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Conformational Analysis of δ-Lactones by DFT Calculations: The Parent Compound and its Monomethyl and Selected Dimethyl Derivatives

Authors

  • Dipl.-Chem. Fabian Weber,

    Corresponding author
    1. Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg (Germany), Fax: (+49) 761-2036100
    • Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg (Germany), Fax: (+49) 761-2036100
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  • Prof. Dr. Reinhard Brückner

    Corresponding author
    1. Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg (Germany), Fax: (+49) 761-2036100
    • Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg (Germany), Fax: (+49) 761-2036100
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Abstract

The static and dynamic stereochemistry of unsubstituted δ-valerolactone, all monomethylated δ-lactones, and all nongeminally dimethylated δ-lactones was explored with the B3LYP functional and def2-TZVPP basis set. A search strategy was employed which allowed the entire conformational space of any (poly-)substituted δ-lactone to be scanned. It allowed the lowest threshold conformational interconversion pathways to be mapped. The latter can be visualized in appealingly intuitive yet unprecedented diagrams. They trace the energy versus a circular abscissa which describes the passage of the molecule through one complete conformation interchange. The respective plot is C2-symmetrical for the parent compound, which is achiral, and C1-symmetrical for all methylated δ-lactones, which are chiral.

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