Konformationsanalyse des Ulcustherapeuticums Pirenzepin durch R?ntgenstrukturanalysen, empirische und semiempirische Rechnungen

Ohne Zusammenfassung

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Conformational analysis of the anti-ulcer drug pirenzepine by means of X-ray analyses and empirical and semiempirical calculations

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Ausführlich publiziert in [1]     

Konformationsanalyse von Ringverbindungen

Ohne Zusammenfassung

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Conformation analysis of cyclic compounds

     

Konformationsanalyse von Gallenfarbstoffen mit Hilfe von Kraftfeldrechnungen

A force field constructed for bile pigments and parametrized on partial structures of bile pigments was used to calculate the minimum energy geometries of diastereomeric bilatrienes-abc. In addition the relative energies of these isomers were deduced and the energies of interconversion between the mirror images of the more or less helical (Z,Z,Z)-syn, syn, syn-form were calculated for various paths.

     

Zur Anwendbarkeit von Ringstrommodellen in der Konformationsanalyse

The classical (Johnson-Bovey) and quantum mechanical (Haigh-Mallion) approach accounting for the shielding contribution to protons in the proximity of aromatic nuclei are compared with respect to their applicability in conformational analysis. This is accomplished by means of the¹H-NMR spectra of various cyclophanes their geometries being fairly well known from X-ray data or other independent methods. The chemical shifts of the monitor protons (all of them being situated above or below the plane of the benzene ring considered) are consistent with shielding effects predicted by the classical theory notwithstanding the fact that the benzene hexagons are not strictly planar in any of these systems. In contrast, the quantum mechanical treatment considerably underestimates the shielding of protons in those regions.

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Mit 2 Abbildungen     

Konformationsanalyse der Stereoisomeren von Triphenylheptan mittels depolarisierter Rayleigh-Streuung

Ohne Zusammenfassung     

Beiträge zur Konformationsanalyse der Aryl—Methoxy-Bindung

The lanthanide induced shifts of a series of methoxy-indanones and-indanols were recorded and interpreted in terms of hindered rotation about the aryl—methoxy bond. A planar conformation was found in all cases, the populations of the two planar positions being determined by the substituentortho to the methoxyl group. Some of the compounds are very suitable forNOE experiments; these measurements supported theLIS results. Moreover a semiempirical quantum-mechanical method [MINDO/3] was used to calculate the relative stabilities of the romaters of anisole; again the planar conformation is predicted to be the most stable one.

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Mit 5 Abbildungen

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Auszugsweise vorgetragen beim Österreichisch-Deutschen Chemikertreffen vom 26. bis 29. April 1976 in Salzburg, Österreich.