Issue 1, 2016

Fluorine in fragrances: exploring the difluoromethylene (CF2) group as a conformational constraint in macrocyclic musk lactones

Abstract

The CF2 group is incorporated into specific positions within the lactone ring of the natural musk lactone, (12R)-(+)-12-methyl-13-tridecanolide, a constituent of Angelica root oil, Angelica archangelica L. The approach is taken as it was anticipated that CF2 groups would dictate corner locations in the macrocycle and limit the conformational space available to the lactone. Three fluorine containing lactones are prepared by organic synthesis. One (8) has CF2 groups located at the C-6 and C-9 positions, another (9) with CF2 groups at the C-5 and C-9 positions, and a third (10) with a CF2 group at C-8. Two of the fluorine containing lactones (8 and 10) were sufficiently crystalline to obtain X-ray crystal structures which revealed that the CF2 groups do adopt corner locations. All three lactones were subject to computational analysis at the B3LYP-D3/6-311+G** level to assess the relative energies of different conformers. In all cases, the global minima and most of the lowest energy minima have squared/rectangular geometries and located the CF2 groups at the corners. The lowest energy structures for 8 and 10 closely approximated the observed X-ray structures, suggesting good convergence of theory and experiment in determining relevant low energy conformations. All three compounds retained a pleasant odour suggesting the rings retained sufficient conformational flexibility to access relevant olfactory conformations.

Graphical abstract: Fluorine in fragrances: exploring the difluoromethylene (CF2) group as a conformational constraint in macrocyclic musk lactones

Supplementary files

Article information

Article type
Paper
Submitted
28 sen 2015
Accepted
04 noy 2015
First published
04 noy 2015
This article is Open Access
Creative Commons BY license

Org. Biomol. Chem., 2016,14, 211-219

Fluorine in fragrances: exploring the difluoromethylene (CF2) group as a conformational constraint in macrocyclic musk lactones

M. J. Corr, R. A. Cormanich, C. N. von Hahmann, M. Bühl, D. B. Cordes, A. M. Z. Slawin and D. O'Hagan, Org. Biomol. Chem., 2016, 14, 211 DOI: 10.1039/C5OB02023A

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