. Fülöp, E. Forró, G. Bernáth, I. Miskolczi, A. Martinsen, P. Vainiotalo, J. Heterocycl. Chem., paper accepted.. Synthesis and Stereochemistry of Stereoisomeric 6-Methyl-Substituted Pyrimido[6,1-a]Isoquinolines (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 1165-1171 
    Details
    ISSN: 0947-3440
    Schlagwort(e): Pyrimido[6,1-a]isoquinolin-2-ones ; Fused-skeleton pyrimidinones ; Conformational analysis by NMR ; MM2 calculations ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Stereoisomeric (1R*,3R*)- and (1R*,3S*)-6,7-dimethoxy-3-methyl-1,2,3,4-tetrahydroisoquinoline-1-acetamides 5-8 react with formaldehyde or benzaldehyde to furnish stereoisomeric pyrimido[6,1-a]isoquinolin-2-ones 9-18. The relative configurations and the predominant conformations of the products have been determined by NMR spectroscopy, and for (4S*,6R*,11bR*)-9,10-dimethoxy-6-methyl-4-phenyl-1,3,4,6,7,11b-hexahydropyrimido[6,1a]isoquinolin-2-one (11) by X-ray diffraction.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jlac.199719970618
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  • 9
    Digitale Medien
    Digitale Medien
    Correlation analysis of the 13C chemical shifts of substituted benzaldehyde 2-aminobenzoylhydrazones. Study of the propagation of substituent effects along a heteroatomic chain (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 55-66 
    Details
    ISSN: 0894-3230
    Schlagwort(e): Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The 13C chemical shifts of eight series of para- or meta-substituted benzaldehyde 2-aminobenzoylhydrazones possessing both amide and imine functionalities were measured. The 13C chemical shifts were used to study the transmission of electronic substituent effects along the heteroaromatic side-chain of the substituted aromatic ring. In addition to the C=N bond, the benzoylhydrazones possess in their side-chain polarizable C=O and phenyl π-units. The benzylidenic ring-substituent chemical shifts were analysed by the dual substituent parameter approach to separate the inductive and resonance effects. The negative ρI and ρR values observed (i.e. reverse substituent effects) indicate a significant π-polarization of the C=N bond. The highly negative ρR values, especially those in the case of meta substitution, suggest a contribution from a marked secondary field-transmitted resonance effect. The results are compared with those obtained for other hydrazones or imines. Variation of the electron-withdrawing ability of the N2 substituent is seen to have a systematic effect on the ρI values. Reverse substituent effects are also observed at the C-1″ site of the 2-aminobenzoyl ring while C-4″ shifts show normal behaviour, consistent with the general concept of the π-polarization that each π-unit of the side-chain is polarized largely as a localized system. Accordingly, the π-polarization effect is seen efficiently to propagate also along a heteroaromatic chain. On the other hand, the C=O sites exhibit normal, although fairly slight, dependence on the benzylidenic substituent indicating an insignificant role of π-polarization at that site. The effects of the solvent, CDCl3 vs. DMSO-d6, on the ρI and ρR values are also considered. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Electron ionization mass spectra of some cyclohexane fused 2-N-phenyliminoperhydro-1,3-oxazines and related thiazines (1990)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 4 (1990), S. 279-282 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The 70 eV electron ionization mass spectra of six cyclohexane fused 2-N-phenyliminoperhydro-1,3-oxazines and six related thiazines were recorded and their fragmentation patterns were studied by metastable-ion analysis and exact mass measurement. All the compounds examined lost a hydrogen atom from their molecular ion in a process best described as intramolecular cyclization. The most typical fragmentations were the loss of various alkyl radicals from the M+· or [M—H]+ ions with the simultaneous migration of one or more hydrogen atoms from the carbocyclic part to the heterocyclic part of the molecule. N-Substitution clearly affected the type and extent of different reactions. In general, the fragmentation patterns of the thiazine derivatives were more complicated than those of the related oxazines. In all cases studied, the cis- and trans-fused isomers gave rise to so similar spectra that their adequate differentiation was not possible.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290040804
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