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Neier, Reinhard

Nom
Neier, Reinhard
Affiliation principale
Fonction
Professeure ordinaire
Email
Reinhard.Neier@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/383
_
0000-0003-0890-1797

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  • Publication
    Accès libre
    1-Methoxycarbonyl-substituiertes 2,3-Dihydropyridin-4(1H)-on (= Methyl-1,2,3,4-tetrahydro-4-oxopyridin-1-carboxylat) als Chromophor für die photochemische [2 + 2]-Cycloaddition
    (1991)
    Guerry, Philippe
    ;
    Blanco, Philippe
    ;
    Brodbeck, Heinz
    ;
    Pasteris, Olivier
    ;
    Neier, Reinhard 
    With olefins having an electron-acceptor as well as with olefins having an electron-donor substituent, 1-methoxycarbonyl-substituted dihydropyridinone 12 undergoes [2 + 2] cycloaddition in good preparative yields. The photochemical cycloaddition is highly regioselective. For preparative purposes, the ring junction can be equilibrated to the thermodynamically more stable cis-junction. Only the ’endo’/’exo’ selectivity at the C-atom bearing the olefin substituent cannot be controlled. The photodimerization of 12 is the only side reaction. Using a slight excess of the olefin, the photodimerization can be suppressed. The protecting group at the N-atom of the dihydropyridinone can be varied in order to introduce an internal sensitizer, as shown with 1-acyl-substituted compound 29, which underwent the cycloaddition process even with sunlight.
  • Publication
    Accès libre
    Photophysics and photochemistry of 4-Dihydropyridinones
    (1990)
    Aeby D.
    ;
    Eichenberger, Eugen
    ;
    Haselbach, E.
    ;
    Suppan, P.
    ;
    Guerry, Philippe
    ;
    Neier, Reinhard 
    Dihydropyridinones (DHP) react photochemically with olefins to form cycloaddition products. The reactions proceed through the lowest excited state T, of the DHPs, with rate constants which depend on the olefin and can approach the diffusional limit in the most favourable cases. Intra- and inter-molecular sensitization and quenching have been investigated, as well as spectroscopic properties such as absorption and luminescence spectra, and in particular electron energy loss spectra which have established the energy of the reactive T, state as 295 kJ mol"' (3.07 eV).
  • Publication
    Accès libre
    The photochemical[2 + 2]cycloaddition to N-methoxycarbonyl-5,6-dihydro-4-pyridone
    (1989)
    Guerry, Philippe
    ;
    Neier, Reinhard 
    The N-methoxycarbonyl-5,6-dihydro-4-pyridone (1) undergoes photochemical [2 + 2] cycloaddition with a series of differently substituted alkenes in high yield and with extremely high regioselectivity.
  • Publication
    Accès libre
    Photochemical Cycloadditions to 5,6-Dihydro-4-pyridones
    (1987)
    Guerry, Philippe
    ;
    Neier, Reinhard 
    5,6-Dihydro-4-pyridones (3a-3c) undergo photochemical [2 + 2]-cycloaddition with olefins activated by an electron withdrawing group. Alkyi substituted double bonds could only be brought to react in the intramolecular cases 3d and 3e.
  • Publication
    Accès libre
    Reduktion von 4-Pyridionen
    (1984)
    Guerry, Philippe
    ;
    Neier, Reinhard